The enigmatic beetle tribe Nototylini (Carabidae) is revised and a key to species is provided. Two species from South America are included in the genus. One species, Nototylus fryi (Schaum), is reviewed and a second, Nototylus balli Erwin & Kavanaugh, sp. nov., is described as new. Each species is known from a single specimen, neither of which is in good condition. The possible function of what appears to be a unique antennal grooming structure on the front femur is discussed.

La tribu enigmática de escarabajos Nototylini (Carabidae) se revisa y se provee una clave para las especies. Dos especies de América del Sur están incluidas bajo este género. Se revisa una especie, Nototylus fryi (Schaum), y una segunda, Nototylus balli sp. nov., se describe como nueva. Ambas especies se conocen de un solo espécimen, ninguno de los cuales está en buenas condiciones. Se discute la posible función de lo que aparece ser una estructura para acicalamiento antenal el fémur anterior.

Une révision taxonomique de la tribu énigmatique de coléoptères Nototylini (Carabidae) est présentée et une clé pour l’identification d’espèces est fournie. Deux espèces d’Amérique du Sud sont incluses dans le genre. Une espèce est examinée (Nototylus fryi (Schaum)) et, une deuxième est décrite comme nouvelle espèce (Nototylus balli sp. nov.). Chaque espèce est connue à partir d’un seul spécimen dont aucun est en bon état. La possible fonction de ce qui semble être une structure de toilette antennaire sur le pro-fémur est discutée.

Uma enigmática tribo de besouros, Nototylini (Carabidae), é revisada, e uma chave para as espécies de Nototylus é fornecida. O gênero agora inclui duas espécies: Nototylus fryi (Schaum), aqui redescrita, e Nototylus balli sp. nov., descrita como nova. Ambas são conhecidas por somente um espécimen em mal estado de conservação. Discute-se a função de uma estrutura singular do femur anterior, possivelmente usada na escovagem da antena.

Brazil, French Guiana, rainforest, antennal comb

Brasil, Guyana Francesa, bosque lluvioso, peine antenal

Brésil, Guyane, forêt tropicale, structure de toilette antennaire

Brasil, Guiana Francêsa, floresta tropical, pente antenal

The affinities of the taxon Nototylus as described by Schaum in 1863 (under the preoccupied name Tylonotus) based on a single specimen have posed a conundrum for carabidologists since Schaum’s time. Complicating the interpretation of the form and structure of this unique specimen is the fact that its poor initial preservation has led to its almost complete disarticulation during subsequent studies (see Deuve 1994).

It has been reported that, unlike all other carabid beetles except highly evolved Paussini adults, adults of Nototylus fryi (Schaum), the type species of the genus, have no antennal cleaner on the anterior tibia, hence the origin of a long-standing debate about whether or not it belongs in the family Carabidae (Deuve 1994). Although Schaum’s original description made no mention of an antennal cleaner, nor was one shown in his illustrations, and Deuve (1994) made no mention of an antennal cleaner in his fine overall redescription, Erwin (1979, 2011) noted that the overall shape of the beetle is very ozaenine-like. Throughout their evolutionary history, carabid beetles have made sure that their antennae are kept clean, mainly through the development of combing structures (“antennal cleaners”) on the front legs, typically on the front tibiae. The selection pressure of ants on the Paussinae (including Ozaenini) and termites on taxa such as the Orthogonini has resulted in incredible transformations in carabid adult structures, so if Nototylus is another ant- or termite-associated group, then the “loss” of an antennal comb from the protibia would not be surprising (Fig. 1; Deuve 1994: fig. 11).

We here report on a second Nototylus specimen, one in somewhat better condition and representing a second species. This specimen, together with a re-examination of Schaum’s original specimen, permits us to report that there does indeed appear to be an antennal grooming structure present in Nototylus adults, but one in a different place and perhaps having a different function than is typical for a carabid. The purpose of this paper is to describe this new species and thereby confirm that the tribe Nototylini is still extant, at least in undecimated tropical forests in French Guiana. Nototylus fryi was described from the Brazilian State of Espíritu Santo, which is now mostly sugar cane fields, cacao plantations, and cattle ranches; and it has been considered that this species is likely now extinct (but see notes below).

This study is based on the examination of the only two Nototylus specimens known. Codens used in the text for institutions in which data or specimens are deposited (with names of curators in parentheses) are as follows:

NHMUK The Natural History Museum, London, United Kingdom (Beulah Garner);

NMNH National Museum of Natural History, Smithsonian Institution, Washington, DC, USA (Terry L. Erwin).

