Thyone articulata Vaney, 1908a: 295, 1908b: 426, pl. 4, figs. 43, 44.
Thyonina articulata Thandar, 1990: 217 (syn. & records), figs. 1d, 8, 10e-f.
Type Unknown, perhaps in Scotland.
Type locality Saldanha Bay, WCP.
Material examined
SAM-A27973, UCT Ecol. Surv., Van Veen, False Bay, St. FAL 419, 34 o 12.5' S, 18 o 37' E, 15.V. 1961, 48 m, 9 spec; SAM-A27974, St. FAL 434, 34 o 15.2' S, 18 o 33.2' E, 16.v. 1961, 42 m, 3 spec., SAM-A27975, St. FAL 937, False Bay, WCP, 25.i.1967, 19 spec.
Distribution Saldanha Bay to Port Elizabeth, 16- 162 m.
Remarks
The specimens at hand are juvenile, measuring 2.5 mm x 1.75 mm to 3 mm x 2 mm. They are barrelshaped, uniformly white, with both anal teeth and papillae. The podia are mostly in ambulacra, in 2-4 rows, with a few also in the interambulacra. The material is clearly referable to the well known southern African temperate endemic, Thyonina articulata (Vaney, 1908) but in at least two specimens smooth, four-holed plates (ca. 55 µm), first described from the anal region by Cherbonnier (1952), are also sparingly distributed in the general body wall. This is perhaps a juvenile character. The calcareous ring, despite its early stage in development, is typical as are the end-plates of the podia. However, Thandar (1990) drew attention to a sympatric, atypical form of the species, dredged from Dassen Island (west coast) at 29 m with the bottom material also described as shelly sand. They are barrel-shaped, 24-42 mm long, yellowish in colour with brownish blotches, with the calcareous ring usually consisting of a single series of interradial elements, the end-plates seldom with a complex rim and the retractors originating as 1-3 strands. Natasen Moodley (2000), on the other hand, draws attention to another sympatric, atypical form dredged from False Bay, which is U-shaped, much longer (up to 62 mm) than the typical form but with a similar complement of spicules. Regrettably these three forms must await molecular investigations.