Sinodrepanus exsul
Creators: name: Montanaro, Giulio
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Scarabaeidae
Sinodrepanus
Sinodrepanus exsul

description: Sinodrepanus exsul (Sharp, 1875)
(Figs. 1a–b, 2a–d, 2i, 3a, 3c, 3e)
Oniticellus exsul Sharp, 1875: 53 (original description)
Drepanochirus exul [sic!]: Boucomont & Gillet, 1921: 19
Cyptochirus exsul: Boucomont & Gillet, 1927: 103
Drepanocerus exsul: Arrow, 1931: 381, 385; Janssens, 1953: 36, 37; Balthasar, 1963: 66 (as synonym of D. falsus); Biswas & Chatterjee, 1985: 151 (as synonym of D. falsus; probably to be ascribed to S. schoenfeldi new species); Sewak, 2003: 253 (to be ascribed to S. schoenfeldi new species?); Sewak, 2004: 106, 121; Sewak, 2006: 219 (as synonym of D. falsus); Sewak, 2009a: 35; Sewak, 2009b: 56; Sewak, 2009c: 36
Drepenocerus exsul [sic!]: Sewak, 2003: 283 (to be ascribed to S. schoenfeldi new species?)
Sinodrepanus exsul: Simonis, 1985: 98; Krikken, 2009: 21 (as synonym of S. falsus); Montanaro, 2021: 585
Sinodrepanus excul [sic!]: Kabakov & Napolov, 1999: 73 (as synonym of S. falsus)
Type locality: Siam.
Type material examined. Holotype, ♂ (MNHN): Siam / Mouhot [wc, line 1 hb, line 2 pb] // Oniticellus / exsul / Type D.S. [wc, hb except “Type” pb] // Ex Musaeo / D. Sharp 1890 [wc, pb] // MUSÉUM PARIS / 1952 / COLL. R. OBERTHÜR [wc, pb] // A. Janssens det. 195 / Drepanocerus / falsus Sharp ♂ / (sub nom. exsul) [wc, hb except line 1 pb] // TYPE [rc, pb] // HOLOTYPE [rc, pb] // HOLOTYPE / Sinodrepanus / exsul (Sharp) [wc, pb] // MNHN / EC8104 [wc, pb].
Additional material examined (5♂♂, 9♀♀). Laos: Champasak province, Bolaven Plateau, Ban Thôngvay (=Xékatam) vicinity, old logging road N of village, selectively logged forest, 15°13.96’N 106°31.731’E, 1035m, carrion trap (squid), 8–16.vi.2008, A. Solodovnikov, M. Thayer & A. Newton legit [5♂♂, 7♀♀, FMNH]; Champasak province, Bolaven Plateau, Muang Paxong, Ban Thôngvay, edge of disturbed primary rainforest, near clearing, 15°14.054’N 106°31.867’E, 1200m, fruit baited trap on ground, 8–16.vi.2008, A. Solodovnikov & J. Pedersen legit [1♀, ZMUC]; Champasak province, Bolaven Plateau, Ban Thôngvay, disturbed forest, 10-16.vi.2008, S. Tarasov legit [1♀, MZH].
Diagnosis. Sinodrepanus exsul can be easily differentiated from all other Sinodrepanus species by the combination of the following characters: i) sternites 3–6 almost entirely smooth laterally, except for a narrow transverse anterolateral setigerous band, while they are evenly punctured in all other Sinodrepanus; ii) the longest setae on elytral interstria 5 irregularly spread, not arranged into tufts; iii) males with a deep obtuse notch between clypeal teeth (Fig. 3a); iv) parameres with basolateral plate almost absent (Figs. 2a–c); and v) females with a small third denticle between clypeal teeth (Fig. 3d). Contrarily to other Sinodrepanus species, whose females are very similar one another, females of S. exsul can be readily distinguished by the median clypeal denticle and the laterally smooth sternites. This species is very close to S. schoenfeldi new species, from which it can be readily differentiated, in addition to the laterally smooth sternites, the deeply notched male clypeus and male genitalia, by having elongated and not rounded punctures on pronotal disc (Fig. 3e).
