Stauraster Valette, 1929

Gale, Andrew Scott, 2021, Taxonomy and phylogeny of the ‘ football stars’ (Asteroidea, Sphaerasteridae), Journal of Systematic Palaeontology 19 (10), pp. 691-741 : 700

Genus Stauraster Valette, 1929

Type species. Stauraster billodense Valette, 1929 (= Pentaceros primaevus von Zittel, 1880 , herein).

Diagnosis. Stauranderasterid with short, rapidly tapering arms, made up of seven columns of similarly sized and -shaped ossicles (radials, adradials, superomarginals, inferomarginals). Disc including two circlets of ossicles; outer ring made up of primary radials and interradials and inner one of inner calycinal plates surrounding ce. Radials transversely broad, sub-rectangular. Sculpture of deeply impressed granule pits on abactinals and marginal ossicles.

Remarks. Spencer & Wright (1966) included Stauraster as a possible synonym of Hadranderaster Spencer, 1907 . However, the discovery of more complete material demonstrates that Stauraster is a distinct genus, which lacks the small ossicles intercalated between the abactinals and marginals that are present in Hadranderaster abbreviatus ( Geinitz, 1871; see Spencer 1907, pl. 24, fig. 1). The sculpture of the body ossicles is also quite different in the two genera; in H. abbreviatus , the shallow spine pits are fine and very dense, whereas in S. primaevus they are less dense and deeply impressed ( Fig. 5A–G, I–K ); in addition, there is a smooth margin around the ossicles. The characteristics and distinctiveness of Stauraster were discussed by Villier et al. (2004a, b). Because Stauraster billodense is considered a subjective junior synonym of P. primaevus , the latter becomes the type species of Stauraster ( ICZN Article 11.6.1).

Figures

Figure 5. Morphology of the stauranderasterid outgroup, Stauraster primitivus (von Zittel, 1880). A–C, arm, in abactinal, lateral and actinal views, respectively (MZA L246). D–N, isolated ossicles; D–G, I, ossicles from primary circlet; D, E, primary interradial (NHMUK EE 17624); F, G, centrale (NHMUK EE 17625); H, ambulacral ossicle, actinal view (NHMUK EE 17626); I, inner calycinal ossicle (NHMUK EE 17627); J–L, radials (NHMUK EE 17628–17630); M, N, adambulacral ossicles, in abactinal and proximal/distal views, respectively (NHMUK EE 17631–17632). O, reconstruction of apical region of Stauraster. Provenance: A–C, upper Oxfordian of Switzerland. D–N are from the lower Oxfordian, Cardioceras bukowskii ammonite Subzone, basal Couches de Passage, Andelot-Morval, Jura, France (see Gale 2019, for locality details). Colours as in Figure 1. Scale bars: A–C = 10mm; D–G, I–L = 5 mm; H, M, N = 0.5 mm.