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ZooKeys 271: 1–401, doi: 10.3897/zookeys.271.4062
A systematic revision of Operclipygus Marseul (Coleoptera, Histeridae, Exosternini)
Michael S. Caterino 1,†, Alexey K. Tishechkin 1,‡
1 Department of Invertebrate Zoology, Santa Barbara Museum of Natural History, 2559 Puesta del Sol, Santa Barbara, CA 93105 USA

Corresponding author: Michael S. Caterino (

Academic editor: M. Fikácek

received 28 September 2012 | accepted 16 January 2013 | Published 20 February 2013

(C) 2013 Michael S. Caterino. This is an open access article distributed under the terms of the Creative Commons Attribution License 3.0 (CC-BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

For reference, use of the paginated PDF or printed version of this article is recommended.


We revise the large Neotropical genus Operclipygus Marseul, in the histerid tribe Exosternini (Histeridae: Histerinae). We synonymize 3 species, move 14 species from other genera, sink the genus Tribalister Horn into Operclipygus, and describe 138 species as new, bringing the total to 177 species of Operclipygus. Keys are provided for the identification of all species, and the majority of the species are illustrated by habitus and male genitalia illustrations. The species are diverse throughout tropical South and Central America, with only a few species extending into the temperate parts of North America. The majority of species can be recognized by the presence of a distinct stria or sulcus along the apical margin of the pygidium, though it is not exclusive to the genus. Natural history details for species of Operclipygus are scant, as most specimens have been collected through the use of passive flight interception traps. Many are probably generally associated with decaying vegetation and leaf litter, where they prey on small arthropods. But a small proportion are known inquilines, with social insects such as ants and termites, and also with some burrowing mammals, such as Ctenomys Blainville. The genus now includes the following species groups and species: Operclipygus sulcistrius group [Operclipygus lucanoides sp. n., Operclipygus schmidti sp. n., Operclipygus simplistrius sp. n., Operclipygus sulcistrius Marseul, 1870], Operclipygus mirabilis group [Operclipygus mirabilis (Wenzel & Dybas, 1941) comb. n., Operclipygus pustulifer sp. n., Operclipygus plaumanni sp. n., Operclipygus sinuatus sp. n., Operclipygus mutuca sp. n., Operclipygus carinistrius (Lewis, 1908) comb. n., Operclipygus parensis sp. n., Operclipygus schlingeri sp. n.], Operclipygus kerga group [Operclipygus kerga (Marseul, 1870), Operclipygus planifrons sp. n., Operclipygus punctistrius sp. n.], Operclipygus conquisitus group [Operclipygus bicolor sp. n., Operclipygus conquisitus (Lewis, 1902), Operclipygus friburgius (Marseul, 1864)], Operclipygus impuncticollis group [Operclipygus bickhardti sp. n., Operclipygus britannicus sp. n., Operclipygus impuncticollis (Hinton, 1935)], Operclipygus panamensis group [Operclipygus crenatus (Lewis, 1888), Operclipygus panamensis (Wenzel & Dybas, 1941)], Operclipygus sejunctus group [Operclipygus depressus (Hinton, 1935), Operclipygus itoupe sp. n., Operclipygus juninensis sp. n., Operclipygus pecki sp. n., Operclipygus punctiventer sp. n., Operclipygus sejunctus (Schmidt, 1896) comb. n., Operclipygus setiventris sp. n.], Operclipygus mortavis group [Operclipygus ecitonis sp. n., Operclipygus mortavis sp. n., Operclipygus paraguensis sp. n.], Operclipygus dytiscoides group [Operclipygus carinisternus sp. n., Operclipygus crenulatus sp. n., Operclipygus dytiscoides sp. n., Operclipygus quadratus sp. n.], Operclipygus dubitabilis group [Operclipygus dubitabilis (Marseul, 1889), Operclipygus yasuni sp. n.], Operclipygus angulifer group [Operclipygus angulifer sp. n., Operclipygus impressifrons sp. n.], Operclipygus dubius group [Operclipygus andinus sp. n., Operclipygus dubius (Lewis, 1888), Operclipygus extraneus sp. n., Operclipygus intermissus sp. n., Operclipygus lunulus sp. n., Operclipygus occultus sp. n., Operclipygus perplexus sp. n., Operclipygus remotus sp. n., Operclipygus validus sp. n., Operclipygus variabilis sp. n.], Operclipygus hospes group [Operclipygus assimilis sp. n., Operclipygus belemensis sp. n., Operclipygus bulbistoma sp. n., Operclipygus callifrons sp. n., Operclipygus colombicus sp. n., Operclipygus communis sp. n., Operclipygus confertus sp. n., Operclipygus confluens sp. n., Operclipygus curtistrius sp. n., Operclipygus diffluens sp. n., Operclipygus fusistrius sp. n., Operclipygus gratus sp. n., Operclipygus hospes (Lewis, 1902), Operclipygus ibiscus sp. n., Operclipygus ignifer sp. n., Operclipygus impositus sp. n., Operclipygus incisus sp. n., Operclipygus innocuus sp. n., Operclipygus inquilinus sp. n., Operclipygus minutus sp. n., Operclipygus novateutoniae sp. n., Operclipygus praecinctus sp. n., Operclipygus prominens sp. n., Operclipygus rileyi sp. n., Operclipygus subterraneus sp. n., Operclipygus tenuis sp. n., Operclipygus tiputinus sp. n.], Operclipygus farctus group [Operclipygus atlanticus sp. n., Operclipygus bidessois (Marseul, 1889), Operclipygus distinctus (Hinton, 1935), Operclipygus distractus (Schmidt, 1896) comb. n., Operclipygus farctissimus sp. n., Operclipygus farctus (Marseul, 1864), Operclipygus gilli sp. n., Operclipygus impressistrius sp. n., Operclipygus inflatus sp. n., Operclipygus latemarginatus (Bickhardt, 1920) comb. n., Operclipygus petrovi sp. n., Operclipygus plicatus (Hinton, 1935) comb. n., Operclipygus prolixus sp. n., Operclipygus punctifrons sp. n., Operclipygus proximus sp. n., Operclipygus subrufus sp. n.], Operclipygus hirsutipes group [Operclipygus guianensis sp. n., Operclipygus hirsutipes sp. n.], Operclipygus hamistrius group [Operclipygus arquus sp. n., Operclipygus campbelli sp. n., Operclipygus chiapensis sp. n., Operclipygus dybasi sp. n., Operclipygus geometricus (Casey, 1893) comb. n., Operclipygus hamistrius (Schmidt, 1893) comb. n., Operclipygus impressicollis sp. n., Operclipygus intersectus sp. n., Operclipygus montanus sp. n., Operclipygus nubosus sp. n., Operclipygus pichinchensis sp. n., Operclipygus propinquus sp. n., Operclipygus quinquestriatus sp. n., Operclipygus rubidus (Hinton, 1935) comb. n., Operclipygus rufescens sp. n., Operclipygus troglodytes sp. n.], Operclipygus plicicollis group [Operclipygus cephalicus sp. n., Operclipygus longidens sp. n., Operclipygus plicicollis (Schmidt, 1893)], Operclipygus fossipygus group [Operclipygus disconnectus sp. n., Operclipygus fossipygus (Wenzel, 1944), Operclipygus foveipygus (Bickhardt, 1918), Operclipygus fungicolus (Wenzel & Dybas, 1941), Operclipygus gibbulus (Schmidt, 1889) comb. n., Operclipygus olivensis sp. n., Operclipygus simplicipygus sp. n., Operclipygus subdepressus (Schmidt, 1889), Operclipygus therondi (Wenzel, 1976)], Operclipygus impunctipennis group [Operclipygus chamelensis sp. n., Operclipygus foveiventris sp. n., Operclipygus granulipectus sp. n., Operclipygus impunctipennis (Hinton, 1935) comb. n., Operclipygus latifoveatus sp. n., Operclipygus lissipygus sp. n., Operclipygus maesi sp. n., Operclipygus mangiferus sp. n., Operclipygus marginipennis sp. n., Operclipygus nicodemus sp. n., Operclipygus nitidus sp. n., Operclipygus pacificus sp. n., Operclipygus pauperculus sp. n., Operclipygus punctissipygus sp. n., Operclipygus subviridis sp. n., Operclipygus tripartitus sp. n., Operclipygus vorax sp. n.], Operclipygus marginellus group [Operclipygus ashei sp. n., Operclipygus baylessae sp. n., Operclipygus dentatus sp. n., Operclipygus formicatus sp. n., Operclipygus hintoni sp. n., Operclipygus marginellus (J.E. LeConte, 1860) comb. n., Operclipygus orchidophilus sp. n., Operclipygus selvorum sp. n., Operclipygus striatellus (Fall, 1917) comb. n.], incertae sedis: O. teapensis (Marseul, 1853) comb. n., Operclipygus punctulatus sp. n., Operclipygus lama Mazur, 1988, Operclipygus florifaunensis sp. n., Operclipygus bosquesecus sp. n., Operclipygus arnaudi Dégallier, 1982, Operclipygus subsphaericus sp. n., Operclipygus latipygus sp. n., Operclipygus elongatus sp. n., Operclipygus rupicolus sp. n., Operclipygus punctipleurus sp. n., Operclipygus falini sp. n., Operclipygus peregrinus sp. n., Operclipygus brooksi sp. n., Operclipygus profundipygus sp. n., Operclipygus punctatissimus sp. n., Operclipygus cavisternus sp. n., Operclipygus siluriformis sp. n., Operclipygus parallelus sp. n., Operclipygus abbreviatus sp. n., Operclipygus pygidialis (Lewis, 1908), Operclipygus faltistrius sp. n., Operclipygus limonensis sp. n., Operclipygus wenzeli sp. n., Operclipygus iheringi (Bickhardt, 1917), Operclipygus angustisternus (Wenzel, 1944), Operclipygus shorti sp. n. We establish the following synonymies: Phelisteroides miladae Wenzel & Dybas, 1941 and Pseudister propygidialis Hinton, 1935e = Operclipygus crenatus (Lewis, 1888); Phelister subplicatus Schmidt, 1893b = Operclipygus bidessois (Marseul, 1889). We designate lectotypes for Operclipygus sulcistrius Marseul, 1870, Phelister carinistrius Lewis, 1908, Phelister kerga Marseul, 1870, Phelister friburgius Marseul, 1864, Phelister impuncticollis Hinton, 1935, Phelister crenatus Lewis, 1888, Phelister sejunctus Schmidt, 1896, Pseudister depressus Hinton, 1935, Epierus dubius Lewis, 1888, Phelister hospes Lewis, 1902, Phelister farctus Marseul, 1864, Phelister bidessois Marseul, 1889, Phelister subplicatus Schmidt, 1893, Phelister plicatus Hinton, 1935, Phelister distinctus Hinton, 1935, Phelister distractus Schmidt, 1896, Pseudister latemarginatus Bickhardt, 1920, Phelister hamistrius Schmidt, 1893, Phelister plicicollis Schmidt, 1893, Phelister gibbulus Schmidt, 1889, Phelister subdepressus Schmidt, 1889, Phelister teapensis Marseul, 1853, Phelister pygidialis Lewis, 1908, Phelister iheringi Bickhardt, 1917, and Phelister marginellus J.E. LeConte 1860. We designate a neotype for Operclipygus conquisitus Lewis, replacing its lost type specimen.


Histeridae, Histerinae, Exosternini, Operclipygus, myrmecophily, Neotropical region


The Exosternini, a tribe in the subfamily Histerinae, represents one of the largest groups of histerid beetles in the New World. With nearly 200 described species, its diversity is rivalled only by Haeteriinae. Exosternini is represented in the New World by 11 described genera: Phelister Marseul, 1853, Pseudister Bickhardt, 1917, Tribalister Horn, 1873, Baconia Lewis, 1885, Hypobletus Schmidt, 1896, Conchita Mazur, 1994, Nunbergia Mazur, 1978, Kaszabister Mazur, 1972, Mecistostethus Marseul, 1870, Yarmister Wenzel, 1939 and Operclipygus Marseul, 1870 (Mazur 2011). With only a few recent exceptions (Kaszabister: Dégallier et al. 2012; Mecistostethus: Caterino et al. 2012) they are all poorly known, with undescribed species outnumbering described ones. None of the larger genera have ever been revised, or even adequately defined. In this paper we present a comprehensive revision of one of the largest of these genera, Operclipygus.

Operclipygus was first established by Marseul for a single Brazilian species, Operclipygus sulcistrius Marseul (1870). Both the genus name and that of the type species refer to one of the key characters of the group, a sulcus along the apical margin of the pygidium (abdominal tergite 7), which emphasized its ‘operculate’ nature. Marseul recognized similarities to Phelister, though for reasons unexplained placed the genus ‘entre les Platysoma et les Cylistix’ (tribe Platysomatini). Apparently the unusual cylindrical habitus of the type species prevented subsequent authors (or even Marseul himself) from placing additional species in Operclipygus, though many species described in subsequent years had a variably sulcate pygidium. Operclipygus remained in Platysomatini through the revisions of Bickhardt (1917, 1921). The majority of species we include here were originally described in Phelister, and though several authors recognized the close relationship of many of these (most notably Bickhardt 1917, Hinton 1935c, and Wenzel and Dybas 1941, under other generic names) it was not until Wenzel (1976) studied the type of Operclipygus sulcistrius that it was recognized that Operclipygus should properly be applied to a significantly larger group. Several authors have been further misled by a near complete (though frequently grudging) dependence on the form of the prosternal/mesoventral junction, first established by Bickhardt (1917) as a primary tribal-level character separating Exosternini, where Operclipygus properly belongs, from Histerini, where under other generic names many of these species have been placed. Thus, Bickhardt (1917) established the genus Pseudister for several species formerly included in Phelister that had the mesoventrite emarginate, and placed it, along with many of the species now included in Operclipygus, in Histerini. Hinton (1935) followed him, adding some new species to Pseudister, and reassigning some additional species from Phelister. Wenzel and Dybas (1941) disagreed with the assertion of a close relationship among all these species, establishing the genus Phelisteroides for several of them, and describing many new ones. Finally, in 1976, Wenzel synonymized Phelisteroides with Operclipygus, recognizing it as Exosternini, and paving the way for the present concept of the genus.

Wenzel (1976) listed 24 species in Operclipygus. Dégallier (1982) described an additional species, Operclipygus arnaudi. Mazur (1984) moved one additional species into the genus from Phelister, and subsequently described an additional one himself (Mazur 1988), and the genus now stands at 27 described species (Mazur 1997, 2011). In the present study we synonymize 3 species, move 14 species from other genera (mainly Phelister and Pseudister), synonymize the genus Tribalister (see Operclipygus marginellus group), and describe 138 new species, bringing the total to 177 species of Operclipygus.

As the original recognition of the genus rested on the pygidial sulcus, Wenzel's (1976) treatment continued to recognize this as the defining character, adding that the species also have ‘a single lateral pronotal stria, triangular prosternal keel formed by the union of the striae, anterior mesosternal margin broadly, shallowly emarginate, pygidium very densely, almost contiguously punctulate, […], tarsal grooves straight, only their inner margin well defined, ’ although he acknowledged this was a tentative, and probably inadequate definition. While the present study expands the boundaries of the genus somewhat, mainly through attempting to define the genus in a more phylogenetically meaningful way, it has become clear that all of the characters listed by Wenzel as defining his concept of Operclipygus have multiple exceptions. Through phylogenetic analyses of higher-level relationships among Neotropical Exosternini, these exceptions have begun to be clarified. However, many of the character states found in what we consider unquestionably Operclipygus are found in species and lineages that are otherwise rather dissimilar. We largely adhere to the results of a comprehensive phylogenetic analysis of morphological and molecular characters including all named and unnamed species of Neotropical Exosternini (Caterino et al. in prep). However, the support for many critical branches is not great, and some results do not have unambiguous taxonomic implications. We present here what we consider to be the most clearly defensible delineation of the genus, only synonymizing other taxa where the results appear unambiguous. However, there is no question that future refinement and analysis will be necessary. Above all we are concerned with filling out the picture of the species diversity, and presenting sufficient information to allow them to be recognized and identified by other workers. We consider a solid higher taxonomy a much less critical goal in the face of the ongoing biodiversity crisis.

Materials and methods

Type material of all named species was examined by one or both of the authors. Conventional imaging was done using a Visionary Digital's ‘Passport’ portable imaging system, which incorporates a Canon 7D with MP-E 65mm 1–5× macro zoom lens. Images were stacked using Helicon Focus software. SEM imaging was done on a Zeiss EVO 40 scope, with most specimens sputter-coated with gold. We present only selected images as necessary to identify the species in this paper. However, multiple photographs of all species have been archived in MorphBank ( ), and are also available through the Encyclopedia of Life ( ). Following histerid conventions, total body length is measured from the anterior margin of the pronotum to the posterior margin of the elytra (to exclude preservation variability in head and pygidial extension), while width is taken at the widest point, generally near the elytral humeri.

