Dichotella gemmacea (Milne Edwards & Haime, 1857)

Gorgonia gemmacea Valenciennes MS. In: Milne-Edwards (& Haime), 1857: 185.

Verrucella gemmacea Milne Edwards & Haime, 1857: 185, pl. B2, fig. 7 (Red Sea —doubtful).

? Dichotella divergens Gray, 1870a: 50; Bayer & Grasshoff 1994: 26–29, fig. 3.

Opinion: There is no evidence that this species occurs in the region.

Justification:

These Indian records seem to be either invalid or unconfirmable: Kumar et al. 2014a: 8, pl. 1, fig.A–D (Andaman Is.); Fernando et al. 2017: 242, pl. 112, fig. A–D (Andaman Is.).

Literature analysis: Gorgonia gemmacea was a Valenciennes manuscript name that Milne-Edwards (& Haime) (1857) reassigned as Verrucella gemmacea and which is now accepted as Dichotella gemmacea. This taxon seems to only occur in the Indo-West Pacific. It has a dichotomous colony form with many thick branches and polyps that curve over and lie scale-like against the branch surface when contracted.

The descriptive part of the accounts given by Kumar et al. (2014a) and Fernando et al. (2017) are identical, but their colony is sparsely branched with long, thin whip-like branches and has polyps that have contracted level with the branch surface. Their specimen probably represents a new species of the genus, but their description is extremely compromised by sharing modified versions of 2 sclerites with other species. From the left, the first figured sclerite is repeated as the second sclerite in their description of Junceella juncea, where it is stretched, and the second sclerite is repeated as the third sclerite of the bottom row in their description of Verrucella corona, where the size is reduced. Kumar et al. (2015) just lists the species and figures the same specimen from the 2014 and 2017 publications above.

The account by Fernando et al. (2017) gives an extensive list of synonyms, three of which also occur in their account of a species named, “ Nicella gemmacea (Valenciennes, 1855) ”, which is given in the same publication and also in that of Fernando (2011). The three synonyms are: “ Gorgonia gemmacea Valenciennes, 1857, p. 185 ” (which was actually only a manuscript and the equivalent of their reference “ Gorgonia gemmacea Milne Edwards & Haime, 1857, p. 185 ”; “ Jucella (sic) gemmacea Nutting 1910 ”; and “ Jucella (sic) sanguine (sic) Nutting, 1910 ”. Gorgonia gemmacea is accepted as Dichotella gemmacea, as are Nutting’s Junceella gemmacea and Junceella sanguine.

It is not clear what the authors’ intentions were with the inclusion of Nicella gemmacea, but the identity of the specimen is probably the same as that of the specimens Fernando (2011) and Fernando et al. (2017) assigned to Ellisella grasshoffi and it is also very similar to Ellisella bayeri Fernando, 2011.