Osorius micropterus BLACKWELDER, 1943

Irmler, Ulrich, 2015, New Neotropical genera and species of the tribe Osoriini (Coleoptera: Staphylinidae: Osoriinae), Beiträge Zur Entomologie = Contributions to Entomology 65 (1), pp. 173-196 : 182-183

Osorius micropterus BLACKWELDER, 1943

Blackwelder’s type was studied. Unfortunately, it is a female. Furthermore, Blackwelder separated O. exalatum from O. microptera only by the shape of the clypeus. The type specimen of O. microptera has lost the head. There- Antennae slightly longer than head; second antennomere elongate; 1.5 times as long as wide; conical third antennomere distinctly shorter than second; following antennomeres increasing in width; fourth antennomere slightly longer than wide; tenth antennomere quadrate.

Pronotum: 1.02 mm long, 1.02 mm wide; widest close to anterior angles; anterior angles obtusely rounded; very slightly narrowed posteriad; in posterior half with indis- tinct concave emargination; shortly in front of posterior angles with deep concave emargination; lateral margin fine; in dorsal aspect, visible throughout its total length; margin continued to posterior edge; setiferous punctation deep and dense; along midline much denser than laterad; partly forming short furrows; on lateral disc, interstices between punctures as wide as diameter of punctures; within impunctate midline with deep elongate impression; between coarse punctation with dense micro-punctation; without microsculpture; surface polished and shiny.

Elytra: 1.05 mm long, 1.10 mm wide; widest in posterior third; shoulders rectangular, but rounded; setiferous punctation deep and moderately dense; in indistinct rows; on average, interstices between punctures twice as long as diameter of punctures; coriaceous microsculpture weak; surface moderately shiny.

Abdomen with regular punctation; setiferous punctation dense and deep; interstices between punctures approximately half as wide as diameter of punctures; setae slightly longer than interstices between punctures; deep netlike microsculpture; surface matt.

Protibia: 0.62 mm long, 0.25 mm wide; shape semicircular; outer edge with 13 spines in approximately equal distances from each other; not inserted on digits; posterior face densely covered by yellow setae; in posterior aspect, inner emargination with comb totally covered.

Aedaegus without endophallus; thick; apical lobe placed in obtuse angle to basal lobe; apical third also angled and narrowed to obtuse apex.

Diagnosis: At present only this species is known from the genus that is characterised by the unique structure of the protibia. It mostly resembles some species of Osoriellus , but the total coverage of the inner emargination is never found in Osoriellus .