Tachytrechus alatus

Brooks, Scott E. & Cumming, Jeffrey M., 2008, The Tachytrechus alatus species group (= Syntomoneurum Becker) revisited: new species and revised species group limits (Diptera: Dolichopodidae), Zootaxa 1676, pp. 1-27 : 3-4

Key to species of the Tachytrechus alatus species group

1. Two notopleural bristles, posterior bristle sometimes very reduced ........................................................... 2

- One notopleural bristle ............................................................................................................................... 4

2. Palpus with large, stout seta on lower margin (Fig. 8A); face and upper third of clypeus metallic greenishcoppery, abruptly pale yellow on lower part of clypeus; mid tarsus with tarsomere 2 subequal or shorter than basitarsus. Male: clypeus with strong medial carina, lower margin truncate (Fig. 8A); wing with two adjacent costal swellings (Fig. 8B); hypandrium lacking elongate ventral projection and subapical process ( Figs. 9 C, 9D) (southern Mexico and Guatemala, Fig. 12 ) .................................. transversus (Van Duzee)

- Palpus lacking large, stout seta on lower margin (Figs. 3A, 3B, 10A); face and clypeus not as above; mid tarsus with tarsomere 2 longer than basitarsus. Male: clypeus lacking medial carina, lower margin rounded (Figs. 3A, 10A); wing without costal swelling (Figs. 3C, 10B); hypandrium with elongate ventral projection and lamellate subapical process on right side ( Figs. 4 A, 4B, 11A, 11B) ................................... 3

3. M with distinct S-shaped bend; R4+5 and M subparallel in distal portion (Figs. 3C, 3D); tibiae and tarsi

mainly dark; upper part of face metallic greenish or bluish, lower part of face and clypeus silvery. Male: wing membrane unevenly infuscated (Fig. 3C); fore tibia mainly dark, apex slightly swollen with silvery anterodorsal patch; male fore tarsomeres 2 and 3 enlarged with anterior surface bare and silvery (Fig. 3E) (northern Costa Rica, Fig. 12 ) ...................................................................... costaricensis Brooks sp. nov. - M with weak sinuous bend; R4+5 and M slightly converging distally (Fig. 10B); tibiae and basal part of tarsi pale; face and clypeus brownish. Male: wing membrane evenly infuscated (Fig. 10B); fore tibia pale, apex unmodified; fore tarsomeres 2 and 3 not as above, tarsomere 2 with anterodorsal row of long curved hairs (Fig. 10D) (southern Costa Rica, Fig. 12 ) ................................................. zumbadoi Brooks sp. nov.

4. M with two 90° bends (Figs. 1A, 1B); R2+3 of male very short, ending at costa before midpoint of wing; crossvein dm-cu of male close to wing base, well before midpoint of wing (Fig. 1A); crossvein dm-cu of female just before midpoint of wing, slightly shorter than distal part of CuA1 (Fig. 1B); right basiventral epandrial lobe with prominent basal projection; hypandrium with a pair of sickle-shaped projections on right margin just beyond middle (Fig. 1C) ( Peru, Fig. 13 ) ................................................. alatus (Becker)

- Bends in M obtuse; R2+3 of male ending at costa well beyond midpoint of wing; crossvein dm-cu at or slightly beyond midpoint of wing in both sexes, longer than distal part of CuA1 (Figs. 2A, 5A, 6A, 6B, 7A, 7B); right basiventral epandrial lobe lacking prominent basal projection; hypandrium either lacking pair of sickle-shaped projections on right margin (Figs. 2B, 6D, 7C), or with single elongate sickle-like projection near middle and lamellate subapical process both on right side (Figs. 5C, 5E)........................ 5

5. M with weak sinuous bend; R4+5 and M convergent distally (Figs. 6A, 6B); hind femur dark metallic green; larger flies (body length 7.9–8.5 mm, wing length 10–11 mm). Male: wing with elongate costal swelling (Fig. 6A); clypeus parallel sided and truncate below (Fig. 6C); hind femur with 2–3 preapical bristles; right and left basiventral epandrial lobes greatly elongated, symmetrical, curved and tapered distally; apicoventral epandrial lobe short, projected posteriorly (Fig. 6E); cercus round ( Colombia, Fig. 13 ) ........................................................................................................................................ giganteus (Brooks)

