Gondwanodromia, Sinclair & Saigusa, 2022

Sinclair, Bradley J. & Saigusa, Toyohei, 2022, A New Aquatic Associated Genus of Trichopezinae from the Southern Hemisphere (Diptera: Empidoidea: Brachystomatidae), Records of the Australian Museum (Rec. Aust. Mus.) 74 (3), pp. 75-98 : 76-77

Gondwanodromia gen. nov.

urn:lsid:zoobank.org:act:CBBBF605-C250-40CC-A747-E523086022D4

“new genus 3” Sinclair & Cumming, 2000: 185. “Undescribed genus” Saigusa, 2006: 211.

“Undescribed genus A” Sinclair, 2011: 31.

Type species: Gondwanodromia mikae sp. nov.

Taxonomic note. This new genus was originally identified as “new genus 3” from Australia ( Sinclair & Cumming, 2000). Saigusa (2006) listed some morphological characters of “undescribed genus” based on an undescribed species from northern Patagonia, which is now the type species of Gondwanodromia . Later, Sinclair (2011) identified a similar new genus from New Zealand, referred to as “Undescribed genus A”. These generic concepts have been re-evaluated and they are now considered congeneric.

Diagnosis. The genus is readily distinguished by the following combination of characters: eyes with or without ommatrichia; both sexes dichoptic with broad frons lacking setae; postpedicel subtriangular, gradually tapered with apical stylus or postpedicel strap-like, elongate, without apical stylus, bearing simply peg-like apical sensillum; palpus drooping, narrow and elongate ( Figs 3 , 30 ); female labrum more robust than male; R 4+5 branched, veins without setae; male terminalia symmetrical, unrotated, held upright in part by enlarged sternite 8, erect, arched anteriorly, epandrium and hypandrium not fused, epandrium without dorsal bridge, phallus tubular, narrow; female tergite 7 without posterior fringe, female tergite 8 with or without short internal medial apodeme and female syntergite 9+10 (acanthophorites) with numerous short thickened setae.

Description. Male. Head. Dichoptic, eyes usually bare ( Fig. 30 ); frons very broad and bare; face broad, shorter than membranous clypeus; ocellar triangle prominent with pair of ocellar setae inserted anterior or anteromedial to lateral ocelli and 1–2 pairs of shorter setae; upper postocular seta arched over eye; 2–3 pairs of vertical setae. Antenna dark, scape subequal to or longer than pedicel, with short dorsal setae; pedicel with circlet of stout setae; postpedicel subtriangular, gradually tapered, subequal or slightly longer than apical stylus ( Figs 13 , 37 , 44, 46 ), or postpedicel strap-like, greatly lengthened, pubescent, without apical stylus ( Figs 16 , 21 , 30 , 39 ); apex with short, peg-like, or longer sensillum. Proboscis elongate, longer than eye height ( Fig. 30 ). Palpus drooping, arched and elongate along edge of proboscis ( Figs 3 , 30 ), one-half to three-quarters length of labrum; bearing fine setae longer than width of palpus. Lacinia slightly shorter than palpus, stylus-like; stipes long and narrow. Labrum stout, straight; epipharyngeal blades robust, articulated; epipharyngeal carina absent. Hypopharynx stout, straight, subequal in length to labrum. Labellum well developed, fleshy, with numerous short setae; prementum with several setae; 6–8 pseudotracheae well developed ( Fig. 19 ). Clypeal ridge long and slender, as long as cibarium, articulated together with labrum at labrofulcral articulation point.

Thorax. Prosternum fused to proepisterna; proepisternum with scattered setae. Scutal setae long and conspicuous. Acrostichal setae uniserial or biserial, with pair of upright anterior setae; dorsocentral setae uniserial, anterior pair divergent from row and increasing in length posteriorly; 2–3 long notopleural setae; 1–2 pairs of scutellar setae on each side. Laterotergite with short setae; dorsal mesepimeron pocket present. Wing ( Figs 16 , 20 , 38 ). Relatively slender, infuscate; anal lobe weakly developed, without alular incision; alula not developed; basal costal seta present; pterostigma faint, elongate-oval overlapping apex of R 1. Costa circumambient with biserial row of slender marginal setae, sometimes with erect dorsal setae; Sc incomplete, ending short of costa; all veins bare; R 4+5 branched; R 4 slightly sinuous, ending slightly closer to R 2+3 than to R 4+5; cell dm emitting 3 veins, reaching wing margin; cell cua rounded with CuA recurrent; CuA+CuP reduced to short streak. Halter with 2–3 setae below knob, occasionally shaft rather elongate. Legs. Fore tibia with anteroventral apical comb; hind tibia with posteroventral apical comb. Mid tibia often slightly to strongly swollen with modified setae ( Fig. 13 ). Tarsomere 5 partially flattened, truncate apically, without apical projection ( Figs 22, 23 ); claw moderately long; pulvillus pale, highly pubescent, shorter than claw; empodium slender, with distinct ventral pubescence ( Figs 22, 23 ).