We present extensive descriptions for the majority of species. At the same time, we term these ‘diagnostic descriptions’, to emphasize the fact that they focus on those character systems in which differences among species are typically found. They are not intended to be exhaustive descriptions of each species’ morphology. We have attempted to make most of them consistent in character content and order, facilitating comparison as well as their reuse of descriptions in other contexts, such as in species pages and other media, which we would generally encourage. However, in a few cases, groups of species are so similar, separable mainly by one or two, often genitalic characters, that it seemed pointless to repeat extensive descriptions for all, in which the important differences might be easily missed. The ‘remarks’ sections attempt to highlight the few most important key characters of each species. Ordering of species within species groups is intended to reflect phylogeny to a certain degree, facilitating comparisons among closely related species and their diagnoses.

The material examined lists provide verbatim data only for holotypes and lectotypes, and summary data for all other material, whether paratypes or nontypes. Standardized (to the extent possible) type localities for each species are presented to facilitate verbatim data interpretation. Within verbatim records, data are enclosed in double quotes, with data on separate labels separated by a slash ‘/’. The summary data generally avoids excessive repetition. Each record begins with the number of specimens exhibiting identical data. Records separated by commas are largely identical, differing only in the datum presented, most frequently distinct dates or collectors. Distinct localities are separated by semicolons, and records from distinct countries are separated by periods (full-stops).

Specimens were provided by the following institutions:

AKTC Alexey Tishechkin Collection, Santa Barbara, USA

AMNH American Museum of Natural History, New York, USA

BDGC Bruce Gill Collection, Ottawa, Canada

BMNH Natural History Museum, London, UK

CASC California Academy of Sciences Collection, San Francisco, USA

CEMT Coleção de Entomologia, Universidade Federal do Mato Grosso, Cuiabá, Brazil

CHFP Fabio Penati Collection, Genoa, Italy

CHJG Jeffrey P. Gruber Collection, Madison, USA

CHND Nicolas Dégallier Collection, Paris

CHPK Piet Kanaar Collection, Leiden, The Netherlands

CHPWK Peter Kovarik Collection, Columbus, USA

CHSM Slawomir Mazur Collection, Warsaw, Poland

CMNC Canadian Museum of Nature, Ottawa, Canada

CMNH Carnegie Museum of Natural History, Pittsburg, USA

CNCI Canadian National Collection of Insects, Ottawa, Canada

EMEC Essig Museum of Entomology, Berkeley, USA

ECOSUR El Colegio de la Frontera Sur, San Cristóbal de Las Casas, México

FMNH Field Museum, Chicago, USA

FSCA Florida State Collection of Arthropods, Gainesville, USA

GBFM Museo Fairchild, Universidad de Panama, Panama City, Panama

IAVH Instituto Alexander von Humboldt, Villa de Leyva, Colombia

INBIO Instituto Nacional de Biodiversidad, San Jose, Costa Rica

IRSNB Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium

LSAM Louisiana State Arthropod Museum, Baton Rouge, USA

LUND Entomological Museum of Lund University, Lund, Sweden

MACN Museo de Ciencias Naturales ‘Bernardino Rivadavia’, Buenos Aires, Argentina

MCZC Museum of Comparative Zoology, Harvard University, Cambridge, USA

MEL Museo Entomológico de León, Nicaragua

MHNLS Museo de Historia Natural La Salle, Caracas, Venezuela

MHNG Museum d’Histoire Naturelle, Geneva, Switzerland

MNHN Museum National d’Histoire Naturelle, Paris, France

MSCC Michael Caterino Collection, Santa Barbara, USA

MUSM Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima, Peru.

OUMNH Oxford University Museum of Natural History, Oxford, UK

RMNH National Natuurhistoisch Museum, Leiden, Netherlands

SBMNH Santa Barbara Museum of Natural History, Santa Barbara, USA

SEMC Snow Entomology Museum, University of Kansas, Lawrence, USA

TAMU Texas A&M University Collection, College Station, USA

UCONN University of Connecticut Insect Collection, Storrs, USA

UDG Universidad de Guadalajara, Guadalajara, Mexico

UFPR Universidade Federal do Paraná, Curitiba, Brazil

UNESP-IS Universdade Estadual Paulista, Faculdade de Engenharia de Ilha Solteira, Ilha Solteira, Brazil

UNL University of Nebraska State Museum, Lincoln, USA

USFQ Universidad San Francisco de Quito, Ecuador

USNM National Museum of Natural History, Washington, USA

WBWC William B. Warner collection, Phoenix, USA

ZMHB Zoological Museum of Humboldt University, Berlin, Germany

ZISP Zoological Institute, Russian Science Academy, Saint Petersburg, Russia

Characters of Operclipygus, terminology and variability

Much of the morphological terminology used is based on Wenzel and Dybas (1941), but modified to follow more recent treatments by Helava et al. (1985), Ôhara (1994), Kanaar (1997) and Lawrence et al. (2011). However, the species included here, and in other Exosternini have required the refinement of some existing terms, and introduction of a few new ones. The labeled illustrations provide an overview of our terminology for external (Figs 12) and male genitalic (Fig. 3) morphology.

Figure 1.

Dorsal (top) and ventral habitus of generalized Operclipygus, labeled to show terminology.

Figure 2.

Frontal (top) and lateral habitus of generalized Operclipygus, labeled to show terminology.

Figure 3.

Dissociated male genital segments and aedeagus of Operclipygus sulcistrius, labeled to show terminology.

Overall body shape – Body shapes vary considerably among the species of Operclipygus, varying in length/width ratio, roundness, whether narrowed more strongly toward the head or toward the pygidium, as well as in dorsoventral convexity. Body color and subtle texturing also show significant variation among species. All these characters of general appearance can be very useful in identification. At the same time they are difficult to describe, and best appreciated in photograph. We provide dorsal habitus photos for most species described in the paper, but we refer readers to online images for other perspectives.

Head – Informative characters of the head include varying completeness and shape of the frontal stria (Fig. 4). It is frequently interrupted at the middle (Fig. 4B) or doubly interrupted at the sides (Fig. 4C), occasionally both. It may be outwardly arcuate across the entire frons, sinuate over the antennal bases and straight in the middle, or rarely arched dorsad at the middle. Variation within species is usually minimal in these characters, although there are noted exceptions. The supraorbital stria may be present or absent, varies somewhat in degree of impression, and when present may be connected to the sides of the frontal stria or detached.

Figure 4.

Head characters of Operclipygus. A Frons of Operclipygus gilli B Frons of Operclipygus hamistrius C Frons of Operclipygus foveiventris D Frons of Operclipygus nubosus E Mandibles of Operclipygus schmidti F Mandibles and labrum of Operclipygus peregrinus G Antennal club of Operclipygus foveiventris H Antennal club of Operclipygus rufescens I Antennal club of Operclipygus confertus.

The convexity of the frons offers a number of useful characters, although these are difficult to adequately describe. Most often the frons and epistoma together are weakly depressed over most of the space between the eyes. There are a few species, or groups of species, like the Operclipygus impressifrons group, where this depression is markedly deeper (Fig. 28C). Alternatively, in a few groups, most notably the Operclipygus kerga group, the entire frontal area is flat to weakly convex (Fig. 11B).

We utilize a few characters of the labrum in the key and the descriptions, mainly the length/width ratio and the apical shape, which varies from weakly emarginate to weakly rounded. In many species the apical margin appears emarginate across the dorsal margin, but has a distinct process emerging from the ventral surface. This is frequently associated with a pronounced asymmetry in the emargination.

The only mouthpart characters we make regular use of are the presence and shape of basal teeth on the mandibles. The majority of species have a small subacute tooth at the base of the right mandible, but nothing on the left (Figs 4C, F). Where the left mandible bears a tooth it is generally larger and blunter than that on the right (Fig. 11B). It is rare, and taxonomically useful, to have both teeth present and more or less similar in appearance (Fig. 4E). There is relatively little variation in other mouthparts, and they are not detailed beyond the generic description, except in a couple of distinctive cases.

The antennal club exhibits some variation, although most of that is at higher levels in the tribe. Most Operclipygus have a similar club in which the basal annulus is weakly inwardly arcuate and interrupted, the middle annulus is weakly widened and densely setose in the middle of the dorsal and ventral surfaces, and the apical annulus is reduced to small setose patches on dorsal and ventral surfaces (Fig. 4G). The middle annulus is interrupted in numerous species, so that it appears to terminate in expanded setose patches (Fig. 4H). In a small number of species in the Operclipygus hospes group, there is a distinct round sensorium on the upper basolateral surface of the club (Fig. 4I) We have not made extensive use of these characters due to the difficulty of observing them clearly in the majority of specimens.

Pronotum – The pronotum offers a large number of characters informative for phylogenetic relationships and for species recognition. Perhaps the most significant are newly documented gland openings on the pronotal dorsum. External gland openings, while numerous in Histeridae, have not been well documented. They are in many cases easily homologized among disparate taxa, though a more thorough accounting is needed. Most Neotropical Exosternini exhibit two pairs of gland openings along the anterior pronotal margin. In a few groups, particularly in Operclipygus, the medial pair of these openings varies greatly in position, ranging from the plesiomorphic position along the margin behind the eyes (Fig. 5A) to the middle or even further posterad on either side of the pronotal disk (Fig. 5B, C). Several lineages can be easily diagnosed through their position. While at first these openings are not obvious, in most clean specimens they are readily visible.

Figure 5.

Pronotal and elytral characters of Operclipygus. A Pronotum of Operclipygus farctus B Pronotum of Operclipygus punctiventer C Pronotum of Operclipygus foveiventris D Pronotum of Operclipygus hamistrius E Pronotum of Operclipygus mortavis Right elytron of Operclipygus mortavis G Right elytron of Operclipygus maesi H Right elytron of Operclipygus foveiventris.

The various striae of the pronotum are also very useful in recognizing species and groups of species. The marginal stria generally runs continuously along the front and sides of the pronotum, usually immediately dorsad the actual edge. In many species it is broadly interrupted behind the head (Fig. 5A), or occasionally simply weakened. In some members of the Operclipygus hamistrius group the marginal stria crosses the lateral margin near the anterolateral corner, descending to run along the ventral margin (Fig. 5D). In a few such cases there is a distinct, fine groove where it crosses the margin. What we call the lateral submarginal stria is generally (e.g. Ôhara 1994, Kanaar 1997) referred to simply as the lateral stria. However, in many Operclipygus this stria is continuous with a stria behind the anterior pronotal margin, and we prefer to refer to this entire stria as submarginal stria, with lateral and anterior portions. It is frequently interrupted behind the eye, with the ends of the anterior portion recurved for a variable distance posterad (Fig. 5B). This nearly always occurs in concert with the median pronotal gland openings being displaced posterad, suggesting a developmental relationship between them. We refer to the narrow portion of the pronotal disk, between the lateral marginal and submarginal striae as the pronotal bead.

Many Neotropical Exosternini exhibit a distinct prescutellar impression, although this is relatively rare in Operclipygus species. Some groups, however, do consistently possess one. In many members of the Operclipygus hospes and Operclipygus dubius groups the prescutellar impression is distinctly elongate, frequently longer than the scutellum, occasionally flame-shaped, and a few species (Operclipygus dubitabilis group) have a small punctiform impression. However, Operclipygus almost never exhibit a prescutellar impression that is distinct and elongate oval (as in many Phelister) and never larger, approaching semicircular (as in several species related to ‘Phelister’ blairi Hinton).

A number of species exhibit what are commonly termed plicae (Fig. 5E). These are a pair of more or less linear depressions extending forward from the base of the pronotum to about its midpoint, usually immediately in front of the bases of the 3rd dorsal elytral striae. These are distinct from stria in that they generally delimit the outer edge of a broad medial depression. The pronotal disk is elevated laterad the plica.

Elytra – Characters of the elytra mostly comprise the traditional configuration of a highly conserved system of longitudinal striae (see Fig. 1). Common modifications include abbreviation from either the anterior or posterior (basal or apical, respectively) ends, some variation in depth of impression, and rarely connection of one or more striae at their basal or apical ends. In a small number of species, primarily those we place in the Operclipygus marginellus group, the outer subhumeral stria is sub- or fully carinate, defining a lateral elytral border separating the dorsum from the epipleuron. Operclipygus species exhibit variation in the number of epipleural striae, which lie very close and parallel to the lateral elytral margin along the side of the body. Many descriptions include the number of ‘complete’ epipleural striae (see Fig. 2). In such cases an additional abbreviated stria may be present. The epipleural striae are always well separated and distinguishable from the subhumeral stria(e).

Other important characters of the elytra include various sculpturing of the disk, particularly along the apical margin. Some species and groups, especially the Operclipygus sejunctus group, exhibit disorganized punctures in the apical half of the elytron, generally increasing in density apically (Fig. 5F). In other groups, especially the Operclipygus impunctipennis group, there may be a well organized series of punctures along the apical margin (Fig. 5G), and in some these coalesce into a distinct stria (Fig. 5H).

Venter – The sterna and ventrites have numerous characters that vary among species and species groups. One of the most significant ventral character systems is the prosternal-mesoventral junction. Traditionally Exosternini as a whole have been defined by an emarginate prosternal base (e.g. Bickhardt 1917). This has been discussed and discredited (e.g. Wenzel 1976), primarily due to the full range of variation exhibited in Operclipygus, from a strongly produced prosternal keel to a strongly emarginate one. The breadth of the prosternum varies considerably in the genus, though this is difficult to describe. The carinal striae of the prosternum are almost invariably present and complete, but they vary somewhat in the angle of convergence and anterior or posterior connection. We refer in some descriptions to secondary striae, which are fine strioles occasionally present alongside the base of the primary carinal striae (Fig. 6A). The prosternal lobe varies in shape and development, as well as in the presence and completeness of its marginal stria, but these are relatively minor and only detailed in descriptions where particularly distinct.

Figure 6.

Ventral and abdominal characters of Operclipygus. A Prosternum of Operclipygus lissipygus B Meso- and metaventrites of Operclipygus schmidti C Meso- and metaventrites of Operclipygus punctiventer D First abdominal ventrite of Operclipygus foveiventris E Pygidium and propygidium of Operclipygus fossipygus F Right elytron of Operclipygus hamistrius.

Beyond the anterior shape of the mesoventrite, its major characters regard the presence of marginal and discal mesoventral striae. The marginal stria is usually present, and ranges from complete and distinct to broadly interrupted. Where interrupted it is often approached by what we term the mesometaventral stria. This latter stria has its apparently plesiomorphic position coincident with the mesometasternal suture. But in most Operclipygus, it is variably displaced anterad. The mesometaventral stria generally forms a continuous arch with the lateral metaventral stria (Fig. 6C). However, in a few taxa, particularly in the Operclipygus marginellus group, these are interrupted laterally, both terminating in a moderate to distinct depression at the inner edge of the mesocoxa.

The metaventrite exhibits a few useful characters of sculpture and striation. The most important and variable is completeness and position of the lateral metaventral stria. The commonest state is that it extends at a slight angle more or less straight and completely toward the inner anterior corner of the metacoxa, though it is commonly abbreviated apically. It may extend in a more lateral direction, toward the middle or outer corner of the metacoxa, in which case it is more often curved. Rarely it meets a recurrent stria, which recurves forward toward the metepisternum. A few species groups (especially Operclipygus sulcistrius and Operclipygus sejunctus groups) have a secondary lateral stria that parallels the primary metaventral stria along its outer edge for some or most of its length (Fig. 6C). A few species, primarily those in the Operclipygus sejunctus group, exhibit coarse punctures on the metaventrite (Fig. 6C). A small number of species show a dimorphism in which the meta- and mesoventrites are depressed and/or finely setose in the males (Fig. 19G).

The main characters of the abdominal ventrites are related to the lateral striae of the first visible ventrite (morphologically the 3rd sternite), which run anteroposteriorly along the inner edge of the metacoxa. There may be one or two of these, termed the inner and outer, and they may be variably complete to obsolete. Frequently the outer stria is abruptly curved laterad behind the metacoxa. Essentially all Operclipygus exhibit a small gland opening near the posteromedial corner of the metacoxa (Fig. 34A), as do many other Exosternini. In some species, particularly in the Operclipygus impunctipennis group, this fovea is enlarged, sometimes greatly (Fig. 6D), and may also be displaced laterad, usually in association with a bent outer lateral abdominal stria. Otherwise few characters of the abdominal venter are used.

Pygidia – While technically part of the abdomen, the 6th and 7th abdominal tergites, termed the propygidium and pygidium, merit special discussion in any Histeridae. These are greatly varied in punctation in Operclipygus. Most importantly they frequently exhibit a very fine, dense ground punctation (Fig. 6E), against which background larger, coarser secondary punctures may be variously impressed. The propygidium rarely exhibits lateral striae, but is generally free of striae. The apical marginal stria/sulcus of the pygidium is, however, extremely varied and important for species recognition. It is completely absent in only very few species, particularly in the Operclipygus hospes group. In most species it is coarsely and completely impressed, with the depth, coarseness and completeness varied among species. The most remarkable modifications include foveate basal enlargements (Fig. 6E), which conceivably funtion as mycangia (Caterino and Tishechkin, pers. obs.). These are, however, found only in a few common species in the Operclipygus fossipygus group.

