Synopsis of the Argentinian scarab genus Pseudogeniates Ohaus (Coleoptera, Scarabaeidae, Rutelinae)

Abstract The scarab beetle genus Pseudogeniates Ohaus (Scarabaeidae: Rutelinae: Rutelini) is endemic to Argentina. The genus includes three species: Pseudogeniates cordobaensis Soula, Pseudogeniates intermedius Ohaus, and Pseudogeniates richterianus Ohaus. We characterize the genus, provide a key to species, redescribe and diagnose each species, provide spatial and temporal distributions, and discuss distributions of the species in relation to eco-regions and areas of endemism in Argentina.

Pseudogeniates species are moderate-sized (12-19 mm), elongate-oval, brown scarabs with striate elytra (Figs 1-3). In many respects, species in the genus are similar in overall gestalt to species in the genus Geniates Ohaus (Rutelinae: Geniatini) or drabcolored species in the genus Anomala Samouelle (Rutelinae: Anomalini). Actually, however, form of the labrum, elytra, protibia and tarsomeres, and position of the terminal spiracle, place the genus in the tribe Rutelini (Rutelinae) (see "Classification"). Female gender bias in the most wide-spread species and the fact that specimens are rarely encountered in collections have both contributed to the difficulty in circumscribing species in the genus. Our work revealed a high degree of intraspecific variation that may be due to spatial or temporal isolation of populations. Thus, in addition to rarity and sex bias, circumscription of species is complicated by variation in character states. Heretofore, there has been no comprehensive review of species in the genus. This research provides a synopsis of the three species in the genus and information on the distribution of these poorly studied species. taxonomic history Ohaus (1910) named the genus Pseudogeniates for one species, P. richterianus Ohaus, and he based the description on female specimens alone. He puzzled over classification of the genus, discussing its affinities with the ruteline tribes Geniatini and Anoplognathini. Both of these tribes are orthochilous rutelines, that is, they belong to a broad group of Rutelinae in which the mouthparts (specifically labrum and mentum) project vertically with respect to the head (Ohaus 1918(Ohaus , 1934Machatschke 1965;Jameson and Hawkins 2005). Based on overall gestalt and proportions of the "hind body", Ohaus (1910) compared P. richterianus with Geniates barbatus Kirby and G. cylindricus Burmeister (both Geniatini from South America). He also compared the genus with Saulostomus weiskei Ohaus and S. felschei Ohaus (both Anoplognathini from Australia) based on the form of the mouthparts. The form of the clypeus and mouthparts were so unusual that when Ohaus first saw specimens, he "believed that the animal was crippled" (Ohaus 1910: 179). After studying two additional female specimens from a different locality, Ohaus realized that these peculiarities were not teratological. Despite lacking male specimens, he described P. richterianus, but he declined placing the new genus and species in a ruteline tribe, stating that this would require additional characters from male specimens (Ohaus 1910).
After obtaining additional specimens of Pseudogeniates and making comparisons with other Argentinian fauna, Ohaus (1914) placed the genus in the tribe Rutelini (Rutelinae), a tribe of homalochilous rutelines that is characterized by the labrum that is horizontally produced with respect to the clypeus. He discussed affinities of Pseudogeniates with Homonyx Guerin and Parhomonyx Ohaus, both of which are distributed in southern South America and both members of the subtribe Pelidnotina. Based on both male and female specimens, Ohaus (1914) described a new species, P. intermedius. Ohaus characterized the two species using differences in the form of the clypeus and antennae: P. richterianus possessed nine-segmented antennae (thus differing from all other Rutelini) and P. intermedius possessed ten-segmented antennae (the hypothesized ancestral state within the Rutelini). The antennal character state in P. richterianus make this species an exception in the key to tribes of Rutelinae (see Jameson 1990Jameson , 2005. However, Ohaus did not have a broad enough sampling of specimens of P. richterianus to understand the intraspecific variation of this character: antennae are either 9-or 10-segmented in P. richterianus. This variation has confounded identification of Pseudogeniates species. The Genera Insectorum on the Rutelini (Ohaus 1934) languished for more than 20 years before publication. Realizing the great delay, Ohaus (1915) published his concepts of higher taxa and descriptions of genera. He formalized use of the subtribe Pelidnotina (as "Pelidnotinorum") and commented on evolution and affinities of Pseudogeniates, Parhomonyx, and Homonyx. He considered Parhomonyx to be an "intermediate stage" that "led Homonyx to Pseudogeniates" (Ohaus 1915: 258), and that characters of the coloration, clypeus, mouthparts, elytra, hind tibia, and antennae indicated these relationships (or this progression of forms). He thought that these taxa were a good example of how differences in rainfall (dry versus wet; e.g., Ponce et al. 2002) and differences in habitat (forest versus steppe) produced adaptations and changes in morphological characters. He also stated that the Argentinian fauna offered a number of examples of these evolutionary transformations, particularly in scarab beetles.