Abdomen. Male tergite 6 often with longest setae; male sternite 7 often prolonged posterolaterally ( Figs 6 , 40 ). Sternite 8 enlarged, broad, providing support to upright terminalia ( Figs 6 , 18 , 40 ). Terminalia ( Figs 5, 7 , 18 , 24–27 , 31–33 , 40 , 43 ). Held upright, directed anterodorsally, symmetrical, unrotated. Epandrium and hypandrium not fused. Epandrium rounded or divided medially, without narrow dorsal bridge. Surstylus weakly differentiated or distinct, sometimes divided into anterior and posterior surstylar processes. Postgonites not differentiated. Phallus narrow, arched, tubular; ejaculatory apodeme narrow to broad, articulated at base of phallus.

Female. Similar to male except as follows: postpedicel shorter than male; labrum more robust than male; midleg unmodified.Abdomen truncate, caudal segments withdrawn into segment 7 ( Figs 15 , 38 ); posterior margin of tergite 7 without row of fine setae. Terminalia ( Figs 11 , 28 , 42 ). Sclerites of segment 8 articulated anterolaterally; anterodorsal margin of tergite 8 with or without short, narrow apodeme, extending into segment 7; posterior margin of tergite 8 with deep, median membranous cleft, medially with transverse row of short setae. Sternite 8 without posterior marginal setae. Syntergite 9+10 (acanthophorites) divided dorsomedially, subtriangular, with row(s) of strong, erect setae. Cercus heavily sclerotized, slightly arched posterodorsally or prolonged distally. Spermathecal receptacle elongate or spherical ( Figs 29 , 36 ), darkly pigmented, with long, unpigmented duct; genital fork small, U-shaped.

Etymology. The generic name is from the ancient supercontinent Gondwana + the Greek, dromia (runner) based on its distributional range on the southern continents of South America and Australasia.

Distribution. Gondwanodromia is widely distributed in the Southern Hemisphere, recorded from Australia, New Zealand and southern South America.

Remarks. Gondwanodromia is assigned to the subfamily Trichopezinae on the basis of the modified female terminalia, especially the presence of a small apodeme on the anterior margin of tergite 8. Genera of Trichopezinae with similar elongate antennae (i.e., strap-like postpedicel) include Ceratempis Melander and Niphogenia Melander from the Nearctic Region, but they differ in the form of the male terminalia and the palpus is not drooping.

Adult flies are found in fast flowing streams and creeks, occurring on emergent rocks and boulders ( Figs 1, 4 ). These habitats are primarily in mountainous and cool hilly regions. Adults can be swept from the rocks or sometimes aspirated directly from the rock surfaces ( Fig. 2 ).

Figures

Figures 1–4. Photographs of living Gondwanodromia and habitats:(1)Arroyo Torrontegui,Argentina; (2)Arroyo Torrontegui,Argentina, with collector Mika Sugimoto; (3) female, Altos del Lircay, Chile (photograph © Steve Marshall); (4) Dead Horse Gap trail, Kosciusko National Park, Australia; November 1994.

Figures 30–33. Gondwanodromia mikae sp. nov.: (30) male head, lateral view; (31) epandrium, dorsal view, right cercus removed; (32) terminalia, lateral view; (33) hypandrium and phallus, lateral view. Scale bars: Figs 31–33 = 0.05 mm; Fig. 30 = 0.1 mm.Abbreviations: cerc – cercus; ej apod – ejaculatory apodeme; epand – epandrium; goncx apod – gonocoxal apodeme; hypd – hypandrium; lc – lacinia; ph – phallus; plp – palpus; pped – postpedicel; sbepand scl – subepandrial sclerite; st – sternite; sur – surstylus.

Figures 13–16.Argentinian and New Zealand species of Gondwanodromia, lateral view:(13) G.femorata sp.nov., male habitus, holotype, scale bar = 1.0 mm; (14) G. femorata sp. nov., male terminalia, scale bar = 0.25 mm; (15) G. femorata sp. nov., female postabdomen, scale bar = 0.25 mm; (16) G. mikae sp. nov., male habitus, holotype, scale bar = 0.75 mm. Abbreviations: epand lb – epandrial lobe; sur – surstylus.

