Thyone sp.

Thandar, Ahmed S., 2008, Additions to the holothuroid fauna of the southern African temperate faunistic provinces, with descriptions of new species, Zootaxa 1697 (1), pp. 1-57 : 14

Thyone sp. indet. 2

Figure 6 H-J

Material examined SAM-A27986, UCT Ecol. Surv., False Bay , St. FAL 377 , 4 o 18.7' S, 18 o 37.2' E, 25.ii. 1959, 72 m, 1 spec.

Description

Specimen small, juvenile, 7 mm long, slightly U-shaped, anterior end narrower. Colour in alcohol uniformly white. Tentacles 10, mid-ventral two reduced. Podia minute, not conspicuous, arranged in double rows per ambulacrum. Calcareous ring delicate, radial and interradial plates compact, meeting broadly at base, forming only a short tube as in the sclerodactylids; radial plates slightly bifid anteriorly, with deep posterior concavity; interradial plates with an anterior triangular projection and a straight posterior margin; posterior processes of radial plates short, broken into few segments. Polian vesicle elongate, stone canal not detected. Gonad immature, only a few short tubules present. Respiratory trees reach anterior of body, each with a few sac-like branches.

Spicules of body wall as tables ( Figure 6H ) with large, multilocular, smooth disc, 60-100 µm (mean 73.5 µm), perforated by four large central holes and up to 20 smaller marginal holes, rims undulating; developing tables as cross-shaped bodies with bifurcating arms and a pair of nodules on surface; spire where present, two-pillared, of moderate height 20-40 µm (mean 29 µm), terminating in several teeth, usually asymmetrically arranged. Podial tables scarce, with strongly curved disc perforated by four large central and one or more smaller terminal holes; spire of moderate height, of two pillars terminating in a pair of divergent teeth; endplates absent. Tentacle spicules ( Figure 6J ) in the form of rosettes and slightly curved rods with irregular margins, with or without perforations. Introvert with tables and other deposits similar to those of tentacles, some rods developed as plates ( Figure 6I ).

Distribution False Bay, WCP, 72 m.

Remarks

The current specimen, also juvenile, comes quite close to the preceding one but differs in the size of the podia, the form of the spires of the body wall tables, the greater curvature of the podial table discs and their scarcity, the absence of end-plates, and the form of the tentacle and introvert spicules. It also comes quite close to T. comata , differing from it in the shape of the tentacle and introvert deposits. Since this and the preceding specimen are both juvenile no emphasis can yet be placed on their calcareous rings However, the ring of the present specimen, like that of the previous species, appears to be of the sclerodactylid rather than of the phyllophorid type (see Thandar 1989). More and adult material is necessary for its correct identification and assignment.

Figures

FIGURE 6A-G.. Thyone sp. indet. 1.. SAM-A27985. A. Tables from dorso-lateral body wall; B. tables from dorso-lateral podia; C. end-plate from dorso-lateral podium; D. plates from tentacles; E. small tables from introvert; F. large table from introvert; G. calcareous ring. H-J. Thyone sp. indet 2. SAM-A27986. H. Tables from body wall; I. rods from introvert; J. rods and rosettes from tentacles. A-F scale a; H-J scale b.