Molpadia triforia ( Cherbonnier, 1965a )

THANDAR, AHMED S., 2007, Additions to the aspidochirotid, molpadid and apodid holothuroids (Echinodermata: Holothuroidea) from the east coast of southern Africa, with descriptions of new species, Zootaxa 1414 (1), pp. 1-62 : 49-51

Molpadia triforia ( Cherbonnier, 1965a)

Figure 23

Trochostoma triforia Cherbonnier, 1965a: 20 , pl. 10; Cherbonnier, 1965b: 672, fig. 13 a–u.

Type MNHNP .

Type locality South Atlantic , 44 miles WNW of Banana, 145 m.

Previous southern African record None.

Material examined

SAM-A27947 , N.E of Umhlanga Rocks , KZN, 29° 46.1' S, 31° 16.6' E , NMDP, St. ZW 2, 90 m, 21 vi 1989, 1 spec ; SAM-A27948 , N.E of Umhlanga Rocks , KZN, 29° 46.1' S, 31° 16.6' E, Meiring Naude, St. ZW 3, R. Kilburn, 21 vi 1989, 90 m., 1 spec.

Description

Form barrel-shaped with tail-like appendage. Spec.from St. ZW 2 ( SAM-A 27947), 40 mm long, 18 mm wide, tail 5 mm. Spec. from St. ZW 3 ( SAM-A 27948), 34 mm long (excluding tail), 19 mm wide, tail 3 mm. Colour dull greyish brown, speckled with red due to phosphatic bodies, uniformly distributed. Tail whitish, sparingly speckled with red, especially in SAM – A27948 . Tentacles 15, short (up to 0.5 mm), white, each with a single pair of digits and an ill-pronounced terminal digit. Anus encircled by five large papillae external to five pairs of smaller papillae, easily demonstrated in SAM – A27948 . Skin rough, thin, translucent.

Calcareous ring (spec. SAM – A27948 — Figure 23F ) of five radial and 10 interradial plates, the former thicker with deep anterior concavity and bifid posterior prolongation; interradial plates with anterior median projection and a ridge on the outer surface. Polian vesicle single, spherical. Stone canal straight, attached, madreporite spherical, coral-like, connected to body wall ( Figure 23E ). Tentacle ampullae transparent, most extending beyond posterior border of calcareous ring. Gut filled with mud, shell fragments, sand and other debris. Gonadal tubules paired, immature, branched. Right respiratory longer, reaching anterior end, left one half as long, both arising independently. Longitudinal muscles paired. Ciliary urns not detected.

Body wall tables ( Figure 23A, B ) with trilobed disc in various stages of development, 190–240 µm (mean 215 µm), perforated by 3–(5) oval, heart-shaped or polygonal holes, spire 130–210 µm (mean 156 µm), of three fused pillars revealing 4–8 cross-bars, tips of spire rarely intact ( Figure 23C ). Tail tables with fusiform disc ( Figure 23D ), 140–275 µm (mean 188 µm), perforated by 2–4 central holes, spire two-pillared, 50–65 µm (mean 56 µm), terminating bluntly. Phosphatic granules numerous. No tentacle spicules.

Distribution South-east Atlantic and south-west Indian Oceans, 90– 145 m.

Habitat Muddy sand, shell debris.

Remarks

It is surprising that this species, originally described from off the NW coast of Angola at 145 m ( Cherbonnier 1965a), and then from the coasts of Cameroon at 65–70 m and Dahomey at 150–200 m ( Cherbonnier 1965b) should now turn up on the east coast of South Africa at 90 m. Perhaps the current material is not identical to that from the West African coast but there is little evidence at this stage to justify its separation. The only differences appear to be the degree of abundance of phosphatic bodies in the southern African material and the usual absence of teeth on the spires of both the body wall and tail tables. These differences are too small to describe a new species in a genus where enough specimens are necessary for comparison. It is well known that the amount of phosphatic bodies does vary with age as they become transformed to other deposits. The paucity of toothed spires may possibly be due to abrasion as they project well out from the surface of the body wall.

Trochostoma was reduced to the synonymy of Molpadia by H.L. Clark (1907). Heding (1931) and Deichmann (1936 & 1940) attempted a re-classification of the molpadids but without much success. Although Pawson (1977) supported H.L. Clark’s synonymy, Cherbonnier and Féral (1981) state that there is enough evidence to resurrect Trochostoma based on features of the calcareous ring and body wall deposits, notably the absence of rosettes and racquet-shaped bodies. Despite this, the species is here transferred to Molpadia until a critical revision of the molpadiids is forthcoming.

Figures

FIGURE 23. Molpadia triforia Cherbonnier, 1965. SAM–A27948. A. tables from body wall; B. incomplete table disc from body wall; C. spires of body wall tables; D. tables from tail; E. madreporite; F. part of calcareous ring; (A–D scale a)