Legs – We utilize relatively few characters of the legs in the descriptions and keys in this paper. The tibiae are markedly expanded in a few species, providing useful characters, mainly within the Operclipygus marginellus group. The tarsi and their claws also provide valuable characters for distinguishing a couple species groups, especially in the arrangment of ventral setae, shape of the apical tarsomere, and shape of the claws. While there is considerable variation in marginal tibial dentation and spines, we have not found states that are sufficiently distinct to be useful for grouping or for species recognition, except in a few extreme cases.

Genitalia, male – Male genitalia, including the telescoping 8th-10th abdominal segments, are extremely useful for recognizing species and species groups, and are described and illustrated extensively throughout the paper (see Fig. 3 for terminology). Accessory sclerites at the base of the 8th tergite (T8) were first noted in Exosternini by Kanaar (1997), who observed muscle attachment to them. These small sclerites are present in most, but not all Operclipygus. In a few cases, we must acknowledge that their absence may be artifactual, as they may become dissociated during dissection. However, they are consistently absent in a few subgroups of species. A new character which we utilize in descriptions relates to the position of the attachment line of the basal membrane of T8. The basal apodemes of this segment lie within the tube of the genitalia, while the distal portion of the tergite forms an external surface. How deeply embedded the apodemes are in the genital tube appears characteristic in many species. This depth is described in relation of the distinct membrane attachment line to the tergite's basal emargination. The ventrolateral apodemes of T8 fall into two distinct categories with respect to symmetry. In many species they project most deeply beneath near their bases, tapering toward the apex, while in others the apodemes project most deeply at their middles, tapering evenly basally and apically. The latter state is generally associated with an interruption of the apicolateral margin of the tergite, where the apodemes end, and an abrupt bend to the apex. This is further often associated with a distinct desclerotization near this bend, indicating flexibility of the dorsal apices.

The male 8th sternite (S8) comprises two halves, usually divided along the midline, though they may be fused for some of that length. The sides of the sternites curve upward, usually curving over dorsally, forming a internally open troughs referred to as apical guides. These are quite varied in degree of dorsal enclosure, as well as in shape of the upper inner edge, and are described for most species. The apices of S8 generally bear some setae, though these may be difficult to see, and are not comprehensively described (or illustrated). In a few species the apices are divergent, and may be broadly membraneous, forming a velum, presumably used in maintaining hold and position on the female.

The male T9 and T10 are intimately associated, with the apices of T9 nearly enclosing T10 dorsally. T9 itself shows little variation among groups, with a couple notable exceptions: in the Operclipygus dubius group its apices are apparently rotated and expanded to form peculiar and varied distal flanges. Like S8, T9 usually comprises separate lateral halves, approximate near their bases. However, they may be fused at this point (again in most species of the highly apomorphic Operclipygus dubius group). T10 also comprises separate lateral halves in most species, though partial or complete fusion along the midline is observed in several taxa. The 9th sternite (S9 - often referred to as the spiculum gastrale) forms an elongate guide that articulates at its apex with the aedeagus. Its shape varies considerably, in basal and apical width, as well as in the depth of emarginations at either end. We generally refer to everything basad the apical expansion as the stem, and the apical portion as the head. The distal margin of the head generally bears an upturned apical flange, which may be complete or interrupted, depending on the depth of the apical emargination. The sides of the head are also variously upturned.

The aedeagus itself comprises the basal piece, the tegmen, and the (internal) median lobe. The proportion of total length accounted for by the basal piece and the tegmen varies among species, less so among groups. The basal piece exhibits some variation in its apical shape, related to tegmen articulation, but we have not made extensive reference to this. The shape of the tegmen is quite variable, though it is most frequently simply narrowly tubular, narrowed and weakly downturned at the apex. Its most important character is the position, shape, and strength of what we term the medioventral process This is a usually dentiform process that may or may not be articulated with the ventrolateral membrane of the tegmen, projecting beneath the tegmen at some distance from its base. In most cases the shape of this process is described as seen in a dorsal view, visible through the body of the tegmen, though the degree of projection is best appreciated in lateral view. The median lobe consists of a pair of proximal apodemes and an apical gonopore. The proximal apodemes may be simple thin rods extending toward the base of the aedeagus, may be uniformly thickened, or are frequently differentiated, with the gonopore ends thicker, and the more proximal portion of the rods thin. The gonopore itself varies primarily in width relative to the tegmen width. The position of the gonopore relative to the apex of the tegmen is probably uninformative due to its presumed mobility for extrusion.

Genitalia, female – Female genitalia, characters of the ovipositor, spermathecae, and associated abdominal segments do show some variation, but mostly at higher, intergeneric levels, so beyond a general characterization of the genus (see description, below) we do not detail female genitalia in this paper. Further documentation of variation within Operclipygus may help to further refine intrageneric relationships and groupings.

Operclipygus Marseul, 1870: 75

Phelisteroides Wenzel & Dybas, 1941: 448; synonymized by Wenzel 1976: 248; Type species: Phelisteroides fungicolus Wenzel & Dybas, 1941: 452.
Tribalister Horn 1873: 299; syn. n. Type species: Phelister marginellus J.E. LeConte, 1860: 311.
Type species:

Operclipygus sulcistrius Marseul, 1870: 75


Size range: Length 1.1–5.6 mm; width 0.8–4.5 mm; Body: ovoid to elongate, sides broadly rounded to sub- or fully parallel, convex to subdepressed; color rufescent to rufo-brunneus, glabrous, rarely piceous or metallic. Head: Frons usually weakly depressed at middle, rarely strongly depressed, flat, or weakly convex; frontal stria complete, interrupted at middle, or doubly interrupted at sides, usually outwardly arcuate, rarely recurved at middle; supraorbital stria generally present across top of frons, arcuate, connected to upper ends of frontal stria or ending free, rarely absent; epistoma flat to subdepressed, very rarely convex, lacking striae along anterior or lateral margins, apex truncate to weakly emarginate; labrum 1.5–3× as wide as long, flat to weakly convex, apical margin generally weakly emarginate, often slightly asymmetrical with weak tooth projecting ventrad, rarely outwardly arcuate; mandibles short, weakly dentate, with tooth more often on right mandible than left, rarely with both mandibles strongly toothed; antennal scape elongate, slightly expanded to apex; antennal club shape elongate oval, rarely circular, with three annuli, the basalmost two frequently interrupted. Pronotum: Pronotal sides generally narrowed to front, anterior margin behind head straight to weakly, very rarely strongly produced; disk with prescutellar impression small or lacking, never as large or larger than scutellum; disk with marginal and anterior gland openings, the innermost pair of which is frequently displaced posteriorly onto pronotal disk; marginal stria usually present along lateral and anterior margins, often interrupted behind eyes, anterior portion rarely absent; lateral submarginal pronotal stria usually present along all or most of pronotal side, simple or rarely subcarinate, rarely abbreviated from posterior end, disconnected or continuous with anterior submarginal stria; anterior submarginal stria usually present in addition to anterior portion of marginal stria; lateral ends of anterior submarginal stria, if free, frequently recurved posterad, sometimes over considerable portion of pronotal length; pronotal disk variously punctate, usually only at sides, rarely with oblique basal plicae. Elytra: one to three epipleural striae present, usually fine and close together; dorsal striae comprising 8 regular striae, highly variable in presence, completeness and degree of impression; elytral disk rarely with apical punctures, which may be diffuse or form a regular series. Prosternum: Prosternal lobe weakly deflexed, usually rounded, rarely subtruncate apically or strongly shortened, usually with marginal stria present, variably abbreviated at sides; prosternal keel projecting, truncate, or emarginate at base, with two carinal striae usually present, complete, and connected anteriorly by narrow arch. Mesoventrite: Anterior mesoventral margin varied in shape in correlation with prosternal keel; marginal mesoventral stria usually complete, rarely interrupted or absent; mesometaventral stria rarely present along mesometaventral suture, more often displaced anterad, often nearly to anterior mesoventral margin, may be angulate or arcuate, generally continuous at sides with lateral metaventral stria. Metaventrite: Disk flat to weakly convex, generally glabrous, impunctate, rarely depressed and/or setose in males, or punctate in both sexes; postmesocoxal stria present, curving close to rear of mesocoxa toward mesepimeron; lateral metaventral stria oblique, extending from inner corner of mesocoxa toward metacoxa, rarely curving toward metepisternum or continued at side by recurrent stria. Abdomen: Abdominal ventrite 1 with one or two lateral striae along inner edge of metacoxa, the outermost rarely curving laterad behind coxa; gland openings behind metacoxa usually small, inconspicuous, rarely developed into deep foveae; propygidium usually wide, short, with pair of gland openings in anterolateral corners, disk with highly varied punctation; pygidium subtriangular, variably punctate, usually with distinct marginal stria, this occasionally developed into deep sulcus, rarely with large foveae in basolateral corners. Legs: protibial margin generally without strong marginal teeth, with 4-8 weak marginal teeth, each bearing a small spine; submarginal row of spines frequently present, along with one to three longitudinal striae on posterior face, two protibial spurs present, the inner one often weak; protarsal setae often sexually dimorphic, simple in females, broadly expanded in males; protarsal claws usually simple, rarely modifed; meso- and metatibiae lacking marginal teeth, with simple series of generally fine spines; meso- and metatarsi generally with two rows of ventral spines, rarely with spines not organized in rows. Male: Accessory sclerites present or absent; 8th tergite parallel-sided to weakly tapered, with conspicuous basal and apical emarginations, ventrolateral apodemes simple, not meeting along ventral midline; 8th sternite usually divided along midline, rarely fused along part of its length, with sides upturned to form weak to moderately strong apical guides, apices usually bearing few fine setae, rarely with numerous conspicuous setae; 9th tergite divided along midline, very rarely fused near base, apices usually simple, converging but separate, ventrolateral apodemes forming moderately to strongly hooked lateral structures; spiculum gastrale (S9) generally elongate, stem weakly expanded at base, head with apical flanges, apicolateral flanges rarely well developed; 10th tergite elongate, usually divided along midline, rarely fused; aedeagus elongate, narrow, tubular, varied in shape, with apical division rather short, apices rarely convergent, usually with moderately strong ventromedial projection, easily visible from above, and often projecting beneath; median lobe usually simple, with small gonopore, elongate proximal apodemes, proximal apodemes rarely strongly differentiated into proximal and distal portions; basal piece usually one-fourth to one-third tegmen length, laterally articulated with tegmen. Female: 8th tergite forming a single plate, apically emarginate; 8th sternite entire or divided along midline with basal baculi detached, articulated with sternites, basally convergent; 9th sternite present, elongate; valviferae paddle-shaped; coxites elongate, apically bi- to tridentate, with distinct, articulated apical stylus; bursa copulatrx completely membraneous; generally with single weakly sclerotized spermatheca, although multiple spermathecae have been observed, inserted beneath apex of bursa copulatrix; spermathecal shape simple, saclike, or frequently forming complex spiral; spermathecal gland present, inserted at base of spermatheca.

Recognizing members of Operclipygus

Collectively diagnosing the group of related species that we assign to Operclipygus is challenging. No single distinctive character remains constant through the group, synapomorphic or otherwise. The presence of a marginal pygidial stria/sulcus is almost sufficient to place a specimen into Operclipygus; only a very small number of excluded species exhibit this character. A marginal pygidial stria is seen in most Mecistostethus, which have the body strongly depressed and dorsally setose (see Caterino et al. 2012). A few species in a couple of undescribed genera also have a pygidial stria but in one case the pygidium itself strongly prolonged and apically pointed; in another there are deep lateral mesoventral foveae and no sutural elytral stria. Otherwise, if a New World histerine specimen has a marginal pygidial stria, it is Operclipygus.

Much harder is placing those true Operclipygus that lack a pygidial stria into the genus. Most of the Operclipygus that lack this stria are in the Operclipygus impunctipennis group, most of which have very fine, dense pygidial ground punctation, a character sufficient to place a specimen in the genus. Others in this group have an apical marginal stria or puncture series on the elytron, also sufficient for placement. Several members of the Operclipygus hospes group lack a pygidial stria, but these can easily be recognized by their elongate, subdepressed body form and their two lateral striae on the 1st abdominal ventrite. Finally a few members of the Operclipygus hamistrius group lack the pygidial stria, but all show conspicuous transverse microsculpture on the pygidium, and generally will have a broken and recurved anterior submarginal pronotal stria.

Taking a different perspective, it is more or less possible to diagnose some other groups of New World Exosternini that might otherwise be confused with Operclipygus:

Phelister sanguinipennis group: This is a relatively small group of species that often occur abundantly in flight intercept trap and carrion and dung pitfall trap samples in the neotropics. They may be similar to some species of Operclipygus, mainly in that they may have an outwardly arcuate anterior pronotal margin, median pronotal gland openings that are displaced posterad onto the pronotal disk, and an anterior submarginal pronotal stria which may be broken and recurved posterad for some distance. But preliminary analyses do not support a close relationship between the groups. Members of the Phelister sanguinipennis group may generally be separated from Operclipygus by the following characters: prescutellar impression usually elongate oval, about as long as scutellum; propygidium strongly transverse, often depressed at sides; pygidium relatively short, lacking marginal sulcus; prosternal keel relatively broad, carinal striae generally at least partly effaced; base of prosternal keel emarginate to truncate, never outwardly arcuate; pronotum with marginal stria usually complete across front, anterior submarginal stria rarely present; central portion of anterior pronotal margin often projecting; outer subhumeral elytral stria never complete (may be absent); inner subhumeral stria never present.

Phelister blairi group: This is a large group of mostly undescribed species that is destined to be removed from Phelister and probably split into multiple genera. The feature by which they most often may be confused with Operclipygus is the posteriorly displaced median pronotal gland openings. They may usually be separated from Operclipygus by the following characters: median pronotal gland openings distinctly annulate; prescutellar impression larger than scutellum, often much larger and semicircular; frons and epistoma narrowly and deeply impressed, the epistoma usually with subcarinate lateral ridges; prosternal keel usually emarginate at base.

Checklist of the species of Operclipygus

Operclipygus sulcistrius group

Operclipygus sulcistrius Marseul, 1870

Operclipygus schmidti sp. n.

Operclipygus lucanoides sp. n.

Operclipygus simplistrius sp. n.

Operclipygus mirabilis group

Operclipygus mirabilis (Wenzel & Dybas, 1941) comb. n.

Operclipygus pustulifer sp. n.

Operclipygus plaumanni sp. n.

Operclipygus sinuatus sp. n.

Operclipygus mutuca sp. n.

Operclipygus carinistrius (Lewis, 1908) comb. n.

Operclipygus parensis sp. n.

Operclipygus schlingeri sp. n.

Operclipygus kerga group

Operclipygus kerga (Marseul, 1870)

Operclipygus punctistrius sp. n.

Operclipygus planifrons sp. n.

Operclipygus conquisitus group

Operclipygus conquisitus (Lewis, 1902)

Operclipygus bicolor sp. n.

Operclipygus friburgius (Marseul, 1864)

Operclipygus impuncticollis group

Operclipygus impuncticollis (Hinton, 1935)

Operclipygus britannicus sp. n.

Operclipygus bickhardti sp. n.

Operclipygus panamensis group

Operclipygus panamensis (Wenzel & Dybas, 1941)

Operclipygus crenatus (Lewis, 1888)

Operclipygus sejunctus group

Operclipygus sejunctus (Schmidt, 1896) comb. n.

Operclipygus pecki sp. n.

Operclipygus juninensis sp. n.

Operclipygus depressus (Hinton, 1935)

Operclipygus setiventris sp. n.

Operclipygus itoupe sp. n.

Operclipygus punctiventer sp. n.

Operclipygus mortavis group

Operclipygus mortavis sp. n.

Operclipygus ecitonis sp. n.

Operclipygus paraguensis sp. n.

Operclipygus dytiscoides group

Operclipygus dytiscoides sp. n.

Operclipygus carinisternus sp. n.

Operclipygus quadratus sp. n.

Operclipygus crenulatus sp. n.

Operclipygus dubitabilis group

Operclipygus dubitabilis (Marseul, 1889)

Operclipygus yasuni sp. n.

Operclipygus impressifrons group

Operclipygus angulifer sp. n.

Operclipygus impressifrons sp. n.

Operclipygus dubius group

Operclipygus dubius (Lewis, 1888)

Operclipygus andinus sp. n.

Operclipygus intermissus sp. n.

Operclipygus variabilis sp. n.

Operclipygus validus sp. n.

Operclipygus lunulus sp. n.

Operclipygus remotus sp. n.

Operclipygus occultus sp. n.

Operclipygus perplexus sp. n.

Operclipygus extraneus sp. n.

Operclipygus hospes group

Operclipygus hospes (Lewis, 1902)

Operclipygus ignifer sp. n.

Operclipygus subterraneus sp. n.

Operclipygus callifrons sp. n.

Operclipygus colombicus sp. n.

Operclipygus incisus sp. n.

Operclipygus prominens sp. n.

Operclipygus tiputinus sp. n.

Operclipygus minutus sp. n.

Operclipygus inquilinus sp. n.

