Biropalostoma spiniferum Guţu & 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 : 26-27

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.

Genus Platylicoa Guţu, 2006

Figures

FIGURE 11. Actenos sp. SG#1, Singapore: (A) adult male, CR1118-P02-01-01, lateral habitus; (B) female with oostegites, CR0717-P02-01, dorsal habitus, with inset showing anterolateral spines (arrows) on pereonites 2–6. Scale bar = 2 mm.

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.