(Figs 13 A, 14)
Siniotrochus myriodontus Gage & Billett, 1986: 266 –272, figs 28 (C–E), 29–31; Bohn, 2005: 232 –234, figs 1 (A–B), 2
Material. M 48 / 1347: 1 posterior fragment (ZSM 20020016). M 48 / 1351: 2 posterior fragments (ZSM 20020015).
Remarks. Gage and Billett (1986) provide an excellent description of this species, including detailed information on a variety of taxonomically important wheel parameters. Given that the current specimens have already been treated in more detail (Bohn 2005) the species is only shortly outlined: body about cylindrical, up to 31 mm long and 7 mm wide; tentacles 12, with four pairs of lateral digits; calcareous ring with 5 radial and 5 interradial plates; body wall with single layer of wheel deposits of the socalled siniotrochid type (Fig. 13 A); wheel diameter 414 (284–560); hub about half the diameter of the wheel, perforated by several holes; spokes 17 (12–25); inwardpointing teeth 42 (30–67); outwardpointing primary teeth 18 (11–31); outwardpointing secondary teeth 6 (0–29) (arrowheads in Fig. 13 A); simple rod deposits present in tentacles and around anus.
Siniotrochus myriodontus closely resembles the northwestern Atlantic Ocean S. phoxus Pawson, 1971 from which it differs by the presence of outwardpointing secondary teeth on the wheels.
Distribution. (Fig. 14) Northeastern Atlantic Ocean (Porcupine Seabight) and southeastern Atlantic Ocean, 3490–5389 m (Bohn 2005; Gage & Billett 1986).
Species Depth (m) Source
Bathycrinus aldrichianus Wyville Thomson, 1876 5415 herein
Porphyrocrinus incrassatus (Gislén, 1933) 2400–2780 Gislén 1933
Deima validum validum Théel, 1879 4088–5426 IFREMER BIOCEAN; herein
Psychropotes depressa (Théel, 1882) 2270 Hansen 1975
Psychropotes longicauda Théel, 1882 2475–3244 IFREMER BIOCEAN
Psychropotes semperiana Théel, 1882 3244–5126 IFREMER BIOCEAN; herein
Peniagone diaphana (Théel, 1882) 3034 IFREMER BIOCEAN
Peniagone purpurea (Théel, 1882) 4660–5415 1 IFREMER BIOCEAN; herein