Osoriellus opacus, 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 : 281

Osoriellus opacus n. sp.

( Figs 83 A-C, 100B)

Type material: Holotype, male: Belize: Orange Walk District, Rio Bravo Conservation Area , Area along Mahogony Trail (17°50'N, 89°01'W), collected by berlese method, 18.4.1996, leg. C. Carlton & V. Moseley ( KMNH).

Paratypes: Belize: Orange Walk Distr., La Milpa Field Station , flight intercept trap, female, 25.05.1997, leg. C.E. Carlton #FIT5, Lot #152 ( UIC) ; Chiquibul Forest Res. Las Cuevas field station (88°59'W, 16°44'N), 500-700 m elevation, 2 males, June 1997, leg. D. Inward ( BMNH) ; Cayo, Las Cuevas Research Station (88°58.24'W, 16°44.00'N), 550 m elevation, male, 22.- 26.5.2000, leg. M. Caterino ( BMNH) .

Diagnosis: The species is very similar to O. schwarzi in size and microsculpture of the head and the pronotum. The lengths of the antennomeres are also similar to O. schwarzi . Compared to O. opacinotus with a similarly matt pronotum, it can be distinguished by the absence of long digits of the protibia and the shinier elytra. It differs in the extreme dense and deep microsculpture of the elytra from both species. Furthermore, the aedeagus is characterised by the thick apical lobe and the numerous sensillae at the inner edge. The aedeagal apical lobes are more slender in O. schwarzi and O. opacinotus .

Description: Length: 5.8 mm. Colouration: Black; legs and antennae light brown.

Head: 0.71 mm long, 1.13 mm wide; eyes not prominent; slightly longer than temples; sides of fore-head concavely convergent to anterior angles; anterior edge even except weak crenate structure at angles; setiferous punctation fine and moderately sparse; punctures on supraocular area denser and punctures partly granulate; without impunctate midline; isodiametric microsculpture dense and deep; surface matt.

Antennae with oblong second and conical third antennomeres slightly longer than wide; following antennomeres increasing in width; fourth and fifth antennomeres more or less quadrate; sixth antennomere slightly wider than long; following antennomeres thicker than preceding antennomeres, but quadrate.

Pronotum: 1.19 mm long, 1.31 mm wide; widest at anterior angles; evenly narrowed to posterior angles in smooth curve; lateral margin slightly widened to posterior angles and, in dorsal aspect, visible throughout its total length; irregular punctation deeper and larger than on head; with wide impunctate midline; interstices between punctures within irregular rows shorter than diameter of punctures; interstices of punctures between rows at least as wide as diameter of punctures; isodiametric microsculpture deep; surface matt.

Elytra: 1.23 mm long, 1.30 mm wide; with deep isodiametric microsculpture; microsculpture still deeper and denser than on pronotum; surface distinctly matter than on pronotum; punctation in irregular rows; nearly invisible in deep microsculpture.

Abdomen with weak netlike microsculpture; much weaker than on fore-body; setiferous punctation dense with impunctate midline.

Protibia: 0.71 mm long, 0.23 mm wide; 9 spines on outer edge; WLR: 2.30; in posterior aspect, comb of inner emargination visible throughout its total length; posterior face sparsely covered by yellow setae.

Aedeagus with thick apical lobe ending abruptly in obtuse apex; inner edge of apical lobe with numerous sensillae.

Etymology: The specific name opacus means matt and refers to the matt elytra.

Figures

Fig. 79-83: Osoriellus-s. str.-group: Osoriellus debilis (79), O. parcus (80), O. schwarzi (81), O. trapezoides (82), O. opacus (83); antenna (A), protibia (B), aedeagus in lateral aspect (C); scale bar: 0.1 mm.