Osoriellus weberi ( BLACKWELDER, 1943 ) 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 : 310-311

Osoriellus weberi ( BLACKWELDER, 1943) new combination

( Figs 119 A-C, 125A)

Osorius weberi BLACKWELDER, 1943: 198

Type material examined: Trinidad: 12 miles N of Arima (61°16W, 10°37'N), male, 23.6.1935, leg. N.A. Weber (holotype in MCZ) .

Further material examined: Brazil: Amazonas, Manaus, INPA / Smithsonian Res. 2 (59°50'W, 2°25'S), leaf litter of terra firme forest, collected by Winkler method, 1 male, 4 females, 3.1994, 1.1994, 2.1994, leg. R. Didham ( BMNH) ; Peru: Dept. Loreto, Campamento San Jacinto (75°51.77'W, 2°18.75'S), collected by flight intercept trap, 175-215 m elevation, male 7.7.1993, leg. R. Leschen ( KNHM) ; Huanuco, Panguana (74°56'W, 9°37"S), cut forest, female, 3.8.1975, leg. W. Hanagarth ( UIC) .

Diagnosis: The species is characterised by the iridescent shine of the head and the digitate protibia. Other species with iridescent shine are smaller and have no digitate protibia. Similarly large species with digitate protibia, e.g. O. lescheni , have no iridescent shine on the head. The thick apical lobe of the aedeagus narrowed abruptly to the acute apex. In ventral aspect, the aedeagus resembles that of O. lescheni and O. loreti , since the circular basal lobe is much thicker than the apical lobe. In the male specimen from Peru, the apical lobe is thicker than in the Central Amazon or Trinidad males, but this may be within the range of the species.

Description: Length: 4.5 mm. Colouration: Dark brown; elytra lighter reddish brown; abdomen, legs and antennae still lighter yellowish brown.

Head: 0.52 mm long, 0.84 mm wide; eyes slightly prominent; nearly twice as long as temples; fore-head convergent to anterior angles in smooth concave curve; anterior edge of clypeus even; setiferous punctation weak and moderately sparse; punctures partly granulate; punctures close to neck and on supraocular area larger; yellow setae as long or slightly longer than interstices between punctures; isodiametric microsculpture weak and dense; surface with iridescent shine; on supraocular area and on lateral neck, microsculpture slightly deeper.

Antennae as long as head and half of pronotum combined; second antennomere oval and distinctly longer than wide; as long as conical third antennomere; antennomeres four to six slightly increasing in width; following antennomeres distinctly wider than preceding antennomeres, but all quadrate.

Pronotum: 0.84 mm long, 0.93 mm wide; widest close to anterior angles; sides convergent to obtuse posterior angles in even curve; posterior angles widely rounded; lateral margin distinct; in dorsal aspect, visible throughout its total length; slightly widened posteriorly; setiferous punctation larger and deeper than on head; moderately sparse; on average, interstices between punctures as wide as diameter of punctures; in irregular row adjacent to impunctate midline denser; impunctate midline in anterior half narrower than in posterior half; yellow setae as long as or slightly longer than interstices between punctures; between normal coarse punctures, with sparse micro-punctation; isodiametric microsculpture weak and less dense than on head; surface without iridescent shine; slightly shiny.

Elytra: 1.01 mm long, 0.95 mm wide; shoulders rounded; sides slightly widened to posterior third; setiferous punctation similarly dense and large as on pronotum; in irregular rows; coriaceous ground-sculpture coarse; surface less shiny than pronotum.

Abdomen with denser setiferous punctation than on forebody; yellow setae much longer than interstices between punctures; narrow midline impuncate; netlike microsculpture weak; surface shiny.

Protibia: 0.42 mm long, 0.13 mm wide; with seven spines at outer edge; apical spines inserted on long digits; WLR: 0.60; in posterior aspect, inner emargination with comb visible in its total length; posterior face sparsely covered by long yellow setae.

Aedaegus angulate in nearly rectangular angle; symmetric; with thick apical lobe; close to apex, apical lobe suddenly narrowed to acute apex; two lateral sensillae at base of apical lobe; at inner edge of apical lobe with row of sensillae close to apex and second row of four sensillae close to base.

Figures

Fig. 119-122: Remaining-species-group: Osoriellus weberi (119), O. infuscatus (120), O. rectangulus (121), O. rufescens (122); antenna (A), protibia (B), aedeagus in ventral and lateral aspects (C); scale bar: 0.1 mm.