Osoriellus majusculus, 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 : 276-277

Osoriellus majusculus n. sp.

( Figs 91 A-C, 99F)

Type material: Holotype, male: Peru: Tambopata Prov., Madre de Dios Dept, 15 km NE Puerto Maldonado, Reserva Cuzco Amazónico (69°03'W, 12°22'S), 200 m elevation, collected by flight intercept trap, Plot #Z1 rail 26, male, 16.7.1989, leg. J.S. Ashe & R.A. Leschen, #519 ( KNHM).

Diagnosis: O. majusculus is one of the largest species in the O.-s. str.-group. It is characterised by the wide lateral margin at the posterior pronotal angles. In the similarly sized O. parcus the lateral pronotal margin is narrow. A slightly widened lateral pronotal margin is also found in O. fumarius and O. caliginosus , but these species are smaller and the pronotal sides are more deeply sinuate.

Description: Length: 6.7 mm. Colouration: Black; elytra reddish brown; legs dark brown; antennae lighter brown.

Head: 0.91 mm long, 1.40 mm wide; eyes slightly prominent; as long as temples; fore-head deeply emarginate; sides of clypeus nearly parallel; anterior edge of clypeus slightly sinuate with acute angles shortly produced; setiferous punctation sparse and moderately deep; irregular midline and moderately large area at base of antennae impunctate; punctation of clypeus sparser than on vertex; interstices between punctures wider than diameter of punctures; punctation of vertex irregular; on average, interstices between punctures as wide as diameter of punctures; on supraocular area punctation still denser and partly granulate; isodiametric microsculpture dense and distinct; surface matt.

Antennae slightly longer than head; second antennomere oval; third conical and as long as second; antennomeres four to six as wide as third, but quadrate; following antennomeres wider than preceding antennomeres and also quadrate; last antennomere elongate.

Pronotum: 1.40 mm long, 1.53 mm wide; widest near anterior angles; evenly narrowed to posterior angles; slight emargination in posterior half; posterior angles approximately rectangular; lateral margin fine in anterior half, slightly wider in posterior half; shortly in front of posterior angles widened; in dorsal aspect, covered close to anterior angles; setiferous punctation dense and deep with narrow impunctate midline; on average, interstices between punctures slightly wider than diameter of punctures; isodiametric microsculpture deep; surfcae matt.

Elytra: 1.74 mm long, 1.65 mm wide; nearly parallel; setiferous punctation distinct; coriaceous ground-sculpture weak; punctures finer and sparser than on pronotum. Abdomen with dense setiferous punctation; isodiametric microsculpture dense; surface matt.

Protibia: 0.79 mm long, 0.29 mm wide; nearly semicircular; 9 spines on outer edge; apical spines inserted on short digits; WLR: 1.53; in posterior aspect, comb of inner emargination visible throughout its total length; posterior face densely covered by long yellow setae.

Aedeagus angulate in nearly rectangular angle; basal lobe nearly as long as apical lobe; apical lobe thick in basal half; in apical third suddenly narrowed to obtuse apex; row of numerous sensillae on inner edge of apical lobe.

Etymology: The specific word majusculus derived from the same Latin word and means slightly larger. It refers to the relatively large size of the species.

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.