Operclipygus tenuis sp. n.

Operclipygus communis sp. n.

Operclipygus belemensis sp. n.

Operclipygus innocuus sp. n.

Operclipygus diffluens sp. n.

Operclipygus confluens sp. n.

Operclipygus fusistrius sp. n.

Operclipygus ibiscus sp. n.

Operclipygus novateutoniae sp. n.

Operclipygus gratus sp. n.

Operclipygus confertus sp. n.

Operclipygus rileyi sp. n.

Operclipygus assimilis sp. n.

Operclipygus praecinctus sp. n.

Operclipygus impositus sp. n.

Operclipygus curtistrius sp. n.

Operclipygus bulbistoma sp. n.

Operclipygus farctus group

Operclipygus farctus (Marseul, 1864)

Operclipygus bidessois (Marseul, 1889)

Operclipygus subrufus sp. n.

Operclipygus plicatus (Hinton, 1935) comb. n.

Operclipygus petrovi sp. n.

Operclipygus distinctus (Hinton, 1935)

Operclipygus atlanticus sp. n.

Operclipygus gilli sp. n.

Operclipygus proximus sp. n.

Operclipygus prolixus sp. n.

Operclipygus impressistrius sp. n.

Operclipygus farctissimus sp. n.

Operclipygus inflatus sp. n.

Operclipygus distractus (Schmidt, 1896) comb. n.

Operclipygus punctifrons sp. n.

Operclipygus latemarginatus (Bickhardt, 1920) comb. n.

Operclipygus hirsutipes group

Operclipygus hirsutipes sp. n.

Operclipygus guianensis sp. n.

Operclipygus hamistrius group

Operclipygus hamistrius (Schmidt, 1893) comb. n.

Operclipygus geometricus (Casey, 1893) comb. n.

Operclipygus rubidus (Hinton, 1935) comb. n.

Operclipygus quinquestriatus sp. n.

Operclipygus campbelli sp. n.

Operclipygus dybasi sp. n.

Operclipygus pichinchensis sp. n.

Operclipygus rufescens sp. n.

Operclipygus impressicollis sp. n.

Operclipygus nubosus sp. n.

Operclipygus arquus sp. n.

Operclipygus propinquus sp. n.

Operclipygus intersectus sp. n.

Operclipygus troglodytes sp. n.

Operclipygus chiapensis sp. n.

Operclipygus montanus sp. n.

Operclipygus plicicollis group

Operclipygus plicicollis (Schmidt, 1893)

Operclipygus cephalicus sp. n.

Operclipygus longidens sp. n.

Operclipygus fossipygus group

Operclipygus fossipygus (Wenzel, 1944)

Operclipygus foveipygus (Bickhardt, 1918)

Operclipygus gibbulus (Schmidt, 1889) comb. n.

Operclipygus fungicolus (Wenzel & Dybas, 1941)

Operclipygus subdepressus (Schmidt, 1889)

Operclipygus simplicipygus sp. n.

Operclipygus therondi Wenzel, 1976

Operclipygus disconnectus sp. n.

Operclipygus olivensis sp. n.

Operclipygus impunctipennis group

Operclipygus impunctipennis (Hinton, 1935) comb. n.

Operclipygus punctissipygus sp. n.

Operclipygus granulipectus sp. n.

Operclipygus pauperculus sp. n.

Operclipygus nicodemus sp. n.

Operclipygus tripartitus sp. n.

Operclipygus latifoveatus sp. n.

Operclipygus lissipygus sp. n.

Operclipygus mangiferus sp. n.

Operclipygus foveiventris sp. n.

Operclipygus marginipennis sp. n.

Operclipygus maesi sp. n.

Operclipygus pacificus sp. n.

Operclipygus nitidus sp. n.

Operclipygus subviridis sp. n.

Operclipygus vorax sp. n.

Operclipygus chamelensis sp. n.

Operclipygus marginellus group

Operclipygus marginellus (J.E. LeConte, 1860) comb. n.

Operclipygus striatellus (Fall, 1917) comb. n.

Operclipygus formicatus sp. n.

Operclipygus hintoni sp. n.

Operclipygus orchidophilus sp. n.

Operclipygus baylessae sp. n.

Operclipygus selvorum sp. n.

Operclipygus dentatus sp. n.

Operclipygus ashei sp. n.

Operclipygus incertae sedis

Operclipygus teapensis (Marseul, 1853) comb. n.

Operclipygus punctulatus sp. n.

Operclipygus lama Mazur, 1988

Operclipygus florifaunensis sp. n.

Operclipygus bosquesecus sp. n.

Operclipygus arnaudi Dégallier, 1982

Operclipygus subsphaericus sp. n.

Operclipygus latipygus sp. n.

Operclipygus elongatus sp. n.

Operclipygus rupicolus sp. n.

Operclipygus punctipleurus sp. n.

Operclipygus falini sp. n.

Operclipygus peregrinus sp. n.

Operclipygus brooksi sp. n.

Operclipygus profundipygus sp. n.

Operclipygus punctatissimus sp. n.

Operclipygus cavisternus sp. n.

Operclipygus siluriformis sp. n.

Operclipygus parallelus sp. n.

Operclipygus abbreviatus sp. n.

Operclipygus pygidialis (Lewis, 1908)

Operclipygus faltistrius sp. n.

Operclipygus limonensis sp. n.

Operclipygus wenzeli sp. n.

Operclipygus iheringi (Bickhardt, 1917)

Operclipygus angustisternus (Wenzel, 1944)

Operclipygus shorti sp. n.

Key to species groups and unplaced species
1 Outer subhumeral stria subcarinate to strongly carinate, forming a lateral elytral margin of varying strength (Fig. 80A) (where weak, in one species from Central Mexico (Fig. 80G), the epistoma has weak oblique lateral striae); lateral submarginal pronotal stria complete, carinate, very close to margin, pronotal disk depressed along its inner edge (Fig. 80C); body otherwise highly varied in appearance, often strongly carinate (Fig. 80A), or conversely with striae strongly reduced (Fig. 82E); never strongly and densely punctate Operclipygus marginellus group (p. 315)
Outer subhumeral stria variously impressed, but rarely carinate; if elytra with lateral carina, then body is densely and uniformly punctate throughout; lateral submarginal pronotal stria, if close to margin, rarely carinate, and pronotal disk not depressed along its inner edge 2
2 Pronotum with a single pair of anterior gland openings, located along pronotal margin behind eye 3
Pronotum with two pairs of anterior gland openings, at least one along the anterior margin laterad eye, the second, median opening variable in position, may be close to anterolateral opening or displaced posterad on pronotal disk by as much as three-fourths the pronotal length 4
3 Body size <3 mm; pronotum with strong basal plicae; frontal striae abruptly bent dorsad near antennal bases, sinuate across middle (Fig. 8F); known only from a cave near Tingo Maria, Huanuco, Peru Operclipygus schlingeri sp. n.
Body large, >5 mm, subquadrate (Fig. 103); pronotum lacking basal plicae; southeastern Brazil Operclipygus iheringi (Bickhardt)
4 Median pronotal gland openings close to anterior pronotal margin, within approximately 10 diameters (Figs 5A, B) 5
Distance between median pronotal gland openings and anterior pronotal margin greater than, usually much greater than, 10 diameters (Fig. 5C); or, pronotal disk strongly and uniformly punctate, obscuring gland openings 41
5 Anterior submarginal pronotal stria continuous with lateral submarginal stria, joined smoothly, without postocular angulation; both pronotal gland openings very close to anterior margin (Fig. 5A), anterior to submarginal stria, median openings no more than two diameters from anterior margin Operclipygus farctus group (p. 182)
Anterior submarginal pronotal stria detached from lateral submarginal stria, or meeting at distinct postocular angulation; median pronotal gland openings ranging from 4-10 diameters from anterior pronotal margin 6
6 Distinct pronotal plicae present (Fig. 5E) 7
Pronotal plicae absent, pronotum at most weakly flattened across base 8
7 Frons flat to convex, with frontal stria complete, transverse; body not unusually large Operclipygus mirabilis group (females) (p. 39)
Frons strongly impressed at middle (Fig. 22A), frontal stria sinuate laterally or interrupted over antennal bases; body large, rounded, strongly convex Operclipygus mortavis group (p. 91)
8 Metaventrite and first abdominal ventrite with coarse punctures (Figs 6C, 19B); second lateral metaventral stria present laterad primary stria; elytra usually with numerous poorly organized punctures toward apex (Fig. 5F) Operclipygus sejunctus group (p. 77)
Metaventrite (and usually first abdominal ventrite) lacking coarse punctures; other characters variable 9
9 Body elongate, parallel-sided (Fig. 7A); prosternal lobe large, subtruncate apically (Fig. 7F); both mandibles with strong basal tooth (Fig. 4E); secondary lateral metaventral stria present Operclipygus sulcistrius group (p. 34)
Body form varied; left mandible usually without, or with only small tooth; prosternal lobe rounded, never subtruncate apically; secondary lateral metaventral stria rarely present 10
10 Body small (usually <2mm), usually elongate, more or less parallel-sided; 1st abdominal ventrite with two complete lateral striae, usually well separated (Figs 30C, 34A); prescutellar impression present, narrow, elongate 11
Body usually larger, rounded or elongate; 1st abdominal ventrite with one or two lateral stria, but rarely with both complete – if two present then close together near metacoxa; prescutellar impression varied, but rarely thin and elongate 12
11 Left mandible with small but distinct basal tooth (Fig. 30A); antennal club large, circular; anterior mesoventral emargination deep, nearly meeting arch of mesometaventral stria (Fig. 30C); lateral metaventral stria approximately longitudinal, directed at inner half of metacoxa; pygidium short, wider than long (Fig. 30D); male genitalia generally short, with broad aedeagus bearing strong medioventral tooth (Figs 31–33) Operclipygus dubius group (p. 113)
Left mandible usually lacking tooth, or with minute denticle; antennal club smaller, more elongate; mesoventral emargination varied; lateral metaventral stria more oblique, extending toward middle or outer third of metacoxa; pygidium generally longer; male genitalia varied, but never as above Operclipygus hospes group (p. 129)
12 Body small (~2mm), rounded; marginal pygidial sulcus deep, strongly crenulate on inner edge (Figs 15B–D); outer subhumeral stria short, present only apically Operclipygus impuncticollis group (p. 64)
Marginal pygidial sulcus rarely strongly crenulate on inner edge (may be absent); other characters varied 13
13 Frons convex, not at all depressed at middle (Fig. 11B); central portion of frontal stria detached from sides, not strongly impressed; inner and outer subhumeral striae complete; pygidium with dense, fine ground punctation (with or without coarser secondary punctures) Operclipygus kerga group (p. 52)
Frons at least weakly depressed in middle; other characters variable, but very rarely with both subhumeral striae complete 14
14 Epistoma, prosternal lobe, prosternal keel, mesoventral disk with dense ground punctation (often other body surfaces as well, esp. pronotum, frons, metaventrite; Fig. 13); central portion of frontal stria absent; elytron with fine series of apical punctures Operclipygus conquisitus group (p. 57)
Epistoma and prosternal lobe lacking dense ground punctation; central portion of frontal stria usually present (may be detached and/or interrupted); apex of elytra rarely with fine series of apical punctures 15
15 Central portion of anterior pronotal margin outwardly arcuate or angulate 16
Central portion of anterior pronotal margin not produced 20
16 Frons very strongly depressed at middle (Figs 28C, E); central portion of anterior pronotal margin strongly angulate at middle; base of prosternal keel weakly emarginate Operclipygus impressifrons group (p. 106)
Frons not so strongly depressed at middle; central portion of anterior pronotal margin more weakly angulate or arcuate; base of prosternal keel varied, rarely weakly emarginate 17
17 Frontal stria complete, central portion connected to sides; pygidial sulcus finely impressed, may be abbreviated basally 18
Frontal stria interrupted at sides, central portion detached; pygidial sulcus strongly impressed, crenulate Operclipygus panamensis (Wenzel & Dybas)
18 Outer subhumeral stria complete, inner absent; abdominal ventrites 3 and 4 with single series of large deep punctures (Fig. 85G); propygidium with dense medial grouping of small but deep punctures (Fig. 85H), with more or less impunctate band along basal and lateral margins; marginal pygidial sulcus complete Operclipygus lama Mazur
Outer subhumeral stria not complete, interrupted at middle or present only in apical half; abdominal ventrites 3 and 4 with more numerous smaller punctures not forming a single series; marginal pygidial sulcus obsolete basally 19
19 Lateral submarginal pronotal stria absent from basal half; outer subhumeral elytral stria present only in apical half; inner subhumeral stria absent; body form strongly narrowed, sides subparallel (Fig. 95C) Operclipygus brooksi sp. n.
Lateral submarginal pronotal stria complete along side; outer subhumeral stria reaching base and apex, but interrupted at middle; fragments of inner subhumeral stria generally present; body moderately narrowed, but sides weakly rounded (Fig. 95A) Operclipygus peregrinus sp. n.
20 Coarse punctures of propygidium discretely limited to central part of disk (though fine series may also be present along extreme lateral margin; Figs 95E, 98E); sides of propygidium with only dense, fine ground punctation 21
Propygidium with coarser secondary punctures more or less uniformly distributed 23
21 Outer subhumeral stria present only in apical half; body shape distinctly rounded (Fig. 95D) Operclipygus profundipygus sp. n.
Outer subhumeral stria complete; body shape subcylindrical, with sides narrow and subparallel (Fig. 98D) 22
22 5th dorsal elytral stria present in apical half and represented by a distinct basal puncture (Fig. 98D); marginal pronotal bead weakly widening toward the front; apex of aedeagus lacking ventrolateral processes Operclipygus parallelus sp. n.
5th dorsal elytral stria present in apical half only, lacking basal puncture; marginal pronotal bead widening toward the front; apex of aedeagus with thin, membranous, ventrolateral processes (Fig. 99E) Operclipygus siluriformis sp. n.
23 Elytra coarsely punctate, partially obliterating otherwise mostly complete elytral striae, particularly the apices of 4th and 5th striae (Fig. 85C); ground punctation of pronotum very conspicuous, but coarse secondary pronotal punctures limited to sides; frontal stria complete, transverse; pygidium with fine ground punctation and dense secondary punctation; marginal pygidial sulcus deeply impressed, complete (Fig. 85E) Operclipygus punctulatus sp. n.
Elytra not coarsely punctate, except rarely along apical margin; other characters variable 24
24 Outer subhumeral stria complete 25
Outer subhumeral stria abbreviated, interrupted, or absent 32
25 Inner subhumeral stria complete Operclipygus cavisternus sp. n.
Inner subhumeral stra abbreviated or absent 26
26 Marginal pygidial stria fragmented, abbreviated, or absent 27
Marginal pygidial stria complete, well impressed 28
27 4th dorsal elytral stria abbreviated; pygidium with dense ground punctation, lacking coarse secondary punctures (Fig. 101D) Operclipygus faltistrius sp. n.
4th dorsal stria complete; pygidium with only sparse ground punctation, with or without secondary punctures Operclipygus teapensis (Marseul)
28 Pronotum with numerous, conspicuous coarse punctures at sides (Fig. 88A); abdominal ventrites 3 and 4 with primary series of large, deep punctures, with few smaller punctures intermingled Operclipygus florifaunensis sp. n.
Pronotum lacking coarse lateral punctures; abdominal ventrites 3 and 4 without single dominant series of large deep punctures .29
29 Elytron with two complete and one partial epipleural striae; pronotal marginal bead wide, convex (Fig. 91A); body larger, ~3.5 mm Operclipygus arnaudi Dégallier
Elytron with one complete epipleural stria (often a second, incomplete); pronotal marginal bead varied, weakly convex; body smaller, ~2–3mm 30
30 Elytron with single epipleural stria, with wide smooth epipleuron below; 4th dorsal elytral stria abbreviated from base 31
Elytron with one complete upper epipleural stria, and an abbreviated lower stria; 4th dorsal elytral stria complete Operclipygus rupicolus sp. n.
31 Punctures of propygidium small, deep, and rather dense; marginal pygidial sulcus very deep and strongly crenulate (Fig. 101B); South America Operclipygus pygidialis (Lewis)
Punctures of propygidium rather large, shallow, and sparse (Fig. 101F); marginal pygidial sulcus deep, but narrower and only weakly crenulate; known from Costa Rica Operclipygus limonensis sp. n.
32 Marginal pygidial sulcus absent (rarely with few weak apical fragments present) 33
Marginal pygidial sulcus present, generally well impressed and complete 34
33 Pygidium with dense, fine ground punctation only, lacking any coarser punctures (Fig. 95G); lateral submarginal pronotal stria complete; pronotum lacking coarse lateral punctures; punctures of propygidium small, concentrated in basal two-thirds Operclipygus punctatissimus sp. n.
Pygidium with dense, fine ground punctation and markedly coarser punctures uniformly interspersed (Fig. 101H); lateral submarginal pronotal stria obsolete in basal half; pronotum with numerous coarse lateral punctures very close to lateral margin (Fig. 101G) Operclipygus wenzeli sp. n.
34 Lateral submarginal pronotal stria obsolete in basal half 35
Lateral submarginal pronotal stria complete along side 36
35 Elytral epipleuron elevated, flat below strong subhumeral swelling, with numerous coarse punctures on side in anterior half (Fig. 92F); outer subhumeral stria present in apical half only Operclipygus punctipleurus sp. n.
Elytral epipleuron normally rounded, subhumeral region less strongly swollen, lacking coarse punctures; outer subhumeral stria present in apical half and as isolated basal fragment Operclipygus falini sp. n.
36 Marginal pygidial stria strongly impressed, diverging from margin toward apex (Fig. 91G); pronotum with linear prescutellar impression about equal in length to scutellum Operclipygus latipygus sp. n.
Marginal pygidial stria following margin throughout, marginal bead uniform in width; prescutellar impression varied (may be absent) 37
37 Body small, ~1.5 mm, broadly rounded (Fig. 91C); lateral metaventral stria curving laterad toward metepisternum Operclipygus subsphaericus sp. n.
Body larger, >2 mm, more distinctly elongate oval; lateral metaventral stria extending posterad toward metacoxa 38
38 Elytron with 4 complete dorsal striae, with only one complete (and possibly additional abbreviated) epipleural stria 40
Elytron with 4th dorsal stria abbreviated from base, present in apical half only 39
39 Base of prosternal keel truncate (Fig. 88A); pygidial sulcus fine, complete (Fig. 88D); vestige of inner subhumeral stria generally present; body rounded (Fig. 88C) Operclipygus bosquesecus sp. n.
Base of prosternal keel outwardly produced; pygidial sulcus weak, obsolete at base (Fig. 98H); inner subhumeral stria absent; body more elongate (Fig. 98F) Operclipygus abbreviatus sp. n.
40 Body large, ~4 mm, piceous; frontal stria distinctly interrupted above antennal bases (and often also at middle); pygidium with both dense ground punctation and very dense secondary punctation (Fig. 17D) Operclipygus crenatus (Lewis)
Body smaller, rufescent; frontal stria complete or very narrowly interrupted over antennal base; pygidium with dense, fine ground punctation with coarser punctures very sparsely intermingled (Fig. 92B) Operclipygus elongatus sp. n.
41 Median pronotal gland openings associated with elaborations of pronotal striae, including anterolateral tubercles and shallow, sinuate channels (Fig. 9); pronotum usually with basal plicae; elytral apices with disorganized punctures, 4th and 5th elytral striae often obscured apically; frons flat to convex, frontal stria complete, transverse; lateral submarginal striae rarely extending inward along anterior margin from corners Operclipygus mirabilisgroup (males) (p. 39)
Median pronotal gland openings never associated with secondary sexual modifications, generally simple in both sexes; elytral apices with or without apical punctures, but 4th and 5th dorsal striae rarely both abbreviated apically 42
42 Pronotal plicae present; head disproportionately large (Fig. 62C); mandibles prolonged at apices (Figs 62E–G) Operclipygus plicicollis group (p. 249)
Pronotal plicae absent 43
43 Body large (>7mm), strongly convex; legs broadly expanded, the meso- and metathoracic legs about two-thirds as wide as long (Fig. 80E); only known from Minas Gerais, Brazil Operclipygus formicatus sp. n.
Body smaller, convex or not; legs elongate, no more than one-third as wide as long 44
44 Median pronotal gland openings obscured by dense pronotal punctation (Figs 24A, D, E); prosternal lobe elevated along midline (Fig. 24B); body generally conspicuously and completely punctate, depressed, elongate; lateral submarginal pronotal stria close to margin, subcarinate, continuous with anterior submarginal stria Operclipygus dytiscoides group (p. 96)
Median pronotal gland openings distinct, situated one-third or more pronotal length behind anterior margin; prosternal lobe not elevated along midline; other characters variable 45
45 Median pronotal gland openings at or just in front of pronotal midline (Figs 54B, D); ventral surface of tarsomeres with dense brush of setae, not in organized lateral series (Fig. 54A); 9th tergite of male genitalia with apices dorsolaterally flattened, divergent (Fig. 55C) Operclipygus hirsutipes group (p. 213)
Median pronotal gland openings behind pronotal midline; ventral surface of tarsi with setae organized in distinct lateral rows; 9th tergite of male never with apices flattened and divergent 46
46 Mandibles strongly dentate (Fig. 45G); epistoma strongly convex; body elongate, parallel sided, subdepressed (Fig. 45F); anterior submarginal pronotal stria detached, strongly recurved posterad; median pronotal gland openings about two-thirds behind pronotal margin Operclipygus bulbistoma sp. n.
Left mandible with at most a very weak tooth; epistoma flat to subdepressed; other characters varied 47
47 Base of prosternal keel weakly emarginate; pygidial sulcus weak, never complete and rarely absent; microsculpture generally present on propygidium (Fig. 6F, 56A), often also on pygidium, metaventrite, and 1st abdominal ventrite; anterior submarginal pronotal stria frequently detached from lateral stria (Fig. 56C); pygidium never with dense ground punctation; elytra always with 4 or more complete dorsal striae; body usually rufescent (Fig. 56D), rarely darker Operclipygus hamistrius group (p. 218)
Base of prosternal keel subtruncate to posteriorly arcuate, rarely emarginate; pygidial sulcus varied from absent to strong, rarely weak and abbreviated; propygidium lacking microsculpture (microsculpture may be present on parts of the venter); anterior and lateral submarginal pronotal striae continuous across anterior margin, anterior portion rarely detached; pygidium frequently with dense, fine ground punctation; elytral striation frequently reduced; body color darker, generally rufopiceous 48
48 Anterior submarginal pronotal stria narrowly detached from lateral, barely recurved posterad at sides (Fig. 105A); anterior pronotal margin projecting at middle, with marginal stria complete along anterior edge; posterior half of lateral pronotal margin bent ventrad, nearly vertical; propygidium with dense ground punctation at sides, with coarse punctures more or less restricted to middle of propygidium; marginal pygidial sulcus complete, but not ending in basal foveae (Fig. 105C) Operclipygus angustisternus (Wenzel & Dybas)
If anterior submarginal pronotal stria detached from lateral stria, then anterior pronotal margin not projecting; other characters varied 49
49 Outer subhumeral stria complete or interrupted at middle, present in basal and apical halves; pygidial marginal sulcus usually deep and coarse, often ending in basal foveae, though sulcus and/or foveae may be lacking 50
Outer subhumeral stria present in apical half only or absent; pygidial sulcus fine, without basal pygidial foveae Operclipygus impunctipennis group (p. 277)
50 Pygidium with deep marginal sulcus widened in basal half, but not abruptly enlarged (Fig. 105E), basolateral foveae absent; 3rd dorsal elytral stria interrupted; aedeagus narrow and elongate, not short and broad, with very weak medioventral process; known only from Venezuela Operclipygus shorti sp. n.
Pygidium with or without marginal sulcus, but sulcus never gradually widened in basal half; basolateral pygidial foveae present or absent; 3rd dorsal elytral stria complete; aedeagus short and broad (e.g., Fig. 65G), with strong medioventral process; median lobe with large gonopore frequently exposed beneath Operclipygus fossipygus group (p. 256)
Operclipygus sulcistrius group

