Osoriellus digitatus, 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 : 299

Osoriellus digitatus n. sp.

( Figs 117 A-C, 124D)

Type material: Holotype, male: Peru: Loreto, Campamento San Jacinto (75°51.77'W, 2°18.75'S), 175-215 m elevation, collected in flood debris, Qd. 16, 2.7.1993, leg. R. Leschen ( KNHM).

Diagnosis: Concerning the long digits of the protibia, the species resembles O. acutus , but both species can be easily differentiated by the shape of the head and the pronotum. The shape of the pronotum of O. digitatus resembles that of O. opticus and O. rectangulus , but these species have much shorter protibial digits.

Description: Length: 3.8 mm. Colouration: Dark brown; clypeus and narrow posterior edge of pronotum light reddish; abdomen slightly lighter brown; legs and antennae light yellowish brown.

Head: 0.43 mm long, 0.78 mm wide; eyes prominent; nearly twice as long as temples; sides of fore-head convergent to anterior angles in smooth concave curve; anterior edge of clypeus even; setiferous punctation moderately deep and dense; on average, interstices between punctures as wide as diameter of punctures; yellow setae approximately as long as interstices between punctures; only few setae of supraocular area much longer; midline and area at base of antennae impunctate; on supraocular area punctation much denser, but not coriaceous; isodiametric microsculpture weak; surface slightly shiny.

Antennae as long as head and half of pronotum combined; second antennomere oval and longer than wide; as long as conical third antennomere; third antennomere one fourth longer than wide; antennomeres four to six slightly increasing in width; following antennomeres distinctly wider than preceding antennomeres, but all approximately quadrate.

Pronotum: 0.77 mm long, 0.90 mm wide; widest at anterior angles; evenly convergent to obtuse posterior angles; lateral margin distinct; in dorsal aspect, visible throughout its total length; widened close to posterior angles; setiferous punctation similarly deep and dense as on head, but punctures slightly larger; on average, interstices between punctures as wide as diameter of punctures; yellow setae as long as diameter of punctures; impunctate midline in posterior half wider than in anterior half; isodiametric microsculpture weak; surface slightly shiny.

Elytra: 0.93 mm long, 0.88 mm wide; shoulders rounded; sides slightly widened to posterior third; setiferous punctation similar to pronotum; in irregular rows; coriaceous ground-sculpture deep, but punctures distinctly visible; surface less shiny than on pronotum. Abdomen with dense setiferous punctation; punctation much denser than on fore-body; without microsculpture; surface slightly shiny than fore-body.

Protibia: 0.47 mm long, 0.12 mm wide; with six spines at outer edge; apical spines inserted on very long digits; WLR: 0.33; in posterior aspect, inner emargination with comb visible throughout its total length; posterior face sparsely covered with long yellow setae.

Aedeagus asymmetric; small; apical lobe smoothly curved; evenly convergent to acute apex; few sensillae at inner edge of apical lobe.

Etymology: The specific name digitatus derived from the same Latin name meaning with fingers and refers to the large digits in the apical part of the protibia.

Figures

Fig. 114-118: Remaining-species-group: Osoriellus neotropicus (114), O. lescheni (115), O. loreti (116), O. digitatus (117), O. opticus (118); antenna (A), protibia (B), aedeagus in ventral and lateral aspects (C); scale bar: 0.1 mm.