Austrothaumalea setipennis Edwards, 2020

Pivar, Robert J., Sinclair, Bradley J. & Moulton, John K., 2020, Revision of the South American species of Austrothaumalea Tonnoir (Diptera Thaumaleidae), Zootaxa 4853 (4), pp. 509-526 : 518-520

Austrothaumalea setipennis Edwards stat. rev.

( Figs 3E , 4D , 5D , 6C , 7C , 8 , 9A )

Austrothaumalea setipennis Edwards, 1930: 113 .

Other references: Stone, 1966: 1 (catalogue); Arnaud, 1977: 284 (distribution); Theischinger, 1986: 316 (phylogenetic discussion).

Oterere setipennis (Edwards) : McLellan, 1988: 575 (new combination).

Other reference: Sinclair, 2008b: 11, 12 ( capricornis species group).

Type material examined. Holotype: ♂, minuten pinned with abdomen mounted in resin, labelled: “Bariloche./ 29.xi.1926.”; “ Austrothaumalea / setipennis Edw./ F.W. Edwards / det. 1930.”; “ Argentina:/ Terr. Rio Negro./ F. & M. Edwards. / B.M. 1927 – 63.”; “HOLO-/ TYPE [white label with red margin]”; “ NHMUK010210691 ” ( BMNH).

Recognition. This species is recognized by the presence of macrotrichia on wing vein M 1 (unique among South American species) and the rod-shaped paramere.

Redescription. Male. n = 4. Length 2.5–2.7 mm. Colouration ( Fig. 3E ). Head dull, brown; pronotum, postpronotum, postpronotal lobe and lateral margins of prescutum brown; prescutum and mesoscutum shiny, primarily yellow, with three yellowish-brown, longitudinal vittae ending in postscutal spot; pleura yellowish brown; two lateral brown spots above scutoscutellar suture; scutellum yellowish brown, sometimes with dark speckles; mediotergite shiny, mainly yellow, slightly darker anteriorly; katepisternum yellow; paratergite dark brown; remaining pteropleuron yellowish brown to brown; posterior basalare yellow; halter yellowish; legs yellow, tarsi darker; abdomen brown, hind margins of tergites whitish; terminalia pale brown.

Head. Eyes above antennae broadly joined, slightly exposing frons above antennae. Flagellomeres 1–3 expanded, subquadrate; 1 as long as 2 and 3 combined; flagellomeres 4–10 thin, cylindrical, becoming progressively more elongate. Vertex clothed in golden setae of uniform length, with sparse long, black orbital setae.

Thorax. Pronotal setae longer than scutal setae. Scutum clothed dorsally in short, black setulae; notopleural, supra-alar and postsutural setae long, black. Pteropleuron bare. Fore- and mid legs with tarsi simple, hind leg with tarsomere 4 bilobed.

Wing. Wing length: 2.8–3.3 mm. Lightly infuscate throughout, slightly darker where R 4+5 meets apex; apex rounded; C and posterior wing margin with fringe of microtrichia; Sc incomplete; R 1 and R 1 (+R 2+3) without weakenings or depigmented gaps; R 1 (+R 2+3) and M 1 with uniseriate, dorsal row of microtrichia along entire length, remaining veins bare; R flexed into cell br; R 2+3 crossvein strong, situated toward apex of R 1 (+R 2+3); bend in R 4+5 well-defined; R 4+5 and M 1 running parallel toward margin; M 1 and M 2 straight; M 4 slightly sinuous; CuA with basal spur shorter than crossvein m-cu.

Abdomen. Abdominal sternite 1 narrow, spectacle-shaped; sternite 2 with slender median sclerite and lightly sclerotized posterior trapezoid, few setae on posterior margin; sternites 3–7 rectangular, weakly sclerotized, setae restricted to posterior half; sternite 8 crescent-shaped, with a few setae, weakly sclerotized, arched slightly into preceding sternite.

Terminalia ( Figs 4D , 5D ). Epandrium broadly elongate-oval from ventral aspect; apical third slightly tapered; posterior margin broad and rounded; lacking pointed posterolateral processes. Hypandrium broad in ventral view, nearly subequal to basal width of gonostylus; narrowest at midpoint, anterior margin not concave. Gonocoxite broadest basally, tapered at midlength toward apex, inner margin smooth. Gonostylus nearly same length as gonocoxite, anterior three-quarters curved inward; nearly same width throughout, gently tapered to distinct tooth at apex. Parameres distally fused, three-quarters length of epandrium, rod-shaped, broadest medially; slowly tapered toward apex, projected ventrally. Gonocoxal plate formed of two lateral, sclerotized arms terminating in pectinate, sawlike structure; short, about half-length of gonocoxite; plate broad basally; basally not fused to hypandrium. Cercus weakly sclerotized, situated along median line of epandrium.

