Diochus parvulus KRAATZ, 1860

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 : 39-41

Diochus parvulus KRAATZ, 1860

Figs 36A–C , 40H , 45C

Diochus parvulus KRAATZ, 1860: 27

Type material examined: male, Holotype: Brazil: Bahia,

coll. Kraatz ( SDEI).

Further material examined: Venezuela: Trujillo Prov., 60.6 km NW Bocono , 1900 ft. elev., litter near stream, 2 males, 5 females, 31.3.1992, leg. L. Herman (6 AMNH, 1 UIC); Tinaco, Quebradon , Cojedes, sandy soil on the river bank, 350 m elev., 3 males, 9.1.1986, leg. M.G. Paoletti ( AMNH) ; Los Chorros , 3 males, 5.1922, leg. F. Psota ( FMNH) ; Ecuador: Sucumbios, Sacha Lodge (76°5'W, 0°5'S), 270 m elevation, malaise trap, female, 3.– 13.4.1994, leg. Hibbs ( KNHM) ; Pichincha, Maquipucuna For. Res. , 50 km NW Quito, 1300 m elevation, banana dull berlesate, 1 male, 4 females, 3.12.1991, leg. C. Carlton & R. Leschen (4 KNHM, 1 UIC) ; Napo Prov., 33 km N Tena, 59 km E on Loreto Rd. , litter nr. stream, 2800 ft. elev., 5 males, 2 females, 4.11.1988, leg. L. Herman ( AMNH) ; Napo Prov., Limoncocha, 250 m elev., Berlese , forest litter, male, 25.6.1976, leg. S. Peck ( FMNH) ; Brazil: Mato Grosso, Campo Verde, farm Santa Luzia (55°209'W, 15°433'S), agric. field, male, 7.4.2014, leg. K. Peña Peña ( UIC) ; Santa Carmen, farm Dona Dozolina (55°113'W, 11°597'S), agric. field, 1 male, 3 females, 2.5.2014, leg. K. Peña Peña ( UIC) ; same region, farm Såo Vincente (55°215'W, 12°037'S), 1 male, 3 females, 4.5.2014, leg. K. Peña Peña ( UIC) ; 1 female, Rio de Janeiro, leg. Squires, Sharp coll. #1905-313 ( BMNH) ; Amazonas, 15 km SW Manaus, Ilha Marchanteria (59°58'W, 3°15'S), tree emerg. trap, #50D, male, 18.3.1982, leg. J. Adis ( UIC) ; same location, but floating meadow, male, 29.4.1981, leg. J. Adis ( UIC) ; same location, but Várzea , female, 20.1.1982, leg. J. Adis ( UIC) ; Santa Catarina, Nova Teutonia , female, 12.1953, leg. F. Plaumann ( FMNH) ; Santa Rita , female, 8.1850, leg. Sahlberg ( FMNH) ; Paraguay: 3 females, without further data ( SDEI) ; Argentina: JuJuy Prov., Termas del Reyes , 2 females, 27.12.1971, leg. L. Herman ( AMNH) ; Buenos Aires, female, 190?, leg. C. Bruch ( FMNH) .

Diagnosis: D. parvulus can be clearly identified by the specific paramere that is largely widened at apex and widely, but not deeply emarginate. Moreover, the colouration of the elytra with the anterior half mostly darkened paramere (B) and antenna (C); scale bar: A, B: 0.1 mm, C: 0.2 mm.

seems to be a character that can be used to distinguish it from the related species D. nanus , D. perplexus and D. apicipennis with mostly unicoloured elytra.

Description: Length: 3.1–3.2 mm. Colouration: yellow; abdominal segments III–VI slightly darker, light brown; anterior half of elytra black; black area prolonged on disc to two third of elytral length; legs and antennae yellow with medial antennomeres darker.

Head: 0.41 mm long, 0.34 mm wide; eyes slightly prominent; temples 1.5 times as long as eyes; EL: HL = 0.28; temples slightly divergent posteriad; PW: EW = 1.12; posterior angles widely rounded to straight posterior margin; neck one third as wide as head; setiferous punctation coarse and sparse; moderately wide midline impunctate; row of five to six punctures adjacent to midline; interstices between punctures shorter on interocular area than on posterior vertex; on interocular area, interstices between punctures as wide as diameter of punctures; on posterior vertex, interstices twice or three times as wide as diameter of punctures; microsculpture weak; transverse netlike meshes; surface slightly shiny.

Antennae slightly longer than head; first antennomere one fourth longer than second; second and third conical; approximately one third longer than wide; fourth to tenth antennomere wider than long; fourth only shortly wider than long; seventh to ninth antennomere twice as wide as long; tenth slightly longer; all antennomeres pubescent and with few longer setae.

Pronotum: 0.49 mm long, 0.43 mm wide; widest shortly behind middle; distinctly stronger narrowed to anterior margin than to posterior margin; in dorsal aspect, fine lateral margin visible in posterior half; anterior angles more widely rounded than posterior angles; setiferous punctures extremely sparse; row of four pairs of punctures along impunctate midline; interstice of anterior pair twice as wide as interstice between posterior pairs of punctures; few setiferous punctures laterad; microsculpture similar as on head; surface polished.

Elytra: 0.48 mm long, 0.58 mm wide; sides divergent to posterior margin; shoulders distinct, but smoothly rounded; posterior margin emarginate in concave curve; setiferous punctures in four longitudinal rows; row along suture with approximately seven punctures; surface with weak coriaceous ground sculpture; less shiny than pronotum.

Abdomen with densely pubescent tergites; pubescence on apical tergites denser than on distal tergites.

Aedeagus broad; seminal vesical of endophallus 0.6 times as long as central lobe; basal inner duct with looped; ending in sclotised forceps; paramere antenna (B) and paramere (C); scale bar: A, B: 0.1 mm, C: 0.2 mm.

extremely widened at apex; slightly shorter than central lobe; apical margin with two short concave emarginations; outer angle prolonged to short acute tooth; inner angle broad and with two setae; third seta on triangular prominence between two emarginations; few sensillae in basal shaft.

Spermatheca 0.18 mm long, 0.15 mm wide; bursa copulatrix in lateral position to coiled approximately circular duct; duct few irregular 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.