Isaurus tuberculatus Gray, 1828

Reimer, James D., Poliseno, Angelo & Hoeksema, Bert W., 2014, Shallow-water zoantharians (Cnidaria, Hexacorallia) from the Central Indo-Pacific, ZooKeys 444, pp. 1-57 : 7-8

Taxon classification Animalia Zoantharia Zoanthidae

4. Isaurus tuberculatus Gray, 1828 Figures 4A, B, 5

Specimens examined

(n=3). RMNH Coel 40472, Rumphius Biohistorical Expedition station 27, Leitimur, south coast, Hutumuri, Ambon Bay, Moluccas (03°41'50"S, 128°17'00"E), intertidal under stones, collected on November 27, 1990 by J.C. den Hartog; RMNH Coel 40473, Rumphius Biohistorical Expedition station 27, Leitimur, south coast, Hutumuri, Ambon Bay, Moluccas (03°41'50"S, 128°17'00"E), intertidal under stones, collected on November 27, 1990 by J.C. den Hartog; RMNH Coel 40567, Fauna Malesiana Marine Sulawesi Expedition station SUL.04, bay south of Pulau Putus, Lembeh Strait, North Sulawesi (01°31'N, 125°16'E), depth approx. 1 to 2 m, on October 27, 1994 by J.C. den Hartog.

Photographic records.

NA.

Description.

Species in this genus are zooxanthellate, not incrusted, with a simple mesogleal sphincter muscle, and have non-erect, recumbent polyps that do not have lacunae or mesogleal canals, unlike Zoanthus species. Isaurus tuberculatus has tubercles on the exterior surface of polyps (=endodermal invagination) (Figures 4A, B). For detailed discussion of Isaurus tuberculatus , refer to Muirhead and Ryland (1985), with phylogenetic analyses in Reimer et al. (2008b).

Specimens examined in this study varied greatly in size from relatively large RMNH Coel 40567 (height 28-31 mm, width = 6-7 mm, n=2 polyps) to relatively small RMNH Coel 40473 (height average 10.6 mm, width average 2.9 mm, n=7 polyps). However, Isaurus polyps are known to vary greatly in size both between different colonies and within large colonies ( Larson and Larson 1982; Muirhead and Ryland 1985; Reimer et al. 2008b). Furthermore, the two other valid Pacific Isaurus spp. asides from Isaurus tuberculatus are both very distinct from these specimens, and found in Fiji and southwestern Australia, respectively. Thus, the identity of these specimens as Isaurus tuberculatus is largely certain.

Distribution.

Regions recorded in this study (Figure 5). Moluccas (14), Lembeh Strait (17).

Previous records. Originally described from the West Indies, this species is distributed throughout the subtropical and tropical Atlantic and Indo-Pacific (e.g. Muirhead and Ryland 1985), although populations in each ocean basin likely constitute different species ( Reimer et al. 2008a). In the Indo-Pacific, it has previously been reported from the Great Barrier Reef, Fiji, Hawaii (summarized in Muirhead and Ryland 1985), and also from Indonesia ( Sinniger et al. 2005), New Caledonia ( Laboute and Richer de Forges 2004), and Japan ( Reimer et al. 2008b).

Remarks.

As seen in previous studies ( Reimer et al. 2008b), it appears from the low numbers of specimens here that Isaurus is either somewhat rare throughout its range, or cryptic in nature (e.g. well-camouflaged), resulting in few reports of this species.