Figures 37–40.Australian and New Zealand species of Gondwanodromia, lateral view:(37) G. mutabilis (Collin), male habitus (abdomen dissected), scale bar = 1.0 mm; (38) G. tasmanica sp. nov., female habitus, scale bar = 0.75 mm; (39) G. thredbo sp. nov., male habitus, holotype, scale bar = 0.75 mm; (40) G. thredbo sp. nov., male terminalia, scale bar = 0.25 mm.Abbreviations: a sur – anterior surstylus; epand – epandrium; hypd – hypandrium; p sur – posterior surstylus.

Figures 43–47. New Zealand species of Gondwanodromia: (43) G. tongariro sp. nov, holotype, male terminalia, scale bar = 0.25 mm; (44) G. femorata sp. nov., female midleg, scale bar = 0.5 mm (courtesy Canterbury Museum); (45) G. femorata sp. nov., female abdomen, scale bar = 0.5 mm (courtesy Canterbury Museum); (46) G. wardi sp. nov., holotype (abdomen dissected), lateral view, scale bar = 0.5 mm (courtesy Canterbury Museum); (47) G. wardi sp. nov., holotype (abdomen dissected), dorsal view, scale bar = 0.5 mm (courtesy Canterbury Museum). Abbreviations: epand lb – epandrial lobe; sur – surstylus.

Figures 19–23. Gondwanodromia mikae sp. nov.: (19) labellum, lateral view, scale bar = 0.05 mm; (20) wing, scale bar = 1.0 mm; (21) male antenna, lateral view, scale bar = 0.1 mm; (22) tarsomere 5, dorsal view, scale bar = 0.05 mm; (23) tarsomere 5, lateral view, scale bar = 0.05 mm. Abbreviations: pped – postpedicel; psdtrch – pseudotrachea.

Figures 5–9. Australian and New Zealand species of Gondwanodromia, lateral view: (5) G. bulbosa sp. nov., male habitus, holotype, scale bar = 0.75 mm; (6) G. bulbosa sp. nov., male terminalia, scale bar = 0.25 mm; (7) G. colomatta sp. nov., male habitus, holotype, scale bar = 0.75 mm; (8) G. elongata sp. nov., male habitus, holotype (prior to abdomen dissection), scale bar = 0.5 mm; (9) G. elongata sp. nov., female habitus,scale bar=0.75 mm.Abbreviations:asur – anteriorsurstylus;cerc –cercus;epand –epandrium;psur – posteriorsurstylus;st– sternite.

Figures 17–18. Male terminalia of New Zealand andAustralian species of Gondwanodromia, lateral view: (17) G. elongata sp. nov.; (18) G. lutea sp. nov. Scale bar = 0.1 mm.Abbreviations: cerc – cercus; epand – epandrium; hypd – hypandrium; ph – phallus; sur – surstylus.

Figures 24–29. Gondwanodromia mikae sp. nov.: (24) epandrium, dorsal view; (25) epandrium, dorsal view; (26) hypandrium and phallus, lateral view; (27) hypandrium and phallus, posterior view; (28) female terminalia, lateral view, scale bar = 0.05 mm; (29) female abdomen, lateral view. Scale bars: Figs 24–28 = 0.05 mm; Fig. 29 = 0.1 mm.Abbreviations: cerc – cercus; epand – epandrium; hypd – hypandrium; ph – phallus; spmth – spermatheca; sur – surstylus; tg – tergite.

Figures 10–12. Terminalia of Gondwanodromia colomatta sp. nov., lateral view: (10) male; (11) female; (12) spermatheca. Scale bar = 0.1 mm. Abbreviations: a sur – anterior surstylus; cerc – cercus; epand – epandrium; hypd – hypandrium; p sur – posterior surstylus.

Figures 41–42. Gondwanodromia tasmanica sp. nov., lateral view: (41) male terminalia; (42) female terminalia. Scale bar = 0.1 mm. Abbreviations: cerc – cercus; epand – epandrium; hypd – hypandrium; sur – surstylus.

Figures 34–36. Gondwanodromia mutabilis (Collin), lateral view: (34) male terminalia; (35) female terminalia; (36) spermatheca. Scale bar = 0.1 mm.Abbreviations: cerc – cercus; epand – epandrium; hypd – hypandrium; ph – phallus; sur – surstylus.