Onthophagus (Sunenaga) streltsovi Tarasov & Kabakov

Tarasov, Sergey I. & Kabakov, Oleg N., 2010, Two new species of Onthophagus (Coleoptera: Scarabaeidae) from Indochina, with a discussion of some problems with the classification of Serrophorus and similar subgenera, Zootaxa 2344, pp. 17-28 : 18-21

Onthophagus (Sunenaga) streltsovi Tarasov & Kabakov , sp. n.

( Figs. 1 a, b; 2c, e, f)

Material examined. Holotype ( ZMUC), male bearing the following labels:

1. White, printed: S LAOS, Bolaven plateau B.Thongvai, N15°14.741' E106°31.916' h= 1150–1300m dung trap, primary montane forest, 8– 16.06.2008, leg. S. Tarasov

2. Orange, printed: HOLOTYPUS Onthophagus streltsovi S. Tarasov & O. Kabakov det. 2009

Paratypes. 147 specimens, South Laos, Bolaven Plateau, B.Thongvai, N15°14.741' E106°31.916', h 1150–1300m, dung trap (human), primary montane forest, 8– 16.06.2008 leg. S. Tarasov ( ZMUC); 1 specimen, South Laos, Bolaven Plateau, B.Thongvai, N15°14.741' E106°31.916', h 1300m, carrion trap, primary montane forest, 12– 16.06.2008, leg. S. Tarasov ( ZMUC); 1 specimen, South Laos, Bolaven Plateau, B.Thongvai, N15°14.741' E106°31.916', h 1150m, carrion trap, disturb montane forest, 10– 16.06.2008, leg. S. Tarasov ( ZMUC); 81 specimens, Laos: Champasak province: Bolaven Plateau, Ban Thongvai, old logging road N of the village, 1095m, 15°14.288'N, 106°31.891'E, selectively logged forest, 8– 16.06.2008; FMHD #2008-039, dung trap (human), A. Solodovnikov, M. Thayer & A. Newton ( FMNH); 134 specimens, Laos: Champasak province: Bolaven Plateau, Ban Thongvai, old logging road N of the village, 1170m, 15°14.494'N, 106°31.807'E, selectively logged forest, 8– 16.06.2008; FMHD #2008-042, dung trap (human), A. Solodovnikov, M. Thayer & A. Newton ( FMNH); 23 specimens, Laos: Champasak province: Bolaven Plateau, Ban Thongvai, old logging road N of the village, 1035m, 15°13.96'N, 106°31.731'E, selectively logged forest, 8– 16.06.2008; FMHD #2008-036, dung trap (human), A. Solodovnikov, M. Thayer & A.

Newton ( FMNH); 6 specimens, Laos: Champasak province: Bolaven Plateau, Ban Thongvai, old logging road N of the village, 995m, 15°13.761'N, 106°31.749'E, selectively logged forest, 8– 16.06.2008; FMHD #2008- 0 33, dung trap (human), A. Solodovnikov, M. Thayer & A. Newton ( FMNH).

Description. Head and pronotum black with slight green luster, rarely slightly red; elytra yellow-brown, intervals with black, interrupted stripes; rarely stripe pattern weakly expressed; pygidium, metasternum laterally, femur yellow or yellow-black; abdominal sternites yellow usually with black stripes basally; antennal club yellow; elytra with short, black setae turning yellow depending on light angle; pronotum, head, pygidium, abdominal side with longer yellow setae. Length 10–12 mm.

Male major ( Fig. 1 a). Head rounded; apex of clypeal margin anteriorly reflexed upwards; frontoclypeal ridge absent in larger males and present with slightly raised strip in smaller males; vertex with small hookshaped horn broadened basally and bent backwards; eyes completely divided with genal appendage; clypeus sparsely punctate; antennal scapus anteriorly with slight ridge, not serrate.

Pronotum convex; anterior, lateral and basal sides marginate, postlateral section strongly sinuate; anterolateral angles rounded, anterior part slightly concave in middle behind cephalic horn; disc sparsely covered with fine punctures (separated by 1–2 puncture diameters) becoming denser and larger laterally; anterior part of propleura with ridge almost reaching propleural lateral margin.

Elytra densely covered with scattered punctures becoming denser on 7th and 8th intervals. Pygidium covered with scattered large punctures separated by 1–2 diameters of a puncture, with longitudinal black strip medially; basal edge marginate.

