Osoriellus bicolor, Irmler, 2014

Irmler, Ulrich, 2014, The Neotropical species of the genus Osoriellus FAGEL, 1959 (Coleoptera: Staphylinidae: Osoriinae), Beiträge Zur Entomologie = Contributions to Entomology 64 (2), pp. 231-354 : 260

Osoriellus bicolor n. sp.

( Figs 60 A-C, 97A)

Type material: Holotype, male: Peru: Huanuco, Panguana (74°57'37"W, 9°37'9"S), Cocha, male, June-September 1975, leg. W. Hanagarth ( UIC).

Paratypes: 2 males, 3 females with same data as holotype ; 2 females, from same locality, but river margin, 6.5.1975 and 26.12.1975, leg. Hanagarth ( BMNH, KNHM, UIC) .

Diagnosis: The species is part of a group of small species that includes O. ashei , O. levyi , and O. loksai . They resemble in size and absence of the microsculpture on the pronotum. O. bicolor can be differentiated from O. ashei by the obtuse anterior angles of the pronotum and from O. loksai and O. levyi by the denser pronotal punctation.

Description: Length: 3.5 mm. Colouration: Reddish; elytra and abdomen lighter red; elytra indistinctly blackish in posterior third; legs and antennae yellow.

Head: 0.53 mm long, 0.65 mm wide; eyes not prominent and short; temples as long as eyes; fore-head distinctly narrowed to front edge of clypeus; clypeal angles produced to minute granules; front edge even; setiferous punctation coarse and denser on vertex than on fore-head; on vertex partly coriaceous; interstices between punctures nearly as wide as diameter of punctures; laterally, interstices between punctures one-fourth as wide as diameter of punctures; on disc with impunctate midline; surface without microsculpture, polished; neck and temples with netlike deep microsculpture; behind eyes with transverse row of short yellow setae.

Antennae with flagellum as long as pronotum; second antennomere slightly thicker than following four antennomeres; apical five antennomeres distinctly thicker than basal five antennomeres of flagellum; more or less quadrate.

Pronotum: 0.65 mm long, 0.65 mm wide; widest at anterior angles; evenly narrowed from anterior to posterior angles; posterior angles smoothly rounded; lateral margin fine; in dorsal aspect, not visible in anterior third; setiferous punctation coarse and dense; punctures large; on average, distance between punctures slightly less than half of diameter of punctures; punctures in irregular longitudinal rows; on both sides of impunctate midline with longitudinal row of 6 to 8 punctures; without microsculpture, but with sparse micro-punctures; surface polished.

Elytra: 0.80 mm long, 0.70 mm wide; with 5 irregular longitudinal rows of coarse punctures; surface with indistinctly coriaceous ground sculpture; slightly shiny, but not polished.

Abdomen distinctly punctate; setiferous punctures coarse and dense; on average, distance between punctures as wide as one-fourth of diameter of punctures.

Protibia: 0.39 mm long, 0.12 mm wide; thick and nearly semicircular; 9 short spines at lateral edge; apical spines not inserted on digits; WLR: 3.5; in posterior aspect, comb at inner emargination partly covered; posterior face densely covered by thick, moderately long setae; on average, setae as long as one third of width of protbia.

Aedeagus rectangularly angulate; apical lobe as long as basal lobe.

Etymology: The specific name means two colours and refers to the colouration of the elytra with the lighter red colour of anterior half and darker colour of posterior half.

Figures

Fig. 58-62: Osoriellus-s. str.-group: Osoriellus levyi (58), O. loksai (59), O. bicolor (60), O. salvini (61), O. eggersi (62); antenna (A), protibia (B), aedeagus in lateral aspect (C); scale bar: 0.1 mm.