Osoriellus setulosus, 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 : 248-249

Osoriellus setulosus n. sp.

( Figs 25A, C , 27C )

Type material: Holotype, male: Panama, Chiriqui, La Fortuna , Hydrological Station Trail (82°12.0'W, 8°42.0'N), forest litter, Berlese, male, 9.6.1995, leg. R. Anderson, #PAN2A95 13A, ( KNHM).

Diagnosis: Among the O.- hirtulus -group, O. setulosus is the smallest species. It can be identified by the small size and the dense and deep microsculpture of the pronotum.

Description: Length: 4.8 mm. Colouration: Reddish brown; legs and antenne lighter brown.

Head. 0.68 mm long, 0.94 mm wide; eyes short and not prominent; temples twice as long as eyes; fore-head elongate; slightly emarginate to anterior angles; anterior edge

Key to the species

1. Large species of 7.4 – 7.8 mm, front edge of clypeus deeply emarginte; angles produced to broad prominences. .. .................................................................................................................................................... O. hirtulus ( FAUVEL, 1891)

- Smaller species between 4.8 mm and 7 mm, front edge of clypeus even. ................................................................... 2

2. Surface of pronotum between dense pubescent punctation with dense microsculpture, matt. ..... O. setulosus n. sp.

- Surface of pronotum between dense pubescent punctation without microsculpture, shiny. ................................... 3

3. Sides of pronotum in front of posterior angles slightly emarginate and flattened. ............................. O. setifer n. sp.

- Sides of pronotum evenly narrowed to posterior angles and not flattened at posterior angles. ............................... 4

4. Smaller species between 5.0 – 6.0 mm length; pronotum subparallel. ........................................... O. pubicollis n. sp.

- Larger species between 6.4 – 7.0 mm length, pronotum more trapezoidal. ............................................................... 5

5. Punctation of head irregularly dense, close to neck denser than on fore-head; aedeagus symmetric. ...................... ....................................................................................................................................................................... O. setosus n. sp.

- Density of punctation of head even; aedeagus asymetric. ............................................................... O. pubescens n. sp.

Elytra: 1.62 mm long, 1.52 mm wide; as densely and deeply punctate as pronotum, but setiferous punctures hardly visible in deep coriaceous ground-sculpture.

Abdomen with dense setiferous punctation; punctation slightly sparser than on pronotum; narrow midline impunctate; with weak netlike microsculpture. of clypeus even; setiferous punctation dense, but not deep; on average, interstices between punctures shorter than diameter of punctures; longitudinal area on central vertex and area at base of antennae impunctate; netlike microsculpture distinct; surface matt.

Antennae slightly longer than head; second antennomere globular; third antennomere quadrate; fourth to sixth antennomeres slightly wider than long; following antennomeres approximately quadrate and only slightly thicker than preceding antennomeres.

Pronotum: 0.94 mm long, 1.08 mm wide; widest closely behind anterior angles; evenly convergent to posterior angles; posterior angles widely rounded; lateral margin fine; finer at anterior angles than at posterior angles; in dorsal aspect, visible througout its total length; setiferous punctation deep and dense; on average, interstices between punctures shorter than diameter of punctures; moderately wide midline impunctate; netlike microsculpture distinct; surface matt.

Elytra: 1.12 mm long, 1.04 mm wide; as densely and deeply punctate as pronotum, but setiferous punctures hardly visible in coriaceous ground-sculpture; surface matt.

Abdomen with dense setiferous punctation and moderately wide impunctate midline on tergites; netlike microsculpture weaker than on head and pronotum and surface shinier.

Protibia: 0.55 mm long, 0.15 mm wide; slender; 7 spines at outer edge; apical spines inserted on short digits; WLR: 1.6; in posterior aspect, comb of inner emargination visible throughout its total length; posterior face with several long yellow setae; on average, setae slightly shorter than protibial width.

Aedeagus rectangularly angulate; asymmetric; left side with thick apical plate; few setae on both sides of inner edges; apical lobe sinuate ending in hook-like acute apex.

Etymology: The specific name means with many setae and refers to the densely setose body.

Figures

Fig. 21-26: Osoriellus-hirtulus-group: Osoriellus hirtulus (21), O. setosus (22), O. pubescens (23), O. pubicollis (24), O. setulosus (25), O. setifer (26); antenna (A), protibia (B), aedeagus in ventral and lateral aspects (C); scale bar: 0.1 mm.

Fig. 27: Osoriellus-hirtulus-group: Head and pronotum and elytra of Osoriellus hirtulus (A), O. pubicollis (B), O. setulosus (C), O. pubescens (D), O. setosus (E), O. setifer (F); scale bar: 0.5 mm.