Rouxicrinus, Mironov, Alexandr N. & Pawson, David L., 2010

Mironov, Alexandr N. & Pawson, David L., 2010, A new genus and species of Western Atlantic sea lily in the family Septocrinidae (Echinodermata: Crinoidea: Bourgueticrinida), Zootaxa 2449, pp. 49-68: 51-52

publication ID

http://doi.org/ 10.5281/zenodo.195174

persistent identifier

http://treatment.plazi.org/id/03D98500-FFC7-FFCC-55DC-F9C812C56486

treatment provided by

Plazi

scientific name

Rouxicrinus
status

new genus

Rouxicrinus  new genus

Etymology: The genus is named for Michel Roux, Muséum national d’Histoire naturelle, Paris, France, in recognition of his contributions to our knowledge of the crinoids.

Diagnosis: Proxistele tapers towards the calyx. Discoid columnals in proxistele numerous, usually more than 30, and united by flat synostoses. Columnals of mesistele short; maximum ratio height/diameter of columnals 1.68. Articular facets of mesistele synarthries ovoid, with wide fulcral ridge along smaller diameter; those of distal synarthries circular. First primibrachials (IBr) separated by well developed interradial projections of radials in small specimens only. Median distal prolongation of IBr 2 absent. IBr 1 shorter than radials. Maximum number of successive muscular articulations in arms 6–10. Most frequent proximal free arm pattern 1 + 2 3 + 4 9 + 10 or 10 + 11; first pinnule on IIBr 6–8 (mode on IIBr 7). When viewed from the side, every second or third Br bearing a P. Stereom of secundibrachials and pinnules with coarse meshes and many needle-like projections giving external surface dissected and thorny especially in distal ossicles. Thorns along upper margin of brachials and pinnulars. Second pinnular shorter than first; third pinnular longer than first in proximal pinnules.

Type species by monotypy: Rouxicrinus vestitus  new species.

Remarks: This new genus differs significantly from both Septocrinus  and Zeuctocrinus  in having numerous low columnals in the proxistele, tapering proximal end of stalk, a more proximal position of P 1, thorns on the Brs and Pns, and a thick cover of soft tissue. The distolateral interradial projections of RR in smaller specimens are a feature shared with Septocrinus  , but not found in Zeuctocrinus  . In life, all specimens of Rouxicrinus  have a white stalk, light cream calyx and Brs, Ps reddish purple; in alcohol stalk white, Ps brownish-violet. Septocrinis and Zeuctocrinus  are monochromatic, light yellowish grey to whitish in alcohol. This colour corresponds to bright yellow in life (like in most hyocrinids); confirmed for Z. gisleni  observed from submersible in Bay of Biscay and on Porcupine bank (M. Roux, pers. com.). Table 1 summarizes these and other differences.

According to Meyer at al. (1978), representatives of two other bourgueticrinid genera, Democrinus Perrier  and Monachocrinus A.H. Clark  , are known from the western Atlantic, from south Florida to Rio de Janeiro, Brazil (including the Caribbean Sea, Gulf of Mexico and Bahama Islands). Democrinus  , with 5 arms, can be immediately distinguished from Rouxicrinus vestitus  . The available information on M. caribbeus  is not sufficient to enable a detailed assessment of its generic or family position, although the holotypes of B. caribbeus  and R. vestitus  are clearly not conspecific. The holotype of M. caribbeus  is well distinguished from R. vestitus  by its high basal ring (taller than broad), fused BB, few discoid proximal columnals (the 10 th columnal is higher than broad), and ovoid distal stalk articular facets ( A.H. Clark, 1908 a, 1908 b, 1915; Gislén, 1938, 1951).