Chambersaecrinus Mironov & Sorokina 1998

Subgenus Chambersaecrinus Mironov & Sorokina, 1998b

Type species of the subgenus: Ptilocrinus brucei Vaney, 1908. Synonymy: Mironov & Sorokina, 1998b: 52.

Emended diagnosis. Subgenus of Ptilocrinus with tegmen variously inflated; conspicuous radial bridges elevated above tegmen from orals to Br5 or more; cover plates well differentiated on tegmen; orals concave (median depression); anal sac always conspicuously higher than oral cone. Tendency for larger interradial tegminal plates to be arranged into a median row when tegmen inflated. Distal stalk syzygies with crenularium weakly differentiated.

Included species. P. brucei Vaney, 1908 [= P. (Chambersaecrinus) flexibilis Mironov & Sorokina, 1998b] (southwestern Indian Ocean, 4,070 to 5,474 m); P. (Ptilocrinus) s tukalinae Mironov & Sorokina, 1998b [= P. (? Ptilocrinus) perforatus Mironov & Sorokina, 1998b] (north and southwestern Pacific, southwestern Indian Ocean, 4,664 to 6,145 m); P. tasmaniaensis Améziane & Roux, 2011 (off Tasmania, 1,715 to 1,815 m).

Remarks. The detailed description of the type series of P. (Ptilocrinus) stukalinae by Mironov & Sorokina (1998b) documented the wide range of variation in crown characters. The single known specimen of P. (? Ptilocrinus) perforatus falls within this range. Moreover, its mesistele symplexies strongly resemble those of P. stukalinae suggesting that they belong to the same species. It has interradial tegminal plates in a median row, confirming the attribution of P. stukalinae to the subgenus Chambersaecrinus. P. stukalinae has a well developed anal sac which seems to be adjacent to the tegmen margin (personal communication of A. Mironov). P. (Chambersaecrinus) flexibilis was established on the basis of a single incomplete specimen (aboral cup broken, stalk unknown) without significant differences from P. brucei.