Nearly 100 years after Ohaus' work on Pseudogeniates, Soula (2009) reviewed the genus based on six specimens in the Ohaus collection (housed at ZMHB), described a new species, P. cordobaensis, based on specimens from the type series of P. intermedius (which included three males and one female specimen), described the type specimens for each of the species of Pseudogeniates, and commented briefly on the unusual character states of the genus. Soula's species descriptions are not comparative; they do not allow separation and identification of species in the genus; and, because they are based on a limited number of specimens, they do not take into account variation within the species. In addition, Soula (op. cit.) did not provide a key to species and diagnoses. For these reasons, Soula's work is of little utility for identification and understanding of biodiversity of this group.

Definition of taxonomic characters and character examination
This research is based on 56 specimens from collections including type specimens. About one third of these specimens (19 specimens) were identified in collections; the remaining two thirds were not identified. Out of the 19 specimens that were identified, 9 were incorrectly identified, 4 were correctly identified, and 6 were type specimens. Two specimens were incorrectly identified to genus. Specimens for this research are deposited at the CMNC (Canadian Museum of Nature Collection, Ottawa, Canada), FMNH (Field Museum of Natural History, Chicago, Illinois, USA); IAZA (Instituto Argentino de Investigaciones de Zonas Áridas, Mendoza, Argentina); MACN (Museo Argentino de Ciencias Naturales, Buenos Aires, Argentina); MLJC (Mary Liz Jameson collection, Wichita, Kansas, USA); UCCC (Universidad de Concepción, Concepción, Chile); USNM (United States National Collection, Washington, D.C., USA); and ZMHB (Museum für Naturkunde der Humboldt Universitat zu Berlin, Berlin, Germany).
Morphological characters formed the basis of this work. The broadest range of potentially phylogenetically informative morphological characters was used for morphological analyses and comparisons. For measurements, we used an ocular micrometer. Body measurements, puncture density, puncture size, and density of setae are based on the following standards. Body length was measured from the apex of the clypeus to the apex of the pygidium. Body width was measured at the widest width of the elytra. Puncture density was considered 'dense' if punctures were nearly confluent to less than two puncture diameters apart, 'moderately dense' if punctures were from two to six puncture diameters apart, and 'sparse' if punctures were separated by more than six puncture diameters. Puncture size was defined as 'small' if punctures were 0.02 mm in diameter or smaller; 'moderate' if 0.02-0.07 mm, 'moderately large' if 0.07-0.12 mm, and 'large' if 0.12 mm or larger. Setae density was defined as 'dense' if the surface was not visible through the setae, 'moderately dense' if the surface was visible but with many setae, and 'sparse' if there were few setae. It should be noted that setae are subject to wear and may be abraded away. Elytral discal striae are defined as the striae located between the elytral suture and the elytral humerus. The interocular width measures the number of transverse eye diameters that span the width on the frons between the eyes. This was measured by placing the ocular micrometer in a position such that it intersects the frons and eyes (dorsal view), focusing on the surface of the frons, and then measuring the width of the frons and width of the eyes without adjusting the focus. Mouthparts, wings, and genitalia were examined and card-mounted beneath the specimen. Some specimens were quite fatty, with internal and external greasy build-up. These specimens were cleaned in acetone prior to dissection.
Characters and specimens were observed with 6-48× magnification and fiber-optic illumination. Digital images of specimens and structures were captured using the Leica Application Suite V3.8. Images were edited in Adobe Photoshop CS2 (background removed, contrast manipulated).
