Osoriellus rectangulus, 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 : 306

Osoriellus rectangulus n. sp.

( Figs 121 A-C, 125F)

Type material: Holotype, male: Ecuador: Sucumbios, Sacha Lodge (76°27.35'W, 0°28.14'S), 270 m elevation, collected by flight intercept trap, 21.- 24.3.1999, leg. R. Brooks ( KNHM).

Paratypes: Ecuador: 2 females with same data as holotype ( KNHM, UIC); Napo, Jatun Sacha Biol. Station (21 km E Puerto Napo), lowland rain forest, collected by flight intercept trap, female, 15.7.1994, leg. Levy & Génier ( KNHM) .

Diagnosis: The species is characterised by the rectangular posterior angles of the pronotum and the rectangular shoulders. Species with similar rectangular shoulders are found in the O.- guiananus -group that differ in the absence of the pronotal setae. In the remainingspecies-group, rectangular shoulders are also found in O. rufescens and O. loreti . O. rectangulus differs from these two species by the shape of the pronotum and the black colouration.

Description: Length: 4.5 mm. Colouration: Black; posterior angles of pronotum, legs and antennae light bown.

Head: 0.58 mm long, 0.86 mm wide; eyes slightly prominent; sligthly longer than temples; fore-head convergent to anterior angles in sinuate curve; anterior edge of clypeus even; setiferous punctation moderately deep and dense; wide midline and area at base of antennae impunctate; punctation of neck without setae and much denser; on vertex, interstices between punctures and length of yellow setae slightly longer than diameter of punctures; on supraocular area, punctation denser and with few longer setae; isodiametric microsculpture on fore-head fine and dense; surface with iridescent shine.

Antennae slightly shorter than head and half of pronotum combined; second antennomere globular and as long as conical third antennomere; following antennomere increasing in width, but each antennomere approximately quadrate.

Pronotum: 0.89 mm long, 0.97 mm wide; widest shortly behind anterior angles; anterior angles rectangular; evenly convergent to posterior angles; posterior angles rectangular; lateral margin fine in anterior half and distinctly widened in posterior half; setiferous punctation moderately dense and deep; wide midline impunctate; on average, interstices between punctures 1.5 times as wide as diameter of punctures; yellow setae distinctly shorter than interstices between punctures; between normal punctures with dense micro-punctation; without microsculpture; surface polished and shiny.

Elytra: 1.10 mm long, 1.02 mm wide; shoulders rectangular; sides approximately parallel; setiferous punctation slightly weaker than on pronotum, but as dense as on pronotum; coriaceous ground-sculpture weak; surface slightly shiny.

Abdomen with fine setiferous punctation and wide impunctate midline on tergites; netlike microsculpture weak; surface with iridescent shine.

Protibia: 0.47 mm long, 0.17 mm wide; outer edge with 9 spines; apical spines inserted on short digits; WLR: 1.0; in posterior aspect, inner emargination with comb visible throughout its total length; posterior face densely covered by long yellow setae.

Aedeagus with broad apical lobe; apical lobe longer than basal lobe; upper edge of apical lobe evenly curved to obtusely rounded apex; inner edge with sparse row of sensillae.

Etymology: The specific name rectangulus derived from the same Latin word meaning rectangular and refers to the rectangular posterior angles of the pronotum and the rectangular shoulders.

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.