Bathycrinus, A. H. Clark, 1917

Mironov, Alexandr N., 2019, See lilies of the genus Bathycrinus (Echinodermata, Crinoidea: Bathycrinidae) from the North-West Pacific hadal trenches, Zootaxa 4604 (3), pp. 401-427 : 414

Bathycrinus sp. cf. B. longipinnus

Synonymy: Bathycrinus sp. sp. — Belyaev 1966: 119;? Bathycrinus volubilis — Mironov 2000: 718, St. 3514.

Material examined. R V Vityaz, cruise 22, St. 3514, TS, 21.10.1955, Isu-Bonin Trench, 27°59′ N, 143°16′ E, 8530– 8540 m, RR-ring with proximal arms, fragment stalk, radix attached to pebble, RD 3.55 mm, IO RAS Cat.no. Ech00758.

Description. RR-ring broken, with large pit between radials and IBrs 1. One radial and one IBr1 deformed (asymmetrical). All free arms incomplete; number of secundibrachials 1 to 8. BB-ring, pinnules, proxistele and distalmost columnals absent. Surface of RR and Brs smooth. Only two IBrs 2 with small knobby processes; all IBrs 1 and three IBrs 2 without knobby processes. Articular surface of knobby processes with spines at top of subparallel stereom columns. Calcite plates between RR and IBrs absent.

Remarks. The specimen is poorly preserved. The pit between radials and IBrs have been formed by a parasite gastropod. The specimen is similar to B. longipinnus except for the absence of calcite plaques. However the absence of calcite outgrowths can be an artifact resulting from growth-inhibiting effect of parasitic invasion. The specimen differs from B. volubilis in having higher RR, less pentalobate RR-ring in cross section, presence of rudimentary knobby processes and thin (flat) cover plates on proximal IIBrs.