Species are characterized by combinations of characters including the form of the mentum and maxilla, form of the metacoxa, and form of the ventral plate of the male parameres. We use the phylogenetic species concept (Wheeler and Platnick 2000) in this work: "A species is the smallest aggregation of (sexual) populations or (asexual) lineages diagnosable by a unique combination of character states." Specimen localities were translated into latitude and longitude using GoogleEarth (http://www.google.com/earth/index.html). Maps were generated by entering these data into Microsoft Excel 2008 and uploaded to EarthPoint (http://www.earthpoint.us/Excel-ToKml.aspx) and GoogleEarth (Supplementary File: Pseudogeniates Locality Table.xls). These tools allow for interactive mapping and addition of data by subsequent users. Description of Argentinian eco-regions follows Ponce et al. (2002). Argentinian areas of endemism follow Cabrera and Willink (1973) and Szumik et al. (2012). Tribal classification. The genus Pseudogeniates is a member of the tribe Rutelini. In overall appearance, however, species in the genus Pseudogeniates are similar to species in the genera Geniates (Geniatini) and Anomala (Anomalini). Species in the genus Pseudogeniates can be separated from both of these tribes based on the margin of the elytra that lacks an obvious membranous border (membranous border present at the elytral apex in both Geniatini and Anomalini). Additional characters that separate the Rutelini and Geniatini include: the labrum that is horizontally produced with respect to the clypeus in the Rutelini (vertically produced in the Geniatini) and protarsomeres that are subcylindrical and lacking ventral setose pads (dorsoventrally flattened and densely setose ventrally in the Geniatini). Additional characters that separate the Rutelini and Anomalini include: protibia with inner, protibial spur apical in the Rutelini (inner, apical spur subapical in Anomalini) and terminal spiracle positioned in pleural suture in the Rutelini (terminal spiracle not positioned in pleural suture in Anomalini). For a key to tribes of Rutelinae, see Jameson (1990Jameson ( , 2005. Subtribal classification. Ohaus (1915Ohaus ( , 1934 placed the genus Pseudogeniates in the tribe Rutelini and subtribe Pelidnotina. Based on morphological data, this subtribe was demonstratively paraphyletic and it was eliminated (Jameson 1998). Soula (2009), without justification or discussion, continued use of this higher-level taxon for the genus. We consider the genus Pseudogeniates to be a member of the tribe Rutelini (without subtribal designation).
Phylogeny. Sister group relationships have not been examined for the genus or for species within the genus.
Similar taxa. Species in the genus Pseudogeniates share several characters with Parhomonyx fuscoaeneus Ohaus, a monotypic taxon that is also endemic to southern South America. The following characters are shared: fringe of setae at apex of elytra, mesosternal process lacking, mandible with one external tooth, elytra striate, and claws simple. However, Pseudogeniates differs from Parhomonyx based on the external margin of the mandible that is straight (external margin lobe-like in Parhomonyx), maxillary teeth lacking (maxilla with well developed teeth in Parhomonyx), maxillary palp rod-shaped (broadly elliptical in Parhomonyx), and fifth tarsomere on all legs of males and females lacking an internal tooth (with two well developed internal teeth on the fifth mesoand metatarsomeres of males and females of Parhomonyx).
Biology. Very little is known of the biology of the species in the genus. Males and females are attracted to lights at night. Based on the extreme wear on the protibia of some specimens, individuals probably are associated with soil and use their front appendages for digging.

Key to species of Pseudogeniates
Diagnosis. Pseudogeniates cordobaensis is separated from other species in the genus by the pentagonal form of the mentum (width subequal to length) that has the inner apex projecting anteriorly and has an inner shelf (Fig. 8). In comparison, the form of mentum is longer than wide in P. intermedius and P. richterianus (Figs 9-10). In P. intermedius, the inner apex of the mentum does not project anteriorly, but does possess an inner shelf (Fig. 9); in P. richterianus, the inner apex projects anteriorly, but does not possess an inner shelf (Fig. 10). The ventral plate of the male parameres in P. cordobaensis is nearly as long as dorsal plate with sides converging to a quadrate apex (Fig.  19). The ventral plate of P. richterianus is about half the length of the dorsal plate (Fig.  21), whereas in P. intermedius the ventral plate is nearly as long as the dorsal plate, but the sides converge with a weak constriction preapically and a rounded apex (Fig. 20). Distribution (Fig. 22). Pseudogeniates cordobaensis is distributed in the Monte de Sierras y Bolsones in the Monte eco-region in Argentina. The distribution of this species coincides with the Montane Forest region (Navarro et al. 2009) and the Yungas Forest area of endemism in Argentina (Szumik et al. 2012). Temporal data. December (9). Remarks. The holotype specimen for this species was part of the type series for P. intermedius, a series that included three specimens from Santiago del Estero and one specimen (=P. cordobaensis) from Huerta Grande in the Sierra de Cordóba, Córdoba Province (Ohaus 1914).
Diagnosis. Pseudogeniates intermedius is known from only three specimens. It is separated from other species in the genus by the form of the mentum (Fig. 9) and the form of the male parameres (Fig. 20). It is distinguished from P. cordobaensis by the form of the mentum (longer than wide and subtrapezoidal in P. intermedius [ Fig. 9]; length subequal to width and pentagonal in P. cordobaensis [Fig. 8]) and apex of the ventral plate of the male parameres (with a weak constriction preapically and a rounded apex in P. intermedius [Fig. 20]; lacking preapical constriction and with quadrate apex in P. cordobaensis [ Fig. 19]). It is separated from P. richterianus by the apex of the mentum (with an inner shelf in P. intermedius; lacking inner shelf in P. richterianus [ Fig. 9 versus Fig. 10]) and length of the ventral plate of the male parameres (nearly as long as dorsal plate in P. intermedius [Fig. 20]; half length of dorsal plate in P. richterianus [ Fig. 21]). Distribution (Fig. 22). Pseudogeniates intermedius is distributed in the Chaco-seco eco-region in Argentina. Temporal data. December (1). Natural history. This species is known from two male specimens and one female specimen, and the natural history is not known.
