Microphorella breviradia

Cumming, Jeffrey M. & Brooks, Scott E., 2022, Establishment of the Microphorella breviradia species group, with a key to the Nearctic species groups of Microphorella Becker (Diptera: Dolichopodidae sensu lato: Parathalassiinae), Zootaxa 5134 (2), pp. 197-214 : 198-199

Microphorella breviradia species group

Diagnosis. The Microphorella breviradia species group can be distinguished from other parathalassiines by the following suite of characters: wing with short R 1 vein that terminates at or before midpoint of wing ( Fig. 3 ); mouthparts with sensory pit on palpus; male abdominal sternite 5 with short broad ventral projection; hypopygium ( Figs 4 , 10, 11, 14 , 19, 20, 21 ) with epandrium and hypandrium partially fused together, right epandrial lamella greatly enlarged and comprising most of hypopygium in right lateral view, hypandrium reduced to narrow subtriangular band positioned on left side of hypopygium; female abdomen ( Figs 31, 32 ) with 7 exposed abdominal segments, telescoping terminalia retracted into segment 7, syntergite 9+10 with acanthophorous setae ( Figs 16, 17 ), syntergite 9+10 and sternite 10 widely separated, cercus ovoid with long apical setae ( Figs 16 , 32 ). See Cumming & Brooks (2019) for additional parathalassiine features possessed by members of this species group.

Remarks. The Microphorella breviradia species group includes three new species from western North America (described below) that share a short R 1 wing vein and a distinctively modified male hypopygium. The former feature is seen in some non-Nearctic parathalassiines (e.g., the Microphorella malaysiana species group, Neothalassius , Chimerothalassius , Eothalassius ), but not in other known extant Nearctic species groups of Microphorella . There is a fossil species of Microphorella described from the middle Eocene Kishenehn Formation in northwestern Montana that may also belong to the M. breviradia species group ( Greenwalt et al. 2022). Members of the species group are generally found along fast flowing rivers and streams ( Figs 6–9 ). Cumming & Brooks (2019) referred to this lineage as the “ Microphorella short R 1 species group” in their phylogenetic analysis of relationships within the Parathalassiinae .

Key to males of species of the Microphorella breviradia species group

1 Head with face broad, nearly twice width of anterior ocellus at narrowest point ( Fig. 5 ); fore tarsomere 5 with tuft of long dorsal setae............................................................................ M. macdonaldi sp. nov.

- Head with face narrow, about width of anterior ocellus at narrowest point ( Fig. 2 ); fore tarsomere 5 with shorter dorsal setae ................................................................................................... 2

2 Hypopygium with basiventral projection(s) on right dorsal surstylar lobe ( Figs 11, 12, 13 ); phallus long and tubular, bearing very slender process medially ( Fig. 10 )................................................. M. breviradia sp. nov.

- Hypopygium without basiventral projections on right dorsal surstylar lobe ( Fig. 20 ); phallus stout and bifid, bearing thick process ventrally ( Fig. 19 )................................................................. M. vespera sp. nov.

Figures

FIGURES 1–5. Microphorella breviradia sp. nov. and M. macdonaldi sp. nov. (males). 1. Habitus of M. breviradia sp. nov., left lateral view. 2. Head of M. breviradia sp. nov., anterior view (CNC487231). 3. Wing of M. breviradia sp. nov., anterior view (CNC487241). 4. Abdomen of M. breviradia sp. nov., right lateral view (CNC1155716). 5. Head of M. macdonaldi sp. nov., anterior view (holotype). Abbreviations: bm-m—basal medial crossvein; cua—anterior cubital (=anal) cell; CuA+CuP— anterior branch of cubital vein + posterior branch of cubital vein; dm—discal medial cell; dm-m—discal medial crossvein; epand—epandrium; h—humeral crossvein; M1, M2, M4—medial veins; (R)—right; R1, R2+3, R 4+5 —radial veins; Sc—subcostal vein; v epand proc—ventral epandrial process.

FIGURES 10–15. Hypopygium of Microphorella breviradia sp. nov. 10. Hypopygium, left lateral view (CNC DIPTERA # 192173). 11. Hypopygium, right lateral view (CNC DIPTERA # 192173). 12. Right epandrial lamella, right lateral view (CNC DIPTERA # 192167). 13. Right epandrial lamella, right lateral view (CNC487206). 14. Hypopygium and sternite 8, dorsal view (CNC DIPTERA # 192173). 15. Right cercus, dorsal view (CNC487206). Abbreviations: cerc—cercus; d sur—dorsal lobe of surstylus; epand—epandrium; hypd—hypandrium; hyprct—hypoproct; (L)—left; pgt lb—postgonite lobe; ph—phallus; (R)—right; v epand proc—ventral epandrial process; v sur—ventral lobe of surstylus.

FIGURES 19–21. Hypopygium of Microphorella vespera sp. nov. (CNC DIPTERA # 105212). 19. Hypopygium, left lateral view. 20. Hypopygium, right lateral view. 21. Hypopygium and sternite 8, dorsal view. Abbreviations: cerc—cercus; d sur—dorsal lobe of surstylus; epand—epandrium; hypd—hypandrium; hyprct—hypoproct; (L)—left; pgt lb—postgonite lobe; ph—phallus; (R)—right; v epand proc—ventral epandrial process; v sur—ventral lobe of surstylus.

FIGURES 31–36. Female abdomens of the Microphorella breviradia, M. chiragra and M. acroptera species groups. 31. M. breviradia sp. nov., left lateral view. 32. M. breviradia sp. nov., dorsal view. 33. Microphorella sp. 1 (M. chiragra species group), left lateral view. 34. Microphorella sp. 1 (M. chiragra species group), dorsal view. 35. Microphorella sp. 8 (M. acroptera species group), left lateral view. 36. Microphorella sp. 8 (M. acroptera species group), dorsal view. Abbreviation: tg—tergite.

FIGURES 16–18. Female terminalia of Microphorella breviradia sp. nov. 16. Terminalia, dorsal view (CNC487214). 17. Terminalia, lateral view (CNC487214). 18. Spermatheca, lateral view (CNC487218). Abbreviations: cerc—cercus; st—sternite; tg—tergite.

FIGURES 6–9. Collection localities and habitats of the Microphorella breviradia species group. 6–7. South Fork of American River (Eagle Rock), California, M. breviradia sp. nov. type locality (first author pictured in Fig. 7). 8–9. West Fork of Patrick Creek, California, M. vespera sp. nov. type locality.