Tachytrechus flavimanus Soares & Capellari & Ale-Rocha 2023, comb. nov.
Creators: name: Soares, Matheus M. M.
name: Capellari, Renato S.
name: Ale-Rocha, Rosaly
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Dolichopodidae
Tachytrechus
Tachytrechus flavimanus

description: Tachytrechus flavimanus (Van Duzee, 1934) comb. nov.
(Figs 12, 13, 14)
Hercostomus flavimanus Van Duzee, 1934: 372. Type locality: Kartabo, Bartica District, Guyana.
Diagnosis (male). Face narrowing in the middle, slightly narrow than ocellar tubercle (Fig. 13D). Postpedicel short, rounded, 1.5X wider than long, orange yellowish (Fig. 13D). Mesonotum mostly dark green, with dorsocentral light green stripe widening posteriorly (Fig. 13E). Legs mostly dark brown to black, except apex of femur I, tibia I and It 1–4 yellow (Figs 13A, 13F); Tarsus I: It 1–4 laterally flattened; anterior surface mostly bare (Fig. 13F). Wing brownish, R 4+5 and M 1 nearly straight and subparallel at apex (Fig. 13G). Hypopygium slightly shorter than abdomen (Fig. 13A, C); cercus wide, L-shaped (dissected), about 1/2 of length of epandrium, dark brown, with long setae at margins (Fig. 14B).
Redescription. Male (based on photographs of holotype and identified specimens from Ecuador and Brazil) (Fig. 13). Body length: 5.5 mm Wing: 5.2 mm long, 1.9 mm wide. Head (Fig. 13A, D). Postocular setae black. Frons trapezoidal (1.5X wider than high), dark green, covered by dense golden pollinosity. Face and clypeus black, covered by dense golden pruinosity, face narrowing in middle, slightly narrow than ocellar tubercle. Clypeus rectangular (1.5X longer than wide), lower margin rounded, ending well above lower eye margin. Palpus short and black, covered by a few small black setae and 2 longer setae near apex. Proboscis pale brown. Pair of divergent strong ocellar setae and pair of tiny postocellar setae; pair of strong, convergent vertical setae and pair of short paravertical setae, about 1/4 length of vertical seta. Postcranium black, covered by dense golden pollinosity, lower postcranium with a few black setae. Antenna orange yellowish; scape with a few short black setae at apical half of dorsal surface, with short acute anterior and ventral processes at apex; pedicel short, with crown of setae at apex; postpedicel short, rounded, 1.5X wider than long, with short yellowish pubescence at apex; arista-like stylus brownish, darker at base, arising dorsally, at middle of postpedicel, about 3/4 of eye height, two-segmented, first segment short, but overlapping apex of postpedicel, covered by short pubescence, second segment long, about 10X longer than first segment, covered by short setulae. Thorax (Fig. 13A, E). Mesonotum mostly dark green, with dorsocentral light green stripe widening at posterior mesonotum and interrupted by dark base of dorsocentral setae; notopleuron and postpronotum covered by dense silvery pruinosity. Scutellum light green. Pleura dark brown, covered by coppery pruinosity. Chaetotaxy: pronotum with row of black setae; acrostichals short, biseriate, ending after fourth dorsocentral seta; 6 pairs of dorsocentral (anterior pair greatly reduced, about half-length of second seta); 1 pre-, 1 sutural and 1 postsutural intra-alars; 2 strong supra-alars, 1 positioned between postpronotal lobe and notopleuron and 1 close to postalar callus; 1 strong postalar; 2 strong notopleurals; 1 strong and 2 minute postpronotals; two clusters of fine setulae on lower and upper surface of proepisternum, lower surface with 1 strong black seta directed ventrally; scutellum with pair of strong medial scutellars and pair of smaller setae laterad, about 1/5 as long as medial scutellars. Wing (Fig. 13G). Membrane brownish. Costa ending at M 1; R 1 ending at basal 3/8 of wing; R 2+3 nearly straight; R 4+5 and M 1 nearly straight and subparallel at apex; cell dm ending at apical 5/8 of wing; length of crossvein dm-m/last part of M 4 (“CuAx ratio”): 2.5; M 4 not reaching wing margin; CuA+CuP present as sinuous fold in membrane. Lower calypter yellow with blackish cilia; halter yellow. Legs (Fig. 13A, F). Dark brown to black, with apex of femur I, tibia I and It 1–4 yellow; setae on legs black, except as noted. Leg I. Podomere ratios: 68, 55, 30/15/10/7/6. Anterior surface of coxa I covered by short vestiture of setae, outer edge with 4 strong setae on apical half, apical edge with 2 strong setae. Femur I covered by short vestiture of setae, with posterodorsal row of short setae at apical 1/5. Tibia I with 2 anterodorsal setae at 1.5/6 and 4/6 (about half-length of preceding seta), 3 dorsal setae at 1.5/6 (short), 3/6 and 1 preapical, 2 posterodorsal setae at 3.5/6, and 1 preapical, and 2 short anterior setae at apex. Tarsus I (Fig. 13F): It 1–4 laterally flattened; anterior surface mostly bare. It 1 with 1 