Fisher, 1910 : 171 Tortonese & A.M. Clark, 1956 : 343 Halpern, 1970b : 79 A.M. Clark & Courtman-Stock, 1976 : 249 Clark & Downey, 1992 : 265 H.E.S. Clark & McKnight, 2001 : 133 New genera, species and occurrence records of Goniasteridae (Asteroidea; Echinodermata) from the Indian Ocean Mah, Christopher L. Zootaxa 2018 2018-12-21 4539 1 1 116 7Q27K Fisher, 1910 Fisher 1910 [151,493,151,178] Asteroidea Goniasteridae Sphaeriodiscus GBIF Animalia Valvatida 81 82 Echinodermata genus     Sphaeriodiscus  Fisher, 1910: 171; 1911: 167;  Tortonese & A.M. Clark, 1956: 343;  Halpern, 1970b: 79;  A.M. Clark & Courtman-Stock, 1976: 249; Downey in  Clark & Downey, 1992: 265;  H.E.S. Clark & McKnight, 2001: 133; Mah 2011: 44.   Diagnosis.Body pentagonal (e.g., Fig. 31A). Abactinal plates weakly tabulate, covered by evenly distributed granules (e.g. Fig. 31B). Marginal plates few, tumid with swollen or enlarged penultimates (e.g., Fig. 31C). Pedicellariae spatulate.   Comments.  Sphaeriodiscustogether with Peltasterand  Ceramaster,which all share similar defining characters, including a pentagonal body shape, relatively few marginal plates, shallow to well-developed abactinal plates, granule-covered, either partially or completely, marginal plates with bald region on the superomarginal surface, and variably granule to spinelet covered abactinal and actinal surfaces. Several characters present among species within these genera overlap or else show poor correspondence with taxonomic concept boundaries. Seven species of  Sphaeriodiscusare currently recognized (Mah, 2018), including five Pacific species, one Atlantic species,  Sphaeriodiscus bourgeti, and  Sphaeriodiscus mirabilisfrom the southern Indian Ocean, included herein. Fisher (1906)established  Sphaeriodiscusbased on an enlarged “ultimate or ante-penultimate” superomarginal plate. Notall of these species fall within the constraints of the original genus definition as clearly as the typespecies,  Sphaeriodiscus ammophilus. Enlarged near-terminal superomarginals are present in many species of each genus and in some specimens, enlarged plates are variably, absent or weakly developed. There has, for example, been some question as to the placement of Peltaster placentain Peltasteror  Sphaeriodiscus(e.g. Tortonese and Clark 1956, Tortonese 1984). Subsequent authors, such as H.E.S. Clark and McKnight (2001), have liberally applied the enlarged ultimate/antepenultimate marginal plate criterion and differing definitions of “enlarged” have qualified different species as  Sphaeriodiscusversus Peltaster.   Type Specimen Note.Perrier’s original type series of  Sphaeriodiscus bourgetiis in the MNHN collections, rendering Halpern’s (1970)conclusion that the MCZ specimens were the only extant types incorrect and designation of the specimens as lectotypeand paralectoype inappropriate.