Austrothaumalea chilensis 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 : 514-515

Austrothaumalea chilensis Edwards

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

Austrothaumalea chilensis Edwards, 1930: 111 .

Other references: Stuardo, 1946: 42 (catalogue); Stone, 1966: 1 (catalogue); Arnaud, 1977: 284 (distribution); Theischinger, 1986: 316 (phylogenetic discussion); Sinclair, 2008b: 11 ( capricornis species group).

Type material examined. Holotype: ♂, minuten pinned with abdomen mounted in resin, labelled: “Ancud./ 17–19.xii.1926.”; “ Austrothaumalea / chilensis Edw./ F.W. Edwards / det. 1930.”; “ S. Chile:/ Chiloe I./ F. & M. Edwards. / B.M. 1927 – 63.”; “HOLO-/ TYPE [white label with red margin]”; “ NHMUK010210688 ” ( BMNH) . Allotype: ♀, same label data as holotype ( BMNH) . Paratypes: CHILE: Region X (Los Lagos): Casa Pangue (1♂, BMNH); Ancud (3♂, 1♀, BMNH) .

Recognition. The gonocoxal plate with long, lateroapical teeth, and the cruciate paramere are characters that readily distinguish this species. The lateral, cross-like projections on the paramere are located apically, not concealed by the gonocoxal plate and are much shorter than those of A. fredericki . This is also the only known thaumaleid in South American to have the gonocoxal plate secondarily fused to the ventral surface of the hypandrium.

Redescription. Male. n = 4. Length 2–2.3 mm. Colouration ( Fig. 3C ). Head dull, dark brown; pronotum and postpronotum brown; postpronotal lobe brown; mesoscutum and pleura brown, somewhat shiny; scutellum and mediotergite brown, shiny; katepisternum dark brown; halter brown, dark at apex of knob; legs pale brown, apices of femora and tarsi darkened; abdomen dark brown; terminalia brown.

Head. Eyes above antennae broadly joined, frons above antennae barely exposed. 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, golden 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: 2.2–3.0 mm. Lightly infuscate throughout, 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 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 reduced to slender median sclerite, few setae on posterior margin; sternites 3–6 rectangular, weakly sclerotized, setae largely restricted to posterior half; sternite 7 semi-circular, a few setae on posterior margin, weakly sclerotized except for anterior margin, arched slightly into preceding sternite; sternite 8 crescent-shaped, bare, well sclerotized, strongly arched into preceding sternite.

Terminalia ( Figs 4B , 5B ). Epandrium elongate-oval from ventral aspect; apical third slightly tapered; posterior margin broad and rounded; lacking pointed posterolateral processes. Hypandrium broad in ventral view, wider than basal width of gonostylus; anterior margin not concave. Gonocoxite broadest basally, inner margin parallel, smooth. Gonostylus shorter than gonocoxite, gently curved throughout, tapered to point. Parameres distally fused, three-quarters length of epandrium, apex cruciform. Gonocoxal plate with well sclerotized base divided into two lateral, sclerotized arms terminating in 2–4 long apical teeth, arranged irregularly; nearly three-quarters length of gonocoxite; inner basal third lightly sclerotized, apical two-thirds membranous; secondarily fused to ventral surface of hypandrium. Cercus weakly sclerotized, situated along midline of epandrium.

Female. n = 2. Similar to male except as follows: Length: 1.8–2.1 mm. Abdomen: Tergites 8–9 noticeably more sclerotized than preceding segments; only anterior margin of sternite 7 well-sclerotized. Terminalia ( Figs 6B , 7B ): Hypogynial valve slightly shorter than tergite 9; posterior margin with rounded shallow cleft in ventral view; densely setose. Tergite 9 rectangular in lateral view, wider than tergite 8, posterodorsal corner projected posteriorly. Sternite 9 (genital fork) connected anteriorly, then divided into two thin arms, projecting laterally before cleft of hypogynial valve and expanded into rounded sclerite; lateral arms extended slightly beyond hypogynial valve, arms nearly meeting along midline; spectacle-shaped in lateral view, with anterior portion circular and posterior portion trapezoidal. Cercus rounded, projected posteriorly; bearing numerous setae. Spermathecal ducts not observed; spermathecal pump located in middle of lateral arm, short, thickened.

Immature Stages. Unknown.

Additional Material Examined. CHILE: Region RM (Santiago) : El Canelo , 10-I-1967, 33°37′S 71°35′W, 950 m, E.I. Schlinger (1♂, CAS) . 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 X (Los Lagos): Isla Chiloé, Ancud , XII-1926, R & E Shannon (1♂ (USNMENT01115810), 2♀ (USNMENT01115808-09) USNM) .

Distribution. Known from the Andes of central Chile, south to Isla Chiloé along the Chilean Coastal Range ( Figs 8 , 9A ).

Remarks. We visited the locality based on GPS coordinates given on the Schlinger specimen label and arrived at a site near the coastal town of San Antonio, where no appropriate thaumaleid habitat was visible. We also visited a site in the Andes, in a small town named ‘El Canelo’, which has a number of mountain creeks with suitable habitat, although the creek, Estero el Canelo (33°34′31″S 70°26′47″W), was fenced off and inaccessible for collecting attempts.

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).