Diochus argentinae, Irmler, 2017

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 : 28

Diochus argentinae spec. nov.

urn:lsid:zoobank.org:act:2353FF33-7AEB-4B05-A9C8-EF6CCCC95684

Figs 29A–C , 40A , 44F

Type material: male, Holotype: Argentina: Buenos Aires,Tigre, 6.1938, leg. M.J. Viana, (labelled by Bernhauer as D. nanus ) ( FMNH).

Paratypes: Argentina: Buenos Aires, Isla Martin Garcia , male, 1939, leg. M.J. Viana ( FMNH) ; Tucuman, Cerro de San Javier , humus, 1000 m elev., male, 8.5.1953, leg. P. Wygodzinsky ( FMNH) ; Rosas , - F.C. Sud, leg. J.D. Daguerre (coll. Bruch) 2 females, (1 FMNH, 1 UIC) ; Brazil: Nova Teutonia (27°11'S, 52°23'W), 300–500 m elev., 2 males, 3 females, 3.1954, leg. F. Plaumann (4 FMNH, 1 UIC) .

Diagnosis: Regarding the structure of the aedeagus, D. argentinae is related to D. schaumii , and D. brunneus . The shape of the paramere is intermediate between both species. The apical widening is longer than in D. schaumii , but shorter than in D. brunneus . The three species and D. angustiformis can be also differenciated by the shape of the head. The sides of head of D. argentinae and D. schaumii are approximately parallel (PW: EW = 1.06), whereas they are slightly divergent in D. brunneus and D. angustiformis (PW: EW 1.26). The head of D. shaumii is longer (length/width ratio 1.35) than that of D. argentinus (length/width ratio 1.25). Furthermore, it can be differentiated from D. brunneus by the unicoloured light brown pronotum. The pronotum of D. brunneus is light brown in its anterior half, but dark brown in its posterior half.

Description: Length: 3.9 mm. Colouration: dark brown; Pronotum slightly lighter brown; posterior margin of elytra light brown; legs light brown; basal two antennomeres lighter brown than following antennomeres.

Head: 0.49 mm long, 0.39 mm wide; eyes large; prominent; EL: HL = 0.30, temples approximately parallel; PW: EW = 1.06; posterior angles widely rounded; setiferous punctation deep; on each side of impunctate midline with row of three punctures; between inner row and eyes with second row of five punctures; postocular area irregularly punctate; without microsculpture; surface shiny.

Antennae slightly longer than head and pronotum combined; first antennomere slightly thicker than following antennomeres; second and third antennomere conical and nearly twice as long as its apical width; fourth antennomere slightly longer than wide; following antennomeres wider than long; penultimate antennomeres approximately one third wider than long; all antennomeres pubescent and with few apical setae.

Pronotum: 0.53 mm long, 0.51 mm wide; sides approximately parallel; anterior third widely rounded; nearly semi-circular; posterior angles shortly rounded; lateral margin fine; in dorsal aspect visible in posterior half; setiferous punctation deep, but sparse; row of three punctures on each side of impunctate midline; between central row and lateral margin several irregular punctures; between coarser setiferous punctures with sparse micropunctation; without microsculpture; surface polished.

Elytra: 0.71 mm long, 0.71 mm wide; sides slightly divergent to posterior angles; shoulders widely rounded; posterior angles nearly rectangular; posterior margin slightly emarginate; setiferous punctation in irregular rows; rows with 7 to 8 punctures; surface wth weak coriaceous ground sculpture; less shiny than head or pronotum.

Abdomen densely pubescent.

Aedeagus moderately thick; seminal vescical of endophallus two third as long as total length of central lobe; basal inner duct ending in irregularly sclerotised appendices; apical hooks thick; parameres moderately thick; not longer than central lobe; apical widening asymmetric; forming a broad triangle; with two setae at apical margin; three sensillae at middle of shaft.

Spermatheca 0.25 mm long, 0.18 wide; bursa copulatrix outside of coiled duct; coiled duct approximately circular.

Etymology: The species name derived from Argentina,

one of the countries where it was found.

Figures

Figs 44: Fore-bodies of Diochus pumilio (A), D. panamaensis (B), D. angustiformis (C), D. brunneus (D), D. schaumii (E), D. argen-

Figs 26–29: Diochus maculicollis group: D. panamensis (26), and Diochus schaumii-group D. schaumii (27), D. angusti-

Fig. 40: Spermatheca of Diochus schaumii-group: Diochus argentinae (A), D. brunneus (B), D. curtipennis (C), D. schaumii (D), D. verhaaghi-group: D. verhaaghi (E), D. santacatarinae (F), D. nanus-group: D. perplexus (G), D. parvulus (H), D. nanus (I), D. apicipennis (J), D. formicetorum (K); scale bar: 0.1 mm.