Osoriellus caliginosus, 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 : 262-263

Osoriellus caliginosus n. sp.

( Figs 93 A-C, 96F)

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 forest, collected by pyrethrum fogg. log infested with Schizopora paradoxa fung., 8.11.2002, leg. R. Leschen, #BOL1L02-048 ( KNHM).

Paratypes: Bolivia: 2 males with data as holotype, but 3.- 9.11.2002 and 2.- 9.11.2002 in secondary forest, collected by flight intercept trap ( KNHM, UIC) .

Diagnosis: As in O. fumarius , the pronotal sides are slightly sinuate in front of the posterior angles. In the similarly sized O. verhaaghi , O. rougemonti , O. opacus and O. schwarzi , the pronotal sides are evenly narrowed in smooth curve from anterior to posterior angles. The two species O. fumarius and O. caliginosus are mainly differentiated by the aedeagus. In O. fumarius the apical lobe is thick and broad, whereas O. caligonosus has an acute apex.

Description: Length: 6.0 long. Colouration: Black; legs and antennae dark brown.

Head: 0.72 mm long, 1.19 mm wide; eyes large and prominent; more than twice as long as temples; sides of fore-head narrowed to anterior angles in smooth sinuate curve; anterior edge of clypeus even; setiferous punctation moderately deep and dense; midline, small area at base of antennae and transverse oval area close to neck impunctate; on average, interstices between punctures as wide as diameter of punctures; on supraocular area slightly denser, more coriaceous and partly granulate; isodiametric microsculpture dense and deep; surface matt.

Antennae slightly longer than head; second antennomere oval; slightly thicker and longer than short conical third antennomere; fourth to sixth antennomeres approximately equally wide and quadrate; following antennomeres distinctly wider, but also approximately quadrate; last antennomere only 1.5 times as long as wide.

Pronotum: 1.10 mm long, 1.28 mm wide; widest close to anterior angles; anterior angles rectangular; sides evenly convergent to posterior angles; posterior angles distinct and nearly rectangular, but obtuse and shortly rounded; lateral margin fine in anterior half; wider in posterior half; in dorsal aspect, covered close to anterior angles; setiferous punctation deeper, but sparser than on head; on average, interstices two to three times as wide as diameter of punctures; in row adjacent to impunctate midline, punctures much denser and partly coriaceous; small areas on lateral and posterior disc impunctate; netlike microsculpture weaker than on head and meshes more elongate; surface slightly shiny.

Elytra: 1.34 mm long, 1.28 mm wide; shoulders nearly rectangular; sides nearly parallel; setiferous punctation as dense as on pronotum, but less deep; in irregular rows; coriaceous ground-sculpture weak; surface moderately shiny.

Abdomen with dense and deep setiferous punctation; much denser than on fore-body; netlike microsculpture moderately deep, but dense; surface matt.

Protibia: 0.63 mm long, 0.22 mm wide; shape nearly semicircular; outer edge with 8 spines; without digits at apex; WLR: 4.0; in posterior aspect, comb at inner emargination partly covered in middle; posterior face densely covered by long yellow setae.

Aedeagus angulate in nearly rectangular angle; apical lobe long and slender; apical lobe thicker at base; in apical third suddenly narrowed to slender nearly acute apex; apical lobe laterally with two sensillae; inner edge of apical lobe with dense row of sensillae.

Etymology: The specific name caliginosus derived from the same Latin word meaning dark and refers to the dark colouration.

Figures

Fig. 90-93: Osoriellus-s. str.-group: Osoriellus seriatus (90), O. majusculus (91), O. fumarius (92), O. caliginosus (93); antenna (A), protibia (B), aedeagus in lateral aspect (C); scale bar: 0.1 mm.