Arenigena 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 : 37-38

publication ID	https://doi.org/ 10.11646/zootaxa.2091.1.1
persistent identifier	https://treatment.plazi.org/id/03D64F13-FFED-D57A-FF1A-FC832A773E01
treatment provided by	Felipe
scientific name	Arenigena Irwin and Lyneborg
status

Treatment

Arenigena Irwin and Lyneborg View in CoL View at ENA

Arenigena Irwin and Lyneborg (1981a:201 View in CoL key, 238 diag., 240 spec. list; 1981b:518 key). Type species Thereva semitaria Coquillett (1893:198) View in CoL by original designation.

Hauser and Irwin (2003:742 Fig. 2 View FIGURES 1–8 ) considered Arenigena View in CoL a sister genus to Ammonaios View in CoL and within the New World therevids the pale macrosetae on the thorax and the lack of an anterior knob on the hind coxa readily separate these two genera. Ammonaios View in CoL possesses the synapomorphies: head with lanceolate, appressed setae; setae on frons extending lateral to antennal base; parafacial setae present; tentorial pits modified; and hypoproct bent ventrally. Arenigena View in CoL is easily separated from Ammonaios View in CoL in having the setae on the head filiform, erect; the frontal setae not extending lateral to the antennal base; the parafacial lacking setae; the tentorial pit unmodified and covered with pubescence; and the hypoproct not bent ventrally.

Arenigena appears to separate into two distinct species-groups based on the shape of the male inner gonocoxal process. The Arenigena marcida species-group of A. bajaensis and A. marcida have the inner gonocoxal process (Fig. 66) narrow and cylindrical. The Arenigena semitaria species-group of A. albiseta , A. floridensis , and A. semitaria have the inner gonocoxal process bilobed, flattened laterally with setae on the dorsal lobe ( Fig. 58 View FIGURES 56–63 ).

Moderate sized flies, male body length 6.2–10.7 (n=49), female 6.8–13.0 (n=39) mm.

Head. Ocellar tubercle raised above level of occiput. Male eyes holoptic, ommatidia smaller ventrally and laterally. Frons with dark pubescent band and setae absent lateral to antennal base. Face slightly projecting beyond eyes (0.05 mm). Antenna shorter than head length; scape cylindrical, longer than wide, longer than pedicel, width subequal to width of flagellum, setae absent on medial surface, macrosetae dark brown; pedicel globular, wider than long, setae dark brown, short, absent on medial surface; flagellum with 3 flagellomeres, first flagellomere oval, apical third narrow, cylindrical (considerable variation was noted in the length of the cylindrical portion of the first flagellomere in some species), second flagellomere cylindrical, short, third flagellomere cylindrical, greater than 4 times length of second flagellomere, pointed apically, flagellum longer than wide, longer than length of scape, basal setae dark brown, short. Parafacial setae absent. Gena generally rounded, occasionally with anterior expansion. Maxillary palpus cylindrical, elongate, over 5 times longer than wide. Occiput concave, pubescence dense; macrosetae dark yellow, sparse. Postocular macrosetae dark yellow, elongate.

Thorax. Macrosetae 3 np, 2 sa, 1 pa, 1–2 dc, 2 sc. Postpronotal lobe concolorous with mesonotum; setae white, elongate. Cervical sclerite pubescence whitish gray; setae white, elongate; macrosetae absent. Prosternum setae white, elongate in and around central depression. Pleuron pubescence gray, dense; setae on propleuron, proepimeron (occasionally absent), anepisternum, katepisternum (generally setae are abundant along the anterior margin, but in some species the pattern is sparse and patchy), laterotergite, metanepisternum, and scutellum; absent on anepimeron and meron. Wing. Setulae absent on R 1. R 4 sinuate. Cell m 3 and cup closed, petiolate. Halter yellow. Legs. Coxae pubescence white, dense; setae white, elongate; macrosetae yellow; hindcoxa with one posterolateral macroseta; midcoxa with setae on posterior area; hindcoxa lacking anterior knob.

Abdomen. Male terminalia brown. Tergite 8 ( Figs. 56 View FIGURES 56–63 , 64, 72, 80, 88) rectangular, anterior margin truncate, posterior margin broadly emarginate. Sternite 8 ( Figs. 57 View FIGURES 56–63 , 65, 73, 81, 89) rectangular, sides rounded, posterior slightly emarginate. Epandrium ( Figs. 56 View FIGURES 56–63 , 64, 72, 80, 88) quadrate; shorter medially than wide. Cerci ( Figs. 56 View FIGURES 56–63 , 64, 72, 80, 88) free, ending basal to apex of hypoproct. Hypoproct ( Figs. 56 View FIGURES 56–63 , 64, 72, 80, 88) ending distal to posterolateral margin of epandrium and apex of cerci; posteroventral area flat. Hypandrium ( Figs. 57 View FIGURES 56–63 , 65, 73, 81, 89) dark brown. Gonocoxite ventral view ( Figs. 57 View FIGURES 56–63 , 65, 73, 81, 89) separated medially, quadrate, sides rounded; inner gonocoxal process ( Figs. 57 View FIGURES 56–63 , 65, 73, 81, 89) large, variable; ventral lobe ( Figs. 57 View FIGURES 56–63 , 65, 73, 81, 89) short. Aedeagus with ventral apodeme ( Figs. 61 View FIGURES 56–63 , 69, 77, 85, 93), broad, not reaching anterior margin of dorsal apodeme; distiphallus dorsal view ( Figs. 60 View FIGURES 56–63 , 68, 76, 84, 92) tapered posteriorly; ejaculatory apodeme ( Figs. 60 View FIGURES 56–63 , 68, 76, 84, 92) not extending to anterior margin of dorsal apodeme. Female terminalia reddish brown. Setae on median lobe of tergite 9 absent. Furca ( Figs. 63 View FIGURES 56–63 , 71, 79, 87, 95) quadrate; anterior and posterior margins closed; lacking anteromedial and posteromedial projections; anterolateral projections short. Common spermathecal duct shorter than length of furca. Spermathecal ducts narrow, ending in large, oval spermatheca. Spermathecal sac large, spherical, narrowed posteriorly. Spermathecae 2.