Osoriellus parumpunctatus, 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 : 282-283

Osoriellus parumpunctatus n. sp.

( Figs 64 A-C, 97D)

Type material: Holotype, male: Paraguay: Villarica , Jan. 1938, leg. F. Schade ( UIC).

Diagnosis: The species can be differentiated from the other similarly large species by the sparsely punctate pronotum. Concerning the size and polished pronotum, it resembles O. minor , O. tuxtlae , and O. bicolor . However, O. minor and O. tuxtlae are larger between 4.6 and 4.8 mm, whereas O. bicolor is smaller with 3.5 mm. The pronotal punctation of O. tuxtlae is much denser than the pronotal punctations of O. minor and O. bicolor . The inner row of punctures adjacent to the impunctate midline has both 8 and 12 punctures in O. bicolor and O. minor , respectively, whereas in O. parumpunctatus it has only 5 to 6 punctures.

Description: Length: 4.1 – 4.2 mm. Colouration: Reddish brown, pronotum and elytra lighter reddish; legs and antennae yellow.

Head: 0.52 mm long, 0.76 mm wide; eyes not prominent; nearly as long as temples; sides of fore-head slightly concave; front margin of clypeus even without lateral granules; setiferous punctation irregularly dense; fore-head and clypeus sparsely punctate; on average, interstices between punctures at least as wide as diameter of punctures; vertex more densely punctate except wide impunctate midline; interstices between punctures less wide than half of diameter of punctures; on narrow supraocular area nearly coriaceously punctate; without microsculpture except on lateral vertex with weak remains of netlike microsculpture; surface on most parts polished and shiny.

Antennae shortly longer than head; second antennomere nearly globular; third conical antennomere shorter than second; fourth antennomere as wide as third, but quadrate; following antennomeres increasing in width; fifth and sixth antennomeres wider than long and slightly wider than fourth; antennomeres 7 to 10 thicker than preceding antennomeres and quadrate.

Pronotum: 0.71 mm long, 0.80 mm wide; widest at anterior angles; slightly and evenly convergent to posterior angles; lateral margin very fine; in dorsal aspect, visible throughout its total length; setiferous punctation sparse; punctures large and in irregular rows; inner row adjacent to impunctate midline with 5 to 6 punctures; interstices between punctures at least as wide as diameter of punctures; between large punctures with sparse micropunctation; surface without microsculpture; polished and shiny.

Elytra: 0.87 mm long, 0.83 mm wide; with weak coriaceous ground-sculpture; setiferous punctation distinctly visible; punctures in irregular rows.

Abdomen with dense setiferous punctation and narrow impunctate midline; tergites VII and VIII less densely punctate than anterior tergites; without microsculpture; surface polished and shiny.

Protibia: 0.48 mm long, 0.16 mm wide; 8 spines on outer edge; WLR: 2.30; in posterior aspect, comb of inner emargination visible in its total length; posterior face with moderately dense setation.

Aedeagus with narrow apical lobe ending in obtuse apex; inner edge of apical lobe with row of few sensillae.

Etymology: The specific name is a combination of the Latin word parum meaning few and punctatus meaning punctate and refers to the sparsely punctate pronotum.

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.