Siniotrochus myriodontus Gage & Billett, 1986

Bohn, Jens Michael, 2006, Crinoidea and Holothuroidea (Echinodermata) of the abyssal Angola Basin — Results of the DIVA­ 1 expedition of FS " Meteor " (Cruise M 48 / 1), Zootaxa 1276, pp. 1-31 : 22-23

Siniotrochus myriodontus Gage & Billett, 1986

( 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 1IFREMER BIOCEAN; herein

Figures

FIGURE 13. (A) Siniotrochus myriodontus Gage & Billett, 1986. Wheel deposit of body wall. (B – C) Neolepidotrochus parvidiscus angolensis Bohn, 2005. Wheel deposits of body wall. (B) Neolepidotrochid type wheel. (C) Myriotrochid type wheel. Arrowheads – outward­pointing secondary teeth.

FIGURE 14. Distribution of Siniotrochus myriodontus Gage & Billett, 1986 and Neolepidotrochus parvidiscus angolensis Bohn, 2005.