The Neotropical species of the genus Osoriellus FAGEL, 1959 (Coleoptera: Staphylinidae: Osoriinae) Author Irmler, Ulrich text Beiträge Zur Entomologie = Contributions to Entomology 2014 2014-12-15 64 2 231 354 https://www.contributions-to-entomology.org/article/view/1859 journal article 2515 10.21248/contrib.entomol.64.2.231-354 5df8bd34-9c04-4499-afe0-018387e11ffb 0005-805X 5461706 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.