The Indochinese members of the Onthophagus (Parascatonomus) aurifex species group (Coleoptera: Scarabaeidae), with the description of a new species Author Tarasov, Sergey Author Krikken, Jan Author Huijbregts, Johannes text Zootaxa 2010 2490 63 68 journal article 10.5281/zenodo.294209 79e02464-c04f-4443-895a-457c4782a91b 1175-5326 294209 Onthophagus (Parascatonomus) alexeevi Tarasov, Krikken & Huijbregts sp. n. ( Figs. 1 , 2 g–k, l) Material examined. Holotype ( ZMUC ), male major bearing the following labels: 1. White, printed: S[outh] CAMBODIA Sianoukville h= 50–150m 3 carrion traps disturb tropical forest 12– 16.05.2008 leg. S. Tarasov 2. Orange, printed: HOLOTYPUS Onthophagus (Parascatonomus) alexeevi S. Tarasov, J. Krikken & J. Huijbregts det. 2009 Paratypes : 53 specimens , South Cambodia , Sianoukville h= 50–150m , 3 carrion traps disturb tropical forest, 12– 16.05.2008 leg. S. Tarasov ( ZMUC ); 1 ɗ & 1 Ψ, Thailand , Umphang river, 16.07N 99.00E , h 1000m , 28/4–6/5.91 leg. D. Kral ( ZISP ); 2 ɗ, W Thailand , 300m , Thung Yai Wildlife Sanctuary, 15.28N 98.48E , Tak Province, Umphang District, Song Bae Stream, 18– 27.4.1988 , M.J.D. Brendell, FIT B ( RMNH ); 1 Ψ, same data and locality, but carrion trap (fish) ( BMNH ); 1ɗ & 1Ψ same locality and date, but evergreen rain forest M.J.D. Brendell, ( BMNH ); 2 ɗ & 1Ψ, W Thailand , 300m , Thung Yai Wildlife Sanctuary, 15.30N 98.48E , Tak Province, Umphang District, Mae Chan/Mae Klong confluence, 27.4– 6.5.1988 , M.J.D. Brendell, oak/bamboo forest ( BMNH ); 1ɗ same data and locality, but edge of Karen clearing ( BMNH ). FIGURES 1. Onthophagus (Parascatonomus) alexeevi , dorsal view, holotype. Description. Head and pronotum cupreous or with greenish metallic luster, elytra black, matt, underside black with metallic cupreous or/and green luster. Length 9.0– 11.5 mm . MALE major ( Fig. 1 ). Head rounded; clypeal margin anteriorly distinctly reflexed, apex with short tooth, tip rounded; frontoclypeal ridge slightly expressed as smooth arcuate strip; clypeus densely, transversely rugulate; vertex simple with slightly protruding plate; eyes completely divided by canthus. Pronotum convex, with slightly steeper anterior declivity in major specimens; anterior and lateral sides of pronotum marginate, base marginate only laterally and medially angulate; anterolateral pronotal angle slightly obtuse; pronotal disc covered with small, simple, sparse punctures (separated by 1–2 puncture diameters) becoming denser and granulose laterally; anterior part of propleura with ridge reaching prosternal lateral side. Elytra with short, yellow, fine setae; sparsely covered with small, simple punctures. Metasternum anteriorly raised, prow-shaped. Protibia with 4 outer teeth, apico-internal angle with small tooth; apical spur modified in males: small, acuminate, slightly bent downward and inward; mesotibial and metatibial apex bearing short setae. Aedeagus as in Figs. 2 g–k, l ( Fig. 2 g is of the holotype ). FEMALE. Head and pronotum armature do not differ from those of males. VARIATION. Slightly expressed in minor specimens by flatter pronotum with slightly denser punctation. HOLOTYPE . The body coloration and length of the holotype as follows; head and pronotum cupreous with greenish metallic luster, underside black with metallic cupreous and green luster. Length 9.7 mm . FIGURE 2. Aedeagi of O. aurifex - group species. a–f, m — O. semifex (a–c, f, m — paratypes, d–e — Vietnam); g–l — O. alexeevi (g–j, l — paratypes, k — holotype); a–k — aedeagus lateral view; l–m — aedeagus dorsal view; a–e, g–h, k– m — aedeagus photographed in glycerin; f, g — aedeagus photographed after drying. Differential diagnosis. The new species is most similar to three other species of O . aurifex complex: O . semifex , O . semiaureus and O . aurifex , which also have the upper side of the forebody shiny metallic. This is in contrast to the other species of the O . aurifex group belonging to O . sarawacus complex, which have an entirely black dorsal surface. The new species can only be reliably separated from these three species using the aedeagus. Among these three species, the aedeagal shape of O . alexeevi is most similar to that of O . semifex but differs in the sclerotized anterior part of parameral apex, which is thinner and without the lower tooth-like short appendage ( Figs. 2 g–k, in Figs. 2 g, j indicated with circle) present in O . semifex ( Figs. 2 a–f, in Figs. 2 a, f indicated with circle). Onthophagus alexeevi also has the membranous surface of paramere preapically excavated ( Fig. 2 l indicated with arrow, see also Fig. 2 j) while this structure is not excavated in O . semifex ( Fig. 2 m indicated with arrow, see also Fig. 2 f). Although the morphological differences between two species are subtle, there is robust evidence of their specific separation. First, the differences in aedeagal shape are stable between two species in the large series of examined material. Second, these two species seems to be sympatric ( Fig. 3 ) and thus the stable differences in aedeagal shape are not a product of geographical variation, which indicated the specific independence of two species. Third, both species are possibly ecologically isolated as they have not been so far collected at the same place ( Fig. 3 ). The new species differs from O . semiaureus and O . aurifex by the different shape and location of the sclerotized anterior part of the parameral apex (for details, see also Krikken & Huijbregts 2008 ). Etymology. The new species is named after Dr. Sergey Alexeev, Kaluga Regional Biological Center, Russia—thanks to whom, one of us (S.T.) became an entomologist. S.T. is much obliged to Dr. Sergey Alexeev for invaluable support and personal help at the beginning of his career, as well as for an interesting and enjoyable time in both expeditions and laboratory work at the Kaluga Regional Biological Center. Distribution and ecology. The new species is known only from West Thailand and South Cambodia ( Fig. 3 ), but is probably widespread in Indochina. All Cambodian specimens were collected in disturbed tropical forest by means of pitfall traps baited with dead fish.