Thyone, Oken, 1815

Thandar, Ahmed S., 2019, On some lesser known sea cucumbers in the Natural History Museum, UK (Echinodermata: Holothuroidea), Zootaxa 4688 (3), pp. 361-381 : 370

Thyone ? elegans Norman, 1869 (? synonym of T. roscovita Hérouard, 1889

Figure 5

Material examined. NHMUK 1985.10 .4.14, Siteb, E. of Seagull Bank, Rhum, 285 m, Dr B. Earll, Marine Conservation Society, 1 spec.

Description. Specimen U-shaped; off-white in alcohol, anterior and posterior ends greyish, length 46 mm; breadth in mid-body 5 mm. Mouth and anus terminal, the latter with five anal teeth. Tube feet minute, retracted, scattered, more numerous ventrally with some indication of their arrangement in double rows anteriorly and posteriorly, with scattering in mid-body. Calcareous ring and associated structures absent. End plates present in tube feet but no ossicles were evident in body wall and tube feet.

Remarks. It is suspected that because of the complete lack of body-wall ossicles and the presence of darker coloured anterior and posterior ends and tube feet end plates, the specimen might represent Thyone elegans (?synonym T. roscovita ) but as the calcareous ring and associated structures are absent, a definite conclusion is not possible. The species could also be T. inermis Heller but McKenzie (1991) states that T. inermis always has deposits in the anal region and is perhaps a clinal variation of T. roscovita (?= T. elegans ).

Figures

FIGURE 5. Thyone?elegans Norman, 1869 /?T. roscovita Hérouard, 1889.