Thoracophorus exilis ( Erichson, 1840 )

Irmler, Ulrich, 2015, Four new species of the genus Thoracophorus Motschulsky, 1857 for the Neotropical region (Coleoptera: Staphylinidae: Osoriinae), Zootaxa 4039 (3), pp. 431-444 : 438

Thoracophorus exilis ( Erichson, 1840)

Figs. 7 A, B, C, 10A

Type material examined. HOLOTYPE. male, St. Thomas without more information ( ZMUH)

Diagnosis. The species extremely resembles T. proximus Irmler, 1985 , T. struyvei n. sp., and T. perplexus n. sp.. It can be mainly identified by the differences of the aedeagus. In contrast to these three species, the paramera do not or only slightly exceed the apex of the central lobe. In lateral aspect, the inner edge of the apical lobe is slightly sinuate such as in T. perplexus n. sp., whereas the inner edges of the apical lobes are straight in T. proximus Irmler, 1985 and T. struyvei n. sp. Moreover, the shape of the apical transparent plate of the paramera differs among the three species: small plate in T. exilis ( Erichson, 1840) , large asymmetric plate in T. struyvei n. sp., and intermediate large plate in T. proximus Irmler, 1985 . Regarding the holotype specimen, T. exilis ( Erichson, 1840) seems to be lighter than the other three species that are darker brown or partly orange brown. The elytral carinae are more distinct than in T. perplexus n. sp., but similar to T. proximus Irmler, 1985 and T. struyvei n. sp. T. aequalis Sharp, 1887 also resembles T. exilis ( Erichson, 1840) in the shape of the head, the antennae and the aedeagus (Figs (8A, B, C), but is distinctly larger.

Description. Length: 2.0 mm. Colouration: light-brown; legs and antennae yellow.

Head: 0.21 mm long, 0.31 mm wide; eyes prominent; approximately twice as long as temples; temples shortly rounded to neck; posterior angle of temples 114°; sides in front of eyes up to base of antennae approximately half as long as eyes and slightly narrowed; clypeus nearly triangular with short straight central part; deeper margined near base of antennae than at central clypeus; pair of swellings on posterior vertex distinct; without punctation; microsculpture deep and dense; surface matte

Antenna as long as head and half of pronotum combined; first and second antennomeres thicker than following four antennomeres; second global; 1.5 times wider than conical third; third antennomere nearly as long as second; antennomeres four to six much shorter, but as wide as third; width of following antennomeres increasing; antennomere four approximately quadrate; antennomere ten nearly twice as wide as long.

Pronotum: 0.27 mm long, 0.35 mm wide; widest at middle; slightly narrowed to anterior angles; anterior angles nearly rectangular; anterior edge slightly prominent in convex curve; more strongly narrowed to posterior angles in concave curve; anterior edge approximately 1.5 times as wide as posterior edge; laterally with deep longitudinal impressions; slightly divided into two deeper impressions; central impression deep and with central swelling in posterior half; without punctures; isodiametric microsculpture deep and dense; surface matte.

Elytra: 0.41 mm long, 0.41 mm wide; shoulders and posterior angles shortly rounded; on each side of suture with three distinct longitudinal carinae; without punctures; isodiametric microsculpture deep, but less dense as on pronotum; surface matte.

Abdomen parallel; segments III to V with slight transverse impression at base; with extremely fine punctation; punctures with short white scales; isodiametric microsculpture dense and deep; slightly less deep than on elytra; surface matte.

Aedeagus smoothly rounded; in lateral aspect, inner edge of apical lobe slightly sinuate; apical lobe not exceeding ventral sclerotised plate; paramera not exceeding apex of central lobe; short transparent plate at apex as wide as paramera; numerous sensillae along paramera.

Figures

FIGURES 4 – 8. Thoracophorus struyvei (4); T. perplexus (5); T. proximus (6); T. exilis (7); T. aequalis (8); aedeagus in lateral aspect (A), antenna (B), shape of temples (C); scale bar: 0.1 mm.