Osoriellus spinosus, 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 : 243-244

Osoriellus spinosus n. sp.

( Figs 15 A-D, 20B)

Type material: Holotype, male: Peru: Tambopata Prov. Madre de Dios Depto., 15 km Ne Puerto Maldonado, Reserva Cuzco Amazónica (69°03'W, 12°33'S), 200 m elevation, ex. Flight intercept rap, 19.07.1989, leg. J.S. Ashe & R.A. Leschen, #522, Plot #Z1U19 ( KNHM).

Paratypes: Peru: 2 males with same data as holotype, 19.7.1989, 13.7.1989 ( KNHM, UIC) ; 3 females, same data as holotype, but Plot Z 2U19; 13.07.1989, #484, Plot Z 1U19, 26.06.1989, #280, Plot #Z1 trail 26, 2.7.1989, #366, Plot Z 2U19 ( KNHM) .

Diagnosis: The species resembles O. oculatus in the shape of the head and pronotum and, thus, can be easily mixed with species of the O.- oculatus -group. In contrast to the species of that group, the aedeagus of O. spinosus is asymmetric. The eyes are slightly less prominent than in O. oculatus . The punctation of the head is less dense, but the pronotal punctation is denser than in O. oculatus . In particular, the dentation of the clypeus differs from O. hanagarthi and O. oculatus . The pronotal shape differs distinctly from O. hanagarthi , since the sides are evenly narrowed such as in O. oculatus and without slight emargination. Within the O.- bicornis -group the species is characterised by the denticulate anterior edge of the clypeus.

Description: Length: 3.5 mm. Colouration: Dark brown; posterior margin of pronotum lighter reddish; legs and antennae light brown.

Head: 0.48 mm long, 0.69 mm wide; eyes not prominent; as long as temples; sides of fore-head narrowed in concave curve to anterior angles; clypeal angles produced to short teeth; adjacent to produced angles with additional two shorter teeth; middle of anterior edge of clypeus even; large setiferous punctation irregularly dense; on average, interstices between punctures as wide as or slightly shorter than diameter of punctures; wide midline and area at base of antennae impunctate; on punctate area with remains of irregular microsculpture; impunctate area polished; in total, surface shiny.

Antennae slightly longer than head; second antennomere oval; nearly twice as long as conical third; antennomeres four to six as wide as preceding antennomeres; antennomeres four to fife approximately quadrate; sixth nearly twice as wide as long; antennomeres seven to ten distinctly wider than preceding antennomeres and slightly wider than long.

Pronotum: 0.65 mm long, 0.71 mm wide; widest at anterior angles; evenly convergent to posterior angles; in posterior half more strongly convergent than in anterior half; posterior angles widely rounded; lateral margin extremely fine; in dorsal aspect, not visible in anterior half; setiferous punctures large and dense; in irregular rows; wide midline impunctate; on average, interstices between punctures as wide as diameter of punctures; within rows, interstices slightly shorter; between normal large punctures with dense micro-punctation; surface shiny.

Elytra: 0.78 mm long, 0.74 mm wide; with setiferous punctation in irregular rows on fine coriaceous ground sculpture; surface shiny.

Abdomen with dense setiferous punctation except on narrow impunctate midline; surface matt.

Protibia: 0.39 mm long, 0.14 mm wide; nearly semicircular; with 10 spines at outer edge; apical spines not inserted on digits; WLR: 4.0; in posterior aspect, comb at inner emargination shortly covered in middle part; posterior face with dense setation.

Aedeagus with long acute apical lobe; inner edge of apical lobe with 9 sensillae.

Etymology: The specific name derives from the same Latin word meaning spiny and refers to the spines on the front edge of the clypeus.

Key to species

1. Smaller than 4.0 mm. .......................................................................................................................................................... 2

- Longer than 4.0 mm. ........................................................................................................................................................... 3

2. Produced angles of clypeus broad and not acute, punctation of pronotum finer. .......................... O. bicornis n. sp.

- Anterior edge of clypeus denticulate, punctation of pronotum coarse. ............................................ O. spinosus n. sp.

3. Longer than 5.0 mm, produced angles of clypeus broad with aditional smaller teeth. ........... O. corniculatus n. sp.

- Smaller than 5.0 mm, angles of clypeus produced to acute simple teeth. ................................................................... 4

4. Sides of pronotum deeply emarginate in front of posterior angles or lateral margin ending slightly in front of posterior angles to form a short emargination. ............................................................................................................... 6

- Sides of pronotum more or less evenly narrowed from anterior angles to posterior angles, without even slight emargination in front of posterior angles. ....................................................................................................................... 5

5. Eyes large and distinctly prominent, longer than temples, pronotum with weak microsculpture, surface shiny. ... ......................................................................................................................................................................... O. bovis n. sp.

- Eyes smaller and only slightly prominent, as long as temples, pronotum with deep microsculpture, surface matt. .................................................................................................................................................................... O. cornutus n. sp.

6. Pronotum deeply emarginate in front of posterior angles, emargination margined, surface with distinct netlike microsculpture. ......................................................................................................................................... O. sinuatus n. sp.

- Lateral margin of pronotum ending in front of posterior angles, posterior angles only shortly emarginate. ........ 7

7. Pronotum only with remains of microsculpture, smoothly narrowed from anterior angles to posterior angles. ....................................................................................................................................................... O. sinuatoangularis n. sp.

- Pronotum with deep netlike microsculpture, shape of pronotum trapezoidal. ......................... O. subsinuatus n. sp.

Figures

Fig. 12-15: Osoriellus-bicornis-group:Osoriellus bovis (12), O. cornutus (13), O. bicornis (14), O. spinosus (15); antenna (A), protibia (B), aedeagus in lateral aspect (C), anterior edge of clypeus (D); scale bar: 0.1 mm.