- M with pronounced S-shaped bend; R4+5 and M subparallel distally (Figs. 2A, 5A, 7A, 7B); hind femur mainly or entirely pale; smaller flies (body length 5.0– 5.7 mm, wing length 5.1–5.8 mm). Male: wing lacking costal swelling; clypeus rounded below; hind femur with 1 preapical bristle; right and left basiventral epandrial lobes relatively short, asymmetrical with right lobe more developed; apicoventral epandrial lobe elongate, projected ventrally (Figs. 2C, 5C, 5D, 7D); cercus subrectangular (Fig. 5D) ..... 6

6. Male fore tarsus with tarsomeres 4 and 5 enlarged (Fig. 5B); hypandrium with lamellate process subapically on right side, with lamellate process along left lateral margin, and with elongate sickle-like projection near middle on right side (Figs. 5C, 5E) ( Peru, Fig. 13 ) ...................................... dios Brooks sp. nov.

- Male fore tarsus with tarsomeres 4 and 5 not enlarged; hypandrium not as above, simple, at most with weak dentiform projection on right margin (Figs. 2B, 7C) ......................................................................... 7

7. Face mainly metallic green. Male: basitarsus of foreleg with weak silvery reflections anteriorly, basitarsus and tarsomere 2 with curved setae ventrally; M and CuA1 not thickened basally (Fig. 2A); apicoventral epandrial lobe extremely well-developed with pointed apex, medial seta positioned near base, lateral seta near middle (Fig. 2C); hypandrium wide, right margin with dentiform projection (Fig. 2B) ( Colombia, Fig. 13 )................................................................................................................................... analis (Parent)

- Face mainly brownish with weak silvery-green reflections. Male: fore tarsus distinctly silvery anteriorly, basitarsus lacking curved ventral setae; M and CuA1 thickened in basal section (Fig. 7A); apicoventral epandrial lobe with blunt apex bearing medial and outer setae (Fig. 7D); hypandrium narrow, right margin lacking projection (Fig. 7C) ( Peru, Fig. 13 ) ........................................................... peruicus Yang & Zhang

Figures

FIGURE 4. Tachytrechus costaricensis Brooks sp. nov. hypopygium: (A) left lateral view; (B) ventral view (postgonite, surstylus and cerci not shown); (C) surstylus, postgonite and apical margin of epandrium (left lateral view); (D) postgonite (dorsal view). Abbreviations: acc proc: accessory epandrial process; apv lobe: apicoventral epandrial lobe; bv lobe: basiventral epandrial lobe; cerc: cercus; dsur: dorsal lobe of surstylus; epand: epandrium; hypd: hypandrium; pgt: postgonite; ph: phallus; vsur: ventral lobe of surstylus.

FIGURE 9. Tachytrechus transversus (Van Duzee) male abdomen and hypopygium: (A) apical portion of abdomen (hypopygium removed); (B) apex of eversible pregenitalic structure (ventral view); (C) hypopygium (left lateral view); (D) hypopygium ventral view (postgonite, surstylus and cerci not shown). Abbreviations: apv lobe: apicoventral epandrial lobe; bv lobe: basiventral epandrial lobe; cerc: cercus; dsur: dorsal lobe of surstylus; hypd: hypandrium; pgt: postgonite; ph: phallus; S: sternite; T: tergite; vsur: ventral lobe of surstylus.

FIGURE 12. Known distribution of Tachytrechus costaricensis Brooks sp. nov., T. transversus (Van Duzee) and T. zumbadoi Brooks sp. nov.

FIGURE 13. Known distribution of Tachytrechus alatus (Becker), T. analis (Parent), T. dios Brooks sp. nov., T. giganteus (Brooks) and T. peruicus Yang & Zhang.