Acrosathe Irwin and Lyneborg

Webb, Donald W., 2009, A revision of the genera Acrosathe Irwin and Lyneborg, Arenigena Irwin and Lyneborg, and Litolinga Irwin and Lyneborg (Diptera: Therevidae: Therevinae) from the Nearctic Region, Zootaxa 2091 (1), pp. 1-67 : 7-8

Acrosathe Irwin and Lyneborg

Acrosathe Irwin and Lyneborg (1981a:201 key, 223 diag., 225 spec. list; 1981b:518 key), Lyneborg (1986:102 diag., 104 male key, 104– 112 spec. desc., Figs 1 – 33 male genit.; 1989:11 cat.), Nagatomi and Lyneborg (1988:600 diag, 601 male /fem. key, 603– 617 spec. desc.; 1989:349 generic key, 352 diag.). Type species Bibio annulata Fabricius (1805:68) by original designation. This genus is Holarctic and Oriental in distribution.

Acrosathe is principally a holarctic genus (8 species in the Palaearctic, 6 species in the Nearctic) with Acrosathe argentea (Kröber) recorded from Taiwan in the Oriental Region ( Lyneborg 1986). The genus is characterized by the male and female frons being covered with pubescence and lacking glossy calli; the parafacial, the central depression of the prosternum, and the posterior surface of the midcoxa setose; the macrosetae on the mesonotum dark reddish brown to black; the male epandrium subequal to or longer in midline length than wide; and the male aedeagus with a pair of accessory aedeagal processes (AAP) adjoining the distiphallus ventrally.

Moderately large sized flies, males 5.8–10.0 mm (n=58), females 7.2–10.4 mm (n=54). Male ocellar tubercle not raised above level of occiput. Male eyes holoptic (slightly separated medially) or dichoptic (separated by width of median ocellus, A. bimaculata (Cole) . Frontal setae extending lateral to antennal base; black pubescent band absent lateral to antennal base. Face moderately projecting beyond eyes (0.14 mm). Antenna shorter than head length; scape cylindrical, longer than wide, over two times length of pedicel, subequal to or wider than flagellum, setae absent medially; pedicel wider than long, setae dark brown, short, absent medially; first flagellomere oval, tapering posteriorly, second flagellomere short, cylindrical, third flagellomere short, tapered apically, flagellum over two times longer than wide, longer than length of scape. Gena not sharply projecting ventrally, lacking anteroventral patch of short, brown setae. Postocular macrosetae in single row.

Thorax. Macrosetae 2–4 np, 1–3 sa, 0–2 pa, 0–2 dc, 2 sc. Postpronotal lobe concolorous with mesonotum; setae white, elongate. Setae present on cervical sclerite (macrosetae absent), in and around central depression of prosternum, on propleuron, anepisternum, katepisternum, laterotergite, scutellum, and metanepisternum; setae absent on proepimeron, anepimeron, and meron. Wing. Setulae absent on R 1. Cell cup closed, petiolate. Pterostigma brown, narrow. Legs. Metakatepisternum without setae. Coxae with setae on posterior half of middle coxa; hind coxa with papillate anterior projection. Male Terminalia . Tergite 8 ( Figs. 1 , 9, 18, 26 34, 43) dark brown, bilobed, anterior margin broadly concave, posterior margin deeply emarginate; setae reddish brown, elongate, separated medially on lateral lobes; median length 0.02 mm. Sternite 8 ( Figs. 2 , 10, 19, 27 35, 44) reduced, anterior margin truncate, rectangular, sides tapered posteriorly; posterior margin slightly emarginate medially. Epandrium ( Figs. 1 , 9, 18, 26 34, 43) dark brown, quadrate, sides broadly rounded; subequal to or longer medially than wide; anterior margin concave; posterolateral margins short, bluntly pointed; setae reddish brown. Cerci ( Figs. 1 , 9, 18, 26, 34, 43) free, expanded laterally; ending distal to posterolateral margin of epandrium and hypoproct. Hypoproct ( Figs. 1 , 9, 18, 26, 34, 43), posterior margin rounded, ending distal to posterolateral margin of epandrium and basal to apex of cerci; apicoventral area flat. Hypandrium ( Figs. 2 , 10, 19, 27, 35, 44) strap-like. Gonocoxite dark brown; ventral view ( Figs. 2 , 10, 19, 27, 35, 44) separated medially, quadrate to rectangular, inner gonocoxal process fused to gonocoxite, narrow, clavate; dorsal view gonocoxal apodeme narrow, not extending beyond anterior margin of gonocoxite; lateral view ( Figs. 3 , 11, 20, 28, 36, 45) oblong, posterior margin tapered to broad point; setae dark brown with several macrosetae posteriorly; ventral lobe ( Figs. 2 , 10, 19, 27, 35, 44) large, flattened laterally. Gonostylus ( Figs. 2 , 10, 12, 19, 21, 27, 35, 44) sinuate, occasionally with broad lateral expansion ( A. falcata ). Dorsal apodeme ( Figs. 4 , 13, 22, 29, 37, 46), broadly expanded laterally, anterior margin rounded; ventral apodeme ( Figs. 5 , 14, 23, 30, 38, 47) narrower than dorsal apodeme, anterior margin rounded, not extending beyond anterior margin of dorsal apodeme; distiphallus dorsal view ( Figs. 4 , 13, 22, 29, 37, 46) tapered posteriorly, ventral view ( Figs. 5 , 14, 23, 30, 38, 47) accessory aedeagal process (AAP) narrow, tapered posteriorly, lacking apical spinous projections; ejaculatory apodeme dorsal view ( Figs. 4 , 13, 22, 29, 37, 46) narrow, slightly expanded anteriorly and posteriorly. Female terminalia. Sternite 8 oval, sides rounded, anterior margin with anteromedial projection; aedeagal guide dark brown, heavily sclerotized. Median lobe of tergite 9 setose. Furca ( Figs. 8 , 17, 25, 33, 42, 49) closed anteriorly and posteriorly, sides sinuate, anteromedial and posteromedial processes absent. Common spermathecal duct shorter than length of furca; spermathecal ducts originating from common spermathecal duct at junction of spermathecal sac. Two spermathecae.

Species included.

Acrosathe bimaculata (Cole)

Acrosathe falcata Webb spec. nov.

Acrosathe otiosa (Coquillett)

Acrosathe pacifica (Cole)

Acrosathe vanduzeei (Cole)

Acrosathe vialis (Osten Sacken)

Figures

FIGURES 1–8. Acrosathe bimaculata. 1. Tergite 8, epandrium, cerci. 2. Sternite 8, gonocoxite ventral view. 3. Gonocoxite, lateral view. 4. Aedeagus, dorsal view. 5. Aedeagus, ventral view. 6. Aedeagus, lateral view. 7. Female head, frontal view. 8. Female internal reproductive organs.