Diochus pumilio BERNHAUER, 1929

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 : 25-26

Diochus pumilio BERNHAUER, 1929

Figs 25A–C , 39H , 44A

Diochus pumilio BERNHAUER, 1929: 193

Type material examined: Syntypes: Mexico: Veracruz, Fauler Stamm Kokospalme (rotting cocos palme), 2 males, 31.10.1926, leg. Dampf, #197 ( FNHM), same location, but Luftkescherung (air catch), female, 3.12.1926, leg. Dampf, same location, but Morscher Stamm (decaying trunk), 11.–12.1926, leg. Dampf ( FMNH). The male without number was selected as Lectotype.

Further material examined: Mexico: Chiapas, El Chorreadoro , 8 km SE Chiapa de Corzo, 650 m elevation, sifted deep leaf litter in rock crevasses, 1 male, 2 females, 11.6.1991, leg. J. Ashe #90 (2 KNHM, 1 UIC) ; Union Juarez, NW slope Volcan Tacana , leaf litter weedy areas under coffee, 1000 m elev., female, 3.1.1977, leg. H. Frania ( AMNH) ; Veracruz, air catch, 1 male, 3 females, 31.12.1926, 11.–12.1926, leg. Dampf ( FMNH) ; Chiapas, Chorreodero , NE Tuxtla Gutz., 730 m elev., tropical deciduous, sifting, litter along stream, female, 5.5.1977, leg. J.S. Ashe ( FMNH) ; S.L.P., 15 mi N Tamazunchale , 500 ft. elev., deposit Atta mexicana , female, 26.6.1973, leg. A. Newton ( FMNH) .

Diagnosis: Within the D. maculicollis-group, Diochus pumilio is characterised by its small size. It is similarly small as the species of the D. nanus-group and can be hardly differentiated from those species. However, D. pumilio is clearly identified by its unique aedeagus with the short and nearly globular seminal vesical and the non-looped basal inner duct.

Description: Length: 2.5 mm. Colouration: yellow; pronotum slightly lighter yellow than head, elytra, and abdomen; basal three antennomeres lighter yellow than following antennomeres.

Head: 0.39 mm long, 0.32 mm wide; eyes slightly prominent; small; temples 2.3 times as long as eyes; EL: HL = 0.22; temples slightly divergent posteriad, PW: EW = 1.11; posterior angles shortly rounded, posterior margin straight; setiferous punctation moderately deep and dense; narrow midline impunctate; on vertex two pairs of punctures adjacent to midline; on clypeus and on supraocular area between pairs of punctures with irregular punctation; postocular area more densely punctate; netlike microsculpture deeper and narrower on clypeus than on vertex; surface moderately shiny.

Antennae as long as head and half of pronotum combined; basal three antennomeres conical; decreasing in length from first to third antennomere; approximately twice as long as at their apical width; following antennomeres distinctly shorter than preceding antennomeres; fourth quadrate; tenth 1.5 times as wide as long; all antennomeres pubescent; basal antennomeres with apical setae.

Pronotum: 0.47 mm long, 0.40 mm wide; widest close to middle; anterior third semi-circular; in anterior half; sides approximately parallel; posterior angles shortly rounded; posterior margin curved in slightly convex curve; lateral margin fine; in dorsal aspect, visible in posterior third; setiferous punctation deep and sparse; along impunctate midline with three pairs of punctures; interstice between anterior pair, 1.5 times as wide as between posterior pairs; laterad four partly deeper punctures; along lateral margin several punctures; without microsculpture, but with weak micro-punctation; surface polished.

Elytra: 0.46 mm long, 0.46 mm wide; sides slightly divergent posteriad, but nearly parallel; shoulders obtuse; posterior angles rectangular; posterior margin deeply emarginate in laterally sinuate curve; setiferous punctation in irregular rows of six to seven punctures; inner row adjacent to suture line; interstice between inner row and second row slightly wider than between two lateral rows; along lateral margin several setiferous punctures; ground sculpture weakly coriaceous; surface slightly shiny.

Abdomen densely pubescent.

Aedeagus moderately thick; seminal vesical of endophallus ovel, but nearly globular; 0.4 times as long as total length of central lobe; basal inner duct thick; slightly curved anteriad; ending in weakly sclerotised forceps; paramere slender; obtusely curved in anterior third; ending in obtusely rounded apex without widening; curved apical part with two long setae; shaft with basal group of sensillae.

Spermatheca irregularly shaped; bursa copulatrix in lateral position to coiled duct; coils of duct irregular and with only few coils.

Figures

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

Figs 22–25:Diochus maculicollisgroup:ofD. maculicollis(22),D. peruvianus(23),D. mexicanus(24),D. pumilio (25);aedeagus (A),

Fig. 39: Spermathecae of Diochus inornatus-group: D. schuelkei (A), D. plaumanni (B), D. tricolor (C), D. vicinus (D); Diochus maculicollis-group: D. brooksi (E), D. ecuadoriensis (F), D. maculicollis (G), D. pumilio (H), D. peruvianus (I), D. mexicanus (J), D. panamaensis (K); Diochus schaumii-group: D. angustiformis (L); scale bar: 0.1 mm.