Hercostomus plumatus, Zhang & Yang & Grootaert, 2008

Zhang, Lili, Yang, Ding & Grootaert, Patrick, 2008, Mangrove Hercostomus Sensu Lato (Diptera: Dolichopodidae) Of Singapore, Raffles Bulletin of Zoology 56 (1), pp. 17-28 : 27-28

Hercostomus plumatus , new species

( Figs. 29–32 )

Material examined. – Holotype. Male , SINGAPORE: Sungei Buloh, 11 May 2005, Mal. 1 (25159, coll. PG, det. LZ, Si812, ZRC).

Paratypes. SINGAPORE: Pulau Ubin , Chek Jawa , 2 females, 30 Dec.2005; 4 females, 30 Dec.2005 (sweeping). Sungei Buloh, 1 male, 27 Nov.2003 (sweeping); 3 males, 1 female, 22 Apr.2005; 5 males, 27 Apr.2005; 4 males, 5 females, 11 May 2005 (3 males and 2 females in IOZ) ; 11 males, 11 May 2005; 2 males, 18 May 2005; 4 males, 25 May 2005; 1 female, 1 Jun.2005; 1 male, 10 June 2005; 1 male, 15 Jun.2005; 1 male, 5 Aug.2005; 1 male, 26 Aug.2005; 1 male, 1 female, 18 Nov.2005; 1 female, 3 Dec.2005; 1 male, 4 Jan.2006.

Diagnosis. – First flagellomere 1.2 times as long as wide. Fore coxa yellow, mid and hind coxae brownish. Dorsal lobe of surstyli with plumose hair.

Description. – Male. Body length 2.4–2.7 mm, wing length 2.2–2.5 mm.

Head metallic green with pale grey pollen. Face narrowing downward, narrower than first flagellomere. Hairs and bristles black. Postocular bristles (including posteroventral hairs) black. Antenna ( Fig. 29 ) brownish; first flagellomere darker, 1.2 times as long as wide; arista dark brown, minutely pubescent with short basal segment. Proboscis brownish yellow with black hairs, palpus brownish yellow with black hairs and black apical bristle.

Thorax metallic green with pale grey pollen. Six strong dc, 5–6 pairs of acr; scutellum with two pairs of bristles (basal pair short and weak). Propleuron with 1 black bristle on lower part. Legs yellow; fore coxa yellow, mid and hind coxae brownish. Mid and hind tarsi from tip of tarsomere 1 onward brownish to brown. Hairs and bristles black. Mid and hind coxae each with 1 exterior bristle. Mid and hind femora each with 1 preapical bristle. Fore tibia with 2 ad and 1 weak pd, apically with 3 bristles; mid tibia with 3 ad, 2 pd and 1 av, apically with 4 bristles; hind tibia with 4 ad, 3 pd and 2 vs., apically with 3 bristles. Relative lengths of tibia and 5 tarsomeres LI 1.0: 0.5: 0.2: 0.15: 0.15: 0.15; LII 1.5: 0.65: 0.4: 0.3: 0.2: 0.2; LIII 1.65: 0.5: 0.7: 0.5: 0.35: 0.25. Wing hyaline, tinged with greyish, veins brown; CuAx ratio 0.9, R 4+5 and M parallel apically. Squama yellow with black hairs. Halter yellow.

Abdomen metallic green with pale grey pollen. Hairs and bristles black. Male genitalia ( Figs. 30–32 ): Epandrium longer than wide, lateral epandrial lobe slightly curved apically with 3 bristles; cercus nearly triangular; hypandrium narrow and straight; aedeagus with 1 minute, inner denticle.

Female. Body length 3.3 mm, wing length 2.9 mm. Similar to male, but fore tibia without weak pd.

Etymology. – The specific name refers to the plumose hair on the dorsal lobe of surstyli.

Distribution. – Singapore.

Remarks. – The new species is somewhat similar to H. brevicornis , new species, but may be separated from the latter by its triangular cercus and aedeagus with 1 inner denticle; in H. brevicornis , new species, the cercus is strongly curved and nearly geniculate and the aedeagus has 2 inner denticles.

Figures

Figs. 29–32. Hercostomus plumatus, new species, male: 29, antenna; 30, male genitalia; 31, cercus; 32, surstyli.