The Acidocerinae (Coleoptera, Hydrophilidae): taxonomy, classification, and catalog of species Author Giron, Jennifer C. https://orcid.org/0000-0002-0851-6883 Department of Entomology, Purdue University, West Lafayette, Indiana, USA & Natural Science Research Laboratory, Museum of Texas Tech University, Lubbock, Texas, USA entiminae@gmail.com Author Short, Andrew Edward Z. Department of Ecology and Evolutionary Biology, and Division of Entomology, Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA text ZooKeys 2021 2021-06-18 1045 1 236 http://dx.doi.org/10.3897/zookeys.1045.63810 journal article http://dx.doi.org/10.3897/zookeys.1045.63810 1313-2970-1045-1 2C3076FD13FB4842A7F6B0EBE9B23795 CDADD9D94DEB5471834AF0F1AB8B48AA Genus Tobochares Short & Garcia , 2007 Figs 1N, O , 2 , 6 , 11A, B , 52 , 53 , 54 , 55 Tobochares Short & Garcia , 2007: 2. Gender. Masculine. Type species. Tobochares sulcatus Short & Garcia , 2007: 4; by original designation. Diagnosis. Small beetles, total body length 1.5-2.6 mm. Body shape oval in dorsal view; moderately to strongly convex in lateral view (Fig. 52 - 54 ); dorsal outline usually evenly curved. Color yellowish brown, orange brown to dark brown, sometimes with paler spots on head, or paler margins of pronotum and elytra; ground punctation moderate to shallow. Shape of head somewhat oval. Eyes not emarginate (e.g., Fig. 11A ) to strongly emarginate (e.g., Fig. 11B ), moderate to small in size, somewhat oval, slightly to strongly projected from outline of head. Clypeus trapezoid, with anterior margin broadly emarginate; membranous preclypeal area often visible. Labrum fully exposed, convex, and anteriorly emarginate. Mentum rather smooth, often medially depressed, or anteriorly shallowly crenulated; median anterior depression marked by transverse carina (e.g., Fig. 53C ). Submentum anteriorly smooth and shiny. Antennae with eight antennomeres, cupule slightly asymmetric with rounded outline. Maxillary palps from short and slender (slightly shorter than the width of the head; e.g., Fig. 53C ) to very short and stout (nearly half the width of the head; Fig. 54E ); maxillary palpomere 4 similar in length to slightly longer than palpomere 3; inner margin of maxillary palpomere 2 straight, outer margin strongly curved along apical 2/3. Elytra without sutural striae (in some species, stria 1 more strongly impressed along posterior half of elytra; Fig. 54C ); elytral punctures seemingly arranged in rows, in some species more pronounced; interserial punctures occasionally longitudinally aligned; serial punctures sometimes impressed into distinct grooves (e.g., Fig. 52A ). Prosternum flat. Posterior elevation of mesoventrite either flat, bulging or with transverse or longitudinal ridge (Fig. 14F, G ); anapleural sutures concave, separated at anterior margin by distance nearly 0.3-0.5 x width of anterior margin of mesepisternum. Metaventrite densely pubescent, except for median glabrous patch, either ovoid and broad (Fig. 14G ) or longitudinal and narrow (Fig. 14F ). Protibiae with spines of anterior row hair-like, semi erect, relatively long and thick; apical spurs of protibia from very short and stout, to enlarged to reach apex of protarsomere 3. Tarsomeres 2-4 densely covered by hair-like spines on ventral face; metatarsomeres 1-4 similar in length, 5 nearly as long as 3 and 4 combined, or metatarsomere 2 similar in length to 5. Metafemora mostly glabrous, with only few scattered setae, sometimes with hydrofuge pubescence along basal half of anterodorsal margin (e.g., Figs 52C, F , 53 C, F ). Fifth abdominal ventrite apically evenly rounded, without fringe of stout setae. Aedeagus trilobed (Fig. 55 ), with basal piece usually very short (nearly 1/3 length of parameres); median lobe usually broader than each paramere; median lobe and parameres apically rounded to truncate; apex of median lobe seldom medially emarginated; gonopore well developed. Figure 52. Habitus of Tobochares spp. A-C T. sulcatus : A dorsal habitus B lateral habitus C ventral habitus D-F T. luteomargo : D dorsal habitus E lateral habitus F ventral habitus. Scale bars: 0.5 mm. Figure 53. Habitus of Tobochares spp. A-C T. communis : A dorsal habitus B lateral habitus C