Thyone venustella Ludwig & Heding 1935
Creators: name: Thandar, Ahmed S.
Publisher: name: Zenodo
Year: 2008
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Holothuroidea
Dendrochirotida
Phyllophoridae
Thyone
Thyone venustella

description: Thyone venustella Ludwig & Heding, 1935   
Figures 4E–K & 5  
 Thyone venusta Schmidt, 1926: 125, fig. b.   
 Thyone venustella Ludwig and Heding, 1935: 203, pl. 2, figs. 15–20.   
 Havelockia venustella Thandar, 1989: 292, figs. 2 & 9a (syn. and records).   
Type Perhaps in Bonn, Germany.  
Type locality Agulhas Bank, WCP, 155 m.  
Material examined  
 SAM-A27982, UCT Ecol. Surv., St. SCD 203, 34 o 51' S, 23 o 41' E, 30.xi. 1960, 183 m, 5 spec. (including fragments); SAM-A27983, St. SCD 234, 34 o 51' S, 23 o 4' E, 30.xi. 1960, 183 m, 1 spec; SAM-A27984, St. SCD 269, 34 o 23' S, 25 o 54' E, 19.vii. 1961, 182 m, 15 spec. (including fragments); Still Bay Shelf Transect, St. 1, 2, 35 o 22' S, 22 o 31' E, 20.vi. 1972, 200 m, 5 spec. (including 2 juvenile), SAM-A27755, WCD 140 (no further data), 11.ix.1962, 1 spec. (juvenile).   
Description  
 Largest specimen 32 mm; colour off-white; anal teeth present. Calcareous ring, here illustrated for the first time, only present in an adult from Still Bay and juvenile (SAM A27755) from St. WCD 140, ring of adult (Figure 5F) partially damaged but typically of Thyone type - elongated, tubular, mosaic-like. Body wall tables of adult (Figures 4E, F & 5C, D) scarce, typically confined to anal region, with 4-5(12)-holed disc, 30-40 µm, with thin margins; spire low, terminating in two clusters of teeth, tables sometimes distorted. Podia with endplates (about 70 µm) (Figures 4G & 5E) but no supporting deposits. Juvenile 6 mm, whitish, podia scattered, more numerous radially, with some indication of arrangement in double rows; calcareous ring (Figure 4K) not fully calcified, except for anterior projections and paired posterior processes; Polian vesicle single; stone canal straight, madreporite elongate; tables (Figure 4H & 5A) with 4- 5 or fewer holed disc; tentacles with developing perforated plates (Figure 5I); introvert with elongated, small-knobbed, multilocular plates with irregular margins (Figure 5H).   
 Distribution Lambert’s Bay to just east of Cape St. Francis, WCP, 155- 400 m.   
 Remarks   
 Because of the poor description of the calcareous ring by Ludwig and Heding (1935), Thandar (1989) dubiously retained the species in Havelockia, the genus in which Panning (1949) initially included the species, thus overlooking the addendum of Panning’s paper, in which he transferred all his Havelockia species, except the type species, back to Thyone. Thandar, however, added some notes and recorded the dimensions of the spicules. Most materials thus far examined by the writer (at ZMUC, the UCT Ecol. Surv. materials at the SAM identified by Ahearn, and the current specimens previously examined by Natasen Moodley 2000) all lack a calcareous ring except for the two specimens described above. The ring is definitely of the Thyone type. Thandar’s (1989) viewpoint that T. propinqua Cherbonnier from shallow-waters of south-west WCP, might represent juvenile of T. venustella is no longer upheld (see remarks under T. propinqua above).
description: Published as part of Thandar, Ahmed S., 2008, Additions to the holothuroid fauna of the southern African temperate faunistic provinces, with descriptions of new species, pp. 1-57 in Zootaxa 1697 (1) on pages 9-12, DOI: 10.11646/zootaxa.1697.1.1, http://zenodo.org/record/5107079