Dumetocrinus antarcticus Bather 1908

• Main Authors: Eléaume, Marc, Bohn, Jens-Michael, Roux, Michel, Améziane, Nadia
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2012
• Subjects: Biodiversity; Taxonomy; Animalia; Echinodermata; Crinoidea; Hyocrinida; Hyocrinidae; Dumetocrinus; Dumetocrinus antarcticus; Antarc*; Antarctic; Antarctic Peninsula; antarcticus
• Online Access: https://doi.org/10.5281/zenodo.6180829; http://treatment.plazi.org/id/D558AA75E01C4C676F85FE5E5E70FB3E

Dumetocrinus aff. antarcticus (Bather, 1908) Figure 3. Synonymy: Dumetocrinus antarcticus Gutt et al. , 2011: 6, fig. 4D. Material examined. Holotype (spec. B) and two paratypes (spec. A, C), IRSNB 1897/1999-10131-589; paratype (spec. D) NHM 1937-4-29-1: Belgica Expedition, Faubert 11, sta. 589, W of Antarctic Peninsula, 70°23’S – 82°47’W, 480 m, 1898. R/V Polarstern cruise ANT XXIII/8, station PS69/710-5 Larsen area, E of Antarctic Peninsula, 65° 32.94’ S – 61° 38.59’ W, depth 242 m, 2007 (1 specimen with distalmost stalk missing). Description. Specimen almost complete except for the distalmost stalk (Fig. 3 A–B); length of preserved stalk 10.0 cm with proximalmost diameter 1.9 mm; height of aboral cup 6.3 mm with diameter at top of radial ring 6.9 mm; ratio of radial upper width to primibrachial width 2.0 to 2.2; arm length about 36 mm; maximum pinnule length 16 mm. Dorsal cup and tegmen smooth and brachials without lateral wings. Relatively gracile arms with up to 20 well-differentiated pinnules on each side; first pinnule always on Br4. Arm pattern 1+2 3 4 5+6 7 8+9 10 11 12 13 (3 cases), one arm broken at Br20 after 12 successive muscular articulations, the single complete arm with brachial pairs at 17+18 and 28+25. Tegmen moderately inflated with anal cone lower than oral cone and conspicuous concave orals (Fig. 3 C). Pinnules without genital inflation and lateral plates, very sharp triangular cover plates as described by John (1937: fig. 2). Proximal columnals articulated by symplexies with 8 crenular units of 1 crenula (Fig. 3 D), distal syzygies with radial crenularium of relatively wide crenulae (Fig. 3 E). Remarks. This specimen differs from specimens of the type-series of D. antarcticus mainly in lacking thecal ornamentation (see John 1937, fig.1), adoral inflation of arms and pinnules, H-shaped plates and lateral plates in pinnules (see Mironov & Sorokina 1998a, fig. 5), and by fewer number of crenular units in symplexies than described by Roux (1980b). However, the arm pattern, typically sharp ...