Ontholestes oculatus (Sharp, 1874)

Hu, Fang-Shuo, 2020, New distributional records of Staphylinina in Taiwan, including a new species of Miobdelus Sharp (Coleoptera: Staphylinidae: Staphylininae: Staphylinini), Zootaxa 4768 (3), pp. 334-360 : 344-346

Ontholestes oculatus (Sharp, 1874)

( Figs. 14–15 , 35–40 )

Material examined. TAIWAN: Kinmen County: 1 male, Tianpu Reservoir (aảửw), Jinsha To., 09-IV-2018, leg. B. H. Ho (cow dung) (FSHc) ; 2 females, same locality as above, 01-IV-2019, leg. Y. H. Ho (cow dung) (FSHc) ; 1 female, same data as above except 03-IV-2019 (FSHc) ; 3 males, Lieyu (ȗë), Lieyu To., 24.4469, 118.2580, 30- IV-2019, leg. C. H. Ma (cow dung) (FSHc, NMNS, TARI) .

Measurements. BL: 11.86 (11.31–12.75); HL: 1.75 (1.56–1.83); HW: 2.85 (2.52–3.15); EyL: 1.29 (1.12–1.45); TL: 0.28 (0.25–0.30); PL: 2.35 (2.05–2.50); ElL: 2.98 (2.74–3.15) (mm).

Re-description. Medium sized species. Habitus ( Figs. 14–15 ) of both sexes with black head, pronotum and elytra covered with brownish yellow and silver setae; scutellum black, with brownish yellow setae on anterior margin; meso- and metathorax covered with gray setae on margin in ventral view; tergites 3–5 covered with brownish yellow setae, but without pair of dark tomentose spots at middle, some individuals also with mixed few silver setae on tergites; anterior margin of tergites 6–8 and each sternite covered with gray setae on anterior part, rather distinct on margin. Colouration with distinct sexual dimorphism. Antennal segments 1–4 brownish yellow in male but darker in female, antennal segments 5–11 dark brown in both sexes; in male, anterior part of labrum brownish yellow, basal part of labrum black, in female entire labrum black; legs brownish yellow, with black spots on femur in male, legs dark brown and femur with slightly larger black spots in female.

Head obtusely quadrangular, not dilated posteriad, with rounded posterior angles, markedly wider than long (ratio: 1.63), eyes very large but convex, tempora markedly shorter than length of eyes in dorsal view (ratio: 0.22); dorsal surface of head densely covered with fine punctation.Antennae moderately long, segment 1 (scape) markedly longer than other segments; segment 2 (pedicel) shortest; segment 3 slightly shorter than segment 1, but markedly longer than other segments; segments 4–10 wider than long, gradually but not obviously becoming shorter; last segment longer than wide, asymmetrically emarginate.

Thorax. Pronotum about as long as wide, slightly dilated in anterior part; anterior margin with acute angle on both sides; with widely rounded posterior margin; disc of pronotum with narrow impunctate midline, not distinct in anterior part but markedly expanded in front of posterior margin; punctation similar to that of head. Scutellum very large, triangular with dense setose punctures. First four segments of front tarsus markedly dilated, sub-bilobed, covered dense setae ventrally, without distinct difference between sexes. Elytra about as long as wide; slightly longer than pronotum (ratio: 1.27); anterior margin of humeral area markedly dilated; slightly dilated posteriad. Hind wings well developed.

Abdomen. Tergite 7 (fifth visible) with apical palisade fringe; tergite 2 (anterior to first fully visible tergite) with fine punctation; general punctation of tergites moderately fine and dense, spread evenly on each tergite.

Male. Sternite 8 ( Fig. 38 ) with obvious, deep, and obtuse medioapical emargination; sternite 9 ( Fig. 37 ) with slightly broad basal portion, apical portion with deep and narrow medioapical emargination. Tergite 10 ( Fig. 39 ) subtrapezoidal, with a shallow arcuate apical margin; numerous pale setae on posterior margin. Aedeagus ( Figs. 35–36 ) with both median lobe and paramere symmetrical; median lobe in ventral view sub-parallel for most of its length, slightly constricted at the middle, dilated and obtuse apically in ventral view; in lateral view, apical portion hook-like. Paramere slender, moderately long, apex narrowly rounded, with three to four pairs of long setae apically; base of paramere with two parallel, sclerotized keels, upper one with shallow emargination medioapically.

Female genital segment. Tergite 10 ( Fig. 40 ) subtrapezoidal, similar to male tergite 10, apex more broadly rounded than in male.

Diagnosis. Ontholestes oculatus is currently the only species of the genus in Taiwan. It can be easily distinguished from other Staphylinina by the generic character: pronotum with acute anterior angles.

Bionomics. Live specimens of O. oculatus were observed to be active on the surface of fresh cow dung during the entire day (Cheng-Han Ma personal communication, 2019).

Distribution. In the lowland regions of China (Guangxi, Hong Kong), Japan (Kyushu) and Taiwan (Kinmen islands) (new record).

Remarks. Yang & Zhou (2012) provided illustrations of O. oculatus but they ignored the shape of the base of the paramere, which made identification confusing. The illustration of Yang & Zhou (2012) should be ignored to prevent misidentification.

Figures

FIGURES 14–19. 14–15. Ontholestes oculatus: male and female. 16. Platydracus juang: male. 17. Thoracostrongylus formosanus: male. 18–19. Thoracostrongylus miyakei: male, lectotype and attached labels; male. Scale bar: 3 mm

FIGURES 35–40. Ontholestes oculatus 35. Aedeagus in ventral view; 36. Aedeagus in lateral view; 37. Sternite 9, male; 38. Sternite 8, male; 39. Tergite 10, male; 40. Tergite 10, female. Scale bar: 0.5 mm