Nesotanais rugula Bamber, Bird & Angsupanich, 2003: 62–67

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 : 38

Nesotanais rugula Bamber, Bird & Angsupanich, 2003: 62–67 , figs. 17–20.

Material examined. Station SG 7: 38 females, 3 males ( ZRC.1993.2601–2626, ZRC.1993.2633–2648). Station SG 30: 15 females, 6 males (No. 36784–36809). Station SG 54: 1 specimen (SEA-7302), 9 April 2014. Station SG 79: Hundreds of specimens .

Remarks. Shiino (1968) erected the genus Nesotanais and designated N. lacustris from the Solomon Islands as the type species. Nesotanais is best characterised by the unusual development of the male cheliped. It has been speculated that these chelipeds are used for sound production, based on the presence of serial ridges on the inner surfaces of their propodus and dactylus (Bamber et al. 2003; Larsen 2005; Kakui et al. 2010). This genus is currently represented by four species ( Anderson 2023), namely N. lacustris , N. maclaughlinae Guţu & Iliffe, 1989 , N. rugula Bamber, Bird & Angsupanich, 2003 and N. ryukyuensis Kakui, Kajihara & Mawatari, 2010 . Coincidently, all these species occurred in sheltered waterbodies (e.g., marine caves, lagoons, lakes, and rivers) in the Indo-West Pacific region ( Shiino 1968; Guţu & Iliffe 1989; Bamber et al. (2003); Angsupanich et al. 2005; Kakui et al. 2010) and these relatively calm environments probably facilitate sound transmission. Kakui et al. (2010) provided an identification key to species of the genus, based on the pleopods, chelipeds and maxillipeds. The specimens from Singapore agree most with N. rugula , which was previously recorded only from its type locality in the Songkhla Lake, Thailand at 1 m depth (Bamber et al. 2003). In Singaporean waters, N. rugula is restricted to relatively sheltered habitats in the inner Johor Straits (i.e., Sungei Cina and Sungei Buloh Wetland Reserve). This small tanaid, of body length about 1.5 mm, can be very abundant when present in this study.