Hercostomus, Loew, 1857

Samoh, Abdulloh & Grootaert, Patrick, 2024, New species and records of the genus Hercostomus Loew (Diptera: Dolichopodidae) from Thailand mangroves, with notes on the Hercostomus fauna of Singapore mangroves, Zootaxa 5446 (2), pp. 179-204 : 195-200

Key to male Hercostomus sensu lato from mangroves in Southeast Asia

(after Zhang et al. 2008)

1 Wing with grey to brown pterostigma at tip R 1; R 4+5 thickened from basal quarter onwards ( Fig. 13 ).................... 2

- Wing lacking stigma at tip R 1; R 4+5 not thickened............................................................ 3

2 Pterostigma elongate, extending beyond start of thickening of vein R 4+5 ( Fig. 13 ); knee of hind femur darkened above ( Figs 13 , 14 ); aedeagus with small denticle, in more basal position........................... H. lanceolatus Zhang et al., 2008

- Pterostigma shorter, reaching level of thickening of vein R 4+5; knee of hind femur not darkened above; aedeagus with larger denticle in more anteriad position................................................. H. limosus Zhang et al., 2008

3 First flagellomere distinctly elongated, at least 2.0 times as long as wide ( Figs 1 , 10 )............................... 4

- First flagellomere not elongated, at most 1.6 times as long as wide.............................................. 7

4 First flagellomere with blunt tip.......................................... H. obtusus Samoh & Grootaert sp. nov.

- First flagellomere with pointed tip ( Fig. 10 )................................................................ 5

5 First flagellomere 2.3 times as long as wide ( Fig. 4 ); all coxae blackish; femora blackish except tip of fore and mid femora; cercus with at least 3 strong bristles on outer margin......................................................... 6

- First flagellomere 3.0 times as long as wide; fore coxa yellow, mid and hind coxae brown, femora yellow; cercus without strong bristles on outer margin.......................................................... H. meieri Zhang et al., 2008

6 Hind femur with two long ventral bristles at base of hind femur, nearly as long as femur is deep; cercus with only three strong, black squamiform bristles on outer margin..................................... H. brevidigitalis Zhang et al., 2008

- Hind femur without long ventral bristles at base; cercus with seven strong, black squamiform bristles along outer margin.................................................................... H. squamatus Samoh & Grootaert sp. nov.

7 First flagellomere as long as wide ( Fig. 8 )................................................................. 8

- First flagellomere longer than wide: 1.3–1.6 x as long as wide................................................. 9

8 Fore coxae yellow, mid and hind coxae black; cercus triangular; aedeagus with strong subapical tooth............................................................................................ H. tiomanensis Zhang et al., 2007

- All coxae yellow, mid coxae at most pale brownish with black anterior stripe; cercus strongly curved, almost geniculate; aedeagus with long slender tip, with 2 inner denticles.............................. H. brevicornis Zhang et al., 2008

9 Fore tarsomere 1 shortened, concave ventrally with 2 long curved ventral bristles; mid tarsomere 1 concave ventrally, with 1 strong ventral bristle near middle and 5 short ventral bristles basally; cercus large, with short apical tail........................................................................................ H. singaporensis Zhang et al., 2008

- Fore tarsus unmodified ( Fig. 15 ); cercus triangular, without apical tail................... H. plumatus Zhang et al., 2008

Figures

FIGURE 1. Hercostomus obtusus sp. nov. Male habitus (photo Abdulloh Samoh).

FIGURE 4. Hercostomus squamatus sp. nov. Male habitus (photo: Abdulloh Samoh).

FIGURE 8. Hercostomus brevicornis Zhang, Yang & Grootaert, 2008. Male habitus (photo Abdulloh Samoh).

FIGURE 10. Hercostomus brevidigitalis Zhang, Yang & Grootaert, 2008. Male habitus (Ma10627) (photo Abdulloh Samoh).

FIGURE 13. Hercostomus lanceolatus Zhang, Yang & Grootaert, 2008. Male habitus. (photo Abdulloh Samoh).

FIGURE 14. Hercostomus lanceolatus Zhang, Yang & Grootaert, 2008. Female habitus. (photo Abdulloh Samoh).

FIGURE 15. Hercostomus plumatus Zhang, Yang & Grootaert, 2008. Male habitus. (photo Abdulloh Samoh).