Diochus tarsalis SHARP, 1876

Irmler, Ulrich, 2017, A review of the Neotropical genus Diochus ERICHSON, 1840 (Coleoptera: Staphylinidae: Staphylininae), Beiträge Zur Entomologie = Contributions to Entomology 67 (1), pp. 1-62 : 7-8

Diochus tarsalis SHARP, 1876

Figs 3A–C , 38B , 41B

Diochus tarsalis SHARP, 1876: 185

Type material examined: male, Syntype: Brazil: Pará ,

Tapajos ( BMNH).

Further material examined: Brazil: Amazonas, Manaus, Ilha de Marchanteria (59°58'W, 3°15'S), Varzéa , 2 males, 21.12.1981, 6.1.1982, leg. J. Adis ( UIC) ; Amazonas, upper Rio Negro, Umarituba (67°242W, 0.046N), female, Feb. 1994, leg. M. v. Tschirnhaus ( UIC) ; Bolivia: Depart. Santa Cruz Espiritu, Rio Yacuma (60°31'W, 16°11'S), 1 female, 1 male, 18.9.1980, leg. W. Hangarth ( UIC) .

Diagnosis: The species closely resembles D. longicornis in size and colouration. Additional to the stronger widened tarsomeres of the anterior legs, already noted by SHARP (1876), the following characters differ from those of D. longicornis : the longer seminal vesical of the endophallus and the hook-like apical process of the paramere.

Description: Length: 4.4–4.6 mm. Colouration: dark brown; pronotum slightly lighter than head; elytra still slightly lighter brown with indistinct darker areas; abdomen dark brown; legs and antennae light brown to yellowish brown; antennomeres one to three lighter than following antennomeres.

Head: 0.60 mm long, 0.51 mm wide; eyes slightly prominent; temples more than twice as long as eyes; EL: HL = 0.25; temples slightly divergent to posterior angles; PW: EW = 1.17; posterior angles widely rounded to neck; neck one third as wide as head; setiferous punctation moderately deep and dense; denser close to posterior angles than in anterior half; wide midline from clypeus to close to posterior margin impunctate; on lateral vertex, interstices between punctures twice as wide as diameter of punctures; close to neck, interstices approximately as wide as diameter of punctures; without microsculpture; surface shiny.

Antennae slightly longer than head and half of pronotum combined; first antennomere twice as long as wide; second antennomere one fourth shorter than first; third antennomere again longer; nearly twice as long as second; three times longer than wide; following antennomeres decreasing in length; fourth antennomere longer than wide; penultimate antennomere nearly quadrate; all antennomeres with short bristles at apex and densely pubescent.

Pronotum: 0.81 mm long, 0.64 mm wide; widest near middle in posterior half; sides slightly rounded and narrowed to anterior and posterior angles in smooth curve; nearly parallel at middle; posterior and anterior angles widely rounded; lateral margin fine; in dorsal aspect, only visible in posterior third; setiferous punctation large, but sparse; along impunctate midline with three punctures; on average, interstices between punctures four to five times as wide as diameter of punctures; along lateral margin with denser row of setiferous punctures; setae of punctures thick and long; without microsculpture; surface shiny.

Elytra: 0.73 mm long, 0.77 mm wide; widest at posterior angles; shoulders distinct, but obtuse; posterior margin slightly emarginate; with irregular longitudinal lines of setiferous punctures; first line adjacent to suture; disc lines more irregular; setae of punctures thick and long, in particular, along lateral margin; setae near shoulders extremely long and thick; weak and indistinct slightly coriaceous ground sculpture; without microsculpture; surface shiny.

Abdomen densely pubescent.

Aedeagus with seminal vesical slightly longer than half of central lobe; basal inner duct looped; inner apical duct coiled; paramere slightly exceeding central lobe; slightly widened at middle; more strongly widened at apex into broad triangular process; process sinuate at anterior margin; ending in short hook-like structure; at inner side with four long setae.

Spermatheca 0.42 mm long, 0.23 mm wide; bursa copulatrix in slightly asymmetric position to coiled duct; coiled oval duct asymmetric with smaller and wider half; nearly parallel at middle.

Figures

Figs 41: Fore-bodies of Diochus longicornis (A), D. tarsalis (B), D. adisi (C), D. ashei (D), D. guianensis (E), D. unicolor (F), D. inornatus (G), D. hanagarthi (H); scale bar: 0.5 mm.

Figs 2–5: Diochus longicornis-group: Diochus longicornis (2), D. tarsalis (3), D. adisi (4), D. guianensis (5); aedeagus (A),

Fig. 38: Spermathecae of Diochus longicornis-group: D. longicornis (A), D. tarsalis (B), D. ashei (C), D. guianensis (D), D. unicolor (E); Diochus inornatus-group: D. inornatus (F), D. hanagarthi (G), D. antennalis (lateral aspect H), D. hermani (I), D. hibbsi (J), D. newtoni (K), D. novus (L); scale bar: 0.1 mm.