Calliaster Gray 1840

Mah, Christopher L., 2018, New genera, species and occurrence records of Goniasteridae (Asteroidea; Echinodermata) from the Indian Ocean, Zootaxa 4539 (1), pp. 1-116 : 17-18

Calliaster Gray 1840 (and the “ Calliaster Group”)

Gray 1840: 280; Döderlein 1922: 47; A.M. Clark & Courtman-Stock 1976: 60; A.M. Clark 1993: 246; Gates & Rowe 1995: 64

(as Calliaster ) Fisher 1913: 645; 1919: 320; A.M. Clark 1993: 246; Liao & Clark 1995: 91; Kogure et al. 2011: 83 (as Astrothauma ) Macan 1938: 391; A.M. Clark 1993: 261; Rowe & Gates 1995: 64 (as Mabahissaster ) H.E.S. Clark 1982: 35, figs 1–7; Rowe 1989: 289; A.M. Clark 1993: 264; Rowe & Gates 1995: 66; H.E.S. Clark & McKnight

2001: 82; (as Milteliphaster )

Diagnosis. A highly variable goniasterid group whose primary characters include the presence of one to several enlarged subambulacral spines present in transverse series, enlarged conical pointed spines present on abactinal, marginal and actinal plates. Abactinal, marginal and actinal plate surfaces bare and smooth. Marginal plates form a prominent abactinal border in most genera but this varies among species (and see taxonomic notes below). Body stellate to strongly stellate with known occurrence only in the Indo-Pacific.

Comments. Calliaster , Mabahissaster , Astrothauma and Milteliphaster all show distinctive potential synapomorphies supporting these genera as closely related, either as part of a single lineage, or possibly as synonymous taxa. Aziz and Jangoux (1985) noted that Mabahissaster along with Astrothauma and Milteliphaster showed similarities with Calliaster . All four genera display large, transversely aligned subambulacral spines and smooth bare, abactinal and marginal plates surfaces. Most have large, conical spines on plate surfaces. This result was supported by Mah’s (2005) morphological-based phylogeny of the Goniasteridae .

In several instances, the identifying characters for these genera have been shown to be either variable or have otherwise displayed weak support as evidence for these groupings. Macan (1938) established Mabahissaster based primarily on the presence of “numerous distal superomarginal plates in contact” and the granulation of the actinal plates. The abutting of superomarginal plates is variably observed in several species of Calliaster , including the type species, Calliaster childreni , albeit only on the superomarginals adjacent to the arm tip. Based on observations of this species, actinal granules are present in larger-sized individuals but absent from smaller sized ones and are interpreted as variable based on size. As no other characters distinguish this genus, Mabahissaster Macan 1938 is entered into the synonymy of the senior Calliaster Gray 1840 . This synonymy described for Mabahissaster herein agrees with the conclusion of Rowe and Gates (1995: 64), which was outlined without a formal character discussion.

Examination of further specimens of Astrothauma and published descriptions of more recently collected material (e.g., Kogure et al. 2011, Liao & Clark 1995) indicate that Fisher’s identifying character, the enlarged preterminal superomarginal is variable and does not occur consistently. Astrothauma is otherwise consistent with the character definition for Calliaster and conceptually is difficult to differentiate from Calliaster . Astrothauma is synonymized with Calliaster .

Further discussion on Milteliphaster is outlined below under the comments for the type species of Milteliphaster woodmasoni . Synonymy above reflects all incorrect usage of Milteliphaster beyond the original description. Much further work on Calliaster remains to be done and, as such, an identification key is premature.