Austrothaumalea apicalis Edwards, 1930

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 : 512-514

Austrothaumalea apicalis Edwards

( Figs 3A , 4A , 5A , 6A , 7A , 8 )

Austrothaumalea apicalis Edwards, 1930: 113 .

Other references: Stone, 1966: 1 (catalogue); Arnaud, 1977: 284 (distribution); Theischinger, 1986: 316 (phylogenetic discussion); Sinclair, 2008b: 12 ( fusca species group).

Type material examined. Holotype: ♀, minuten pinned with right wing mounted on plastic card, pinned beneath specimen, abdomen mounted in resin, labelled: “Bariloche./ 1.xii.1926.”; “ Austrothaumalea / apicalis Edw./ F.W. Edwards / det. 1930.”; “ Argentina:/ Terr. Rio Negro./ F. & M. Edwards. / B.M. 1927 – 63.”; “HOLO-/ TYPE [white label with red margin]”; “ NHMUK010210687 ” ( BMNH) . Paratype: same label data as holotype (1♀, BMNH) .

Recognition. The only described species of South American Austrothaumalea with posterior epandrial projections (also present in some Australian species). This feature, along with the more rounded apex of the paramere and concave posterior margin of the gonocoxal plate distinguish it from A. spatulata . Austrothaumalea apicalis is similar to A. fredericki , with both having darkened wing tips and yellowish body colour.

Redescription. Male. n = 1. Length 2.1 mm. Colouration ( Fig. 3A ). Head dull, dark brown; pronotum and postpronotum brown; postpronotal lobe brown; prescutum with lateral margins brown; mesoscutum uniformly yellowish brown, shiny; scutellum and mediotergite pale brown, shiny; pteropleuron brown with ill-defined darker markings; halter yellowish brown; legs pale brown, apices of femora and tarsi darkened; abdomen dark brown; terminalia brown.

Head. Eyes above antennae broadly joined, barely 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 with yellow setae of uniform length, with a few longer, black orbital setae.

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

Wing. Wing length: 2.7 mm. Lightly infuscate throughout except for distinct dark, apical spot encircling apex of R 4+5 and M 1 ( Fig. 3A ); apex broadly 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, with uniseriate row of microtrichia along entire length, remaining veins bare; R flexed into cell br; R 2+3 crossvein very weak or absent, at most a faint infuscation, situated slightly beyond midpoint of R 1 (+R 2+3); bend in R 4+5 gentle; R 4+5 and M 1 running parallel toward wing margin; M 1 and M 2 straight; M 4 slightly sinuous; CuA with basal spur shorter than crossvein m-cu.

Abdomen. Abdominal sternites 1–4 not observable due to dissection; sternites 5–6 rectangular, weakly sclerotized, anterior margin well sclerotized, setae restricted to posterior third; sternite 7 rectangular, a few setae on posterior third, weakly sclerotized, anterior margin well sclerotized, arched slightly into preceding sternite; sternite 8 crescent-shaped, bare, weakly sclerotized except for anterior margin slightly more sclerotized and arched slightly into preceding sternite.

Terminalia ( Figs 4A , 5A ). Epandrium trapezoidal from ventral aspect; apical half tapered; posterior margin narrow, slightly indented, with single small tooth-like projection from posterolateral margin. Hypandrium broad in ventral view, wider than basal width of gonostylus; anterior margin not concave. Gonocoxite broadest basally, inner margin nearly parallel, smooth. Gonostylus shorter than gonocoxite, basal quarter straight then gently curved medially; broadest at basal quarter, apical three-quarters uniform in width; apex truncate. Parameres distally fused, three-quarters length of epandrium; expanded irregularly toward apex. Gonocoxal plate weakly sclerotized, apical third tapered, posterior margin slightly concave with posterolateral projection on each corner; nearly half-length of gonocoxite; basally not fused to hypandrium. Cercus weakly sclerotized, situated along midline of epandrium.

Female. n = 1. Similar to male except as follows: Length: 2.3 mm. Abdomen: Tergites 8–9 noticeably more sclerotized than preceding segments; only anterior margin of sternite 7 well sclerotized. Terminalia ( Figs 6A , 7A ): Hypogynial valve not projected beyond tergite 9; posterior margin rounded with shallow cleft in ventral view; densely setose. Tergite 9 rectangular in lateral view, wider than tergite 8, lacking lateral projections. Sternite 9 (genital fork) thin, rod-shaped, posteriorly divided into two triangular-shaped sclerites; distal margin of lateral arms extended beyond hypogynial valve, arms nearly meeting along midline, golf club-head shaped in lateral view. Hypoproct arched, thin medially. Cercus rounded, projected slightly posterodorsally; bearing numerous setae. Spermathecal ducts not observed.

Immature Stages. Unknown.

Additional Material Examined. ARGENTINA: Rio Negro: Bariloche , XI-1926, R . & E. Shannon , USNMENT 01115807 (1♂, USNM); CHILE: Region X (Los Lagos): Casa Pangue, Llanquihue , XII-1926, R . & E. Shannon, USNMENT01115806 (1♀, USNM) .

Distribution. Known from adjacent localities on the Chile-Argentina border in the southern Andes ( Fig. 8 ).

Remarks. Edwards (1930) did not describe the male specimen. Alan Stone identified the male specimen herein treated as A. apicalis (year not specified on determination label), but he never formally described it. Since it was collected in the same region as the holotype female, and it is uniquely distinct from all other described males, we also have identified it as the putative male.

The holotype date label reads “.xi- 1.xii.1926 ”, with “.xi-” scratched out with pencil.

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.