Longiflagrum koyonense Angsupanich, 2004

Kong, Chim Chee, 2024, A synopsis of the Tanaidacea (Crustacea: Peracarida) of Singapore, with a review of tanaidacean diversity in Southeast Asia and the South China Sea, Zootaxa 5451 (1), pp. 1-75 : 32

Longiflagrum koyonense Angsupanich, 2004

( Figs. 15A–C )

Longiflagrum koyonense Angsupanich, 2004: 852–859 , figs. 2–5.

Material examined. Station SG9: 8 females (SB 28/5 C10.3); 6 females (SB 28/5 C10.6) . Station SG27: 77 specimens, including 31 females and 11 males ( No. 5087–5162) . Station SG 28: 1 male ( No. 18006B) . Station SG 29: 2 females ( No. 34152–34153) . Station SG 31: 2 females and 1 male ( No. 37002–37004) . Station SG37: 1 male and 2 females (JS-7226). Station SG84: 6 specimens, including 3 ovigerous female (20170617.028, 20170617.029 and 20170617.040), 17 June 2017. Station SG85: 11 specimens , including 1 ovigerous female and 2 males (20170617.075).

Remarks. Guţu (1995b) erected the genus Longiflagrum and designated Apseudes estuarius Boesch, 1973 from Brisbane River, Queensland, Australia as the type species. Diagnostic features of the genus include the (1) equal length of the antennule flagella; (2) presence of long setae on the inner side of the antennal peduncle; (3) wide carpus of pereopod-1; and (4) wide exo- and endopods of the pleopods ( Guţu 1995b, 2008; Angsupanich 2004). Stępień & Błażewicz-Paszkowycz (2009) provided identification keys to species of Longiflagrum , and identified the antennule, antenna and pereopods 4 and 5 as important characters. This genus is currently represented by four species ( Anderson 2023), namely L. estuarius , L. koyonense Angsupanich, 2004 , L. nasutus ( Nunomura, 2005) and L. amphibium Stępień & Błażewicz-Paszkowycz, 2009 . These Longiflagrum species were primarily recorded from intertidal estuarine habitats in the Indo-West Pacific Ocean, specifically Queensland, Port Hedland in Western Australia, Songkhla Lake in Thailand and Manko Lake in Okinawa, Japan ( Boesch 1973; Angsupanich 2004; Nunomura 2005; Bamber 2008c; Stępień & Błażewicz-Paszkowycz 2009).

The present material from Singapore is the first record of L. koyonense outside its type locality in Thailand, where it was collected from 0.7 m depth. In Singaporean waters, this relatively large species, reaching 7.8 mm in body length, was confined to intertidal estuarine habitats (e.g., mudflats and mangroves) where there is a substantial freshwater influx from nearby rivers in the West Johor Strait (i.e., Lim Chu Kang , Sungei Buloh Wetland Reserve and Sungei Mandai ) and Singapore Strait (i.e., Sungei Pandan) .

Figures

FIGURE 15. Longiflagrum koyonense Angsupanich, 2004, JS- 7226, from Singapore: (A) lateral habitus of adult male, with inset showing dorsotransverse row (arrow) of setae on pleonite-1; (B, C) lateral and dorsal habitus, respectively, of non-ovigerous female. Scale bar = 2 mm.