Hercostomus brevidigitalis Zhang, Yang & Grootaert, 2008

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 : 194-195

Hercostomus brevidigitalis Zhang, Yang & Grootaert, 2008 (New record)

( Figs 10–12 )

Material examined. THAILAND: Satun Province, 1 ♂, 2 ♀, Kamphaeng District, Ban Laemson (6°56’27.9”N 99°42’12.4”E), sweep netting, 4. V.2015, coll. A. Samoh; 3 ♂, 1 ♀, Langu District, Pakbara (6°50’30.4”N 99°46’32.9”E), sweep netting, 29.IV.2015, coll. A. Samoh. Krabi Province, 2 ♂, 1 ♀, Khlong Thom District, Ban Ramard (7°42’17.4”N 99°03’48.4”E), sweep netting, 26.IV.2015 . Phang Nga Province, 3 ♂, 1 ♀, Takuapa District, Ban Bang Yai (8°54’27.5”N 98°23’59.6”E), sweep netting, 11.II.2015, coll. A. Samoh. SINGAPORE: 3,164 specimens were collected from mangroves all around Singapore, 906 specimens have been NGS-barcoded and are deposited at LKCNHM .

Remarks. This is a small to medium-sized species (body length 3.2–3.6 mm, wing length 3.2– 3.5 mm). First flagellomere elongate, 2.3 times as long as wide. All coxae black; femora black except tip of fore and mid femora. The hind femur bears two long ventral bristles near base. Squama yellow with black hairs. Male genitalia very long, reaching thorax. Cercus with only 3 black apical squamiform setae ( Fig. 10 ).

The genetic difference of H. brevidigitalis between South-Thailand and Singapore is nearly 2%, but no morphological differences have been seen.

Distribution. THAILAND: Krabi, Phang Nga, and Satun ( Fig. 7 ). SINGAPORE: One of the most common and abundant species.

Figures

FIGURE 7. Distribution map of the mangrove associated species of Hercostomus in Thailand.

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

FIGURE 11. Hercostomus brevidigitalis Zhang, Yang & Grootaert, 2008. Female habitus. (photo Abdulloh Samoh).

FIGURE 12. Hercostomus brevidigitalis Zhang, Yang & Grootaert, 2008. Male terminalia (Singapore, Pulau Ubin Ma10627). A. Tip of terminalia with cercus in lateral view; B. Apex of aedeagus and hypandrium in lateral view; C. Apicoventral lobe of epandrium; D. Cerci and surstyli in ventral view; E. Surstyli in lateral view. Scale 0.1 mm (image P. Grootaert).