Acrosathe bimaculata (Cole)

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 : 9-12

Acrosathe bimaculata (Cole)

( Figs. 1–8 , 50 )

bimaculata Cole (1923a:98 desc.; 1924:191 diag., dist.; 1925: 88 male desc.; 1965:353 cat.) ( Thereva ); Irwin & Lyneborg (1981a:225 listing, comb. change) ( Acrosathe ). Type locality Southern Pines, North Carolina. Holotype female in CUIC.

Diagnosis. The male of Acrosathe bimaculata is distinguished from other species of Nearctic Acrosathe in having the eyes dichoptic (separated by width of median ocellus), the ommatidia of equal size, and the frons with dark brown pubescence dorsally in the shape of two right-angled triangles separated medially by brownish gray pubescence. Females of A. bimaculata are similar to A. otiosa and A. vialis in having a pair of large, dark brown, pubescent circles dorsolaterally on the frons ( Fig. 7 ). Acrosathe bimaculata and A. vialis are separated from A. otiosa in lacking a brown margin on the wing veins and cross-veins. It is separated from A. otiosa in having the scape wider than the flagellum and the furca ( Fig. 8 ) quadrate, about as long as wide.

Description of MALE. Variation (n=10).

Body length 7.3–9.8, 8.1 mm.

Head. Length 0.88–1.14, 1.00 mm. Ocellar tubercle dark reddish brown, pubescence gray, dense; setae dark brown, elongate. Eyes dichoptic, separated by width of median ocellus; ommatidia of equal size. Frons pubescence white, dense, dark brown on dorsal half in form of two right-angled triangles separated medially by brownish gray pubescence; setae white, elongate on ventral third. Antenna dark brown, scape pubescence gray; antenna/head length 0.75–0.90, 0.82; scape length 0.30–0.36, 0.32 mm, width 0.14–0.20, 0.18 mm, length/width 1.5–2.3, 1.8, scape/pedicel length 2.9–4.3, 3.3, scape/flagellum width 1.0–1.3, 1.2, setae white, elongate intermixed with dark brown, elongate setae which grade into dark brown macrosetae; pedicel length 0.08–0.11, 0.10 mm, width 0.12–0.18, 0.14 mm, length/width 0.4–0.8, 0.7; flagellum length 0.38–0.42, 0.39 mm, width 0.14–0.17, 0.15 mm, length/width 2.4–2.7, 2.5, flagellum/scape length 1.1–1.4, 1.2. Parafacial pubescence white; setae white in lateral band. Maxillary palpus brown; length 0.32–0.52, 0.41 mm, width 0.08–0.12, 0.10 mm, length/width 3.6–6.3, 4.2; setae white, elongate. Genal setae white, elongate. Occipital setae white, elongate; dorsal macrosetae dark brown, scattered. Postocular macrosetae dark brown.

Thorax. Macrosetae 2–4, 3 np, 1–2, 2 sa, 0–1, 1 pa, 0–1, 0 dc. Mesonotal pubescence brownish gray; vittae absent; setae white, elongate, subappressed intermixed with dark brown, erect setae. Prosternum setae white. Pleural pubescence gray, dense; setae white, elongate on propleuron, anepisternum, katepisternum, laterotergite, metanepisternum, and scutellum. Wing. Membrane pale gray, veins and cross-veins brown with brown margin at fork of R 4+5, r-m, M 1+2, m-m, M 3, and CuA 1 (occasionally not apparent); cell m 3 closed at wing margin; length 5.5–6.5, 5.9 mm, width 1.7–2.2, 1.9 mm, length/width 2.9–3.4, 3.2. Legs. Coxal pubescence silver, dense; setae white, elongate; apical macrosetae dark reddish brown, hindcoxa with 2 posterolateral macrosetae. Femora dark brown, pubescence light gray; ventral setae white, elongate, dorsal setae white, appressed with yellowish brown setae on apical half. Tibiae reddish brown becoming darker on apical half. Tarsi dark brown.

Abdomen. Dark brown, pubescence white; dorsal setae white, elongate, appressed; lateral setae white, erect. Terminalia (MEI 012654). Dark brown, pubescence gray, dense. Tergite 8 ( Fig. 1 ), setae dark brown. Sternite 8 ( Fig. 2 ), rectangular, sides tapered posteriorly; posterior margin slightly emarginate medially; setae dark brown, continuous across posterior margin. Epandrium ( Fig. 1 ), sides broadly rounded; longer medially than wide; posterolateral margin short, bluntly pointed; setae dark brown. Cerci ( Fig. 1 ) ending distal to apex of hypoproct. Hypoproct ( Fig. 1 ), posterior margin rounded, ending basal to apex of cerci. Gonocoxite ventral view ( Fig. 2 ) rectangular, medial margin straight then tapering posterolaterally to blunt point; setae dark brown with several dark brown macrosetae; lateral view ( Fig. 3 ) oblong, posterior margin tapered to broad point. Gonostylus (as in Fig. 21 ). Aedeagus with dorsal apodeme ( Fig. 4 ) broadly rounded laterally, narrowed anteriorly, anterior margin rounded; ventral apodeme ( Fig. 5 ), narrow, clavate anteriorly, not reaching anterior margin of dorsal apodeme; distiphallus dorsal view ( Fig. 4 ) tapered posteriorly, ventral view ( Fig. 5 ) AAP short, narrow, tapered posteriorly, lateral view ( Fig. 6 ) distiphallus directed posteroventrally, AAP short, pointed, extending posteriorly less than one-half length of distiphallus; ejaculatory apodeme ( Fig. 4 ) reaching anterior margin of dorsal apodeme.

