A synopsis of the Tanaidacea (Crustacea: Peracarida) of Singapore, with a review of tanaidacean diversity in Southeast Asia and the South China Sea Author Kong, Chim Chee 0000-0001-6378-9561 Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore 117558. & Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore 117558. & St. John’s Island National Marine Laboratory, Tropical Marine Science Institute, National University of Singapore, 18 Kent Ridge Road, Singapore 119227. tmscck @ nus. edu. sg; https: // orcid. org / 0000 - 0001 - 6378 - 9561 tmscck@nus.edu.sg text Zootaxa 2024 2024-05-16 5451 1 1 75 http://dx.doi.org/10.11646/zootaxa.5451.1.1 journal article 10.11646/zootaxa.5451.1.1 1175-5334 11232365 911E1D07-22B1-479E-8720-25DBD50D0D56 Biropalostoma spiniferum Guţu & Angsupanich, 2004 ( Figs. 12A–C ) Biropalostoma spiniferum Guţu & Angsupanich, 2004a: 31–36 , figs. 1–3. Material examined. Station SG22 : 1 incomplete female with eggs (CR0511-P02-01-03), 9 May 2011 ; 1 incomplete specimen (CR0112-P02-02-01), 20 January 2012 ; 1 incomplete female with eggs (CR1113-P02-03- 03), 13 November 2013 ; 1 female with oostegites (CR1114-P02-01), 11 November 2014 ; 1 incomplete specimen (CR1016-P02-02-02), 5 October 2016 ; 1 incomplete female brooding mancae I (CR0717-P02-02-02), 19 July 2017 ; 1 incomplete specimen (CR0619-P02-02-02), 13 June 2019 . Station SG23 : 1 damaged specimen (CR1112-P06-02- 02), 6 November 2012 ; 1 incomplete female with oostegites (CR1113-P06-03-03), 13 November 2013 ; 2 incomplete females, including 1 brooding embryos and 1 with empty brood pouch (CR0514-P06-01-02), 1 incomplete female with eggs (CR0514-P06-02) and 1 incomplete specimen (CR0514-P06-03), 8 May 2014 ; 2 incomplete ovigerous females (CR1114-P06-01-01), 12 November 2014 ; 1 female with brood pouch (CR0516-P06-03), 9 May 2016 ; 1 incomplete specimen (CR0717-P06-01), 20 July 2017 ; 1 incomplete male (CR0619-P06-01) and 1 incomplete female with oostegites (CR0619-P06-02), 14 June 2019 ; 2 females with oostegites (CR0820-P06-01) and 1 female with oostegites (CR0820-P06-02), 6 August 2020 . Station SG25 : 2 ovigerous females and 1 female with oostegites (CR1110-P08-02), 16 November 2010 . Station SG26 : 1 incomplete female with oostegites (CR1115-PS06-02- 02), 5 November 2015 ; 1 incomplete specimen (CR1117-PS06-02-01), 6 November 2017 ; 1 incomplete specimen (CR1118-PS06-01/02), 12 November 2018 . Remarks. The genus Biropalostoma was erected by Guţu &Angsupanich, 2004a and is currently represented by two species ( Anderson 2023 ), namely B. goofi ( Bamber & Sheader, 2003 ) and B. spiniferum Guţu & Angsupanich, 2004a , with the latter designated as its type species. Both species are found in the shallow subtidal habitats of Malaysia , Brunei and Thailand at up to 35 m depth ( Bamber & Sheader 2003 , 2005; Guţu & Angsupanich 2004a , b; Bamber 2013). Biropalostoma is characterised by the presence of a distinctive spinose ‘bludgeon-like’ process adjacent to the mandible palp ( Guţu & Angsupanich 2004a ; Guţu 2006, 2008). Other characters shared between the two species include the (1) dorsally curved epistomal spine; (2) pereonites 3–6 longer than wide; (3) antenna peduncle inner margin with hook-like spines; (4) pereopod-1 merus, carpus and propodus with short spiniform setae; and (5) pleopod exopod smaller than endopod. Like other parapseudids, B. spiniferum is a very fragile species and none of the present material examined is complete. Nonetheless, these specimens from Singapore match the diagnostic features of B. spiniferum , and these include the (1) short and ventrally curved rostral spine; (2) wider than long pereonite-2; and (3) absence of ventrodistal spiniform setae on the cheliped merus ( Guţu & Angsupanich 2004a ). This species is also similar to the sympatric Actenos sp. SG#1 by possessing (1) a ventrally curved rostrum and a dorsally curved epistome; (2) posterolateral processes on pleonites at the location bearing pleopods. However, B. spiniferum differs from Actenos sp. SG#1 by the (1) pereonites lacking anterolateral spines (see Fig. 11B ); (2) pereopod-1 coxa bearing setae instead of spines; and (3) pereopod-1 claw not bifid and bearing more (five as compared to two in Actenos sp. SG#1) spiniform setae. Biropalostoma spiniferum was previously recorded only from its type locality in the Andaman Sea at 1.5 m depth. The Singaporean specimens were collected from sandy silt bottoms along the Singapore Strait at 14–54 m depth. The current record is the first for the species outside its type locality and extends its geographical distribution southwards from southwestern Thailand to Singapore . FIGURE 12. Biropalostoma spiniferum Guţu & Angsupanich, 2004 , Singapore: (A) ovigerous female, CR0514-P06- 02, lateral habitus; (B, C) ovigerous female, CR0514-P06-01-02, dorsal and ventral habitus, respectively, with inset showing cephalothorax. Scale bar = 2 mm. Genus Platylicoa Guţu, 2006