The Operclipygus sulcistrius group includes 4 very similar species, which would be considered atypical if it weren’t for the somewhat unfortunate fact that Operclipygus sulcistrius is the type of the genus. These species may be recognized by the following shared characters: elongate, parallel-sided, and subdepressed body form (Fig. 7), with moderately or markedly exaggerated body sculpturing, particularly noticeable in the pronotal striae; anterior submarginal pronotal stria recurved onto the pronotal disk for varying distance; median pronotal glands about 5 puncture widths from the anterior margin; strong, unusually protracted mandibles, both of which bear a strong mesal tooth (Fig. 4E); enlarged, apically subtruncate prosternal lobe (Fig. 7F); prosternal keel projecting deeply into a mesoventral emargination; mesometaventral stria arched strongly forward, almost completely displacing marginal mesoventral stria; lateral metaventral stria doubled; abdominal ventrite 1 with two complete lateral striae; pygidium with complete, deep marginal sulcus. Male genitalia (Fig. 3) with accessory sclerites present; T8 elongate, with deep basal emargination and tangential basal membrane attachment line; ventrolateral apodemes of T8 most strongly developed at base, separated beneath; S8 with apical guides evenly developed from base to apex, ventral halves separate, approximate over entire length; T9 with apices broad, weakly subtruncate; T10 elongate, halves fused in basal one-fifth; S9 rather broad, truncate to subemarginate at base, lacking apical emargination, with thin, continuous apical flange; aedeagus broadly rounded at sides evenly tapered to apex, with moderately strong ‘U’-shaped medioventral process; median lobe about one-third tegmen length.

The four species of this group are known from a total of ten specimens, from localities scattered through much of tropical South and Central America, so are extremely rare. Nothing is known of their biology.

Key to the species of the Operclipygus sulcistrius group
1 5th dorsal elytral stria complete 2
5th dorsal stria abbreviated from base Operclipygus simplistrius sp. n.
2 5th dorsal and sutural elytral striae united in basal arch 3
5th dorsal and sutural elytral striae free anteriorly Operclipygus schmidti sp. n.
3 Anterior pronotal margin strongly elevated behind head; supraorbital stria interrupted at middle; inner subhumeral stria present in apical half Operclipygus lucanoides sp. n.
Anterior pronotal margin weakly elevated behind head; supraorbital stria complete; inner subhumeral stria absent Operclipygus sulcistrius Marseul
Operclipygus sulcistrius Marseul, 1870

Figs 3, 7A
Operclipygus sulcistrius Marseul, 1870: 75.
Type locality.

Unspecified, somewhere along the Amazon in Brazil.

Type material.

Lectotype, here designated (MNHN): original handwritten green disk label barely legible: ?”Operclipygus sulcistrius Amazons Bates 69” [type locality as published is “Fleuve des Amazones”] / “TYPE” / MUSEUM PARIS COLL. DE MARSEUL 2842-90” / “LECTOTYPE Operclipygus sulcistrius Marseul 1870, M.S.Caterino & A.K.Tishechkin des. 2010”. This species was described from an unspecified number of specimens, and the lectotype designation fixes primary type status on the only known specimen.

Diagnostic description.

Length: 2.59 mm, width: 1.68 mm; body rufescent; frontal stria strongly impressed, complete to sides and continuous with supraorbital. Lateral pronotal stria complete, close to margin and carinate, continuous to front through strongly depressed anterior corners, meeting anterior portion of anterior submarginal stria, which is recurved about 1/4 the length of the pronotal disk; pronotal disk moderately convex, punctate throughout, with numerous larger punctures toward sides. Elytra with outer subhumeral and dorsal striae 1-5 complete, strongly impressed, stria 5 attached to sutural stria by basal arch, only the inner subhumeral stria absent. Prosternum with striae meeting in a narrow arch anteriorly, ending well behind presternal suture. Propygidium flat, with many close large, elongate punctures; pygidium with only a few large punctures along basal margin, finely but distinctly punctate elsewhere; apical sulcus well impressed and crenulate around apical margin. Male genitalia as described for the species group (Fig. 3).


This species is only known from the type specimen, from somewhere along the Amazon River (‘fleuve’).


This species can be separated from the others in this group by its basally connected 5th and sutural striae (shared with Operclipygus lucanoides) in combination with the relatively weakly elevated anterior pronotal margin, complete absence of the inner subhumeral striae, and relatively simple frons bordered by a complete supraorbital stria.

Figure 7.

Operclipygus sulcistrius group. A Dorsal habitus of Operclipygus sulcistrius (lectotype) B Dorsal habitus of Operclipygus schmidti C Dorsal habitus of Operclipygus lucanoides D Dorsal habitus of Operclipygus simplistrius E Lateral habitus of Operclipygus lucanoides F Prosternum of Operclipygus schmidti.

Type locality.

PANAMA: Colón: San Lorenzo Forest [9°17'N, 79°58'W].

Type material.

Holotype male: “PANAMA: Colón Pr., San Lorenzo Forest. 9°17'N, 79°58'W. Flight Intercept FIT-B2-16. 21–24 May 2004 A. Tishechkin. AT-490” / “LSAM 0111233” (FMNH). Paratypes (3): locality, collector and methods as for holotype, collected 13–14.v, 18–19.v, and 20–21.v, all 2004 (GBFM, AKTC).

Diagnostic description.

This species is very similar to Operclipygus sulcistrius as described above. It differs in the following characters: length: 2.25–2.31 mm, width: 1.47–1.56 mm; body smaller, rufo-brunneus; supraorbital stria absent; anterior submarginal stria recurved for a shorter distance along pronotal disk, about one-eighth total length; elytral striae less strongly impressed, the 5th and sutural striae not joined by a basal arch; inner subhumeral stria vaguely traceable by a series of punctures in apical half; propygidial punctures smaller and sparser, only slightly elongate, separated by their widths or more; pygidium with numerous larger punctures evenly scattered among the fine, conspicuous ground punctation. Male genitalia indistinguishable from those of Operclipygus sulcistrius (Fig. 3).


Among members of the Operclipygus sulcistrius group, Operclipygus schmidti is distinct in having the 5th and sutural elytral striae complete but not united by a basal arch. It is also unusual in lacking a supraorbital stria.

Map 1.

Records of the Operclipygus sulcistrius group.


We name this species in honor of Johannes Schmidt, the great 19th century German histerid specialist, describer of numerous species of Neotropical Exosternini.

Type locality.

FRENCH GUIANA:Itoupé Table Mountain [3°1.38'N, 53°5.73'W].

Type material.

Holotype male: “GUYANE FR., Mont tabularie Itoupé. 3°1.38'N, 53°5.73'W. 570 m. Piège d’interception, 17 Mar 2010. SEAG leg.” / “Caterino/Tishechkin Exosternini Voucher EXO-00269” (MNHN). Paratypes (4): FRENCH GUIANA: 1: Rés. des Nouragues, Camp Inselberg, 20.viii.2010 (CHND), 1: 28.i.2010; 1: Rés. des Nouragues, Saut Pararé, 4°02'N, 52°41'W, 20.iv.2010 (MNHN); 1: Belvèdére de Saül, 3°1'22"N, 53°12'34"W, 30.ix.2010 (FMNH).

Other material.

SURINAME: Sipaliwini, W bank Suriname R., nr. Jungle Resort Pingpe, 4°02'30"N, 55°27'00"W, 1–11.ii.2012, FIT, A. Hielkema (RMNH).

Diagnostic description.

This species has the most strongly exaggerated sculputuring in the group, but otherwise is very similar to both of the above. It differs in the following characters: length: 2.65–2.68 mm, width: 1.81–1.83 mm; body piceous; frontal stria carinate, continuous with supraorbital stria, which is interrupted medially; pronotal disk strongly depressed along inner edges of lateral and anterior submarginal striae, marginal bead being strongly elevated and subcarinate; anterior submarginal pronotal stria recurved about one-fourth pronotal length (although varied in type material); elytra with inner subhumeral stria present in apical half or more, with the interval between it and dorsal stria 1 strongly elevated; dorsal striae 1-5 and sutural complete, 5th and sutural striae often joined by basal arch; prosternal striae nearly reaching presternal suture anteriorly, joined in a broad arch; propygidium depressed on either side (and correspondingly elevated along lateral edges), punctures large, only slightly elongate, separated by less than half their widths; pygidium as in Operclipygus schmidti, with larger punctures sparsely scattered amongst fine, dense ground punctation. Male genitalia indistinguishable from those of Operclipygus sulcistrius (Fig. 3).


The strongly exaggerated dorsal sculpturing, especially the elevated anterior pronotal margin (Fig. 7E) distinguishes this species rather unambiguously. It is also unique in the group in having the strongly impressed supraorbital stria interrupted at the middle, and in having the apical half of the inner subhumeral stria present along the outer edge of the subhumeral elytral swelling.


This species’ name refers to its exaggerated, subporrect mandibles, reminiscent of a small stag beetle.

Type locality.

BRAZIL: Santa Catarina: Nova Teutonia [27°11'S, 52°23'W].

Type material.

Holotype female: “Nova Teutonia, Sta. Catharina, BRAZ. I:14:1958 Fritz Plaumann leg.” / “FMNH-INS 0000 069 297” / “♀” (FMNH).

Diagnostic description.

While this species shares most of the characters of the group, it is relatively unmodified in terms of sculpturing. Pronotal and elytral striae are all relatively shallowly depressed, with little exaggeration of interstrial intervals. This brief description will distinguish it from other species: length: 2.43 mm, width: 1.53 mm; body rufo-brunneus; anterior submarginal pronotal stria recurved slightly more than one-fourth pronotal disk length; lateral submarginal pronotal stria slightly abbreviated at base; pronotal disk with short, sublinear prescutellar impression, disk relatively impunctate with only small elongate group of punctures near sides, not at all depressed along inner edges of submarginal striae; elytra with outer subhumeral stria present only in apical half, inner subhumeral stria absent, dorsal striae 1-4 complete, 5th present in apical third, sutural very slightly abbreviated at base; prosternal striae nearly reaching presternal suture anteriorly, joined in a broad arch; propygidium evenly convex with large punctures separated by about their widths at the base becoming smaller and more widely separated apically; pygidium with fine ground punctation throughout, with larger scattered punctures confined to basal third. Male: unknown.


