Bathycrinus volubilis Mironov, 2000

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 : 402-405

Bathycrinus volubilis Mironov, 2000

Figs 1 A–G

Synonymy: Bathycrinus sp. B. — Belyaev 1966: 118, 119, fig. 31; Bathycrinus volubilis –Mironov 2000: 714–719, figs 2–4. Non: Bathycrinus ? volubilis — Mironov 2000: 718, St. 3514 (= Bathycrinus sp. cf. B. longipinnus n. sp., see below).

Holotype. IO RAS No. XV-63-1, RV Vityaz, St. 5612, 26.07.1966, aboral cup with arms and stalk, RRD = 2.6 mm.

Type locality. RV Vityaz, cruise 39, St. 5612, 26.07.1966, TS, Kuril-Kamchatka Trench, 45º 25′ N, 153º07′ E, 8185–8400 m .

Material examined. RV Sonne 250, KuramBio II, St. 52,EBS, 0 6.09.2016, 45°29.77′ N, 153°12.16′ E – 45°29.18′ N, 153°11.13′ E, 8737 m, 1 specimen , SMF; RV Sonne 250, KuramBio II, St. 77, EBS, 13.09.2016, 45°13.71′ N 152°51.21′ E E– 45°14.21′ N 152°49.95′ E, 9584 m, 2 spms , SMF; RV Sonne 250, Expedition KuramBio II, St. 78, AGT, 13.09.2016, 45°13.979′ N, 152°48.980′ E – 45°14.482′ N, 152°47.736′ E, 9581.7– 9581.3 m, 50 spms , SMF; RV Sonne 250, KuramBio II, St. 103, AGT, 21.09.2016, 44°12.499′ N, 150°39.035′ E – 44°12.502′ N, 150°37.258′ E, 9292.9–9430.8 m, fragments of the stalks , SMF. RV Vityaz, cruise 14, St. 2217, 29. VI.1953, TS, 44°08′ N, 150°32′ E, 9000–9050 m, 90 spms , IO RAS Cat. no. Ech 00717– Ech 00720 ; RV Vityaz, cruise 19, St. 3176, 0 6.10.1954, TS, 44°08.5′ N, 150°22.0′ E, 8175– 8840 m, 35 spms , IO RAS Cat. no Ech 00721–723 ; RV Vityaz, cruise 22 , RV Vityaz, cruise 39, St. 5612, TS, 26.07.1966, 45°25′ N, 153°07′ E, 8185–8400 m, 254 spms , IO RAS Cat. no. Ech 00724– Ech 00731 ; RV Vityaz, cruise 39, St. 5631, TG, 0 4.09.1966, 43°47′ N, 149°43′ E, 9070–9345 m, 4 spms , IO RAS Cat. no. Ech 00732 ; RV Vityaz, cruise 39, St. 5632, TG, 0 5.09.1966, 43°44′ N, 149°52′ E, 8240–8345 m, 1 sp. , IO RAS Cat. no. Ech00733. Total: 438 specimens from the Kuril-Kamchatka Trench; most of them represented by aboral cup with proximal arms and proxistele, upper diameter of RR-rings (RRD) from 1.4 to 3.7 mm.

Remarks. Original detailed description of Bathycrinus volubilis was based on abundant material (Mironov 2000). Here I give some additional information on intra-species variability. Both BB-ring and RR-ring always strongly pentalobate (quinquelobate) in cross section ( Fig. 1 A–B). Numerous small plates of different shape on sides of upper tegmen ( Fig.1C ). Proximal arm pattern and position of P1 were examined on 216 arms ( Table 1 ); 49 different proximal patterns were found. Among them, 32 different cases were observed once only. Most frequent proximal patterns are 1+2 4+5 7+8 10+11 13 (41%) and 1+2 4+5 7+8 10+11 12 (20%). P1 on Brs 11–15; the most frequent positions on Br12 (31%) and Br11 (24%). Cover plates shape changes from proximal to distal arm. The cover plates on the proximal Brs are usually thick (not flattened) and with rough surface ( Fig. 1D ). On the Brs 4–12 they display two series of rough protuberances. The cover plates on distal Brs and pinnules are thin with a smooth surface ( Fig. 1F ). The number of short columnals forming the proxistele varies from 17 to 69, but in specimens from St. 2217 it varies from 5 to 24; This number does not exceed 31 in the other Bathycrinus species. Knobby processes on IBrs 1–2 are always absent.

Distribution. Kuril-Kamchatka Trench, 8175–9584 m. A specimen from the Izu-Bonin Trench (RV Vityaz, St. 3514) identified as Bathycrinus ? volubilis (Mironov 2000) is referred herein to Bathycrinus sp. cf. B. longipinnus n. sp.

Figures

FIGURE 1. Bathycrinus volubilis, St. 86 (A, C–G) and St. 77 (B), RV Sonne, SMF:A—general view; B—aboral cup and proximal arms; C—plates from the sides of upper tegmen; D—cover plates from proximal arm (Brs 4–12); E—cover plates from Brs 14–20; F—cover plates from pinnules; G—pinnular with right edges. Scale bars: A, B 2 mm; C–G 100 μm.