Sinelobus sp.

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 : 45

Sinelobus sp. SG#1

( Figs. 25A–E )

Material examined. 1 male (S013), CMBS station data not available. Station SG19 : 4 females (including 1 with eggs and 1 with oostegites) and 2 males. Station SG30: 1 incomplete specimen (No. 36784–36809). Station SG33: 1 male ( No. 46017). Station SG 34 : 3 females, including 1 with oostegites (No. 48167–48169).

Remarks. Sieg (1980) erected the genus Sinelobus and designated Tanais stanfordi Richardson, 1901 from the Clipperton Island as the type species. He also synonymised S. stanfordi with several other species, resulting in S. stanfordi having a global distribution ( Sieg 1980). However, some authors disagreed that S. stanfordi is a cosmopolitan species ( Edgar 2008) and suggested that it either contained several cryptic species ( Bamber 2008c) or is an invasive species ( Van Haaren & Soors 2009). Sinelobus stanfordi was subsequently separated into the seven distinct species currently valid in the genus ( Anderson 2023), including S. barretti Edgar, 2008 from Tasmania, Australia, S. pinkenba Bamber, 2008c from Queensland, Australia, S. vanhaareni Bamber, 2014 from the Netherlands, S. bathykolpos Bamber, 2014 from Hong Kong, S. stromatoliticus Rishworth, Perissinotto & Błażewicz, 2018 from South Africa and S. kisui Hirano & Kakui, 2022 from Japan ( Bamber 2008c, 2014; Edgar 2008; Rishworth et al. 2018; Hirano & Kakui 2022). Other records of Sinelobus stanfordi in the Gulf of Thailand ( Guţu & Angsupanich 2004b), Mexico ( García-Madrigal et al. 2005; Cházaro-Olvera et al. 2018) and Argentina ( César & Becerra 2019) also likely belong to different species but their identities have yet to be verified. In general, Sinelobus is found in habitats associated with estuarine conditions such as lagoons, estuaries, rivers and stromatolite pools. Sexual dimorphism is pronounced in Sinelobus and identification keys for known species are available for both females and males ( Bamber 2014; Rishworth et al. 2018; Hirano & Kakui 2022).

The Sinelobus sp. SG# 1 specimens from Singapore resemble S. vanhaareni Bamber, 2014 , especially the male cheliped having two marginal ventral apophyses on the merus and one inner-ventroproximal rounded apophysis on the carpus. Both species also have similar body lengths at 2.7 mm. However, Sinelobus sp. SG#1 can be differentiated from S. vanhaareni by having different setation on the pereopods. Furthermore, S. vanhaareni has yet to be recorded outside Europe even though it has been widely documented as an invasive species in the continent ( Van Haaren & Soors 2009; Bamber 2014; Brzana et al. 2019; Gagnon et al. 2022). Sinelobus sp. SG#1 is a potentially undescribed species and, like its congeners, was found only in estuarine habitats, specifically on the intertidal mudflats in Lim Chu Kang, Sarimbun and Sungei Cina along the inner West and East Johor Straits,

Genus Xenosinelobus Chim & Tong, 2019

Figures

FIGURE 25. Sinelobus sp. SG#1, Singapore: (A, B) non-ovigerous female, No. 48167–48169, dorsal and lateral habitus, respectively; (C, D) adult male, S013, dorsal and lateral habitus; (E) adult male, No. 46017, ventral habitus. Scale bar = 1 mm.