This species is unique in the group in having rather simple pronotal striation, without any depression in the anterolateral corners, and in having the outer subhumeral and 5th dorsal elytral striae abbreviated from base.


This species is named for its relatively simple sculpturing and striation compared with other members of the group.

Operclipygus mirabilis group

The Operclipygus mirabilis group includes eight species, most of which exhibit a unique sexual dimorphism in which the median pair of pronotal discal glands differs in placement and elaboration between the sexes. The name of the only described species is based on the male condition, which is quite remarkable; in males of this species the median gland opening is easily visible atop a pronounced tubercle, which itself sits within a moderately broad anterolateral pronotal depression (Fig. 9A). This is in fact the most pronounced of these dimorphisms present in known species, but most of the species in the group exhibit comparable conditions to varying degrees (Figs 9B–D). Other external characters shared by these species include: frons generally broad, flat to moderately convex; anterior part of frontal stria generally transverse, complete, not sinuate over antennal bases (with one notable exception, Operclipygus schlingeri, where the frontal stria is abruptly bent at the sides and strongly sinuate across the front); lateral submarginal pronotal striae not extending far inward along anterior margin, generally ending at anterolateral corner; pronotal plicae present; apical elytral punctures present, generally associated with apical disruption and abbreviation of the 4th and 5th elytral striae (e.g. Fig. 8C). The aedeagus of most of these species is distinctly ‘hooked’ apically, with the tip abruptly curved (Fig. 10F–H), moreso than in nearly any other Operclipygus. Two of the species we place here are known from females only, but other characters strongly support their assignments here. The real outlier is Operclipygus schlingeri, in which only a single pair of pronotal glands is apparent in the female, and those of the male are not visible dorsally. It appears that they have been displaced beneath the lateral pronotal margin, through a visible and unique anterolateral groove, onto the hypomeron, but it is very difficult to see a distinct opening at the terminus of this groove, and it is not easily visible in any of the available specimens. The aedeagus of Operclipygus schlingeri also does not conform well with the general diagnosis above (Fig. 10H). However, in most other characters it seems to fit well here.

Key to the species of the Operclipygus mirabilis group
1 Inner subhumeral stria present; pronotal plicae present, strong 2
Inner subhumeral stria absent; pronotal plicae present or absent 5
2 Secondary, outer lateral metaventral stria present in addition to inner 3
Only a single lateral metaventral stria present 4
3 Marginal pygidial stria present, distinct Operclipygus carinistrius (Lewis)
Marginal pygidial stria absent Operclipygus mutuca sp. n.
4 Male median pronotal gland opening borne on tubercle surrounded by shallow depression in anterolateral pronotal corner, depression displacing anterior half of lateral submarginal pronotal stria (Fig. 9A); female with numerous coarse punctures along sides of pronotum and along sides of pygidium Operclipygus mirabilis (Wenzel & Dybas)
Male median pronotal gland opening borne on minute tubercle but without surrounding depression (Fig. 9B); lateral submarginal pronotal stria complete; female with lateral pronotal and pygidal punctures finer to inconspicuous Operclipygus pustulifer sp. n.
5 Pygidial stria absent; propygidium with only very few punctures; male median pronotal gland opening borne on minute tubercle laterad apices of recurved anterior submarginal stria (Fig. 8D); northeastern Brazil Operclipygus parensis sp. n.
Pygidial stria present;male median pronotal gland position varied 6
6 Frontal stria abruptly bent near antennal bases, strongly sinuate across front (Fig. 8F); marginal pygidial sulcus deep (though may be interrupted); male median pronotal gland openings not visible dorsally Operclipygus schlingeri sp. n.
Frontal stria more or less transverse, at most weakly sinuate at sides; male median pronotal gland opening found at end of sinuate depression extending posterolaterad from anterior margin 7
7 Male median pronotal gland opening found at posterior end of shallow, sinuate impression extending posterad from granulate depression along anterior pronotal margin (Fig. 9D); anterior submarginal pronotal stria absent; marginal pygidial sulcus distinct, though fine and often obsolete basally; pronotum with numerous coarse punctures along lateral margin; Central America (Panama) Operclipygus sinuatus sp. n.
Male median pronotal gland opening found at end of short impression extending obliquely from anterior pronotal margin, depression smooth, not granulate (Fig. 9C); anterior submarginal stria present, recurved parallel to depression; marginal pygidial sulcus very faint; pronotum lacking coarse lateral punctures; southeastern Brazil Operclipygus plaumanni sp. n.
Operclipygus mirabilis (Wenzel & Dybas, 1941) comb. n.

Figs 8A, 9A, 10A–C, F, Map 2
Pseudister mirabilis Wenzel & Dybas, 1941: 454.
Type locality.

COLOMBIA: Cundinamarca: Puerto Salgar [5°28'N, 74°39'W].

Type material.

Holotype male: “P’to. Salgar, Cund Colomb, VII:31:38” / “Coll. by C.H.Seevers” / “Collection R. L. Wenzel” / “Type Pseudister mirabilis Wenzel & Dybas” (FMNH).

Other material.

PANAMA, Panamá: 1: Barro Colorado Isl., 09°11'N, 79°51'W, 8.vii.1994, D. Banks, FIT (SEMC), 1: external refuse deposit Atta colombica (Guérin-Méneville), 11.ii.1976 (FMNH); Colón: 1: Parque Nac. San Lorenzo, Achiote, 9°12'N, 79°59'W, 10m, 8–22.v.2007, FIT, A. Mercado (FMNH); 1: 50m [from forest edge, as for all A. Mercado specimens; pers. comm.], 9–23.v.2007(GBFM); 1: San Lorenzo Forest, STRI crane site, 9°17'N, 79°58'W, 25–26.v.2003, FIT, A.K. Tishechkin (GBFM), 1: ex. refuse pile Atta colombica, 25.x.2003 (AKTC), 1: FIT, 11–12.v.2004 (LSAM).

Diagnostic description.

Length: 1.90–1.97 mm, width: 1.50–1.68 mm; Body rufo-brunneous, sides rounded, moderately convex; lower part of frons and epistoma weakly depressed at middle, frontal stria outwardly arcuate, faintly sinuate at middle, rarely interrupted at sides; supraorbital stria absent; labrum rather narrow, about 1.5× as wide as long, shallowly emarginate at apex; left mandible untoothed, right mandible with very weak basal incisor tooth; pronotum with strong plicae in basal half, in front of 3rd elytral stria, lateral submarginal pronotal stria complete in female, in male ending one-third behind anterior corner in anterolateral pronotal depression; anterior submarginal stria detached, with ends recurved about one-sixth pronotal length; anterior marginal pronotal stra narrowly interrupted behind head; male with depression in anterolateral corner with central tubercle bearing median pronotal gland opening at its apex; female with median pair of gland openings just laterad ends of recurved anterior submarginal stria, about 8 diameters from anterior margin; pronotal disk with few coarse punctures intermingled with fine ground punctures toward sides; elytra with two complete epipleural striae, outer subhumeral stria briefly interrupted at midpoint, otherwise complete, inner subhumeral stria present, obsolete at anterior and posterior ends, all other dorsal elytral striae complete, 5th and sutural striae connected by an angulate basal arch; few coarse punctures present near elytral apex; prosternum with carinal striae complete, sinuate, close at midpoint, diverging slightly to front, connected by narrow anterior arch, keel with faint secondary carinal striae laterad primary striae; prosternal keel weakly produced posteriorly; anterior mesoventral margin broadly emarginate in continuous arc from corner to corner, marginal mesoventral stria complete, mesometaventral stria arched forward to middle of mesoventral disk, crenulate, extending posterad to middle of each metacoxa; 1st abdominal ventrite with two lateral striae, outer stria abbreviated posteriorly; propygidium with sparse fine ground punctation and coarser punctures scattered, separated by about 2× their diameters; pygidium with similar ground punctation, and very few coarser punctures, particularly near anterolateral corners; pygidial marginal stria absent. Male genitalia (Figs 10A–C, F): accessory sclerites present; T8 with deep, rather narrow basal emargination with well sclerotized basal edge, basal membrane attachment line not intersecting basal emargination, apical emargination shallow, ventrolateral apodemes not meeting at midline; S8 narrowing weakly to apex, with apical guides developed only at apex, ventral halves meeting along most of midline but with median area markedly desclerotized; T9 with apices simple, pointed inward; T10 with halves fully separate; base of S9 widened gradually in basal two-thirds, lacking apical emargination, apical flanges separate, apicolateral flanges well developed; tegmen widest basad midpoint, more strongly narrowed to apex, apex strongly bent ventrad, medioventral process ‘U’-shaped, projecting beneath about one-fourth from base; median lobe about one-third tegmen length, proximal apodemes uniform; basal piece about one-third tegmen length.


The nominate species in this group is the most easily recognized, at least based on males. The distinctive depression bearing the median pronotal gland opening on a small tubercle (Fig. 9A) identifies them instantly. Males of the following species, Operclipygus pustulifer, have a smaller tubercle and no surrounding depression (Fig. 9B). Both of these species have the 5th and sutural elytral striae complete and connected by a basal arch, and also have the inner subhumeral stria more or less complete. The females are more difficult to identify, and are extremely similar to those of Operclipygus pustulifer. Those of Operclipygus mirabilis, however, have more conspicuously coarse punctures along the sides of the pronotum and the pygidium.

The holotype was reportedly collected in a ‘rubbish heap of Atta sp.’ (Wenzel and Dybas 1941), and several recent records confirm this association, specifically with Atta colombica.

Figure 8.

Operclipygus mirabilis group. A Dorsal habitus of Operclipygus mirabilis B Dorsal habitus of Operclipygus mutuca C Dorsal habitus of Operclipygus carinistrius (lectotype) D Dorsal habitus of Operclipygus parensis E Dorsal habitus of Operclipygus schlingeri F Frons of Operclipygus schlingeri.

Figure 9.

Operclipygus mirabilis group. A Pronotum of Operclipygus mirabilis B Pronotum of Operclipygus pustulifer Pronotum of Operclipygus plaumanni D Pronotum of Operclipygus sinuatus.

Map 2.

Records of the Operclipygus mirabilis group.

Figure 10.

Male genitalia of Operclipygus mirabilis group. A T8 of Operclipygus mirabilis B S8 of Operclipygus mirabilis C S9 of Operclipygus mirabilis D S9 of Operclipygus sinuatus E S9 of Operclipygus schlingeri F Aedeagus, dorsal and lateral views, of Operclipygus mirabilis Aedeagus, dorsal and lateral views, of Operclipygus sinuatus H Aedeagus, dorsal and lateral views, of Operclipygus schlingeri.

Type locality.

COSTA RICA: Guanacaste: 9 km S Santa Cecilia, Pitilla Research Station [10°59.3'N, 85°25.5'W].


ype material.

Holotype male: “Est. Pitilla, 9km S. Sta. Cecilia, P. N. Guanacaste, Prov. Guana, COSTA RICA. 700 m Ene [January] 1994, C. Moraga, L N 330200_380200 #2563” (INBIO). Paratypes (18): 17: same data as holotype (INBIO, FMNH, AKTC, MSCC); 1: same data as holotype, but iii.1994 (INBIO).

Diagnostic description.

This species is very similar in most characters to Operclipygus mirabilis and is only described to the extent that it differs from it. Length: 1.72–1.75 mm, width: 1.40–1.44 mm; male with lateral submarginal pronotal stria diverging from marginal in anterior two-thirds, ending behind anterior corner, median pair of pronotal gland openings borne on very weak tubercles; pronotal disk not depressed anteriorly around tubercles; lateral submarginal pronotal stria of female situated slightly further from margin, particularly anteriorly, than that of Operclipygus mirabilis. Male genitalia with apical guides of S8 slightly narrower apically than in Operclipygus mirabilis, S9 also slightly narrower and more elongate; aedeagus essentially indistinguishable.


This species and Operclipygus mirabilis are very similar, differing mainly in the exaggeration of the tubercle of the male pronotum, which in Operclipygus pustulifer lacks any surrounding depression (Fig. 9B).


This species’ name refers to the raised gland opening of the male pronotum.

Type locality.

BRAZIL: Santa Catarina: Nova Teutonia [27°11'S, 52°23'W].

Type material.

Holotype male: “Nova Teutonia, Sta. Catharina, BRAZ. X:16:52, Fritz Plaumann leg.” / “bei Acromyrmex” / “FMNH-INS0000069312” (FMNH). Paratypes (25): all from same locality, dates as follows: 3:, 13: 3.i.1949, 1: 4.x.1952, 1: 5.x.1952, 1: 9.x.1952, 1: 10.x.1952, 1: 13.x.1952, 2: 21.ix.1952, 1: 27.x.1952, 1: no date (FMNH, UFPR, MSCC, AKTC).

Diagnostic description.

This species is very similar in most characters to Operclipygus mirabilis and is only described to the extent that it differs from the above. Length: 1.62–1.93 mm, width: 1.37–1.65 mm; pronotum with well developed basal plicae; anterior submarginal pronotal stria present, recurved with ends divergent; anterior marginal stria complete or barely interrupted at middle; male with divergent, sublinear depression on each side laterad and parallel to divergent arm of anterior submarginal stria, these depressions bearing median pronotal gland openings near their posterior-most ends; lateral submarginal pronotal stria similarly complete in both sexes; elytron lacking inner subhumeral stria, sutural stria obsolete in basal third, not meeting basal arch of 5th stria; pygidium with marginal stria faintly impressed along apical third of margin, rarely obsolete. Male with apical guides of S8 slightly narrower apically than in Operclipygus mirabilis; aedeagus more strongly hooked at apex.


The males of Operclipygus plaumanni and Operclipygus sinuatus have unique pronotal modifications, with the median pair of gland openings born at the end of a shallow, sinuate channel extending posterad or posterolaterad from anterior pronotal margin. In Operclipygus plaumanni this channel is shorter and extends more laterally than posteriorly (Fig. 9C). Its marginal pygidial sulcus is also very faint, barely detectable around the apex.


The species is named for famed German collector Fritz Plaumann (1902–1994), who made his home in Nova Teutonia, Santa Catarina.

Type locality.

PANAMA: Colón: San Lorenzo Forest [9°17'N, 79°58'W].

Type material.

Holotype male: “PANAMA: Colón Pr., San Lorenzo Forest. 9°17'N, 79°58'W. Flight Intercept FIT-I3-13, 13–14 May 2004 A. Tishechkin. IBISCA ‘04”, FMNH. Paratypes: (9): 2: same data as type, except as noted: 1: 17–18.v.2004, 1: 21–24.v.2004 (AKTC, FMNH, GBFM, MSCC); PANAMA: Colón: 2: Parque Nac. San Lorenzo, Achiote, Cafetal B, 9°12'N, 79°59'W, 50m, 8–22.v.2007, FIT, A. Mercado (GBFM, LSAM); 2: Parque Nac. San Lorenzo, Achiote, Cafetal C, 9°11'N, 79°58'W, 100m, 9–23.v.2007, FIT, A. Mercado (AKTC); 1: Parque Nac. San Lorenzo, Achiote, Cafetal A, 9°12'N, 79°58'W, 100m,–10.vii.2007, FIT, A. Mercado (AKTC), 1: 250m, 7–21.v.2007 (AKTC); 1: Barro Colorado Isl., iii.2001, host Eciton burchelli (Westwood), C. & M. Rettenmeyer (UCONN).

Diagnostic description.

This species is very similar in most characters to Operclipygus mirabilis and is only described to the extent that it differs. Length: 1.90–2.15 mm, width: 1.59–1.78 mm; head with supraorbital stria weakly impressed, barely detached from frontal stria at sides; pronotal disk depressed at base, but basal plicae weak to indistinct; anterior submarginal pronotal stria absent, anterior marginal stria complete behind head; male with granulate sculpturing along anterior margin of pronotum, with divergent, sinuate, elongate depressions extending posterad leading to the median pronotal gland openings halfway to posterior margin; coarse lateral discal punctures of pronotum few to absent; female with more distinct lateral coarse punctures, a few fragments of anterior submarginal pronotal stria frequntly visible at sides, and with median gland openings about one-fifth from anterior margin, with very shallow, indistinct impression anterior of them; elytra with inner subhumeral stria absent, sutural stria obsolete in basal third, not meeting basal arch of 5th stria; apical punctures of elytral disk more numerous and diffuse; prosternal carinal striae variably shortened anteriorly, especially in males, meeting in a narrow arch just anterad midpoint of keel; base of keel truncate, not at all projecting posterad, anterior margin of mesoventrite correspondingly truncate, or even very weakly projecting at middle; mesometaventral stria more angulate than rounded at middle, reaching basal third of mesoventral disk; metaventral disk with secondary, outer lateral stria parallel to lateral stria in its basal half; pygidium with ground punctation very conspicuous, marginal pygidial stria present, obsolete in basal corners. Male genitalia (Figs 10D, G) with apical guides of S8 slightly narrower apically than in Operclipygus mirabilis, aedeagus more strongly hooked at apex.