Diagnosis. Pseudogeniates richterianus is a highly variable species. Variation is observed in the antenna (9-or 10-segmented), labrum (weakly or moderately emarginated), length of antennal club (subequal to slightly longer then the stem), elytral apex (spiniform, quadrate, rounded, or obtusely angled), pronotal medial line (weak or obsolete), and form of the clypeus. However, several characters reliably separate this species from others in the genus. Pseudogeniates richterianus is separated from P. intermedius and P. cordobaensis by the form of the mentum (rectangular and without inner shelf in P. richterianus [ Fig. 10]; subtrapezoidal and with inner shelf in P. intermedius [ Fig. 9]; pentagonal and nearly as wide as long in P. cordobaensis [ Fig. 8]), ventral plate of the parameres (half length of the dorsal plate in P. richterianus [Fig. 21]; nearly as long as dorsal plate in P. intermedius and P. cordobaensis [Figs 20 and 19, respectively]), metacoxal corner in female (rounded in P. richterianus; square in P. intermedius and in P cordobaensis), and posterior margin of the metacoxa (not produced posteriorly in P. richterianus; produced posteriorly in P. intermedius and P. cordobaensis). Distribution (Fig. 22). Pseudogeniates richterianus is the most wide-spread species in the genus. It is distributed in the Pampa, Espinal, and Monte de Llanuras y Mesetas Temporal data. November (5), January (3), February (1). Natural history. Based on specimens in collections, there is a female sex bias in this species (24 females: 4 males). Many specimens (male and female) have worn protibiae (Fig. 13), indicating that adults dig in abrasive soil. Label data indicate that this species was collected at mercury vapor light and at 500 m elevation.
Remarks. Ohaus (1914) distinguished P. richterianus from P. intermedius based characters that vary within the species (see "Remarks" for P. intermedius), including number of antennal segments, form of the clypeus, and coloration. Although these characters are unreliable for diagnosis of the species, we provide characters that are useful (see "Diagnosis"). Ohaus (1910) named the species in honor of Herr Hans Richter from Buenos Aires.

Discussion
Species in the genus Pseudogeniates exhibit a great deal of character variation, thus causing historical difficulty with circumscription of the species. Variation in the number of antennomeres, length of the antennal club, and form of the clypeal apex, labrum, elytral apex exhibit intraspecific variability. Variation of this degree is not unprecedented within the Scarabaeoidea. In particular, species associated with high elevations (e.g., Parabyrsopolis Ohaus) and species associated with arid habitats (e.g., Anomiopsoides heteroclyta (Blanchard), Eucranium arachnoides Brullé [both Scarabaeinae], and Allidiostoma hirtum Ohaus [Allidiostomatinae]) are known to possess broad intraspecific variation (Jameson 1990, Ocampo 2007. In some populations, individuals of Parabyrsopolis chihuahuae (Bates) exhibit a wide range in clypeal shapes (quadrate or parabolic, reflexed or not) (Jameson 1990). Individuals of A. heteroclyta exhibit high variability in clypeal shapes and clypeal processes, as well as variation in pronotal sculpture (puncture shape and density) (Ocampo 2007). Species in the Mexican genus Parachrysina Bates are unusual in that some species have 8-segmented antennae and others have 9-segmented antennae (Jameson 1991). Molecular analysis of species of Pseudogeniates, as well as other highly variable species, may reveal underlying mechanisms for high intraspecific variation.
High intraspecific variation may have been the product of historical climatic and concomitant habitat fluctuations. During the Pleistocene, climatic fluctuations in northern Argentina may have resulted in broad regions being inhabited by Yungas forests (reaching to Córdoba province in the south) (Navarro et al. 2009). Subsequently, these forests have been replaced with remnant patches of Yungas, Chaco, and Espinal forests (Navarro et al. 2009). Climatic fluctuations and changing habitats, in combination with the latitudinal and altitudinal gradient of the montane region (Barquez and Díaz 2001), may have assisted in isolating populations (such as ancestral populations of Pseudogeniates), influencing species diversifications, and leading to high levels of endemism (Navarro et al. 2009, Szumik et al. 2012.