Culcitopsis Verrill 1914b

Culcitopsis Verrill 1914b: 21; Koehler 1924: 160

Sphaeraster Dons 1938: 161 –163 [Type species S. berthae Dons 1938] Sphaeriaster Dons 1939: [Nom. nov. for Sphaeraster Dons 1938, preoccupied] Poraniomorpha (Culcitopsis) A.M. Clark 1984: 33 –41 (pt)

Type species: Culcitopsis borealis (Süssbach & Breckner 1911)

Diagnosis. Body weakly stellate in shape (R/r=1.89), body-wall swollen, cushion-like. Abactinal plates forming vestigal reticulate skeleton in larger individuals (R>4.0 cm). Spinlets vestigal or absent. Marginal plates aborted, obscured in thickened skin, marginal border obscured by skin. Actinal surface covered by skin, fasciolar grooves weakly developed. Furrow spines one or two, with one to three subambulacral spines, each sheathed in skin. This diagnostic based in part on Clark and Downey (1992).

Taxonomic notes. Study of USNM E30691 and assessment of characters outlined by A.M. Clark (1984) does little to lend character support for Culctiopsis as a subgenus within Poraniomorpha .

Culcitopsis lacks the fine layer of spination on the surface layer, has a strongly developed layer of tissue over the abactinal, marginal an actinal surfaces, and differs in the arrangement and number of adambulacral spines. Poraniomorpha has more distinctive and more strongly developed imbricate abactinal, marginal, and actinal plates with weakly developed skin relative to Culcitopsis . Papulae occur widely over the abactinal surface in Poraniomorpha but are absent in Culcitopsis .

Study of E30691 also leads to agreement with A.M. Clark (1984) and Clark & Downey (1992) to reject synonymy of Culcitopsis borealis with Poraniomorpha hispida . Comparisons of C. borealis (R=3.6) with comparably sized P. hi spida (R=3.0) show no morphological similarity. Poraniomorpha hispida shows an almost fenestrate abactinal surface with blocky marginal plates whereas C. borealis shows a strongly developed skin, which covers or envelops the abactinal and marginal surface. No well-developed marginal or abactinal plates were observed.