Trachasina crucifera ( Semper, 1869 )

Thandar, Ahmed S., 2006, New species and new records of dendrochirotid and dactylochirotid holothuroids (Echinodermata: Holothuroidea) from off the east coast of South Africa, Zootaxa 1245, pp. 1-51 : 26-27

Trachasina crucifera ( Semper, 1869)

Figure 8

Cucumaria crucifera Semper, 1869: 121 , pl. 1, fig. 1 a–c; Ludwig, 1887:1235, pl. 1, 5–11; Deichmann, 1948: 343, pl. 18, fig. 1–3.

Trachythyone crucifera Panning, 1949: 427 , fig. 15; Clark & Rowe, 1971: 182 (distrib.), fig. 92; Thandar, 1991: 131, fig. 10, 15a (synonymy & records).

? Trachythyone crucifera Panning, 1964: 170 , fig. 9; 1971: 37, 40 (passim).

Trachasina crucifera Thandar & Moodley, 2003: 284 (passim).

Type

Hamburg Museum, Germany, 2760.

Type locality

Aden, Red Sea.

Previous South African record Southern KwaZulu­Natal.

Distribution

West Indian Ocean, from South East Arabia to the east coast of South Africa, including Madagascar and islands of the West Indian Ocean, up to 23 m. Thandar’ s (1991) record of the species occurring in the Bay of Bengal is erroneous and should be discounted.

Habitat

Coral and rock.

Remarks

From the available literature it appears that this is perhaps the deepest record yet for this well­known West Indian Ocean species, which has been well re­described by Panning (1949, 1964) and many other workers and hence does not require a detailed description. Thandar (1991) remarked on the species and Thandar & Moodley (2003) transferred the species to the monotypic genus Trachasina erected for this purpose. The specimen, here examined, is obviously a juvenile, judging from its size, distribution of podia and immaturity of the gonad. It is whitish in colour, including the podia and tentacles, and measures only 18 mm in length. Podia are confined to the ambulacra in single or double rows and are much longer ventrally. The 10 tentacles are of unequal length. The calcareous ring is as previously illustrated for the species (see Thandar 1991: fig. 10i and Cherbonnier 1988: fig. 10g).

The body wall spicules are typically spinous crosses ( Figure 8 A), 65–120 µm long (mean 88 µm) and thick, multilocular plates ( Figure 8 C), 205–410 µm long (mean 300 µm) and 140–230 µm wide (mean 176 µm), with up to 16 holes. Rosettes described for the type by Semper (1869) and perhaps over­looked by other writers or not present in their material, were detected at the base of the podia, but are scarce ( Figure 8 B). Podial deposits include rods with several perforations at the ends and/or in the expanded middle ( Figure 8 D). The pedicel endplates ( Figure 8 E) are small, of same size dorsally and ventrally, with 3–4 series of holes, larger medially and smaller peripherally. The tentacle shaft comprises slightly curved rods ( Figure 8 H), 127–337 µm long (mean 210 µm), with terminal perforations, while smaller, more delicate rods ( Figure 8 G), 3–113 µm long (mean 48 µm), and rosettes ( Figure 8 F), 10–47 µm long, (mean 26 µm), are present in the branches. No deposits, with the exception of a few rosettes, were detected in the introvert. It appears that rosettes of the body wall are juvenile features and so are also the large­size and multilocular nature of the plates.

Figures

FIGURE 8. Trachasina crucifera (Semper, 1869). SAM­A 27908. A. crosses from body wall; B. rosettes from base of dorsal podia; C. plate of dorsal body wall; D. plates and rods from dorsal podia; E. end­plate from dorsal podium; F. rosettes from tentacle tips and branches; G. small rods from tentacle tips and branches; H. large rods from tentacle stalk. All drawn to same scale.