Cucumella triplex Ludwig & Heding, 1935

Thandar, Ahmed S., 2018, On some miscellaneous sea cucumbers (Echinodermata: Holothuroidea) in the collections of the South African Museum with three new species, Zootaxa 4532 (1), pp. 57-85 : 73-75

Cucumella triplex Ludwig & Heding, 1935

( Figure 13 )

Cucumella triplex Ludwig & Heding, 1935: 210 , pl. 2, figs. 39–49; Heding, 1942: 220, figs. 12 & 13; Deichmann, 1948: 359; Heding & Panning, 1954: 66, fig. 16(a–e), Thandar, 1991: 137; Thandar & Arumugam, 2011:47 (passim).

Material examined. SAMC-A 090920 , SM 162, off East London , Eastern Cape Province, South Africa, 32°55’ S, 28°31’ E, heavy dredge, 630 m, 25.V.1978, 3 spec .

Description. Specimens well preserved, slightly U-shaped ( Figure 12A ), colour in alcohol beige-white. Largest about 5 mm long and 2.5 mm wide. Smallest specimen more U-shaped, perhaps due to stronger contraction. In all specimens anterior end broader than posterior, with some tentacles clearly protruding from mouth. All tentacles finger-shaped or digitate. In largest specimen only 5 large tentacles could be easily counted while other large ones have detached but lie free in the fluid, the 2 ventral ones apparently reduced. Medium-sized specimen also with 5 large tentacles and 2 reduced ventral ones. In the smallest specimen there are definitely 10 tentacles with an 8+2 arrangement. Anal papillae present, of which two are better developed than others ( Figure 12A ), but these are not as long as in C. triperforata and not easily demonstrated in the medium specimen. Tube feet reduced and sparse, absent on the dorsal surface of largest individual, which has about 5–7 tube feet per ambulacrum ventrally; medium-sized specimen with few short tube feet antero-dorsally, fewer postero-dorsally and about 6–8 on the three ventral ambulacra. Smallest specimen with very few, apparently retracted tube feet, difficult to demonstrate. Largest specimen (mature male) with translucent body wall, with some internal organs visible through it. Ossicles of dorsal and ventral body wall identical, comprising only tables, mostly with triradiate, sometimes quadri-radiate disc with three or more holes ( Figure 12B & C ); disc 94–131 µm, spire short, up to 31 µm in height, terminating in a tri-forked or quadri-forked apex armed with minute teeth; basic table discs apparently trilocular with more holes developing by partitioning of these or are added on later. Tube-feet deposits ( Figure 12 D ) as simple rods, up to 81 µm, with few marginal spines and usually one or two marginal holes located medially. Tentacle ossicles as rods and plates, the former straight or curved, up to 100 µm long with few marginal spines and holes ( Figure 12E ), resembling tube-feet rods but much larger; plates smooth, multilocular ( Figure 12F ), up to 313 µm.

Distribution. Agulhas Bank to East London, South Africa, 155– 630 m.

Remarks. The tentacle number of the holotype of C. triplex was only arrived at after Heding’s (in Ludwig & Heding, 1935 and Heding 1942) several examinations of the type. Of the current material, only the largest specimen was dissected in order to determine its exact tentacle number but this was not ascertained, as some tentacles were very minute. In all other respects the specimens resemble that described by Heding (in Ludwig & Heding, 1935). Tables with trilocular disc resemble those of C. triperforata but these are later transformed to those with multilocular disc absent in the latter species; disc circular with undulating margins. Intermediate stages between the two types are common. Furthermore, the spire in C. triplex ends in usually three toothed prongs where as those of C. triperforata end in two non-toothed prongs.

Figures

FIGURE 12. Cucumella triperforata Thandar & Arumugam, 2011. SAMC-A090919. A. Specimen (entire); B. Body wall ossicles; C. End-plates from tube feet.

FIGURE 13. Cucumella triplex Ludwig and Heding, 1935. SAMC-A090920. A. Specimen (entire); B. Tables from dorsal body wall; C. Tables from ventral body wall; D. Rods from tube feet; E. Rods from tentacles; F. Plates from tentacles.