Dasythereva, Irwin & Winterton, 2020

Irwin, Michael E. & Winterton, Shaun L., 2020, A new genus of therevine stiletto flies from South America (Diptera: Therevidae), Zootaxa 4838 (1), pp. 52-70 : 55

Dasythereva gen. n.

https://zoobank.org/ urn:lsid:zoobank.org:act:171B8653-7CA0-4EB0-9BE5-BA18494EAF88

Common name. Woolly stiletto flies

Type species. Dasythereva penai sp. n., herein designated.

Diagnosis. Antenna shorter than head; flagellum elliptical, shorter than combined scape and pedicel length; scape slightly bulbous, thicker than pedicel and flagellum; frontal part of head flat with frons only slightly produced anterior to eye, male frons width (at narrowest point) wider than ocellar tubercle, female frons only slightly wider than male; head shape in profile higher than long; face and parafacial densely setose; male with postocular macrosetae scattered over entire occiput, with an additional prominent single row along postocular ridge; thorax with dense setal pile of erect scale-like setae admixed with fine black setae; central depression of prosternum setose; pleuron sparsely pubescent, metanepisternum with postspiracular setae present; metakatepisternum often with a few setae present; femora with multiple anteroventral (av) and posteroventral (pv) setae present; forefemur with dorsal macrosetae absent; hind femur with av setae as a series along segment, pv macrosetae present basally; posterior surface of midcoxa without setae, or with a few setae present; midfemoral vestiture as filiform setae admixed with adpressed, lanceolate and scale-like setae; hind femur and tibia subequal in length to that of fore- and mid legs; hind coxal knob present; scutal chaetotaxy (pairs of macrosetae): supra alar macrosetae, 2; post alar macrosetae, 1; dorsocentral macrosetae, 1–2; scutellar macrosetae, 2; notopleural setae, 1–3; wing ( Fig. 12 ) cell m 3 open; vein R 2+3 reflexed as sigmoid curve; wing membrane opaque white with distinct brown shading in most cells and darkened along wing veins; vein R 1 with setae absent; male terminalia ( Fig. 13 A–E)) with dorsal apodeme of aedeagus broad, subtriangular and covering aedeagus dorsally, distiphallus narrow and directed ventrally; gonocoxite with posterior projections (outer gonocoxal projection) greatly reduced, inner gonocoxal process (igp) articulated, gonocoxite with posteromedial margins proximal; ventral apodeme of aedeagus narrow, ventral lobe large, elongate and rounded. Female acanthophorites with two sets of spines (A1 & A2), A1 series enlarged; sternite 8 posterior margin emarginate posteromedially, two spermathecae present, spermathecal sac large and single lobed ( Fig. 13F ); spermathecal ducts enlarged and membranous near basal attachment to spermathecal sac duct; tergite 8 elongate with broad anteromedial process.

Etymology. Derived from the Greek Dasy – thick with hairs, and nominal genus - thereva . Gender is feminine.

Included species. Dasythereva penai sp. n., D. patagonia sp. n.

Comments. Dasythereva gen n. is a distinctive genus comprising two very similar species with characterised by the entire body being covered in a dense, dishevelled pile of scale-like, white and brown setae admixed with finer black setae. The male frons is much wider than the ocellar tubercle. Members of this genus appear to inhabit sandy areas in Chile and Argentina. Winterton et al. (2016: fig. 1) included this genus in their molecular phylogeny as “Undescribed genus L”. It was recovered in the Cerocatus genus-group (including the Brachylinga genus-group of Holston et al., 2007), although the molecular data did not adequately resolve relationships within this clade. However, Dasythereva gen. n. appears most closely related to Argolepida based on adult morphology. Argolepida is another distinctive Patagonian genus that is associated with sandy areas and shares characters such as scale-like setae on the body, elongate tibial macrosetae and a wide male frons. Dasythereva gen. n. is separable from Argolepida based on their much more robust body shape and larger size, wing cell m 3 open (closed in Argolepida ), parafacial setae present (absent in Argolepida ), leg macrosetae black (white in Argolepida ), frons with extensive setal pile (usually lacking in Argolepida ) and the scale-like setae covering body being erect and dense, giving a woolly appearance (smooth and adpressed in Argolepida ).

Figures

FIGURE 12. Dasythereva gen. n., wings. A. D. penai sp. n., male; B. D. patagonia sp. n., male; C. D. penai sp. n., female; B. D. patagonia sp. n., female.

FIGURE 13. Dasythereva patagonia sp. n., Male genitalia.A. epandrium; B. gonocoxites, ventral view; C. same, lateral view; D. aedeagus, lateral view; E. same, dorsal view. Female genitalia. F. Furca and internal genitalic structures. Scale line: 0.2 mm. Abbreviations: ag, accessory gland; d, distiphallus; da, dorsal apodeme of parameral sheath; ea, ejaculatory apodeme; f, furca; ga, gonocoxal apodeme; gs, gonostylus; igp, inner gonocoxal process; ogp, outer gonocoxal process; s, spermatheca; sd, spermathecal duct; ss, spermathecal sac; ssd, spermathecal sac duct; vl, ventral lobe.