Comprehensive DescriptionRead full entry
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.