Diochus nanus ERICHSON, 1839

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 : 35-38

Diochus nanus ERICHSON, 1839

Figs 35A–C , 40I , 45D

Type material examined: female, Lectotype: Columbia, without more data, coll. Moritz ( ZMHB).

Paralectotype: female, with same data as lectotype ( ZMHB) .

Additional material examined: Costa Rica: Heredia, 3 km S. Puerto Viejo, OTS-La Selva (84°01'W, 10°26'N), 100 m elevation, 2 females, Sept. 1992, leg. P. Hanson ( KNHM) ; Rd. Barrigones (Osa),> Chacarita (83°15'- 26'W, 8°36'-48'N), 0–250 m elevation, pastures, plantages, devastated forest, car net, 1 male, 3 females, 11.12.2012, leg. Schülke & Grünberg (1 MSC, 3 UIC) ; S Rincon de la Vieja, Rd. Hacienda Guachipilin> Santa Maria (85°20.15'-22.45'W, 10°42.43'-45.10'N), 520–700 m elevation, car net, farmland & dry forest, 1 male, 2 females, 4.12.2012, leg. Schülke & Grünberg ( UIC) ; Osa Peninsula, Rd. Bahia Drake> Rincon de Osa (83°29'-40'W, 8°41'-42'N), 0–400 m elevation, car net, devastated forest & plantations, 1 male, 2 female, 9.12.2012, leg. Schülke & Grünberg ( MSC) ; Alajuela Prov., Rd. Colonia Puntarenas> Rio Negro (84°46'-57'W, 10°50'-53'N), 40–90 m elevation, fincas, meadows, forest remnants, car net, 1 female, 18.12.2013, leg. Schülke Grünberg ( MSC) ; Guanacaste Prov., Nicoya Peninsula, PN Diria, Area Conservacion Tempisce (85°35.44'W, 10°09.43'N), river bank and old car track, 2 females, 15.12.2013, L.M. Schülke (1 MSC, 1 UIC) ; Sardinal , 2 females, 23.2.1941, leg. A. Bierig ( FMNH) ; Pearl Island, San Miguel , 2 females, leg. Champion ( FMNH) ; Panama: Colon Prov., Maria Chiquita , composted grasses at beach, 1 male, 5 females, 3.1.1981, leg. W. Suter ( FMNH) ; Colombia: Magdalena, Cañaveral (73°56'W, 11°19'N), 200 m elevation, leaf litter, male, 11.8.1985, leg. J. Longino #708 ( KNHM) ; Suriname: Marienburg , sweep from grass, female, 19.5.1916, leg. C.B. Williams ( BMNH) ; Saint Thomas: 3 males, 6 females, without additional data, coll. Kraatz ( SDEI) ; without further data, coll. Eppelsheim, 3 males, 9 females (3 FMNH, 9 NMW) ; same location, 7 females, but leg. v. Eggers ( NMW) .

Diagnosis: D. nanus can be separated from the other species of the group by the less widened paramere. The eyes are as large as in D. perplexus and D. parvulus . It can be distinguished from D. parvulus by the unicoloured elytra and from D. perplexus by the deeper microsculpture of the head and the striate microsculpture at the anterior angles of the pronotum.

Description: Length: 2.8 mm. Colouration: light brown to yellowish; abdomen slightly darker brown with posterior margin of abdominal segment lighter; legs and antennae yellow.

paramere (B) and antenna (C); scale bar: A, B: 0.1 mm, C: 0.2 mm.

Head: 0.40 mm long, 0.37 mm wide; eyes slightly prominent; large; temples twice as long as eyes; EL: HL = 0.28; temples slightly divergent posteriad; PW: EW = 1.13; posterior angles widely rounded; posterior margin approximately straight; setiferous punctation moderately deep and dense; wide midline impunctate; adjacent to midline irregular row of three to four punctures; between medial row and eyes two further rows of punctures; postocular area more densely punctate; netlike microsculpture more distinct on clypeus and interocular area; weaker on posterior vertex; surface moderately shiny.

Antennae slightly longer than head; first antennomere longer and thicker than following antennomeres; second antennomere two third as long as first; twice as long as wide; third antennomere conical; only slightly longer than wide; following antennomeres rectangular; wider than long; fourth slightly wider than long; eighth and ninth nearly twice as wide as long; all antennomeres pubescent and with apical setae.

Pronotum: 0.52 mm long, 0.43 mm wide; sides approximately parallel; posterior angles widely rounded; posterior and anterior margins nearly semi-circular; lateral margin fine; in dorsal aspect visible in posterior half; setiferous punctation moderately deep and sparse; adjacent to wide impunctate midline with row of three punctures; interstice between anterior pair of punctures one third wider than between posterior pairs of punctures; between inner row and lateral margin few sparse punctures; along lateral margin several punctures; with weak microsculpture in anterior half, surface shiny.

Elytra: 0.52 mm long, 0.55 mm wide; shoulders shortly rounded; sides divergent to posterior angles; posterior margin emarginate; setiferous punctures in irregular rows of six to seven punctures; between suture and lateral margin four rows of punctures; ground-sculpture weak; surface moderately shiny.

Abdomen densely pubescent.

Aedeagus elongate; seminal vesical two third as long as central lobe; basal inner duct looped; ending in complex sclerotised forceps; paramere slender; apex obtusely angulate; not projecting central lobe; widened shortly in front of bifurcate apex; each process obtusely rounded; outer process with one short seta; inner process with two short setae; shaft with numerous sensillae.

Spermatheca 0.25 mm long, 0.15 mm wide; bursa copulartix in lateral position to coiled duct; coiled duct with irregular approximately oval coils.

Figures

Figs 45: Fore-bodies of Diochus santacatarinae (A), D. perplexus (B), D. parvulus (C), D. nanus (D), D. apicipennis (E), D. formicetorum (F); scale bar: 0.5 mm.

Figs 34–37: Diochus nanus-group, Diochus perplexus (34), D. nanus (35), D. parvulus (36), D. apicipennis (37); aedeagus (A),

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.