Osoriellus exiguus ( NOTMAN, 1925 ) 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 : 267

Osoriellus exiguus ( NOTMAN, 1925) new combination ( Figs 43 A-C, 94A)

Osorius exiguus NOTMAN, 1925: 16

Type material examined: Cuba: Cayamas (80°34'W, 22°16'N), male, leg. E. Schwarz (holotype in NHMW) .

Further material examined: Cuba: Prov. Granma, PN Turquino, on trail up to ca. 0.5 km S (by air) from La Platica (76°53.3'W, 20°0.5'N), 920 m elevation, sifting of leaf litter and decaying wood in the secondary forest with many tree ferns and rich understory vegetation with meny ferns, 3 males, 7 females, 23.- 27.06.2012, leg. DelerHernández & Fikáček, #MF20 ( NMP, UIC) ; same region, saddle below La Mariposa, ca. 0.8 km SE La Platica (by air) (76°52.9'W, 20°0.5N), 1050 m elevation, sifting of leaf litter and decaying wood in the low secondary evergreen forest with rather rich understory vegetation and many roots, 4 males, 4 females, 24.06.2012, leg. Deler-Hernández & Fikáček, # MF22 ( NMP) ; same region, slope below Pico Naranjo ca. 0.4 km N La Platica (by air) (76°53.3'W, 20°0.9'N), 950 m elevation, sifting of rather dry leaf litter and decaying wood in the secondary bushes with thin litter layer and rather rich understory (moss, grasses), 1 female, 24.06.2012, leg. Deler-Hernández & Fikáček, # MF23 ( NMP) ; Belize: Cayo, Las Cuevas Research Station (88°58.24'W, 16°44.00'N), 550 elevation, flight intercept trap, 3 males, 3 females, 22.- 26.5.2000, 18.- 21.5.2000, 27.- 31.5.2000, female, sifted under rotten log, 22.5.2000, leg. M. Caterino ( BMNH) ; Costa Rica: Puerto Viejo, 3 km S, La Selva Biol. Stn ., female, 16.04.1988, leg. Hespenheide ( KNHM) .

Diagnosis: O. exiguus is one of the smallest species of the genus and darker in colour than the other small species, i.e. O. coruscus . In O. exiguus the head is dark brown in cotrast to the light brown remaining body, whereas O. coruscus is totally yellow to light brown. In contrast to O. coruscus , the apical margin of the clypeus is even and angles without granules. The species also resembles O. indescriptus and without dissecting of the aedeagus the two species cannot be certainly identified. The punctation of the pronotum in O. indescriptus is slightly deeper and denser than in O. exiguus and colouration is darker. The aedeagus of O. indescriptus has a thick, nearly triangular apical lobe, whereas the apical lobe of O. exiguus is slender.

Description: Length: 2.5 mm. Colouration: Light red; head brown; elytra, legs and antennae yellow; posterior margin of elytra dark.

Head: 0.42 mm long, 0.56 mm wide; eyes small; temples as long as eyes; apical edge of clypeus even; setiferous punctation on disc distinct and dense; wide midline and area at base of antennae impunctate; punctation of clypeus less dense; on clypeus, interstices between punctures at least as wide as diameter of punctures; setae pointing to middle; on vertex, interstices between punctures half as wide as diameter of punctures; surface without microsculpture, shiny.

Antennae short and stout; slightly longer than head; second antennomere thick and oval, nearly as thick as first antennomere; third and fourth antennomeres distinctly smaller than second; fourth and fifth antennomeres quadrate; following two antennomeres two times wider than long; last four antennomeres distinctly thicker than preceding antennomeres, but only slightly wider than long.

Pronotum: 0.52 mm long, 0.57 mm wide; widest at anterior angles; evenly narrowed to posterior edge; posterior edge smoothly rounded; setiferous punctation large and dense; interstices between punctures less than half as wide as diameter of punctures; wide impunctate midline; setae of punctures pointing to middle; surface without microsculpture, polished.

Elytra: 0.61 mm long, 0.56 mm wide; with coriaceous ground-sculpture; punctures slightly visible between coarse ground-sculpture.

Abdomen densely and coarsely punctate; setae of punctures pointing posteriorly; without microsculpture, surface shiny.

Protibia: 0.32 mm long, 0.09 mm wide; with 8 spines at outer edge; apically without digits; WLR: 3.0; in posterior aspect, comb at inner emargination partly covered in middle; posterior face with long yellow setae.

Aedeagus smoothly curved; apical lobe slender; apex of apical lobe obtuse; without sensillae at inner edge of apical lobe.

Figures

Fig. 43-47: Osoriellus-s. str.-group: O. exiguus (43), Osoriellus indescriptus (44), O. coruscus (45), O. luteus (46); O. punctatellus (47); antenna (A), protibia (B), aedeagus in lateral aspect (C); scale bar: 0.1 mm.