Hercostomus brevicornis, 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 : 21-22

Hercostomus brevicornis , new species

( Figs. 11–13 )

Material examined. – Holotype. Male , SINGAPORE: Sungei Buloh, 11 May 2005, Mal. 1 (25159, coll. PG, det. LZ, Si811, ZRC).

Paratypes – SINGAPORE: Sungei Buloh , 1 male, 1 female, 22 Apr.2005; 1 male, 1 female, 27 Apr.2005; 4 males, 3 females, 11 May 2005 ( IOZ) ; 1 female, 18 May 2005; 1 male, 1 female, 25 May 2005; 1 male, 1 Jun.2005; 1 male, 10 Jun.2005; 1 female, 6 Jul.2005; 1 male, 20 Jul.2005; 1 male, 27 Jul.2005; 2 females, 5 Aug.2005; 1 female, 26 Aug.2005; 1 male, 7 Sep.2005; 4 females, 16 Sep.2005; 1 female, 14 Oct.2005; 2 females, 28 Oct.2005; 1 female, 18 Nov.2005; 2 females, 3 Dec.2005; 3 males, 7 females, 4 Jan.2006.

Diagnosis. – All coxae yellow, but mid coxa at most pale brownish with a narrow black anterior stripe. Cercus strongly curved, nearly geniculate. Aedeagus with 2 small, inner denticles.

Description. – Male. Body length 2.9–3.1 mm, wing length 2.7–2.8 mm.

Head metallic green with pale grey pollen. Face wider than first flagellomere. Hairs and bristles black. Postocular bristles (including posteroventral hairs) black. Antenna ( Fig. 11 ) yellow, with first flagellomere brownish, first flagellomere as long as wide, obtuse apically; arista brown, minutely pubescent with very short basal segment. Proboscis yellow with black hairs, palpus yellow with black hairs and black apical bristle.

Thorax metallic green with pale grey pollen. Six strong dc, 6–7 pairs of acr; scutellum with 2 pairs of bristles (basal pair short and weak). Propleuron with 1 black bristle on lower part. Legs yellow; all coxae yellow, except mid coxa pale brownish with a narrow black anterior stripe. Fore tarsus from tip of tarsomere 1 onward 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, apically with 2 bristles; mid tibia with 3 ad, 2 pd and 1 av, apically with 4 bristles; hind tibia with 3 ad, 4 pad and 2 av, apically with 2 bristles. Hind tarsomere 1 with 1 vs. at base. Relative lengths of tibia and 5 tarsomeres LI 1.25: 0.75: 0.35: 0.25: 0.15: 0.15; LII 2.0: 1.0: 0.55: 0.45: 0.2: 0.2; LIII 2.15: 0.7: 1.0: 0.6: 0.4: 0.24. Wing hyaline, tinged with greyish; veins brown, R 4+5 and M parallel apically, CuAx ratio 1.0. Squama yellow with black hairs. Halter yellow.

Abdomen metallic green with pale grey pollen. Hairs and bristles black. Male genitalia ( Figs. 12–13 ): Epandrium longer than wide, with inner lateral epandrial lobe spine-like, outer lateral lobe wide apically with 3 bristles; cercus strongly curved, nearly geniculate; hypandrium narrow and straight apically; aedeagus with 2 small inner denticles.

Female. Body length 2.3–2.5 mm, wing length 2.1–2.2 mm. Similar to male.

Etymology. – The specific name refers to the short first flagellomere, being as long as wide.

Distribution. – Singapore.

Remarks. – The new species is somewhat similar to H. plumatus , new species, but may be separated from the latter by the cercus being strongly curved and nearly geniculate. Hercostomus brevicornis , new species, is also somewhat similar to Hercostomus congruens Becker, 1922 , described from Taiwan in having the first flagellomere as long as wide and all coxae yellow, but may be separated by the epandrial lobe being wide apically, aedeagus with 2 inner denticles and cercus strongly curved, nearly geniculate. In H. congruens , the lateral epandrial lobe is rather narrow apically, aedeagus is without denticles and cercus has a rounded ventral apex ( Becker, 1922).

Figures

Figs. 11–13. Hercostomus brevicornis, new species, male: 11, antenna; 12, male genitalia; 13, cercus. iel, inner epandrial lobe; oel, outer epandrial lobe.