Osoriellus melancholicus, 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 : 254-255

Osoriellus melancholicus n. sp.

( Figs 36 A-C, 41F)

Type material: Holotype, male: Peru: Dept. Loreto, Campamento San Jacinto (75°51.77'W, 2°18.75'S), collected by berlese extraction at Qd. 22, 175- 215 m elevation, 2.7.1993, leg. R. Leschen ( KNHM).

Paratypes: Peru: 2 females with same data as holotype, but collected from flowerfall by berlese extraction and at 11.7.1993 ( KNHM, UIC) ; Dept. Loreto, 1.5 km N Teniente Lopez (76°06.92'W, 2°35.66'S), 210-240 m elevation, collected by flight intercept trap, female, 24.7.1993, leg. R. Leschen ( KNHM) ; Brazil: Amazonas, Manaus, 26 km N of Manaus, Reserva Ducke , collected by flight intercept trap, male, 1995-1996 ( BNHM) .

Diagnosis: Concerning the pronotal microsculpture, O. melancholicus can be confused with O. breviceps , but the shape of the pronotum is distinctly different. Additionally, the anterior edge of the clypeus is emarginate and not even as in O. breviceps .

Description: Length: 6.3 long. Colouration: Black; legs and antennae brown.

Head: 0.81 mm long, 1.24 mm wide; eyes slightly prominent; nearly twice as long as temples; sides of fore-head narrowed to anterior angles in smooth sinuate curve; anterior angles obtuse; anterior edge of clypeus deeply emarginate; punctation deep; central area on clypeus and area at base of antennae impunctate; on clypeus, interstices between punctures at least as wide as diameter of punctures; on vertex with denser punctation; centrally, interstices between punctures half as wide as diameter of punctures; laterally, interstices between punctures still shorter, partly coriaceous; punctures on clypeus with short yellow setae; punctures on vertex without setae, except one pair of setiferous punctures in centre close to neck and several setiferous punctures on supraocular area; without microsculpture; surface shiny.

Antennae as long as head and half of pronotum combined; second antennomere oval and as long as conical third; antennomeres four and five as wide as preceding antennomeres; width of following antennomeres increasing, but each antennomere approximately quadrate.

Pronotum: 1.24 mm long, 1.37 mm wide; widest shortly behind anterior angles; anterior angles obtuse and rounded; evenly narrowed to posterior angles; shortly in front of posterior angles slightly emarginate; posterior angles nearly rectangular and slightly produced laterad; lateral margin fine in anterior half; widened to posterior angles; in dorsal aspect; covered shortly close to anterior angles; deep and coarse punctation irregularly dense; near midline denser than laterally; impunctate midline narrow in anterior half and widened in posterior half; close to midline punctation nearly coriaceous; on lateral disc, interstices between punctures as wide as diameter of punctures or closer; punctures without setae; between normal coarse punctures with dense micro-punctation; very weak longitudinal reticulate microsculpture; surface slightly shiny.

Elytra: 1.51 mm long, 1.44 mm wide; shoulders shortly rounded; sides nearly parallel; punctation slightly finer than on pronotum; in irregular rows; ground sculpture deep; surface slightly shiny.

Abdomen with dense setiferous punctation; narrow midline impunctate; punctures partly granulate and on segment VII and VIII partly elongate; irregular microsculpture very weak; surface slightly shiny.

Protibia: 0.77 mm long, 0.20 mm wide; slender; with 7 spines on outer edge; apical spines inserted on long teeth; WLR: 0.36; in posterior aspect, inner emargination with comb visible throughout its total length; posterior face sparsely covered by long yellow setae.

Aedaegus thick; with basal lobe and apical lobe approximately equally long; apical lobe thick at base; then suddenly narrowed to thin apex; inner edge of apical lobe with dense row of sensillae; apical third of inner edge without sensillae.

Etymology: The specific name melancholicus derived from the same Latin word meaning dark and refers to the black colouration.

Figures

Fig. 32-37: Osoriellus-guiananus-group: Osoriellus guiananus (32), O. breviceps (33), O. solidus (34), O. macrops (35), O. melancholicus (36), O. diversus (37); antenna (A), protibia (B), aedeagus in lateral aspect (C); scale bar: 0.1 mm.