New species and records of the genus Hercostomus Loew (Diptera: Dolichopodidae) from Thailand mangroves, with notes on the Hercostomus fauna of Singapore mangroves Author Samoh, Abdulloh Princess Maha Chakri Sirindhorn Natural History Museum (PSUNHM), Prince of Songkla University, Kho Hong, Hat Yai, Songkhla, Thailand, 90110 Author Grootaert, Patrick National Biodiversity Centre, NParks, Singapore; Lee Kong Chian Natural History Museum, National University of Singapore; Department of Entomology, Royal Belgian Institute of Natural Sciences, Vautierstraat 29, B- 1000 Brussels, Belgium & Princess Maha Chakri Sirindhorn Natural History Museum (PSUNHM), Prince of Songkla University, Kho Hong, Hat Yai, Songkhla, Thailand, 90110 text Zootaxa 2024 2024-04-30 5446 2 179 204 http://dx.doi.org/10.11646/zootaxa.5446.2.2 journal article 10.11646/zootaxa.5446.2.2 1175-5326 11101578 B1B73538-4AD4-4E0B-843F-74411F6E9AB3 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 . 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). 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.