Endoxocrinus (Diplocrinus) wyvillethomsoni ( Jeffreys, 1870 )

David, Jerome, Roux, Michel, Messing, Charles G. & Ameziane, Nadia, 2006, Revision of the pentacrinid stalked crinoids of the genus Endoxocrinus (Echinodermata, Crinoidea), with a study of environmental control of characters and its consequences for taxonomy, Zootaxa 1156, pp. 1-50 : 39-40

Endoxocrinus (Diplocrinus) wyvillethomsoni ( Jeffreys, 1870)

Figures 17 , 19 b, 20d.

Synonymy: Pentacrinus wyville­thomsoni Jeffreys, 1870: 157, nomen nudum; Pentacrinus wyvillethomsoni Thomson, 1872: 767 ; Pentacrinus wyville­thomsoni Carpenter, 1884: 313; Isocrinus wyville­thomsoni Döderlein, 1907: 19; Endoxocrinus wyville­thomsoni A.H. Clark, 1908b: 152; Pentacrinus (Endoxocrinus) wyville­thomsoni Koehler & Vaney, 1910: 6; Cenocrinus (Diplocrinus) wyville­thomsoni Döderlein, 1912: 20–21; Annacrinus wyville­thomsoni A.H. Clark, 1923: 11; Diplocrinus (Annacrinus) wyvillethomsoni Roux, 1977: 64 ; Endoxocrinus (Diplocrinus) wyvillethomsoni David, 1998: 202 (unpublished data); Endoxocrinus (Annacrinus) wyvillethomsoni Roux et al., 2002: 820 .

Emended diagnosis

A species of the subgenus Diplocrinus with 10 to 21 smooth arms (mode 19) up to 10.5 cm long (mean 7 cm); arm branching usually isotomous; non­muscular articulation Br1+2 intermediate between synostosis and syzygy, showing a general symmorphy, tending to a true synostosis distally and to a syzygy between primibrachials; concave proximal facet of IBr2 with axial canal lumen bilobate and a radial syzygial crenularium at its aboral border; number of internodals per noditaxis 20–56 (mode 32); stalk length strongly variable, 3.5–22.5 cm (mean usually ~ 11 cm); middle and distal stalk pentagonal to circular in cross section; columnals usually homometric and relatively high; proximalmost diameter of stalk up to 4.2 mm (mean 2.9 cm); rudimentary cirri present to 3rd nodal; proximal cirri oriented upward; always 5 robust cirri; symplexies usually with 3 to 5 main crenulae per interpetaloid zone, tending to a radial pattern; cryptosymplexies flat or with slight general symmorphy; syzygial stereom predominating on interpetaloid zones and on a regular outer border of the facet; axial canal filled up by large meshed stereom not clearly separated from perilumen; secondary lumen small or absent.

Type locality

Off Portugal at a depth of 1980 m.

Lectotype: Catalogue no. 1885.3.30.19, Natural History Museum, London; we designate as the lectopype the Porcupine specimen which resembles most closely Figure 1 , Plate 18 ( Carpenter 1884).

Occurence

Northeastern Atlantic from the northern Bay of Biscay to Madeira and south of the Canary Islands at depths from 1246 m (possibly 900 m) to 2070 m ( Conan et al., 1981). The species was recently photographed via ROV at 1214 m in the Bay of Biscay (unpublished data from Vital cruise, courtesy of O. Brosseau, MNHN Paris).

Figures

FIGURE 1. Morphology of diplocrinine crinoids. General external morphology (a), and proximal portion of the stalk and crown showing isotomy (b) or endotomy (c) of arm branching. Facet of the symplexial articulation between columnals (d), and detailed portion of the heteromorphic stalk (e).

FIGURE 17. The northeastern Atlantic phenotype wyvillethomsoni. Specimen from the Bay of Biscay collected by the Thalassa Cruise (see Roux, 1976).

FIGURE 19. Distal facet of nodals (cryptosymplexies) identifying the four species of Endoxocrinus. (a): E. (E.) parrae, (b): E. (D.) wyvillethomsoni, (c): E. (D.) alternicirrus, (d): E. (D.) maclearanus.