Osoriellus opticu

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 : 304-305

Osoriellus opticu s n. sp.

( Figs 118 A-C, 125D)

Type material: Holotype, male: Bolivia: Santa Cruz Dept, 3.7 km SSE Buena Vista, Hotel Flora y Fauna (63°33.15'W, 17°29.95'S), 400-450 m elevation, primary foest, collected by flight intercept trap, male, 3.- 9.11.2002, leg. R. Leschen, #BOL1L02-052 ( KNHM).

Paratypes: Bolivia: 5 males, 1 female with same data as holotype ( KNHM, UIC) ; Cochabamba, Cochabamba, 67.5 km NE Est. Biol. Valle del Sajita, Univ. de San Simon (64°47.52'W, 17°06.33'S), 300 m elevation, collected by flight intercept trap, male, 7.- 9.2.1999, leg. Genier ( KNHM) ; Peru: Madre de Dios, Pentiacolla Lodge, 5.5 km NW El Mirador Trail, Alto Madre de Dios River (71°15.28'W, 12°30.10'S), 500 m elevation, collected by flight intercept trap, male, 23.- 26.10.2000, leg. R. Brooks ( KNHM) .

Diagnosis: The species is characterised by the large and thick eyes. Similarly large eyes are found in O. ocularis and O. oculatus of the O.- ocularis -group and in O. orbiculatus of the remaining-species-group. The species of the O.- ocularis -group can be differentiated by the denticulate anterior edge of the clypeus. O. orbiculatus differs by the larger and deeper pronotal punctures from O. opticus .

Description: Length: 4.6 mm. Colouration: Dark brown; posterior edge of pronotum, elytra and abdomen slightly lighter brown; legs and antennae light brown.

Head: 0.53 mm long, 1.00 mm wide; eyes thick; more than four times longer than temples; sides of fore-head convergent in smooth concave curve to anterior angles of clypeus; anterior edge of clypeus slightly emarginate; setiferous punctation dense and moderately deep; on vertex, partly coriaceous; moderately wide midline and small area at base of antennae impunctate; on vertex, interstices between punctures less than half as wide as diameter of punctures; yellow setae on clypeus approximately as long as interstices between punctures; on vertex, setae distinctly longer than interstices between punctures; microsculpture weak and fine; surface with iridescent shine.

Antennae as long as head and half of pronotum combined; second antennomere oval; longer than short conical third antennomere; following antennomeres increasing in width, but all antennomeres approximately quadrate.

Pronotum: 0.92 mm long, 1.04 mm wide; widest close to anterior angles; anterior angles rectangular; sides evenly convergent to obtuse posterior angles; posterior angles rounded, but nearly rectangular; sides in front of posterior angles nearly parallel; lateral margin finer in anterior half than in posterior half; in posterior half widened; in dorsal aspect, covered close to anterior angles; setiferous punctation sparser than on head, but punctures slightly larger; on average, interstices between punctures slightly wider than diameter of punctures; in irregular row adjacent to impunctate midline, interstices partly shorter; on average, yellow setae as long as interstices between punctures; without microsculpture, but with dense micro-punctation; surface polished and shiny.

Elytra: 1.13 mm long, 1.12 mm wide; shoulders rounded; sides slightly widened posteriorly; widest in posterior third; setiferous punctation as dense and deep as on pronotum; in irregular rows; coriaceous ground-sculpture moderately deep.

Abdomen with dense setiferous punctation; narrow midline on tergites impunctate; netlike microsculpture weak; surface shiny.

Protibia: 0.62 mm long, 0.18 mm wide; 8 spines on outer edge; apical spines inserted on moderately long digits; WLR: 1.0; in posterior aspect, inner emargination with comb visible throughout its total length; posterior face sparsely covered by long yellow setae.

Aedeagus asymmetric with moderately thick and long apical lobe; apical lobe evenly narrowed to acute apex; inner edge of apical lobe with row of approximately ten sensillae.

Etymology: The specific name opticus derived from the same Latin word meaning optic and refers to the large eyes of the species.

Figures

Fig. 114-118: Remaining-species-group: Osoriellus neotropicus (114), O. lescheni (115), O. loreti (116), O. digitatus (117), O. opticus (118); antenna (A), protibia (B), aedeagus in ventral and lateral aspects (C); scale bar: 0.1 mm.