Female. n = 2. Similar to male except as follows: Length: 2.5–2.8 mm. Abdomen: Tergites 8–9 noticeably more sclerotized than preceding segments; only anterior margin of sternite 7 well-sclerotized. Terminalia ( Figs 6C , 7C ): Hypogynial valve not projected beyond tergite 9; posterior margin rounded with cleft in ventral view; densely setose. Tergite 9 rectangular in lateral view, wider than tergite 8, lacking lateral projections. Sternite 9 (genital fork) connected anteriorly, then divided into two thick arms ending before cleft of hypogynial valve; lateral arms extended beyond hypogynial valve, nearly meeting along midline, triangular in lateral view. Cercus rounded, projected slightly posteroventrally; bearing numerous setae. Three spermathecal ducts arising near cleft of hypogynial valve, only two terminating in irregularly rounded, weakly sclerotized spermathecal receptacles.

Immature Stages. Unknown.

Additional Material Examined. CHILE: Region IX (Araucanía): Rte. 71, 15-XII-2016, 38°13′20.3″S 71°44′41.1″W, elev. 1047 m, seep, J.K. Moulton & R. J. Pivar (1♀); Region XI (Aysén): Coihaique-Aysén Rd. , 6-II- 1985, J.A. Downes (3♂, 1♀, CNC) .

Distribution. Known from the Andes of southern Chile, this species holds the southern-most record of thaumaleids in South America ( Figs 8 , 9A ).

Remarks. The holotype date label reads “ 28.xi-1.xii.1926 ”, where ‘8’ has a 9 written over it in pencil, and ‘- 1.xii.’ is scratched out.

Figures

FIGURE 3. Adult habitus photographs of Austrothaumalea, lateral view. A, A. apicalis (♂); B, A. spatulata (♂); C, A. chilensis (♂); D, A. fredericki sp. nov. (♂); E, A. setipennis stat. rev. (♀). R2+3, second + third radial vein. Scale bars = 1.0 mm.

FIGURE 4. Ventral views of male Austrothaumalea terminalia. A, A. apicalis; B, A. chilensis; C, A. fredericki sp.nov.; D, A. setipennis stat. rev.; E, A. spatulata. Abbreviations: c, cercus; gcx, gonocoxite; gcxP, gonocoxal plate; gst, gonostylus; hypd, hypandrium; pm, paramere.Arrow denotes apical epandrial projection. Scale bars = 0.1 mm.

FIGURE 5. Lateral views of male Austrothaumalea terminalia. A, A. apicalis; B, A. chilensis; C, A. fredericki sp. nov.; D, A. setipennis stat. rev.; E, A. spatulata. Abbreviations: c, cercus; epand, epandrium; gcx, gonocoxite; gcxP, gonocoxal plate; gst, gonostylus; hypd, hypandrium; pm, paramere. Arrow denotes apical epandrial projection. Scale bars = 0.1 mm.

FIGURE 6. Ventral views of female Austrothaumalea terminalia. A, A. apicalis; B, A. chilensis; C, A. setipennis stat. rev.; D, A. spatulata. Abbreviations: c, cercus; gen fk, genital fork; hypct, hypoproct; hyp vlv, hypogynial valve; lat arm, lateral arms; spthc, spermatheca.. Scale bars = 0.1 mm.

FIGURE 7. Lateral views of female Austrothaumalea terminalia. A, A. apicalis; B, A. chilensis; C, A. setipennis stat. rev.; D, A. spatulata. Abbreviations: c, cercus; gen fk, genital fork; hypct, hypoproct; hyp vlv, hypogynial valve; lat arm, lateral arm; spthc p, spermathecal pump. Scale bars = 0.1 mm.

FIGURE 8. Known distribution of South American Austrothaumalea.

FIGURE 9. Examples of Austrothaumalea habitats in Chile. A, rock face seep where A. chilensis and A. setipennis stat. rev. were collected (38°13′20.3″S 71°44′41.1″W); B, collection site of A. fredericki sp.nov. (41°08.47′S 72°35.28′W); C, collection site of A. spatulata (34°59′48.8″S 70°48′37.0″W); D, northernmost collection site of A. spatulata in the Chilean Matorral, inset showing small trickle of water where specimen was collected (34°46′29.2″S 70°40′03.9″W).