FEMALE. Similar to male except for following. Variation (n=4).

Body length 8.9–9.8, 9.5 mm.

Head. Length 1.10–1.12, 1.11 mm. Frons pubescence white, dense on ventral third, dorsal two–thirds yellowish brown with pair of dark brown pubescent circles ( Fig. 7 ); setae dark brown, elongate dorsally. Antenna dark brown, pubescence white; antenna/head length 0.75–0.82, 0.77; scape length 0.35–0.40, 0.37 mm, width 0.17–0.20, 0.19 mm, length/width 1.8–2.0, 1.9, scape/pedicel length 3.5–4.0, 3.7, scape/flagellum 1.1–1.3, 1.2 width, setae white, elongate intermixed with dark brown, elongate setae which grade into dark brown macrosetae; pedicel length 0.10 mm, width 0.14–0.20, 0.17 mm, length/width 0.56–0.71, 0.62; flagellum length 0.38–0.40, 0.39 mm, width 0.15–0.18, 0.16 mm, length/width 2.1–2.5, 2.4, flagellum/scape length 1.0–1.1, 1.1. Maxillary palpus length 0.44–0.56, 0.51 mm, width 0.10–0.12, 0.12 mm, length/width 3.7–4.7, 4.4.

Thorax. Macrosetae 3 np, 2 sa, 1 pa, 0–1 (MEI 012653 has one dorsocentral macrosetae on left side). Mesonotum pubescence brownish gray; dorsocentral vitta dull brown, lateral vittae not evident. Wing. Length 6.7–7.5, 7.1 mm, width 2.2–2.5, 2.3 mm, length/width 3.0–3.2, 3.1. Cell m 3 closed, petiolate. Halter stalk dark brown, knob pale yellowish brown. Legs. Tibiae yellowish brown becoming darker apically.

Abdomen. Dark brown, pubescence white; dorsal setae white, elongate, appressed; lateral setae white erect. Terminalia (OSUC 0011206). Furca ( Fig. 8 ), quadrate, narrowed posteriorly, anterolateral projection absent; length 0.60 mm, width 0.30 mm.

FIGURES 9–17. Acrosathe falcata . 9. Tergite 8, epandrium, cerci. 10. Sternite 8, gonocoxite ventral view. 11. Gonocoxite, lateral view. 12. Gonostylus, dorsal view. 13. Aedeagus, dorsal view. 14. Aedeagus, ventral view. 15. Aedeagus, lateral view. 16. Female head, frontal view. 17. Female internal reproductive organs. Scale = 0.1 mm. Abbreviations: AAP = accessory aedeagal process, C = cercus, CD = common duct, CSpD = common spermathecal duct, DA = dorsal apodeme, Dp = distiphallus, EA = ejaculatory apodeme, Epa = epandrium, F = furca, Gs = gonostylus, Gx = gonocoxite, H = hypandrium, Hpt = hypoproct, Igp = inner gonocoxal process, Sp = spermatheca, SpD = spermathecal duct, SpS = spermathecal sac, S8 = sternite 8, T8 = tergite 8, VA = ventral apodeme, VL = ventral lobe.

Immature stages. Unknown.

Distribution. Acrosathe bimaculata is known from North Carolina ( Fig. 50 ).

Habitats and Phenology. Adults of Acrosathe bimaculata has been hand-collected on sand in February through April.

Specimens examined. Type specimens. The holotype female (MEI 170268) of Thereva bimaculata Cole ( CUIC Type No. 569.1) is labeled "SW Foster Collector, Southern Pines , 4–6 1906 N.C.". Other specimens .

UNITED STATES. NORTH CAROLINA. Bladen County. White Lake [34.6333, -78.5000] , 14.III.1953, Fulton , B.B., 1♂ MEI 090144 ( NCSU) , sand. Moore County. Southern Pines [35.174, -79.393] , 11.IV.1906, Foster , S.W., 2♀ MEI 075670–1 ( CUIC) ; 14.IV.1911, Manee , A.H., 1♀ MEI 012653 ( ANSP) ; 8.IV.1912, 1♂ MEI 100964 ( MEIC) ; 9.IV.1912, 1♂ MEI 113505, 1♀ 113504 ( USNM) ; 10.IV.1912, 1♂ OSUC 0011205 ( OSU) , 11.IV.1912, 1♂ OSUC 0011206 ( OSU) ; 14.IV.1912, 1♂ OSUC 0011207 ( OSU) ; 1.IV.1913, 1♂ MEI 012654 ( ANSP) . Robeson County. Lumberton [34.618, -79.009] , 29.II.1980, Marshall , S.A., 6♂ MEI 013513 ( MEIC) , 013516 ( INHS), 013512, 013514–5, 013517 ( DEBU).

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.

FIGURE 50–53. Distribution map. 50. Acrosathe bimaculata closed circle, Arenigena floridensis closed triangle, Litolinga tergisa open circle. 51. Acrosathe falcata closed circle, Ac. pacifica open circle. 52. Acrosathe otiosa. 53. Acrosathe vanduzeei.

FIGURES 18–25. Acrosathe otiosa. 18. Tergite 8, epandrium, cerci. 19. Sternite 8, gonocoxite ventral view. 20. Gonocoxite, lateral view. 21. Gonostylus dorsal view. 22. Aedeagus, dorsal view. 23. Aedeagus, ventral view. 24. Aedeagus, lateral view. 25. Female internal reproductive organs.