Males of Operclipygus sinuatus are distinguished by the long, sinuate channel extending nearly half the length of the pronotum (Fig. 9D), and by the granulate impressed area along the anterior margin of the pronotum. The females are quite similar to most others in the mirabilis group, but have very weak pronotal plicae, lack an inner subhumeral elytral stria, and have a fine, distinct marginal pygidial stria.


This species’ name refers to the sinuous track of the male gland opening on the pronotal disk.

Type locality.

BRASIL: Mato Grosso:Fazenda Mutuca [15°18.9'S, 55°58.2'W]

Type material.

Holotype female: “BRASIL: Mato Grosso, Mpio. Cuiabá, Fazenda Mutuca, 15.3145°S, 55.9703°W. Flight intercept traps. 24 Jan 2009 F.H. Gava & J.R. Rocha”, CEMT. Paratypes (2): Pernambuco: 1: Tapéra, Reichensperger (BMNH); 1: same as paratype but also with host label Acromyrmex octospinosa pallida Crawley [now synonymous with Acromyrmex octospinosus (Reich) s. str.] (BMNH).

Diagnostic description.

Length: 1.72–1.87 mm, width: 1.44–1.62 mm; frons flat, with complete frontal stria; supraorbital stria absent; pronotum with strong plicae in basal third; lateral submarginal pronotal striae complete, curving inward anteriorly nearly to meet recurved anterior submarginal stria; anterior marginal stria interrupted for width of head; median pronotal gland openings situated alongside of recurved submarginal stria; elytra with all dorsal striae elevated, subcarinate, with three complete epipleural striae, outer subhumeral stria barely interrupted at middle, inner subhumeral stria more or less complete, just abbreviated at base and apex, striae 1-5 and sutural complete, 5th and sutural connected by a basal arch; apices of elytra with numerous coarse punctures tending to obscure apices of striae; prosternal keel truncate at base, with complete carinal striae united in a narrow arch just short of presternal suture, secondary carinal striae absent; mesoventral margin very weakly projecting at middle, marginal stria complete, mesometaventral stria weakly arched onto mesoventrite, turned posterad well mediad mesocoxa, with secondary lateral metaventral stria present from inner edge of mesocoxa nearly to metacoxa; 1st abdominal ventrite with two lateral striae, outer stria abbreviated at inner corner of metacoxa; propygidium with sparse fine ground punctation and coarser punctures scattered, separated by about 2× their diameters; pygidium with similar ground punctation, and very few coarser punctures, particularly near anterolateral corners; pygidial marginal stria barely traceable along sides as an incomplete marginal crease. Male not known.


Even lacking male specimens, Operclipygus mutuca is easily distinguished by the presence of a strong pronotal plica, complete sutural and inner subhumeral striae, and generally elevated, subcarinate elytral striae (Fig. 8B). It is very similar in these characters to Operclipygus carinistrius, but lacks the deeply impressed marginal pygidial sulcus of that species.


This species’ name refers to its type locality, Fazenda (farm) Mutuca, near Cuiabá, Mato Grosso, Brazil, which the authors had the good fortune to visit during a 2011 field trip. It is a noun in apposition.

Operclipygus carinistrius (Lewis, 1908) comb. n.

Fig. 8C, Map 2
Phelister carinistrius Lewis, 1908: 159.
Type locality.

Not specified beyond Bahia State, Brazil.

Type material.

Lectotype female, here designated: “Bahia, A.G.” [Lewis’ description says only Brazil] / “Type” / “Phelister carinistrius Lewis Type” / “G. Lewis Coll. B.M.1926-369” / “LECTOTYPE Phelister carinistrius Lewis, 1908 M.S. Caterino & A.K.Tishechkin des. 2010” (BMNH); Paralectotype female: same data as lectotype (BMNH). This species was described from an unspecified number of specimens, and the lectotype designation fixes primary type status on one of two known syntypes.


Operclipygus carinistrius is very similar to Operclipygus mutuca, differing only in the following characters: anterior submarginal pronotal stria recurved more distinctly straight posterad; prosternal keel very weakly emarginate at base, with carinal striae complete, united in narrow anterior arch; outer subhumeral stria complete, inner subhumeral stria present in apical two-thirds, dorsal striae 1-5 and sutural complete; 5th and sutural striae connected by a basal arch; elytral disk with scattered punctures near apex; propygidial punctures small, separated by about their diameters; pygidium smooth, apical marginal sulcus well developed, especially at sides as series of close, subcontiguous punctures. Male not known.


Operclipygus carinistrius is only known from its type specimens, both females. But based on numerous characters it can be placed in the Operclipygus mirabilis group, very close to the preceding species, Operclipygus mutuca. They differ primarily in the presence in Operclipygus carinistrius of a distinct pygicial sulcus, which is absent or at most very faint in Operclipygus mutuca.

Type locality.

BRAZIL: Pará: Monte Alegre [1°43'S, 54°20'W].

Type material.

Holotype of undetermined sex (probably male but genitalia missing): “BRASIL: Pará, Monte Alegre 1°43'S, 54°20'W Piège d’interception 10–27.ix.1992” / “Caterino/Tishechkin Exosternini Voucher EXO-00351” (UFPR). Paratype (1): same data as type (CHND).

Diagnostic description.

Length: 1.37–1.40 mm, width: 1.09–1.10 mm; Very small species, frons markedly convex, frontal stria complete or barely interrupted, supraorbital stria absent; pronotal disk with short basal plicae, extending forward no more than one-fourth pronotal length; lateral submarginal pronotal stria close to marginal, ending just short of anterolateral corner; anterior submarginal pronotal stria close to margin, obliquely divergent at sides, displacing marginal stria for entire width of anterior emargination; elytra with two complete epipleural striae, outer subhumeral stria complete, not interrupted, inner subhumeral stria absent, striae 1-5 complete, 5th stria subacutely hooked anteriorly, not meeting sutural stria, which is obsolete in basal third; prosternal keel truncate at base, striae extending entire length of keel, connected by anterior arch, secondary lateral strioles absent; anterior mesoventral margin shallowly arcuate, marginal stria complete; 1st abdominal ventrite with only a single lateral stria; propygidium and pygidium with only very fine, sparse ground punctures, lacking coarser punctures; propygidium with conspicuous transverse waves of microsculpture; pygidium lacking apical marginal stria. Male not known.


Although males are most highly distinctive in this group, these specimens are adequately distinguishable to justify recognition as a distinct species. The specimens were poorly preserved, losing their genitalia prior to mounting. However, both have very weak tubercles on each side of the anterior submarginal pronotal stria, which would appear to represent the median pronotal gland openings of the male. The discovery of definite males would permit a more confident characterization of the species. In any case, Operclipygus parensis can be recognized by the combination of small size, weak pronotal plicae, absence of inner subhumeral stria, absence of a marginal pygidial sulcus, and presence of very weak tubercles on the anterolateral pronotal corners.


This species is named for the Brazilian state where it is found.

Type locality.

PERU: Huanuco: Tingo Maria, Monson Cave [9°18'S, 75°59'W].

Type material.

Holotype male: “PERU: Monson Cave Tingo Maria XII-15-1954” / “E.I.Schlinger, & E.S.Ross collectors” / “Caterino/Tishechkin Exosternini Voucher EXO-00188” (CASC). Paratype (1): same data as type (CASC).

Diagnostic description.

Length: 1.53–1.56 mm, width: 1.31–1.33 mm; body rufobrunneus, elongate oval, with conspicuous ground punctation throughout, especially on pronotum; frons flat, sides of frontal stria convergent anteriorly, abruptly bent dorsomediad above antennal bases, continuous but strongly bisinuate across middle of frons; epistoma weakly emarginate; labrum narrow, only slightly wider than long, apex rounded; mandibles markedly narrowed to apices, left untoothed, right with small, acute basal tooth; pronotum with sides relatively straight in basal two-thirds, convergent to front; pronotal disk with strong basal plicae extending forward from base of 3rd dorsal stria, with only very faint prescutellar impression, ground punctation very conspicuous, with numerous coarser punctures toward sides; marginal pronotal stria broadly interrupted behind head; lateral submarginal pronotal stria close to margin, complete, joined with anterior submarginal stria (male) or free anteriorly (female); pronotum with only single pair of anterior gland openings, in female located along anterior margin close to anterior pronotal corners, in male apparenly displaced onto hypomeron in the vicinity of an anterolateral groove formed by marginal stria; elytron with two complete epipleural striae, outer subhumeral stria complete, inner subhumeral stria absent, dorsal striae 1-5 complete, 5th stria weakly arched to sutural at base, 4th and 5th striae weakly fragmented toward apex, sutural stria present in apical three-fourths; elytral disk with conspicuous, disorganized punctures along apical margin; prosternal keel trunctate at base, carinal striae complete, free basally, united in rather broad anterior arch; prosternal lobe narrowed, subtruncate apically, with marginal stria obsolete at middle, but well impressed and diverging from margin to presternal suture at side in male, female prosternal lobe with fine marginal stria apically, not impressed at side; mesoventral margin shallowly emarginate, marginal stria interrupted; mesometaventral stria broadly arched forward on mesoventrite, reaching about one-third behind anterior margin, continued posterad by lateral metaventral stria to inner third of metacoxa; metaventral disk with ground punctation only; 1st abdominal ventrite with one complete lateral stria; propygidium with sparse but conspicuous ground punctation, small coarse punctures evenly interspersed, separated by 1–2× their diameters; pygidium with conspicuous ground punctation and few slightly coarser punctures intermixed; marginal pygidial sulcus well impressed, complete to base, interrupted apically in holotype, complete in paratype. Male genitalia (Figs 10E, H): accessory sclerites absent; T8 rather short, with sides subparallel in basal two-thirds, abruptly narrowed to apex, narrowly emarginate apically, with broad, shallow basal emargination, basal membrane attachment line distad basal emargination, ventrolateral apodemes nearly meeting at midline; S8 narrowed strongly to apex, apical guides narrow, only barely widening to apex, ventral halves weakly divergent; T9 with apices simple, pointed inward; T10 with halves fully separate; stem of S9 narrow, rounded basally, apical emargination narrow, apical flanges separate; tegmen short, broad, sides rounded, rather evenly curved dorsoventrally, medioventral process ‘U’-shaped, projecting beneath about one-fourth from base; median lobe about one-third tegmen length, proximal apodemes uniform; basal piece nearly one-half tegmen length.


The unique frontal stria of Operclipygus schlingeri (Fig. 8F) is sufficient to recognize it among Neotropical Exosternini.


We name this species for one of its collectors, Dr. Evert Schlinger, also in recognition of his support of entomology at the Santa Barbara Museum of Natural History.

Operclipygus kerga group

This group contains three more or less cryptic species, most easily distinguished by aedeagus shape. The most distinctive external character they share is a flat to moderately convex frons (Fig. 11B), with the central part of the frontal stria detached from the sides and present as a short transverse line, or completely absent. Nearly all other Operclipygus have the frons at least slightly depressed in the middle. In addition, they are characterized by the following characters: body rounded, moderately and evenly convex; disk of pronotum with few or no coarse lateral punctures; inner subhumeral stria more or less complete; pygidium with dense, fine ground punctation and variably few and sparse coarser punctures; pygidial marginal stria relatively weak, abbreviated at sides to almost absent in some species/individuals.

Key to the species of the Operclipygus kerga group
1 Marginal pygidial sulcus absent (Fig. 11D); pronotum lacking coarse lateral punctures Operclipygus planifrons sp. n.
Marginal pygidial sulcus present; pronotum with or without coarse lateral punctures 2
2 Marginal pygidial sulcus weak, often fragmented or abbreviated basally (Fig. 11C); aedeagus abruptly narrowed in apical third, its apices angulately truncate (Fig. 12G) Operclipygus punctistrius sp. n.
Marginal pygidial sulcus complete; aedeagus with sides evenly rounded to base and apex (Fig. 12F) Operclipygus kerga (Marseul)
Operclipygus kerga (Marseul, 1870)

Figs 11A–B, 12A–C, F, Map 3
Phelister kerga Marseul, 1870: 77; Pseudister kerga: Bickhardt 1917: 165; Operclipygus kerga: Wenzel 1976: 259.
Type locality.

Unspecified, somewhere along the Amazon in Brazil.

Type material.

Lectotype, here designated, of undetermined sex: “Phelister kerga, Amazon” / “LECTOTYPE Phelister kerga Marseul 1870, M.S.Caterino & A.K.Tishechkin des. 2010” (MNHN). This species was described from an unspecified number of specimens, and the lectotype designation fixes primary type status on the only known original specimen.

Other material.

BOLIVIA: Santa Cruz: 6: 4–5km SSE Buena Vista, Hotel Flora y Fauna, 17°29.9'S, 63°39.1'W, 15–24.xii.2003, FIT, S. & J. Peck (AKTC); 2: [country record only] (ZMHB). BRAZIL: Pará: 1: Monte Alegre, 3°9'S, 52°3'W,, 3.vii.1992, FIT (CHND); 1: 10–, FIT (CHND). 5: Tucuruí, 3°45'S, 49°40'W, 10–29.vii.1985, FIT (CHND); 1:, 7.vii.1986, FIT (CHND). FRENCH GUIANA: 1: Belvèdére de Saül, point de vue, 3°1'22"N, 53°12'34"W, 30.xi.2010, FIT, SEAG (CHND). PERU: Cusco: 1: Cock of the Rock Lodge, NE Paucartambo, 13°3.3'S, 71°32.7'W, 1120m, 4.xi.2007, 9.xi.2007, FIT, D. Brzoska (SEMC). 1: Manu rd. km 165, Consuelo, 10.x.1982, beating dead branches, L. Watrous & G. Mazurek (FMNH); 1: 12.x.1982, rotten palm, L. Watrous & G. Mazurek (FMNH). Junín: 4: Pampa Hermosa Lodge, 22km N San Ramon, 10°59.3'S, 75°25.5'W, 1220m, 24–27.xi.2007, FIT, D. Brzoska (SEMC). 1: 11km NE Puerto Ocopa, Los Olivos, 11°7.00'S, 74°15.52'W, 1200m, 26–28.iii.2009, Window trap, A.V. Petrov (AKTC); 1: 24–26.iii.2009, Window trap, A.V. Petrov (MUSM). 1: 7.5km NE Puerto Ocopa, Cananeden, 11°4.9'S, 74°16.1'W, 1180m, 11.i.2007, A.V. Petrov (AKTC); 1: 15km NW Satipo, Rio Venado, 11°11.709'S, 74°46.119'W, 1150m, 17–24.v.2012, A.V. Petrov, DNA Extract MSC-2322 (AKTC). Loreto: 2: km 63, rd. Iquitos - Nauta, Rio Itaya, 4°15.205'S, 73°26.074'W, 140m, 10–14.ii.2010, A.V. Petrov (AKTC). 1: 9–13.i.2011, A.V. Petrov (MUSM). Madre de Dios: 1: Los Amigos Field Sta., Luisa Bamboo forest, 12.5422°S, 74.1170°W, 274m, 2–11.i.2007, pitfall, bamboo forest, J. Jacobs (CASC). 1: Manu National Park, Zona res., Rio Manu, Cocha Juarez, trail nr. Manu Loge, 18–24.ix.1991, FIT, A. Hartman (FMNH). 16: Manu National Park, Pantiacolla Lodge, Alto Madre de Dios River, 12°39.3'S, 71°13.9'W, 420m, 14–19.xi.2007, FIT, D. Brzoska (SEMC). 1: Manu National Park, Pantiacolla Lodge, 5.5km NW El Mirador Trail, Alto Madre de Dios River, 12°39'10"S, 71°15'28"W, 500m, 23–26.x.2000, FIT, R. Brooks (SEMC). 6: Manu National Park, Cocha Cashu Bio. Sta., 11°53'45"S, 71°24'24"W, 350m, 17–19.x.2000, FIT, R. Brooks (SEMC). 2: Manu National Park, Cocha Salvador, 12°0'12"S, 71°31'36"W, 310m, 20–21.x.2000, FIT, R. Brooks (SEMC). 2: Tambopata, Reserva Cuzco Amazonico, 15km NE Puerto Maldonado, Quebrada Mariposa, 12°33'S, 69°03'W, 200m,, FIT, R. A. Leschen (SEMC). VENEZUELA: Monagas: 11: Caripe Cueva Guácharo, 700m, 20–30.vii.1987, malaise trap, forest over coffee, S. & J. Peck (FMNH).

Diagnostic description.

