Hercostomus lanceolatus, 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 : 22-24

Hercostomus lanceolatus , new species

( Figs. 14–19 )

Material examined. – Holotype. Male , SINGAPORE: Pulau Ubin, Chek Jawa, 26 Oct.2005, Mal. 2 (25399, coll. PG, det. PG, Si1393, ZRC).

Paratypes. SINGAPORE: Pulau Ubin , Chek Jawa, 1 male, 1 female, 22 Dec.2005 ; Sungei Buloh , 1 male, 15 Jun.2005 ; 1 male, 28 Oct.2005 ; 1 male, 4 Jan.2006.

Diagnosis. – Wing with long narrow, yellowish brown stigma at tip of R 1; stigma reaching beyond level of thickening of

THE RAFFLES BULLETIN OF ZOOLOGY 2008

R 4+5. R 4+5 thickened from basal quarter onward, but narrow again before reaching wing border. Aedeagus with a small denticle more basad in position than in G. limosus . Hind femur with tip dorsally darkened.

Description. – Male. Body length 2.8–3.4 mm, wing length 2.8–2.9 mm.

Head metallic green with pale grey pollen. Face wider than first flagellomere, densely grey dusted. Hairs and bristles black. Postocular bristles (including posteroventral hairs) black. Antenna ( Fig. 14 ) yellow; first flagellomere brown, 1.1 times as long as wide, obtuse apically; arista brown, minutely pubescent with very 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, 7–8 pairs of acr short and hair-like; scutellum with 2 pairs of bristles (basal pair short and weak). Propleuron with 1 black bristle on lower part. Legs yellow; fore coxa yellow with blackish base, mid and hind coxae black with yellow apex. Hind femur with knee dorsally brown. Fore tarsus from tip of tarsomere 2 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 and 1 weak pd, apically with 2 bristles; mid tibia with 3 ad, 2 pd and 1 av, apically with 4 bristles; hind tibia with 3 ad, 4 pd and 1 av, apically with 2 bristles. Mid tarsomere 1 with 2 short vs.; hind tarsomere 1 with 1 vs. at base. Hind tarsomere 1 with a black, curved posterior spine at base, directed upwards underneath posterior comb of hind tibia. Relative lengths of femur, tibia and 5 tarsomeres: LI: 1.00: 0.95: 0.50: 0.20: 0.15: 0.10: 0.10; LII: 1.20: 1.37: 0.62: 0.37: 0.27: 0.15: 0.15; LIII: 1.25: 1.55: 0.45: 0.62: 0.45: 0.30: 0.20. Wing ( Fig. 15 ) hyaline, with yellowish to brown stigma near end of R 1, The stigma consists of a widening of the tip of R 1 and a yellowish to brown colouring of the wing membrane. The stigma is narrow ( Fig. 15 ), widely separated from R 2+3. It extends beyond the level where the thickening of R 4+5 starts. R 4+5 thickened from basal quarter, to a little before ending in costa. R 4+5 and M distinctly parallel apically. M a little thickened at bulge. Squama yellow with black hairs. Halter white.

Abdomen metallic green with pale grey pollen. Hairs and bristles black. Male genitalia ( Figs. 16–19 ). Epandrium distinctly longer than wide, lateral epandrial lobe acute apically; cercus subrectangular, yellow with yellow hairs; hypandrium short and thick, aedeagus with 1 inner large, brown denticle near apex.

Female. Body length 2.3 mm, wing length 2.1 mm. Identical to male in most characters, but stigma absent.

Etymology. – The specific name refers to the lanceolate shape of the wing stigma.

Distribution. – Singapore

Remarks. – Although H. lanceolatus , new species, is very closely related to H. limosus , new species, we consider them as a distinct species. H. lanceolatus is much smaller, the stigma is lanceolate and longer and the denticle on the aedeagus is smaller and more basad in position. H. limosus is larger, has a shorter and wider stigma and a stronger denticle on the aedeagus, that is closer to the tip of the aedeagus. For a comparison with H. notatus Becker, 1922 , we refer to the remarks under H. limosus .

Figures

Figs. 14–19. Hercostomus lanceolatus, new species, male: 14, antenna; 15, wing; 16, male genitalia; 17, claw-like appendage on aedeagus; 18, ventral lobe of surstyli; 19, dorsal lobe of surstyli.