Methods and species concepts follow Erwin and Kavanaugh (1981) and Kavanaugh and Erwin (1991). The diagnosis and description format follow as closely as possible that suggested in Erwin and Johnson (2000). Measurements of length (ABL, SBL) and width (TW) follow those suggested by Ball (1972) and Kavanaugh (1979): ABL (apparent body length), measured from apex of labrum to apex of longer elytron; SBL (standardized body length), equals the sum of the lengths of the head (measured from apex of clypeus to a point on midline at level of the posterior edge of compound eyes), pronotum (measured from apical to basal margin along midline), and elytron length (measured from apex of scutellum to apex of the longer elytron); and TW, (total width), measured across both elytra at their widest point.

The images provided of the adult beetles described herein show most of the character states referred to in the description. The habitus images of the adult were made with a Visionary DigitalTM high resolution imaging system. Figures are all of the holotypes. The ADP number, which is a unique identification number for the specimen, links the specimen and associated illustrations and/or image to additional information in electronic databases at the National Museum of Natural History, Smithsonian Institution in Washington, DC (NMNH).

The photograph of a mesotibia and its setae were taken with a Leica Z6Apo lens and DMC4500 camera, and the close-up photograph of the setal apex with a Leica DM5500B compound microscope and DMC425C camera. Leica Application Suite v4.9 software was used to capture each image, and stacks of images from different focal positions were merged using the PMax procedure in Zerene Systems’ Zerene Stacker.

Geographical data of the new species were provided by the collector. A map (Fig. 9) indicates where the exact locale is in French Guiana. An English vernacular name also is proposed here because common names are becoming increasingly needed in conservation and/or agricultural and forestry applications.

The setae in the profemoral grooming structure of the two specimens of Nototylus are unlike those seen in the protibial antennal cleaners of all other carabids. Here, they are long, slender, flexible, and apically ovospatulate (Fig. 8), whereas those of antennal cleaners of other carabids are stout, not or barely flexible, and sharply pointed apically. This suggests that the profemoral grooming structure seen here may have a somewhat different function than the protibial antennal cleaner of other carabids, the function of which is clearly seen when watching carabids groom themselves. The location of the profemoral structure in Nototylus is certainly one suitable for grooming the antenna; but the form and flexibility of these setae appear more suited to painting or coating the antenna than to scraping or cleaning it. Coupled with the occurrence of similar ovospatulate setae on the ventral surface of the protibia and the ventromedial surface of the mesotibia, it seems more likely that these setae function in applying or at least spreading some substance over the antennae and other parts of the body. The source of such a hypothetical substance is unknown, and we observed no structures, such as the variously located secretory trichomes seen in most if not all other carabids (and other beetles) that live with ants or termites.

These other colony “guests” use such substances to gain acceptance within the host colony. If our hypothesis that Nototylus live with ants or termites is correct, then the observed grooming structure and unusual setae may help to facilitate this symbiotic relationship. Clearly, we need to find and observe a living Nototylus adult to see how these structures are used.

We had hoped, with this new specimen, to gather both molecular data and morphological data for nototyline male genitalia for the first time. Each of these data types could have led us to a better understanding of tribal relationships. Unfortunately, upon dissection the new specimen also turned out to be a female, as is the single known specimen of N. fryi (well-illustrated by Deuve 1994). Even more disappointing was the failure of our attempts to extract and sequence DNA from the specimen; these attempts will be reported in a separate publication. Consequently, we are no closer to understanding nototyline phylogenetic relationships than we have been for the last century and a half. At least we now know that this enigmatic group is still extant and that finding additional, fresh specimens, ideally even live specimens, is a real and most desirable possibility.

We thank Beulah Garner, at the Natural History Museum in London for the loan of the holotype of N. fryi Schaum, and also extend a hearty thanks to Charyn Micheli (for the map, and friendly review of the manuscript) and Karolyn Darrow (for the images and plate design), both of the Department of Entomology, National Museum of Natural History, at the Smithsonian Institution in Washington DC. We also warmly thank Charyn Micheli for the translation of the Abstract into Spanish, Laura S. Zamorano for the translation of the Abstract into French, and Wayne Mathis and Alessandra Rung for the translation of the Abstract into Portuguese. Wendy Moore, University of Arizona, Tucson, provided a very helpful review of the manuscript. We are also indebted to JL Giuglaris the collector and Allen Albert, who received the specimen of our new species from the collector, recognized it through comparisons with on-line images of N. fryi and then made the specimen available to us for description and molecular analysis, as well as deposit in a public museum (NMNH).