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 Poligarida beni Bamber & Marshall, 2013 ( Figs. 16A–B ) Poligarida beni Bamber & Marshall, 2013: 256–262 , figs. 1–4. Material examined. Station SG25 : 2 incomplete specimens (CR1209-P08-01), 3 December 2009 . Remarks. Sphyrapodids are characterised by the enlarged pereopod-1 as well as the absence of spines on the cephalothorax, ocular lobes and pereopod coxa ( Guţu 1980 ; Larsen 2005 ). Poligarida belongs to the subfamily Sphyrapodinae Guţu, 1980 , which is differentiated from its sister subfamily Pseudosphyrapodinae Guţu, 1980 by the absence of the mandibular palp ( Guţu 1980 ). This is the only sphyrapodin genus with a cephalothorax that is wider than long ( Bamber & Marshall 2013 ) and is also characterised by the following morphological traits: (1) antennule inner flagellum with two articles; (2) antenna without squama; (3) antenna peduncle article-2 elongate, at least four times longer than article-3; (4) maxillule without palp; and (5) pereopods without complex setation and lack hook-like apophyses on basis ( Bamber & Marshall 2013 ). There are only two species in the genus, and both were recorded only from shallow subtidal ( 20–90 m ) sandy habitats in Brunei ( Bamber & Marshall 2013 ). Poligarida beni can be distinguished from P. keriakis Bamber & Marshall, 2013 by (1) the presence of distal tubercles on anterior margin of rostrum ( Fig. 16B ); (2) the presence of anterolateral spines on pereonite-3; (3) the absence of a spine on the outer margin of antennule peduncle article-1; (4) having less spiniform setae on pereopod- 1 propodus; and (5) the presence of seta on pleopod basis ( Bamber & Marshall 2013 ). The Singaporean specimens closely resemble P. beni but differ slightly by the triangular anterolateral apophyses on pereonite-3 being blunt instead of acute. Poligarida beni was previously recorded only from its type locality in Brunei at 20 m depth. In Singaporean waters, this species was collected only from the station SG25 (see Fig. 2 ), which is located at the north of Kusu Island, at a depth of 12– 30 m . The two specimens from this material measured 1.0 and 1.7 mm , making this species the smallest apseudomorphan in Singapore waters.