Acanella rigida Wright & Studer, 1889

Ramvilas, Ghosh, Alderslade, Philip & Ranjeet, Kutty, 2023, The taxonomy of Indian gorgonians: an assessment of the descriptive records of gorgonians (Anthozoa: Octocorallia: Alcyonacea) recorded as occurring in the territorial waters of India, along with neighbouring regions and the Andaman and Nicobar Islands, and the highlighting of perceived unethical practice, Zootaxa 5236 (1), pp. 1-124 : 111

Acanella rigida Wright & Studer, 1889

Acanella rigida Wright & Studer, 1889: 31–32 , pl. 9, fig. 4 (Banda Sea): Kükenthal 1919: 577 (Banda Sea).

Acanella sibogae Nutting, 1910b: 14 , pl. 3, figs. 2, 2a; pl. 5, fig. 4 ( Malaysia).

? Acanella rigida Saucier et al. 2017: 376 , fig. 10 ( Papua New Guinea).

Opinion: There is not enough evidence to affirm this species occurs in the region.

Justification:

These Indian records seem to be either invalid or unconfirmable: Thomson & Henderson 1906: 32–33, pl. 9, fig. 14 ( Laccadive Sea).

Literature analysis: This species was originally described from the Banda Sea, Indonesia, and included a figure of a small group of spindle-shaped sclerites from unknown parts of the colony but did not include any illustrations of the important sclerite arrangement on the polyps. Kükenthal (1919) maintained the original diagnosis. Saucier et al. (2017), without seeing the holotype, identified a specimen from off Papua New Guinea with this species and figured a polyp with large sinuous spindles curving obliquely around the body. They stated, as did the original description, that some of these sclerites can extend over the whole length of a polyp. The original description described the polyps sclerites as, “Spicules very irregular in shape, large, some wavy in outline, others curved, or with one end narrow and the other irregularly expanded, all with more or less well-developed spines. Some of the large, external, curved, spindle-shaped spicules surrounding the polyps measure 3.5 mm. in length, with a diameter in the thickest portion of 1 mm ”. The 1 mm dimension was perhaps a misprint, but two, stout, irregular cigar-like forms were included in their figure. In comparison, the polyp body sclerites illustrated by Saucier et al. (2017) seem rather more uniform. However, their material came from the same general locality as the original specimen and maybe conspecific. Saucier et al. (2017) synonymised Acanella sibogae and also A. japonica Kükenthal, 1915 with A. rigida . But these authors emphasis on polyps with long spindles curving around the polyp from base to summit seems at odds with the polyps of A. japonica figured by Kükenthal (1919: figs 254, 255). Also, the polyps and the polyp sclerites of A. japonica are much smaller. The Laccadive Sea record is attributable to Thomson & Henderson (1906) who provided an extremely brief description and a figure of a group of four spindles. Given there is still some uncertainty about the characters of the species even now, Thomson & Henderson had very limited knowledge of them and there is little evidence they had this species.