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

Abstract

A revision of the stalked crinoid species attributed to the genus Endoxocrinus A.H. Clark, 1908 (Diplocrininae, Pentacrinitidae, Crinoidea, Echinodermata) is conducted using studies on phenotype variation and its relation with environment. Specimens collected via submersible at five sites in the Bahamas exhibit distinct phenotypes that correlate with different apparent ecological niches and serve as references for interpreting specimens dredged in Atlantic and Pacific Oceans where detailed information on their benthic environment is unknown. Documentation of ecophenotypic convergences or divergences allows us to distinguish between adaptive characters and those revealing genetic affinities, and to discuss allopatric evolution and bathymetric zonation. The results suggest the following taxonomy: the genus Endoxocrinus is subdivided into two subgenera, i.e., Endoxocrinus A.H. Clark, 1908 and Diplocrinus Döderlein, 1912 (Annacrinus A. H. Clark, 1923 becomes a junior synonym of Diplocrinus); the subgenus Endoxocrinus is monospecific with E. (E.) parrae [Gervais (in Guérin, 1835)] from the western tropical Atlantic; the subgenus Diplocrinus includes E. (D.) alternicirrus (Carpenter, 1882) from the western and central Pacific, E. (D.) maclearanus (Thomson, 1872) from the western tropical Atlantic, and E. (D.) wyvillethomsoni (Jeffreys, 1870) from the northeastern Atlantic. Endoxocrinus (E.) parrae includes three subspecies adapted to different habitats and depths: E. (E.) parrae parrae usually in 154–518 m with moderate to high current velocity and moderate turbulence to laminar flow, E. (E.) parrae carolinae (A.H. Clark, 1934) in 504–724 m with moderate current velocity and high turbulence, and E. (E.) parrae prionodes H.L. Clark, 1941 in 402–832 m with high current velocity in laminar flow. E. (D.) alternicirrus includes two subspecies, E. (D.) alternicirrus alternicirrus in 625–1476 m and E. (D.) alternicirrus sibogae (Döderlein, 1907) usually in 364–800 m. E. (D.) maclearanus has a depth range of 432–878 m and occurs as a dwarf variety minimus n. var. in high current velocities and high turbulence. E. (D.) wyvillethomsoni from depths of 1214–2070 m lives on various substrates under a variety of hydrodynamic conditions.

Palaeoenvironmental Control on Distribution of Crinoids in the Bathonian (Middle Jurassic) of England and France

“…Variations in length of pluri− columnals could influence posture and distribution relative to current flow and topography, as suggested by Messing and Llewellyn (1992). Although David et al (2006) showed clear relationships between environment, morphology, and taxon− omy in the genus Endoxocrinus, these data cannot be directly applied to the Jurassic forms, largely due to the incomplete nature of the dataset in this paper. However, David et al (2007) revealed a link between bathymetry and substrate and the importance of internodals per noditaxis and columnal height to columnal diameter palaeoecoloical reconstruction.…”

Scale worms (Polychaeta: Aphroditiformia) associated with cold-water corals in the eastern Gulf of Mexico

“…16353-1 the substrate consisted of carbonate sandstone rock fragments with some coarse carbonate sand (foraminifera ooze) and shell debris and in MSM 20/4 Station 16374-1 of dead coral rubble of about 10 cm length, heavily colonized by diverse epibionts and the stalked crinoid Endoxocrinus (Diplocrinus) maclearanus minimus (Isselicrinidae) (cf. David et al, 2006). diagnosis Body dorsoventrally flattened, short, with up to 50 segments; dorsum more or less covered by elytra or short posterior region uncovered.…”

A New List of Cuban Crinoids (Echinodermata: Crinoidea)

“…Taxonomy has been updated following Messing (2001); Messing & White (2001); Roux et al (2002) and David et al (2006). We use the higher classification of Hess and Messing (2011).…”

“…Gervais (in Guérin, 1835, Pl. 147, fig.1) translated Parra's description, reproduced his figure, and applied to it the Latin binomen Encrinus parrae (now Endoxocrinus parrae) (A.H. Clark, 1908;David et al 2006). Almost a century after Parra, Pourtalès (1868) described the first comatulid from Cuban waters, Antedon (now Crinometra) brevipinna, collected during the first deep-sea dredging efforts in the western hemisphere (see also Arango & Molina, 1878).…”