Feracrinus Mironov and Sorokina 1998a

Ameziane, Nadia & Roux, Michel, 2010, Stalked crinoids from Tasmanian seamounts. Part 1: Hyocrinidae, Journal of Natural History 45 (3 - 4), pp. 137-170 : 138-140

Genus Feracrinus Mironov and Sorokina 1998a

Ailsacrinus Mironov and Sorokina, 1998a: 404–405 .

Feracrinus Mironov and Sorokina, 1998a: 410 .

Camaecrinus Mironov and Sorokina, 1998b: 21–22 .

Feracrinus Mironov and Sorokina, 1998b: 20 .

Ptilocrinus sensu lato pars. Roux et al., 2002: 822.

Type species of the genus

Feracrinus aculeatus Mironov and Sorokina, 1998a

Emended diagnosis

Proximal arm pattern usually 1+2 3 4 5+6 7+8 or 5+6 7 followed in middle arm by successive brachial pairs or a+b c d+e f distal arms with fewer than five successive muscular articulations in juvenile and up to 22 in large adult. First pinnule always on Br4. Proximal part of genital pinnules with one row of lateral plates on each side, sometimes joined by stereome bridges over gonad in H-shaped plates. Anal cone lower or higher than oral cone. Basals fused or basal ring with one to three sutures. Stalk symplexies and distal syzygies with well-developed crenularium; symplexial crenular units 6–10 of one to three crenulae; distal stalk syzygies with labyrinthic crenularium.

146°E 147°E 148°E

Remarks

Mironov and Sorokina (1998a) established two new hyocrinid genera, Feracrinus and Ailsacrinus . The genus Ailsacrinus previously used by Taylor (1983) for a Jurassic millericrinid crinoid, was renamed Camaecrinus Mironov and Sorokina, 1998b . These genera were described from three species from the North Pacific (off eastern Japan), each based on a single specimen. Two of them, Camaecrinus peripterus and Feracrinus aculeatus came from the same station, and the third one, Camaecrinus klikushini , from a nearby area at about the same depth. Having arms relatively gracile, tegmen with orals predominating, and distal columnals as high as wide, the relatively small holotype of C. klikushini appears to be a young specimen in which ornamentation is moderately developed. The holotype of C. peripterus is an older specimen with developed tegminal plates restricting the size of the oral cone, more robust arms, and all columnals wider than high. The juvenile pattern of stalk symplexies observed in C. klikushini appears at the centre of distal syzygies of C. peripterus . The holotype of F. aculeatus is the oldest specimen and has an inflated tegmen and stalk symplexies with strongly irregular hieroglyph-like crenular units. The main characters of the genital pinnules, orals and arm pattern are about the same in the three specimens, except for variations in ornamentation. As a result, given the variation observed in Feracrinus koslowi sp. nov. (see below), these three specimens are interpreted as representing the ontogenic sequence of a single species. Consequently, Camaecrinus becomes a junior synonym of Feracrinus . Mironov and Sorokina (1998b) placed Feracrinus in their new subfamily Dumetocrininae and Camaecrinus in the subfamily Hyocrininae Carpenter, 1884 . So, the validity of criteria used to establish such subfamilies must be questioned as previously pointed out by Roux (2004) for the subfamily Calamocrininae , which was established by A.M. Clark (1973).

Included species

Feracrinus aculeatus Mironov and Sorokina, 1998a ; F. koslowi sp. nov.