ventral habitus D-F T. fusus : D dorsal habitus E lateral habitus F ventral habitus. Scale bars: 1 mm. Differential diagnosis. Tobochares are among the smallest acidocerines. Some members of the group are unique in the presence of impressed elytral striae ( Tobochares striatus species group; Giron and Short 2021a ). Tobochares without elytral striae may resemble some Agraphydrus (with eight antennomeres and mostly glabrous femora), and other than their distributions ( Tobochares in the New World, Agraphydrus in the Old World) and slight differences in overall body shape, they can only be differentiated by the shape of the aedeagus (slender in Tobochares , Fig. 55 ; overall broader in Agraphydrus , Fig. 20 ). Within the New World, Tobochares is most likely to be confused with Ephydrolithus , which also contains small, seepage-inhabiting species, although currently the ranges of the two genera do not quite overlap. However, the difference in the number of antennomeres (nine in Ephydrolithus ) provides a clear point of separation. Figure 54. Habitus of Tobochares spp. A, B T. kappel : A dorsal habitus B lateral habitus C, D T. akoerio : C dorsal habitus D lateral habitus E, F T. kolokoe : E dorsal habitus F lateral habitus G, H T. goias : G dorsal habitus H lateral habitus. Scale bars: 1 mm. Figure 55. Aedeagi of Tobochares spp. A T. benettii B T. fusus C T. luteomargo D T. emarginatus E T. kusad F T. kasikasima G T. anthonyae H T. autures I T. communis J T. romanoae K T. akoreio . Scale bars: 0.5 mm ( A-C ); 0.1 mm ( D-K ). Distribution. Neotropical : Brazil ( Amapa , Amazonas, Goias , Roraima), French Guiana, Guyana, Suriname, Venezuela; Fig. 6 . Natural history. Most Tobochares specimens have been collected at hygropetric habitats, including isolated hygropetric seeps as well as wet rock surfaces along rivers and waterfalls. They can sometimes be found in large numbers. One species, T. fusus , has been collected in both seepage habitats as well as terrestrially in the rotten fruits of Clusia (see Kohlenberg and Short 2017 and Giron and Short 2021a for more details). Larvae. The immature stages of Tobochares remain unknown. Taxonomic history. Short and Garcia (2007) described the genus and one species from Venezuela. Additional species were described from Suriname, one by Short and Kadosoe (2011) and two more by Short (2013) . The genus was revised by Kohlenberg and Short (2017) , including the description of five new species and the characterization of one specimen from Tobogan de la Selva (Venezuela) left undescribed until additional material can be studied. The genus was reviewed again just a few years later by Giron and Short (2021), in the light of new molecular evidence, describing 15 additional new species and establishing four diagnosable species groups. Remarks. There are 24 described species of Tobochares . The genus is rather highly variable in its external morphology: there is variation in coloration, the degree of emargination of the eyes and the degree of development and extension of the elytral striae. The form of the aedeagus is also somewhat variable, although not as extreme as in some genera such as Chasmogenus or Helochares . The genus is much richer in species and more broadly distributed in the Amazon region than as currently published. We have examined numerous additional specimens from around the Amazonian region, particularly the southern Amazon (e.g., Brazil: Rondonia) from where the genus is currently unknown. We would not be surprised if the genus exceeded 50 species when more attention is paid to seepage habitats in this region. Species examined. Holotypes, paratypes, and additional specimens of all described species, as well as several undescribed species were examined for this study. Selected references. Short and Garcia 2007 : original description of the genus and its type species; Short and Kadosoe 2011 : description of one additional species; Short 2013 : description of two additional species; Kohlenberg and Short 2017 : revision of the genus and description of five new species; Giron and Short 2021a : review of the genus with description of 15 new species and establishment of four species groups; Short et al. 2021 : phylogenetic placement.