Osoriellus argentinus ( BERNHAUER, 1911 ) 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 : 258

Osoriellus argentinus ( BERNHAUER, 1911) new combination

( Figs 77 A-C, 99D)

Osorius argentinus BERNHAUER, 1911: 403

O. acupunctus BERNHAUER, 1933 , 332 new synonymy O. ogloblini BERNHAUER, 1933: 332 new synonymy

Type material examined: Argentina: Missiones , male without further data, leg. C. Bruch (holotype FMNH); female leg. Ogloblin (as O. ogloblini in FMNH); Buenos Aires, female, 15.12.1899, leg. Silvestri (as O. acupunctus in FMNH).

Further material examined: Paraguay: Villarica (25°45'S, 56°25'W), 125 m elevation, 16 specimens from July, August, September, October, November, January and March 1937, leg. F. Schade ( AMNH, UIC); 1 male without further data, identified by Bernhauer as O. acupunctus , 3 females, leg. Drake identified as O. frater by Bernhauer ( SDEI); Brazil: Pará, Jacaréacanga, at light, male, Jan. 1970, leg. F.R. Barbosa ( AMNH).

Diagnosis: The species highly resembles O. mexicanus and O. brevipennis in size and shape of the pronotum. It can be differentiated from O. mexicanus by the presence of at least remains of microsculpture on the head. In contrast to O. brevipennis , the shape of the pronotum is less triangular. BERNHAUER (1933) described O. acupunctus and O. ogloblini considering the nearly lacking microsculpture of the head and the deeper punctures on the elytra. Unfortunately, the type specimens of O. ogloblini and O. acupunctus are females and, therefore, a study of the aedegaus was not possible. Within the large number of specimens in the AMNH the microsculpture of the head varies extremely from very deep ground-sculpture with slightly shiny surface to nearly polished surface. Additionally, the microsculpture of the abdomen varies in the same way. Furthermore, the row of punctures along the impunctate midline of the pronotum is not a differentiating character between N. argentinus and N. ogloblini . I found no other characters to separate the species even between the aedeagi of the non-type O. acupunctus of SDEI and O. argentinus . Thus, the species described by BERNHAUER (1933) are within the variability of O. argentinus .

Description: Length: 5.3 – 6.0 mm long. Colouration: Black, antennae and legs brown.

Head: 0.75 mm long, 1.20 mm wide; eyes as long as temples; clypeus with short granules at angles, front edge of clypeus between lateral granules even; punctation distinct and dense; interstices between punctures as wide as diameter of punctures or slightly shorter; yellow setae of punctures pointing centrally; lateral punctures partly coriaceous and granulate; surface with dense and moderately deep isodiametric microsculpture; area at base of antennae polished without microsculpture.

Antennae with first antennomere as long as three following antennomeres; antennomeres 2 to 4 short and quadrate; antennomeres 7 to 10 distinctly wider and thicker than preceding antennomeres.

Pronotum: 1.20 mm long, 1.25 mm wide; widest at anterior angles; evenly convergent to posterior angles in slightly convex curve; posterior angles smoothly rounded; in dorsal aspect, fine lateral margin visible from anterior to the posterior angles; punctation coarse and dense; interstices between punctures less than half of diameter of punctures; wide midline impunctate; between coarse punctation with fine micro-punctation; without microsculpture except on lateral posterior part; surface shiny.

Elytra: 1.30 mm long. 1.20 mm wide; setiferous punctation similar as on head; on average, interstices between punctures as wide as diameter of punctures; punctures moderately deep, but less deep than on pronotum; surface with weakly coriaceous ground-sculpture, surface moderately shiny.

Abdomen with distinct and dense setiferous punctation; with moderately deep netlike microsculpture; surface slightly shiny.

Protibia: 0.70 mm long, 0.29 mm wide; thick; nearly semi-circular; with 10 spines on outer edge; two apical spines inserted on short digits, WLR: 1.6; in posterior aspect, comb at inner emargination partly covered in middle; anterior face with longitudinal row of five yellow setae; posterior face densely covered by thick setae; setae approximately one third as long as protibial width.

Aedaegus with slender apical lobe; apical lobe evenly curved to shortly rounded apex; apical lobe with one lateral sensilla and group of 5 sensillae at base.

Figures

Fig. 73-78: Osoriellus-s. str.-group: Osoriellus frater (73), O. latipes (74); O. mexicanus (75), O. brevipennis (76), O. argentinus (77), O. crassus (78); antenna (A), protibia (B), aedeagus in lateral aspect (C); scale bar: 0.1 mm.