Lanceophora lanceolata, Thandar, Ahmed S., Zettler, Michael L. & Arumugam, Preyan, 2010

Thandar, Ahmed S., Zettler, Michael L. & Arumugam, Preyan, 2010, Additions to the sea cucumber fauna of Namibia and Angola, with descriptions of new taxa (Echinodermata: Holothuroidea), Zootaxa 2655, pp. 1-24 : 14-15

Lanceophora lanceolata n. sp.

Figures 8 & 9

Diagnosis. A small, slightly curved, barrel-shaped species, up to 10 mm long. Anal teeth present. Holotype with only eight large, poorly branched tentacles. Tube feet in 1–2 zigzag rows, interambulacra naked. Calcareous ring without obvious posterior prolongations, both radial and interradial plates anteriorly bifid. Polian vesicle single. Body wall deposits of two types: superficial layer comprising a perforated, bulbous, spinose, basal portion with an elongated lance-like projection, and a deeper layer of smooth to slightly knobbed to spinous multilocular plates. Anal deposits as smooth, perforated plates. Tube feet comprising table-like rods with a bifurcate basal portion and a short or lance-like, spire-like portion; end-plates present. Tentacle stalks with large, multilocular plates; tentacle tips with rods and rosette-shaped deposits.

Etymology. The specific name derives from the lance-like extensions of the superficial body wall deposits

Material examined. Holotype, SAM A28101 , AHAB-9, stn. -88, dredge, Angola, 7.235° S, 12.684° E, 11.17, 28.v.2004, 41 m, Forster & Zettler, Paratypes, SAM A28102, same data as holotype, 2 specimens.

Description of holotype. Specimen small, slightly curved or U-shaped; length 10 mm, breadth in midbody 3.5 mm ( Figure 8 A). Preserved colouration beige-ash brown, uniform. Mouth and anus terminal, the latter encircled by five teeth appearing as valves, flanked by terminal podia. Tentacles retracted, only eight large tentacles counted, poorly branched. Tube feet well developed, short, in two zigzag rows per ambulacrum ventrally and in a single or double zigzag rows dorsally, suckers well developed; interambulacra naked. Skin thin, soft; spinal projections of ossicles seen protruding from body wall.

Calcareous ring ( Figure 8 B) poorly calcified, soft, typically cucumariid with no posterior prolongations to the radial plates; both radial and interradial plates anteriorly bifid, each with a posterior concavity. Polian vesicle short, single. Stone canal short, straight, terminating in a well calcified madreporite. Retractor muscles short. Longitudinal muscles thin, undivided. Gonadal tubules unbranched. Respiratory trees consisting of one long branch extending to anterior third of body and several short branches restricted to base. Cloaca wide.

Body wall ossicles of two types: a superficial layer of deposits with an elongated lance-like projection and a deeper layer of smooth to slightly knobbed to spinous multilocular plates (118–152 µm, mean 137.8 µm, SD ± 10.9, n = 10). Each superficial deposit ( Figure 8 C) comprises a perforated, bulbous, spinose basal portion bearing a lance-like projection, with a narrow proximal portion which rapidly expands to form wing-like structures with thick margins around an accentuated midrib. Plates of deeper layer multilocular, oval to circular, with an undulating margin, knobs/spines, when present, often medially restricted ( Figure 8 D). Anal deposits in the form of smooth, mostly elongated, perforated plates ( Figure 8 E). Tube feet deposits comprising rods with a bifurcate basal part, with a hole at each end and in the middle, and an elongated spinelike portion similar in form to the superficial body wall deposits ( Figure 9 A); other tube feet deposits more table-like, also with a bifurcate base, perforated one or more times at ends, and a perforated, short, spire-like portion with a large central hole ( Figure 9 B). End-plates present ( Figure 9 C). Tentacle deposits of various form, base of tentacle with large multilocular plates ( Figure 9 D), tentacle tips with slender to stout rods, perforated once or more at ends ( Figure 9 E), and rosette-shaped deposits ( Figure 9 F).

Distribution. Type locality only, 41 m.

Habitat. Sandy substrate.

Remarks. It is with some hesitation that the three specimens are described as a new species although they come very close Cucumaria souriei Cherbonnier, 1949a , described from Dakar ( Senegal), differing from it in its size (10 mm vs. 27mm), distribution of the ventral tube feet and some aspects of its body wall deposits. While the first two differences may be attributable to age of the materials, the ossicles appear to be different. Despite the fact that the superficial deposits are of the same form, in the present material the basal portion of these deposits are mostly feebly knobbed/spinose and the lance-like extensions bear a prominent midrib. In C. souriei the basal part of these deposits are mostly smooth with only a few feebly knobbed and the midrib of the projections, if present, neither described nor illustrated. A second point of contention, which appears more valid than the first, is that Cherbonnier (1949a) only vaguely refers to the rounded plates which in our specimens are very prominent, and unlike that illustrated by Cherbonnier, mostly finely knobbed/spinose. In other respects the two species appear very close. It would be interesting to determine the actual form and concentration of the two types of body wall deposits in C. souriei . Regrettably the holotype of C. souriei was not initially located by the French Museum and the specimen finally received and purported to represent C. souriei , turned out to be referable to Panningia crosnieri Cherbonnier, 1963 originally described from Cameroon.

The new species differs from P. crosnieri in the more elaborate extensions of the superficial body wall deposits and the absence of any obvious posterior processes of the radial plates of the calcareous ring. In P. crosnieri the prolongations of the deposits is held at an angle to the basal part. In the current material the basal part and the extension are in apparently one plane as in C. souriei . P. crosnieri , in addition, has equal tentacles and short and massive posterior processes to the radial plates. Although posteriorly, the radial plates of our species may appear to have incipient prolongations, these are due to the deep posterior concavity of each plate.

It must be emphasized that while the lance-like extensions of the deposits in the new species are similar to those of C. souriei , their basal portions and the deeper plates are typical of P. crosnieri . Hence the three species are closely related.

Figures

FIGURE 8. Lanceophora lanceolata n. sp. Holotype, SAM A 28101. A. Specimen entire; B. calcareous ring; C. superficial deposits with lance-like projection from body wall; D. body wall plates; E. anal plates.

FIGURE 9. Lanceophora lanceolata n. sp. Holotype, SAM A 28101. A-B. Tube feet deposits; C. endplate; D. deposits from base of tentacles; E. slender to stout rods from tentacles tips; F. rosette-shaped deposits from tentacle tips.