Osoriellus humicola, 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 : 271-272

Osoriellus humicola n. sp.

( Figs 63 A-C, 97E)

Type material: Holotype, male: Honduras: Octotepeque , 12.7 km E & 2.4 km S Ocotepeque, Mp O. Sinuapa (89°04'W, 14°27'N), forest litter berlese, 1450 m elevation, 15.6.1994, leg. R. Anderson, #118A ( KNHM).

Paratypes: Honduras: 1 female and 1 male with same data as for holotype ( KNHM, UIC) ; Guatemala: Tactic , Verapaz, 6. km W, sifting litter, under bushes of road side, trop. mont. forest, 1 female, 22.11.1991, R. Baranowski .

Diagnosis: The species extremely resembles O. eggersi in size and both shape and punctation of the pronotum. It can be separated by the less dense punctation of the fore-head and mainly by the shape of the aedeagus. In O. eggersi , the punctation of the fore-head is as dense as on the vertex. In O. humicola , the punctation of the forehead is distinctly sparser than on the vertex. The apical lobe of the aedeagus of O. humicola is evenly curved on outer edge and the apex is obtuse, whereas in O. eggersi the outer edge of the apical lobe is sinuate and the apex is acute. The distribution of sensillae is similar, but the setae of the sensillae of O. eggersi are very long.

Description: Length: 3.8. Colouration: Brown; pronotum and elytra lighter brown; legs and antennae reddish.

Head: 0.55 mm long, 0.80 mm wide; eyes not prominent; temples 1.5 times as long as eyes; sides of fore-head evenly narrowed in slightly concave curve to anterior angles; setiferous punctation irregularly dense and deep; on vertex denser than on fore-head; wide midline and area at base of antennae impunctate; on vertex, interstices between punctures half as wide as diameter of punctures; on fore-head, interstices at least as wide as diameter of punctures; without microsculpture; surface polished and shiny.

Antennae slightly longer than head; second antennomere longer than wide and nearly 1.5 times as long as conical third antennomere; antennomeres 4 to 6 as wide as preceding antennomeres, but quadrate; antennomeres 7 to 10 distinctly wider than preceding antennomeres and nearly twice as wide as long.

Pronotum: 0.74 mm long, 0.79 mm wide; widest at anterior angles; anterior angles obtuse in short curve; in anterior half, sides slightly narrowed posteriad; in posterior half, sides distinctly convergent to widely rounded posterior angles; lateral margin very fine; in dorsal aspect, invisible in anterior half; setiferous punctation dense and coarse; impunctate midline narrower than on head; punctures partly coriaceous; interstices between punctures less than half as wide as diameter of punctures; with sparse micro-punctation; without microsculpture; surface polished and shiny.

Elytra: 0.80 mm long, 0.80 mm wide; setiferous punctation dense and coarse; in irregular rows; ground-sculpture weakly coriaceous.

Abdomen with dense setiferous punctation except on narrow impunctate midline; without microsculpture; nearly polished and shiny.

Protibia: 0.42 mm long, 0.15 mm wide; with 10 spines at outer edge; WLR: 2.60; in posterior aspect, comb at inner edge visible throughout its total length; posterior face densely covered by yellow setae.

Aedeagus with evenly curved apical lobe ending in obtuse apex; inner edge of apical lobe with two groups of sensillae; basal group with six sensillae; apical group with four sensillae.

Etymology: The specific name derived from the Latin word humus meaning soil and refers to the litter dwelling behaviour of the species.

Figures

Fig. 63-67: Osoriellus-s. str.-group:Osoriellus humicola(63), O. parumpunctatus (64),O. obtusicollis (65),O. tuxtlae(66),O. asperatus (67); antenna (A), protibia (B), aedeagus in lateral aspect (C); scale bar: 0.1 mm.