Length: 2.40–2.87 mm, width: 2.18–2.46 mm; body rounded at sides, moderately convex dorsally; frons slightly convex; frontal stria interrupted on each side; supraorbital stria complete across vertex, barely separated from portion of frontal stria in front of eyes; pronotum with lateral submarginal stria complete, free anteriorly; anterior submarginal pronotal stria present; median pronotal gland openings slightly behind anterior margin, near apices of recurved submarginal stria; pronotal disk with few or no coarse lateral punctures; antescutellar fovea present, small, ovoid; elytra with outer subhumeral, inner subhumeral, and striae 1-3 complete, striae 4 and 5 usually subequal, present in apical third to one-half, sutural stria present in apical two-thirds; prosternal keel striae convergent and connected anteriorly, keel projecting posteriorly; marginal mesoventral stria complete; mesometaventral stria outwardly arcuate, nearly in contact with marginal mesoventral stria at middle; central portion of metaventral disk impunctate, small fragment of secondary lateral metaventral stria generally present; propygidium uniformly covered with round punctures separated by one-fourth their diameters; pygidium with dense, fine ground punctation, with small but coarser punctures sparsely intermingled, apical marginal stria complete, finely crenulate. Male genitalia (Figs 12A–C, F): accessory sclerites present; T8 short, basal emargination broad, apical emargination narrow, basal membrane attachment line separated from basal emargination by one-third its depth, ventrolateral apodemes not meeting at midline, most strongly developed basally, narrowed toward apex; S8 with narrow apical guides gradually widened to apex, halves approximate in basal half, weakly diverging to apex; T9 with apices bluntly rounded, ventrolateral tooth well developed, just beyond midpoint; T10 halves separate; S9 narrowest near apex, expanded toward base, parallel sided in basal fourth, base truncate to weakly emarginate, lacking apical emargination, apical flanges separate; tegmen with sides evenly rounded to base and apex, medioventral process fine, narrowly rounded, weakly projecting beneath just basad midpoint; basal piece just less than one-third tegmen length; median lobe about one-half tegmen length.


Of two specimens in ZMHB, one bears a label ‘Phelister bimarginatus’, apparently in Bickhardt's handwriting. However, this is a nomen nudum. Presumably, Bickhardt intended to describe this species before deciding it was Operclipygus kerga.

The type locality is merely the Amazon region. Beyond that it is widespread in much of the Amazonian basin, except where it is replaced by its close relatives, described below.

Figure 11.

Operclipygus kerga group. A Dorsal habitus Operclipygus kerga (lectotype) B Frons Operclipygus kerga C Pygidia of Operclipygus punctistrius D Pygidia of Operclipygus planifrons.

Figure 12.

Male genitalia of Operclipygus kerga group. A T8 of Operclipygus kerga B S8 of Operclipygus kerga C S9 of Operclipygus kerga S9 of Operclipygus punctistrius E S9 of Operclipygus planifrons F Aedeagus, dorsal and lateral views, of Operclipygus kerga G Aedeagus, dorsal and lateral views, of Operclipygus punctistrius H Aedeagus, lateral view, of Operclipygus planifrons.

Map 3.

Records of the Operclipygus kerga group.

Type locality.

BOLIVIA: Cochabamba: 67.5 km E Villa Tunari, Valle Sajta Biological Station [17°6.3'S, 64°46.9'W].

Type material.

Holotype male: “BOLIVIA: COCHABAMBA 67.5km E Villa Tunari, Est. Biol. Valle Sajta, Univ. San Simon 300m, 17°06'19"S, 64°46'57"W, 7–9.II.1999, F. Génier, lowland rain forest, ex. f.i.t. 1 99-041” / “Caterino/Tishechkin Exosternini Voucher EXO-00095” (CMNC). Paratypes (36): all same locality as type, 9: same date as type, 25: 9–13.II.1999 (CMNC, FMNH, MSCC, AKTC).

Diagnostic description.

This species is difficult to separate from Operclipygus kerga by external characters. It is on average slightly smaller (length: 2.31–2.65 mm, width: 2.03–2.40 mm) and frequently has the sides of the pygidial marginal stria abbreviated, or present only as a disconnected series of punctures (Fig. 11C). Specimens must be dissected for definite identification, and the aedeagus is highly distinctive, with the tegmen abruptly narrowed in the apical third, having the apices angulately truncate, and with the medioventral process more narrowly rounded, but more strongly projecting beneath. In addition, S9 is more robust, with a wider, truncate base and wider lateral flanges, and is more strongly sclerotized.


This species may only be separated from Operclipygus kerga by the characters in the description, particularly by the form of the aedeagus (Fig. 12G).


. This species’ name refers to the frequent reduction of the pygidial sulcus to a series of marginal punctures.

Type locality.

ECUADOR: Orellana: Yasuní Research Station [0°40.5'S, 76°24'W].

Type material.

Holotype male: “Ecuador: Napo, mid.Rio Tiputini, Yasuní Res. Stn. 0°40.5'S, 76°24'W, FIT#3. 28Jun-5Jul 1999 AKT#049 C.Carlton & A.Tishechkin” / “LSAM 0013189” (FMNH). Paratypes (8): 1: same locality as type, 23.vii–4.viii.1999, FIT, A.K. Tishechkin (LSAM). ECUADOR: Orellana: 2:Yuturi Lodge, Rio Napo, 0°32'54"S, 76°2'18"W, 270m, 20–21.iii.1999, FIT, R. Brooks & D. Brzoska (SEMC). 1: Tiputini Biodiversity Station, 0.6376°S, 76.1499°W, 4–, FIT, M.S. Caterino & A.K. Tishechkin, DNA Extract MSC-2181 (SBMNH). Pastaza: 1: Cusuimi, Rio Cusuimi 150km SE of Puyo, 320m, 15–31.v.1971, beating & sifting rotten foliage, B. Malkin (FMNH). Sucumbíos: 1:Sacha Lodge, 0.5°S, 76.5°W, 270m, 14–24.iii.1994, malaise trap, Hibbs (SEMC). COLOMBIA: Putumayo: 2: Santa Rosa (Kofan Indian village): headwaters of Rio San Miguel, 16–20.x.1970, on fermenting stump of cut palm, B. Malkin & P. Burchard (FMNH).

Diagnostic description.

As with the previous, this species is nearly identical to Operclipygus kerga in external characters. It is very similar in size (length: 2.40–2.53 mm, width: 2.12–2.22 mm). The only consistent difference is the near complete absence of a pygidial marginal stria (Fig. 11D). In a few individuals some fragments of this stria are visible near the apex, but in most it is completely absent. The genitalia are also very similar to Operclipygus kerga, with a slightly narrower, more elongate S9 (Fig. 12E), and a tegmen that is slightly thicker dorsoventrally (as viewed in lateral aspect; Fig. 12H.)


This species may only be separated from Operclipygus kerga by the characters in the description.


This species’ name refers to its flat frons, shared generally by members of the Operclipygus kerga group.

Operclipygus conquisitus group

The three species in this group are united primarily by the presence of very dense ground punctation on atypical parts of the body (as opposed to its common presence on the pygidium in many Operclipygus). This punctation occurs on much of the body of Operclipygus bicolor and Operclipygus conquisitus, while it is much more restricted in Operclipygus friburgius. Support from other characters is hard to find, however, and the lack of a male of Operclipygus friburgius leaves some doubt as to its relationships.

Key to the species of the Operclipygus conquisitus group
1 Dense ground punctation limited to epistoma, prosternal lobe, prosternal keel, pygidium, and mesoventrite (Fig. 13E) Operclipygus friburgius (Marseul)
Dense ground punctation present on most body surfaces, including on pronotum and metaventrite (but excluding elytra) 2
2 Body bicolored (Fig. 13B), elytra reddish with rest of body rufo-brunneus; mesometaventral stria doubled, with one arch on mesoventrite and a parallel arch posterad mesometaventral suture (Fig. 12C) Operclipygus bicolor sp. n.
Body uniformly rufobrunneus; venter with single mesometaventral stria arched onto mesoventrite Operclipygus conquisitus (Lewis)
Operclipygus conquisitus (Lewis, 1902)

Figs 13A, 14A–D, Map 4
Phelister conquisitus Lewis, 1902: 235; Operclipygus conquisitus: Wenzel (1976: 257).
Phelisteroides ruptistrius Wenzel, 1944: 141; synonymized by Wenzel (1976: 257).
Type locality.

BRAZIL: Pará: Santarém [2°26'S, 54°42'W].

Type material.

Phelister conquisitus: Type missing. Published type locality: “Ulster Co. N.Y.” [in error!]; Neotype male, here designated: “Santarem” (BMNH). This specimen was determined by Hinton, himself having apparently studied Lewis's type before its loss (Hinton 1935a: 588). Phelisteroides ruptistrius: Holotype: (CMNH), not examined. Paratype: “Santarem Brazil, Acc. No. 2966” / Dec. (FMNH), examined, 2010.

Other material.

BRAZIL: Mato Grosso: 1: Claudia, 11°24.5'S, 55°19.5'W, 17–27.x.2010, FIT, A.F. Oliveira (CEMT). ECUADOR: Orellana: 1:Res. Ethnica Waorani, 1km S Onkone Gare Camp, Trans. Ent., 0°39'10"S, 76°26'W, 220m, 6.vii.1995, fogging, T.L. Erwin (USNM). PERU: Loreto: 1: Iquitos - Nauta rd., km 58, Rio Itaya, 4°15.738'S, 73°28.052'W, 120m, 5–9.v.2009, Window trap, next to entrance, Eciton burchelli statary bivouac in hollow treee, A.V. Petrov (AKTC). 3: 68km SW Iquitos to Nauta, Rio Itaya, 4°11'S, 73°26'W, 110m, 1–3.iii.2008, A.V. Petrov (AKTC). 3: 26–30.ii.2008, A.V. Petrov (AKTC). 4: 18–19.i.2008, A.V. Petrov (AKTC, FMNH). 1: 9.ii.2007, A.V. Petrov (MUSM). 2: 1–5.iii.2008, A.V. Petrov (MUSM). 1: Left bank of Rio Amazonas 70km SSW Iquitos to Nauta, 140m, 25.ii.2008, A.V. Petrov (AKTC). 3: km 63, rd. Iquitos - Nauta, Rio Itaya, 4°15.205'S, 73°26.074'W, 140m, 9–13.i.2011, A.V. Petrov (AKTC). 4: 8–17.i.2010, A.V. Petrov (AKTC, MUSM). 1: 10–14.ii.2010, A.V. Petrov (AKTC).

Diagnostic description.

Length: 2.00–2.34 mm, width: 1.68–2.00 mm; body ovoid, widest behind middle, rufobrunneus, with fine, dense ground punctation on frons, pronotum, and all sterna. Frons and epistoma convex; frontal stria present only along inner edge of eye, absent across front, not joining fine supraorbital; pronotum with marginal stria complete across anterior margin; lateral submarginal pronotal stria complete at side, curving inward at front but ending freely; anterior submarginal stria crenulate, weakly recurved at sides; pronotal disk with few larger punctures towards sides; median pronotal gland openings difficult to detect amidst ground punctation, but present about one-third of pronotal length behind anterior margin, directly behind ends of anterior submarginal stria; elytra with one complete epipleural stria, outer subhumeral stria present in apical half, inner subhumeral stria absent, striae 1-3 complete, 4th present in basal half, arched inward at base but not reaching sutural stria, also represented by apical fragments, occasionally complete, 5th stria only present in apical fourth, often fragmented, sutural stria in apical 2/3; elytral disk with narrow band of small punctures sparsely scattered along apical margin; prosternal keel broad, flat, truncate at base, carinal striae evenly convergent, joined by broad anterior arch and fine basal line; prosternal lobe with marginal stria complete, strongly impressed; anterior margin of mesoventrite shallowly, inwardly arcuate, not distinctly emarginate, marginal stria complete; mesometaventral stria narrowly arched to midpoint of mesoventral disk, crenulate, posteriorly extending toward inner third of metacoxa; 1st abdominal ventrite with inner lateral stria complete, outer abbreviated posteriorly; propygidium with fine, rather sparse ground punctation, with small ocellate punctures irregularly separated by about their diameters, denser toward base; pygidial ground punctation fine, moderately dense, additional small punctures very sparsely interspersed; apical sulcus fine but nearly complete to base. Male genitalia (Fig. 14A–D): accessory sclerites present, small; T8 short, sides weakly convergent, rounded, angled in to apex, apical emargination narrow, basal emargination deep, broad, meeting basal membrane attachment line at apex, ventrolateral apodemes most strongly developed at base, narrowing to apex; S8 with sides divergent in apical third, apical guides strongly developed in apical half, apices broad and bluntly rounded, with several conspicuous apical setae, ventral halves separate throughout length, diverging slightly apicad; T9 with sides parallel in basal half, converging to narrow, subacute opposing apices; T10 with halves separate; S9 with stem narrowest near midpoint, rather abruptly widened to broadly subtruncate base, apical margin with very shallow median emargination, apical flanges short and separate; tegmen widest just beyond midpoint, abruptly narrowed toward apex, then widened, apices obliquely truncate, apical third of tegmen abruptly bend downward, medioventral process weak, very narrowly ‘U’-shaped, barely projecting beneath, about one-third from base; basal piece about one-third tegmen length; median lobe also about one-third tegmen length, with filamentous stems of proximal apodemes very short.


The presence of very conspicuous fine, dense ground punctation on the head, pronotum (Fig. 13A), and sterna is unique to this species.

The published type locality of Ulster Co., New York, USA has been convincingly discredited (Hinton 1935a), and the species is instead known to occur in Amazonian parts of South America. The type specimen was deposited at BMNH along with Lewis's collection, and the pin, point, and original labels are present in that collection. However, no specimens corresponding to the species distinctive characters have been found. One of us (MSC) was resident at BMNH during the conversion of the histerid collection from slats to unit trays, and a thorough search was conducted at that time (year 2000). Wenzel's synonymous Operclipygus ruptistrius, which agrees in all respects with Operclipygus conquisitus, was described from this area, as well.

Figure 13.

Operclipygus conquisitus group. A Dorsal habitus of Operclipygus conquisitus B Dorsal habitus of Operclipygus bicolor C Metaventrite of Operclipygus bicolor D Dorsal habitus of Operclipygus friburgius E Ventral habitus of Operclipygus friburgius.

Map 4.

Records of the Operclipygus conquisitus group.

Figure 14.

Male genitalia of Operclipygus conquisitus group. A T8 of Operclipygus conquisitus B S8 of Operclipygus conquisitus C S9 of Operclipygus conquisitus D Aedeagus, dorsal and lateral views, of Operclipygus conquisitus E Aedeagus, dorsal and lateral views, of Operclipygus bicolor.

Type locality.

FRENCH GUIANA: Itoupé Table Mountain [3°1.38'N, 53°5.73'W].

Type material.

Holotype male: “GUYANE FR., Mont tabulaire Itoupé. 3°1.38'N, 53°5.73'W. 570 m. Piège d’interception, 17 Mar 2010. SEAG leg.” / “Caterino/Tishechkin Exosternini Voucher EXO-00548” (MNHN). Paratypes (14): FRENCH GUIANA: 8: same data as type (CHND, FMNH, MSCC, AKTC). 4: same locality as type, 24.iii.2010, FIT, SEAG (CHND), 1: 31.iii.2010, FIT, SEAG (CHND). 1: Route de l’est, après la riviere Comté, 4°39'N, 52°20'W, 7.i.1978, G. Nazaret (CHND).

Diagnostic description.

This species is very similar in many respects to Operclipygus conquisitus, especially in the presence over much of the body of dense ground punctation. It is described only to the extent that it differs here: length: 1.97–2.18 mm, width: 1.65–1.87 mm; frons with central part of frontal stria present; pronotum lacking dense ground punctation, median pronotal gland openings just beyond apices of weakly recurved anterior submarginal stria, only about 8 puncture widths from anterior margin; elytra distinctly reddish, darkened slightly along suture; base of prosternal keel weakly emarginate; mesoventrite weakly projecting; marginal mesoventral stria complete; metaventrite with secondary anterior stria, parallel to mesometaventral stria, but just reaching to mesometaventral suture; pygidium with coarse, secondary punctures slightly denser than in Operclipygus conquisitus. Male genitalia (Fig. 14E): accessory sclerites present, not unusually small; T8 with sides weakly convergent in basal two-thirds, angulate to narrow apex, apical emargination narrow, basal emargination broadly rounded, basal membrane attachment line distad by about one-half emargination depth from its apex, ventrolateral apodemes symmetrical anteriorly and posteriorly, nearly meeting at midline; S8 with sides parallel, apical guides narrow, widended to apex, apices subtruncate, ventral halves approximate in basal fourth, weakly diverging to near apex; T9 with apices subacute, slightly convergent; T10 with halves separate; S9 with stem narrowed at middle, widened to basal fourth, basal sides subparallel to truncate base, head with lateral flanges rather broad, apex lacking median emargination, apical flanges narrowed at middle, but continuous; tegmen narrow, parallel-sided in basal half, strongly narrowed to subacute apex, apical third bent ventrad, with thin ‘U’-shaped medioventral process projecting beneath about one-fourth from base; basal piece nearly one-half tegmen length; median lobe slightly over one-half tegmen length, proximal apodemes undifferentiated, thin and separate.


The red coloration of the elytra (Fig. 13B) of Operclipygus bicolor is practically sufficient for identification. There are very few bicolored histerids in the Neotropics, and even fewer Exosternini. This character, in addition to the dense ground punctation of the head and sterna allow confident identification of this species.


This species’ name refers to its bicolored appearance.