Sphaeriodiscus Fisher, 1910

Mah, Christopher L., 2018, New genera, species and occurrence records of Goniasteridae (Asteroidea; Echinodermata) from the Indian Ocean, Zootaxa 4539 (1), pp. 1-116 : 82

publication ID	https://doi.org/10.11646/zootaxa.4539.1.1
publication LSID	lsid:zoobank.org:pub:2C72727B-79C5-407F-BD92-B12F98196800
DOI	https://doi.org/10.5281/zenodo.5990831
persistent identifier	https://treatment.plazi.org/id/193787A0-FFB3-FFCE-F4CB-FF5747B5CE50
treatment provided by	Plazi (2019-03-28 16:04:18, last updated 2024-11-28 19:27:13)
scientific name	Sphaeriodiscus Fisher, 1910
status

Treatment

Sphaeriodiscus Fisher, 1910 View in CoL

Sphaeriodiscus Fisher, 1910: 171 View in CoL ; 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 View FIGURE 31 ). Abactinal plates weakly tabulate, covered by evenly distributed granules (e.g. Fig. 31B View FIGURE 31 ). Marginal plates few, tumid with swollen or enlarged penultimates (e.g., Fig. 31C View FIGURE 31 ). Pedicellariae spatulate.

Comments. Sphaeriodiscus together with Peltaster and 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 Sphaeriodiscus are currently recognized (Mah, 2018), including five Pacific species, one Atlantic species, Sphaeriodiscus bourgeti , and Sphaeriodiscus mirabilis from the southern Indian Ocean, included herein. Fisher (1906) established Sphaeriodiscus based on an enlarged “ultimate or ante-penultimate” superomarginal plate. Not all of these species fall within the constraints of the original genus definition as clearly as the type species, 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 placenta in Peltaster or 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 Sphaeriodiscus versus Peltaster.

Type Specimen Note. Perrier’s original type series of Sphaeriodiscus bourgeti is 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 lectotype and paralectoype inappropriate.

References

Clark, A. M. & Courtman-Stock, J. (1976) The echinoderms of Southern Africa. British Museum of Natural History, London, 277 pp.

Clark, A. M. & Downey, M. E. (1992) Starfishes of the Atlantic. Chapman and Hall, London, 794 pp. https: // doi. org / 10.5860 / choice. 30 - 2659

Clark, H. E. S. & McKnight, D. G. (2001) The Marine Fauna of New Zealand: Echinodermata: Asteroidea (sea-stars), Order Valvatida. NIWA Biodiversity Memoir, 117, 1 - 270.

Fisher, W. K. (1906) The starfishes of the Hawaiian islands. Bulletin of the United States Fish Commission, 23, 987 - 1130.

Fisher, W. K. (1910) New genera of starfishes. Annals of the Magazine of Natural History, Series 8, 5 (26), 171 - 173. https: // doi. org / 10.1080 / 00222931008692747

Halpern, J. A. (1970) Goniasteridae (Echinodermata: Asteroidea) of the Straits of Florida. Bulletin of Marine Science, 20 (1), 193 - 286.

Tortonese, E. & Clark, A. M. (1956) On the generic position of the asteroid Goniodiscus placenta Muller & Troschel. Annals and Magazine of Natural History, Series 12, 9, 347 - 352. https: // doi. org / 10.1080 / 00222935608655821

Tortonese, E. (1984) Notes on the Mediterranean sea-star Peltaster placenta (M. Tr.) (Echinodermata, Asteroidea). Bollettino del Museo civico di storia naturale di Ferona, 11, 99 - 112.

Figures

FIGURE 31. Sphaeriodiscus biomaglo n. sp. Holotype IE-2013-17197. R=3.3, r=2.2 cm. A. Abactinal surface. Scale bar=1.0 cm. B. Closeup showing abactinal plates and granulation. Scale bar=0.5 cm. C. Arm tip and superomarginal plate surface. Scale bar=0.5 cm. D. Actinal plate surface. Scale bar=1.0 cm. E. Closeup of furrow and adambulacral spination. Scale bar=0.3 cm.