Redescription of the male (non-type). Flat, elongated, integument microreticulated, dark brown and partially with metallic lustre; antennae reddish-brown; body surface almost wholly covered by simple or ocellate punctures carrying light brown scale-like setae. Length: 9.7 mm. Head. Subpentagonal, clypeus covered by dense ocellate setigerous punctures; vertex with two weak, short longitudinal carinae bearing long testaceous setae; carinae dividing the interocular space into three almost equal segments; presence of an effaced bulge on the frons; head surface smooth above tentorial pits; lateral edge of genae obtusely angular; head margin slightly notched and broadly angular in correspondence of clypeogenal junctions; anterior clypeal margin with two upturned teeth separated by a triangular, obtuse notch. Pronotum. Subquadrangular, widening anteriorly, lateral margin approximately straight posteriorly; anterolateral angles curved; posterior angles broadly rounded; posterior margin broadly rounded, obtuse medially; covered with ocellate setigerous punctures of uneven size, punctures longitudinally elongated on disc. Pronotal disc with 8 ill-defined longitudinal carinae bearing long testaceous bristles (in order, from medial to lateral): 2 carinae on either side of the midline, reaching the anterior pronotal border but expiring before posterior edge, converging at about the anterior 2/5 of their length, where they are connected by a faint transverse bulge; laterally to these, 2 short carinae connected to the posterior pronotal border and 2 short oblique carinae anteriorly, connecting to the anterior part of the medial carinae; other 2 bulge-like oblique carinae on the posterior and anterior thirds of pronotum, close to the lateral margins. Elytra. Flat on the whole, interstria 1 raised, interstria 6 depressed longitudinally; interstriae 5–7 obliquely elevated next to humeral callus, interstria 6 depressed a little behind callus; striae broad, their borders clearly ridged, punctures marked, each one carrying a scale-like seta; stria 6 strongly sinuous; interstriae uniformly covered with setigerous punctures; interstriae 1–3, 5 and 7 with a tuft of long setae apically; interstriae 1, 5 and 7 carrying longer setae, setae on interstria 5 irregularly distributed; interstria 8 covered with longer and more scattered setae. Scutellum tapering posteriorly, smooth. Legs. Anterior surface of femur covered by dense small setigerous punctures and by scattered ocellate punctures carrying thicker setae. Protibia with distal margin obliquely truncated; ventral protibial margin strongly curved, slightly produced distally; apical protibial spur with distal half bent posteriorly; dorsal protibial margin with three small teeth. Tergite 8. Densely setigerous; strongly swollen medially, with two broad bulges; strongly depressed along anterior margin; with a longitudinal medial carina connected to the anterior margin. Ventral body surface. Abdominal sternites with a tuft of setae laterally next to the epipleuron; S3 densely setigerous medially, smooth laterally except for a transverse setigerous band along the anterolateral margin; S4–6 with scattered setae medially, smooth laterally except for a transverse setigerous band along the anterolateral margin; sternites 7–8 densely setigerous on the entire surface. Metaventral disc covered by small ocellate punctures intermixed with few bigger punctures, with a pair of symmetrical shallow depressions next to posteromedian margin; lateral metaventral surface microreticulated, with big ocellate puctures intermixed with few smaller punctures. Genitalia (Figs. 2a–d). Basolateral plate of parameres almost absent; parameral apices strongly bent ventrally at a straight angle in lateral view; parameral apices slightly tapering in posterior view. Lamella copulatrix (LC) four-lobed: superior left lobe with a flattened digitiform expansion bent posteriorly; superior right lobe sinuous; inferior left lobe thin, arched; inferior right lobe separated from the rest of the LC, associated with an inconspicuous additional sclerite.
Description of the female (non-type). Similar to the male except for the following characters. Head. Space between clypeal teeth more broadly curved than in the male, with a small median tooth. Legs. Protibial teeth larger than in the male; ventral protibial margin not strongly curved. Tergite 8. Shorter than in the male. Ventral body surface. S8 longer than in the male. Genitalia (Fig. 2i). Vagina relatively poorly but uniformly sclerotised, with many folds; infundibulum bent at a right angle distally; proximal part of receptaculum seminis relatively well developed.
Variation. Body size ranges from 7.8 to 10.2 mm. Clypeal margin can be more or less notched and angular in correspondence of clypeogenal junction. The medial clypeal tooth of females can be more or less evident, but it is always visible—the only exception among the examined material being very worn specimens in which the denticle is absent and the clypeal notch deeper.
Verified distribution. Laos, Thailand (Fig. 4). Kabakov & Napolov (1999) recorded S. falsus from Vietnam, and considered S. exsul as a synonym of it. This record should be reassessed and the specimens re-examined to confirm their identity. See the “ Indian Sinodrepanus: an overlooked diversity?” section for more comments on its distribution.
Ecology. Sinodrepanus exsul was found on the Bolaven Plateau (Laos) on the edges of a logged forest and of a disturbed primary rainforest. It was collected with traps baited with rotting squid and fruit, suggesting rather generalist feeding preferences.
Etymology. Latin noun meaning “exile” or “wanderer”.
Remarks. This species was confused with S. falsus, until Montanaro (2021) resurrected it from the synonymy with this latter taxon. It was also confused in some collections with S. schoenfeldi new species, to which it is extremely close.
description: Published as part of Montanaro, Giulio, 2024, New or poorly known species of Sinodrepanus Simonis, 1985 (Coleoptera: Scarabaeidae: Oniticellini), with the first identification key for the genus, pp. 577-595 in Zootaxa 5537 (4) on pages 579-581, DOI: 10.11646/zootaxa.5537.4.10, http://zenodo.org/record/14240160