Rumphella aggregata

Rumphella aggregata (Nutting, 1910)

Plexaura aggregata Nutting, 1910a: 4–5, pl. 1, fig. 1, 1a; pl. 4, fig. 1 (Seba, Savu Island).

Rumphella aggregata (new comb.) Bayer 1955: 212, fig. 2a–b.

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: 56, pl. 25, fig. A–D (Andaman and Nicobar Islands); Fernando et al. 2017: 220, pl. 101, fig. A–D (Andaman and Nicobar Islands.

Literature analysis: This species was originally erected by Nuttting as Plexaura aggregata for a specimen from Indonesia, and was later transferred to the new genus Rumphella by Bayer (1955). There are obvious differences between the traits of this species and those of the material described in the accounts (both identical) given by Kumar et al. (2014a) and Fernando et al. (2017). In the Indian papers the colonies are described as having thick, “whip-like” branches with blunt tips, which somewhat matches the illustration of the collected specimen where the terminal branches actually appear to be thin and tapered (“whip-like”). This is all in contrast to the non-tapering branches of R. aggregata with their characteristsic clavate tips as shown in Nutting’s figure (1910a: pl. 1, fig. 1). The colony in the underwater photograph in the Indian papers does not appear to be the same as the collected specimen and looks more like a Hicksonella. The Indian material is also described as being “dirty white to grey in colour when live”. The species is photosynthetic and so this is possibly the colour when colonies have their polyps extended.

The sclerites of Nutting’s holotype are poorly drawn and do not show the spiny nature of the sclerites, which are very similar to those described for Hicksonella princeps (see Alderslade 1986: 93, fig. 6). The spiny warts are quite different to the warts on the sclerites of the Indian specimen. Of particular note are the subsurface spindles figured in the Indian account that bear little resemblance to the very characteristic girdled form shown by Alderslade and also in Bayer’s figure 2a. Additionally, the small “four radiates” and capstans illustrated for the Indian material are not reported for this species.

Kumar et al. (2015) just list the species and provide the same image of the collected colony that appears in the 2014 and 2017 papers above, while Kumar et al. (2018a) just list the species. This species has only been reported from the Central West Pacific and Indonesia. In this region, large bushy colonies with long, upright branches could be Rumphella antipathies Linnaeus (see Grasshoff 1999: 19)