Zeuxo cf. coralensis Sieg, 1980

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 : 42-43

Zeuxo cf. coralensis Sieg, 1980

( Figs. 23A–C )

Zeuxo coralensis Sieg, 1980: 225–231 , fig. 63.

Material examined. Station SG 42: 1 ovigerous female ( SA11-003 ). Station SG 46: 1 male (SS-6291). Station SG 60: 2 females (INT-1181). Station SG 67: 2 females (1 with oostegites) (INT-0890) .

Remarks. The present material resembles Z. coralensis in having (1) three aesthetascs on the antennule terminal article; (2) plumose lateral setae on pleonites 1–3 and simple lateral setae on pleonites 4–5; and (3) three articles on the uropod endopod. However, these Singaporean specimens are much smaller than Z. coralensis (1.4–1.8 mm vs. 3–4.5 mm) that was originally described from the Maldives at 4 m depth ( Sieg 1980). While body length is mostly conservative in Zeuxo species, large intraspecific variation in body size has been demonstrated in at least one species. For example, Z. beringi Kudinova-Pasternak, 1989 has a size range of 1.8–4.9 mm. However, the Singaporean specimens have dotted pigmentation throughout the body ( Figs. 23A–C ), a condition that is not shared with Z. coralensis . This pattern has been documented in only one congener, namely Z. nannioggae Bamber, 2005 from the Great Australian Bight but this species bears one aesthetasc on the antennule terminal article and four articles on the uropod endopod (Bamber 2005). The usefulness of pigmentation pattern as a taxonomic character for distinguishing Zeuxo species has been embraced by several workers ( Edgar 2008; Bamber et al. 2012; Okamoto et al. 2020; Okamoto & Kakui 2022) but also dismissed by Larsen et al. (2014). Until the type specimens of Z. coralensis have been examined, it remains uncertain whether the Singaporean specimens belong to the same species as the ones from the Maldives. It is important to note that the original description of Z. coralensis also included material from Japan ( Kakui 2017). Subsequent observations of this species were recorded from mangroves, rocky shores, marine caves, and ship hulls in the Atlantic Ocean: Spain ( Sánchez-Moyano & García-Gómez 1998; Navarro-Barranco et al. 2015), Brazil ( Masunari & Sieg 1980; Pires 1980; Tararam et al. 1996; Aviz et al. 2012; Bueno et al. 2015; García et al. 2015), Mexico ( Winfield et al. 2013, 2017) and Florida, USA ( Camp 1998). The wide geographical distribution of Z. coralensis suggests that it is either a cosmopolitan species or a species complex. In Singaporean waters, Zeuxo cf. coralensis was collected from the intertidal coral reefs of the Southern Islands (i.e., Lazarus Island, Pulau Biola, Pulau Sudong and St. John’s Island).

Figures

FIGURE 23. Zeuxo cf. coralensis Sieg, 1980, Singapore: (A) female with oostegites, INT- 0890, dorsal habitus; (B) female with oostegites, SEN-EXP-00.0-TAN10, lateral habitus; (C) ovigerous female, SEN-EXP-02.5-TAN04, lateral habitus. Scale bar = 500 µm.