conspicuous basiventral seta; It 1–4 with 2 ventral, 1 anteroventral and 1 posteroventral setae at apex. Leg II. Podomere ratios: 80, 83, 40/25/12/10/9. Anterior surface of coxa II covered by short setae, inner and apical edges with row of strong setae, outer edge with 2 strong setae at apical half. Trochanter II with 1 long, strong seta on inner edge and 1 long seta on outer edge. Femur II covered by short vestiture, with ventral rows of long, fine setae at basal 1/3, with anterodorsal row of 4 long, strong setae at apical 1/3 (apicalmost longer), 1 antero- and 1 posteroventral preapical short setae. Tibia II with 3 anterodorsal setae at 0.5/6 (about half-length of second seta), 1/6 and 3.5/6, 3 posterodorsal setae at 1/6, 2/6, 4/6, 1 ventral seta at 2/6 and 1 posteroventral at 3/6, 1 dorsal, 1 anterodorsal, 1 antero- and 1 posteroventral and 1 posterior setae at apex. Tarsus II: IIt 1 with strong basiventral seta. Leg III. Podomere ratios: 75, 90, 30/41/24/14/12. Lateral surface of coxa III with row of fine setae ending in 1 long, strong seta and 1 short, slender near apex. Femur III twice diameter of femur I at broadest point, with anterodorsal row of 5 long, strong setae at apical 1/2 (3 apicalmost longer), 1 anteroventral and 1 posteroventral preapical short setae. Tibia III with 4 anterodorsal setae at 0.5/6 (about half-length of second seta), 1/6, 2.5/6, 4/6, 3 posterodorsal setae at 1/6, 2/6, 3.5/6, 1 dorsal seta at 5.5/6, 1 ventral seta at 4/6, 1 anterodorsal and 1 ventral setae at apex, ventral row of short, erect setae from basal 1/6 to apical 4/6. Tarsus III: IIIt 1 with strong basiventral seta and ventral row of more conspicuous setae. Abdomen (Fig. 13A, C). Metallic blue green, with large lateral patches of silvery pruinosity, covered by short black setae, slightly longer on distal margin of tergites, tergite 6–7 bare, sternite 8 dark brown, covered by short black setae, longer at distal margin. Hypopygium (Fig. 14). Slightly shorter than abdomen. Epandrium dark brown, suboval, 1.7X longer than high at highest point, with 3 apicoventral setae (only sockets observed), apicoventral lobe undeveloped (Fig. 14A); ventral lobe of surstylus short and dorsoventrally flattened, somewhat oval, with 1 short digitiform projection near base, with 1 apical seta (Fig. 14D); dorsal lobe of surstylus as long as ventral lobe, kidney-shaped in ventral view, gradually narrowing towards apex in lateral view, with 1 dorsal long seta, and 1 apical seta (only socket observed) (Fig. 14E); postgonite upturned, truncated and dorsoventrally flattened at apex, overlapping ventral lobe of surstylus, with pair of long preapical setae and 2 pairs of short setae at apex (Fig. 14C, F); hypandrium weakly sclerotized, narrowing at apex (Fig. 14A, C); phallus plain, narrowing at apex (Fig. 14C); basal sclerite of spermpump subtriangular in ventral view, long and strongly sclerotized, connected posteriorly to sperm pump (Fig. 14A, C); sperm pump shorter than ejaculatory apodeme, somewhat kidney-shaped (Fig. 14A, C); ejaculatory apodeme somewhat fan-shaped, strongly sclerotized basally (Fig. 14A, C); proctiger flattened basally, widening at apex (Fig. 14C); cercus wide, quadrangular, with apicoventral short lobe, when unfolded L-shaped in form, about 1/2 of length of epandrium, dark brown, with long setae at margins (Figs 13C, 14B). Female. Unknown.
Examined type material. HOLOTYPE ♁ (based on photographs) (Fig. 13A, B, C, D) labelled as: “ Bartica District [Cuyuni-Mazaruni, ca 6°24′13.2″N 58°37′27.1″W] | British Guiana [Guyana] | 20.v.1924 ”; “ Hercostomus | flavimanus [handwritten] | Holotype Van Duzee” (AMNH).
Additional examined material. ECUADOR: Prov. [Province] Orellano [sic. Orellana], Yasuni Natl. [National] Park, Yasuni, Research Stn. [Station], on leaves, 0°40′50″S 76°24′2″W; 250m, 28.iv.–8.v.2009, H.J. Cumming (1 ♁, INPA, dissected). BRAZIL: Acre, Mâncio Lima, Serra do Divisor National Park, Igarapé do Amor [ca 7°36′31.9″S 72°53′38.6″W], Malaise trap, 4.iii.–4.iv.2007, Calor, A. R. & Viana, D. leg. (1 ♁, CNC).
Remarks. Tachytrechus flavimanus comb. nov. can be easily distinguished from other New World species in the genus by veins R 4+5 and M 1 nearly straight and subparallel at apex, It 1–4 laterally flattened (MSSC) and femur III with anterodorsal row of 5 long and strong setae at apical 1/2.
Distribution. Brazil (state of Acre), Ecuador (both new country records) and Guyana (Fig. 15). Widely distributed in Amazon biome.
description: Published as part of Soares, Matheus M. M., Capellari, Renato S. & Ale-Rocha, Rosaly, 2023, New or little-known Neotropical Dolichopodidae (Diptera) (II): genus Hercostomus Loew excluded from the Neotropics, pp. 181-208 in Zootaxa 5254 (2) on pages 201-203, DOI: 10.11646/zootaxa.5254.2.2, http://zenodo.org/record/7727356