Protibia with four outer teeth, internal apical angle with large tooth about two times smaller than apical spur; apical spur modified in males: small, acuminate, slightly bent outward; mesotibial and metatibial apex produced into three distinct lobes bearing short and long setae.

Aedeagus as in Figs. 2 e, f. Lamella copulatrix as in Fig. 2 c.

Female ( Fig. 1 b). Female differs from male by clypeus slightly reflexed along anterior margin and incised medially, with each side of the incision lobed; frontoclypeal ridge present; vertex without horn; head and pronotum sparsely covered with large, dense punctures separated by a diameter or less; pronotum less convex; internal apical angle of protibia with small indistinctive tooth; apical spur of protibia larger, more acuminate and slightly bent inward.

Var i at io n. Males vary allometrically in the degree of expression of some features of the clypeus, horn, pronotum and punctation. Small males usually have less anteriorly reflexed clypeus; vertex not armed with horn, or, sometimes, only with small tubercle; pronotum more flat, not concave, disc more densely punctured.

Holotype ( Fig. 1 a). Major male, length 11.4 mm. Head and pronotum black with slight green luster; elytra yellow-brown, intervals with black, interrupted stripes; pygidium yellow-black; metasternum laterally and femur yellow; abdominal sternites yellow with black stripes basally, antennal club yellow; apex of clypeal margin anteriorly reflexed upwards; vertex with small hook-shaped horn broadened basally and bent backwards; Pronotum convex, slightly concave in middle behind cephalic horn; disc sparsely covered with fine punctures (separated by 1–2 puncture diameters) becoming denser and larger laterally.

Differential diagnosis. This species is similar to O. digitatus Arrow, 1931 from Sikkim, India (we have examined the male lectotype of O. digitatus , which is deposited at the BMNH). Both species posses similar body shape, especially of the head and pronotum; vertex in males armed with small horn bent backwards; internal apical angle of protibia with large tooth in males; protibial apical spur small, acuminate, slightly bent outward; mesotibial and metatibial apex produced into three distinct lobes; aedeagus and lamella copulatrix similarly shaped. The characters separating two these species are summarized in Table 1 . Both species are probably also similar to O. kaengkrachangus Masumoto, Ochi & Hanboonsong, 2008 from Thailand. Unfortunately the types of the latter have not been examined, but as we can see from its original description, O. kaengkrachangus shares almost the same combination of characters with O. streltsovi and O. digitatus : head and the rest of body specifically shaped; “protibiae with inner side of terminal edge bluntly projected; terminal spur rather bold”. Also, all three species have similar shape of aedeagus. Only one remarkable character, the male vertex with small horn bent backwards, is not reported for O. kaengkrachangus . This is likely due to the lack of major males in the type series.

These three species probably represent a monophyletic group. Reasons for its current taxonomic position are provided in the “Discussion” section below.

Etymology. The new species is named after Dr. Alexey Streltsov, Professor of Kaluga University in Russia, to whom we are much obliged for personal help and support during research as well as in everyday life. In particular, it was thanks to Alexey Streltsov that the long field trip to Laos by S.T. was possible. Distribution and Ecology. The species is known from many specimens, but only from the type locality in Bolaven Plateau, South Laos ( Fig. 4). Almost all specimens were collected in montane forest by means of pifall traps baited with human dung.

Figures

FIGURE 1. Habitus of Onthophagus. a, b— O. streltsovi; c, d— O. nampatensis; a, c—males, holotypes; b—female, paratype; d—small male paratype.

FIGURE 2. Elements of genitalia of Onthophagus. a— O. seniculus (fused area of SL and SR indicated by arrow); b— O. anguliceps (separation of SL and SR indicated by arrow); c, e, f— O. streltsovi; d— O. manipurensis; a – d—lamella copulatrix; e—aedeagus, lateral view; f—aedeagus, apical view.

Tables

TABLE 1. Diagnostic characters separating the new species O. streltsovi from O. digitatus.

Characters	O. streltsovi	O. digitatus
Matasternal posterior depression	Absent	Present
Coloration	Head and pronotum black; elytra yellow- brown, intervals with black interrupted stripes; pygidium, metasternum laterally, abdomen,	Black
Punctation of pronotum	Disc sparsely covered with fine punctures becoming denser and larger laterally	Disc not punctate, smooth; pronotum covered with large punctures laterally
Aedeagus	Parameral preapical section distinctly excavated	Parameral preapical section without excavation