Osoriellus denticornis, 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 : 236-237

Osoriellus denticornis n. sp.

( Figs 10 A-D, 11D)

Type material: Holotype, male: British Guyana: Essequibo River, Moraballi Creek, male, 1929, leg. Oxford University Expedition, BM #1929-485 ( BMNH).

Diagnosis: Acording to the structure of the aedeagus and the placement of the lateral sensillae, O. denticornis is placed to the O.- oculatus -group, although strongly produced angles of the clypeus are also found in the O.- bicornis -group. However, in the O.- bicornis -group, the aedeagus is asymmetric with lateral opening. The species can be easily identified by the specific structure of the clypeus among all Neotropical Osoriellus species.

Description: Length: 3.4 mm. Colouration: Dark brown; abdomen slightly lighter brown; legs and antennae yellow. Head: 0.54 mm long, 0.67 mm wide; eyes slightly prominent; fore-head narrowed to anterior angles of clypeus in concave curve; anterior angles of clypeus strongly produced to broad bidentate teeth; anterior edge of clypeus deeply emarginate between lateral teeth; outer edge of lateral teeth smoothly curved; inner edge straight; setiferous punctation dense and deep; on vertex denser than on clypeus; setae long and yellow; longer than two times of diameter of punctures; interstices between punctures on vertex shorter than diameter of punctures; small area on vertex and at base of antennae impunctate; without microsculpture; surface shiny.

Antennae as long as head and quarter of pronotum combined; second antennomere oblong and distinctly longer than conical third; following three antennomeres not wider than third, but shorter; fourth approximately quadrate; sixth wider than long; following antennomeres distinctly wider than preceding antennomeres; approximately quadrate.

Pronotum: 0.57 mm long, 0.69 mm wide; widest at anterior angles; narrowed in smoothly even curve to obtuse posterior angles; lateral margin fine; in dorsal aspect, not visible in anterior quarter; setiferous punctation coarse and dense; yellow setae long; longer than three times of diameter of punctures; on average, interstices between punctures as wide as diameter of punctures; wide midline impunctate; without microsculpture; surface shiny.

Elytra: 0.72 long, 0.68 mm wide; sides nearly parallel; shoulders obtusely rounded; setiferous punctation coarse and dense; yellow setae as long as on pronotum; interstices between punctures less wide than diameter of punctures; coriaceous ground sculpture weak.

Abdomen densely and deeply punctate; yellow setae as long as on fore-body; without microsculpture; surface shiny.

Protibia: 0.38 mm long, 0.13 mm wide; 7 long spines at outer edge; apical spines inserted on moderately long digits; WLR: 1.1; in posterior aspect, comb at innern emargination visible throughout its total length; posterior face with moderately dense, long yellow setation.

Aedeagus stout; symmetric; apical lobe thick and sinuate at upper edge; only slightly longer than width of basal lobe; three sensillae on lateral face of apical lobe.

Etymology: The specific name is a combination of the Latin word dens meaning tooth and cornis meaning horn and refers to the structure of the clypeal angles.

Figures

Fig. 6-10: Osoriellus-oculatus-group: Osoriellus ocularis (6), O. oculatus (7), O. hanagarthi (8) O. sexdentatus (9) O. denticornis (10); antenna (A), protibia (B), aedeagus in lateral aspect (C), anterior edge of clypeus (D); scale bar: 0.1 mm.