Psolidothuria yasmeena, Thandar, Ahmed S., 2006

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 : 44-45

Psolidothuria yasmeena sp. nov.

Figure 15

Diagnosis

Small, up to 8 mm long, U­shaped to fusiform species, with tapering posterior end. Colour in alcohol white to yellowish­white. Tentacles eight, a few ventral ones reduced. Anal teeth/papillae absent. Podia sparse, apparently non­retractile, emitting from between scales, arranged in rows in ambulacra, better developed ventrally with 5–7 podia per ventral ambulacrum. Calcareous ring simple, delicate, ribbon­like. Spicules of body wall comprise simple, multilocular, imbricating, often faintly knobbed thecal plates, up to about 450 µm long. Plates of oral and anal siphons usually without knobs; more holes in dorsal (14–27) than in ventral plates (10–24).

Type

SAM A­ 279134, paratypes SAM­A27915.

Type locality

Between Port St. Johns and East London, 32 28.6’ S, 28 58.8’ E, R.V. ‘Meiring Naude’, St. SM 226, 24.vi.1979, 710– 775 m.

Material examined

Holotype and 24 paratypes.

Etymology

This species is named after my younger daughter Yasmeen, whose continuous interest in my work, even after my retirement, has been enough to keep me active for so long.

Description

Holotype (male) U­shaped to fusiform ( Figure 15 G), anterior end short, posterior end elongated, tapering. Length along ventral surface 8 mm, along dorsal surface 5.5 mm. Tentacles 8 ­ five large, ventral three small, retracted ­ all tentacles finger­shaped but finely branched ( Figure 15 H). Anal papillae/teeth absent. Colour white, yellowish­white in regions where viscera are visible through translucent body wall. Body wall covered by thecal plates from between which emerge relatively few podia, arranged in rows in ambulacra, better developed ventrally. Left and right ventral ambulacra with about five podia each, odd ambulacrum with 6–7 podia (mid­ventral ones paired), left and right dorsal ambulacra with 6–7 reduced podia each. Podia apparently non­retractile, whitish, with reduced suckers, decreasing in size anteriorly and moreso posteriorly.

Calcareous ring ribbon­like ( Figure 15 I), delicate, poorly calcified; radial plates without posterior processes but with a posterior concavity and a triangular anterior projection; interradial plates slightly narrower than radial plates, more or less of same shape, but anterior projections slightly shorter than those of radial plates. Internal anatomy as in Figure 15 G. Polian vesicle single, sac­like. Stone canal free, extremely short, terminating in an oval, poorly calcified madreporic body. Stomach distinct, intestine with a single loop. Respiratory trees poorly developed, without branches, each terminating in a slightly curved distal end. Cloaca elongate. Longitudinal muscles unpaired, retractors well developed, originating from anterior third of longitudinal muscles. Gonad as two tufts of tubules, four apparently mature tubules on right and three on left of mesentery.

Spicules of body wall comprise multilocular, imbricating, simple thecal plates; dorsal plates ( Figure 15 A) 305–457µm (mean 376 µm); ventral plates 248–405 µm (mean 323 µm), of one layer of calcareous material. Plates of oral and anal siphons usually without knobs, while superficial plates of the body wall usually with knobs, up to 12 knobs per dorsal plate and up to six per ventral plate, only occurring at free margin of plate; margin of plate irregular; holes large (14–27 in dorsal and 10–24 in ventral plates). Podial deposits include smaller plates with fewer holes and other much smaller deposits in the form of perforated rods and plates (ventrally 86–224 µm, mean 144 µm) ( Figure 15 C); endplates reduced (ca. 150 µm) with no regular arrangement of large and small holes ( Figure 15 B). Tentacles supported by perforated plates (38–110 µm, mean 61 µm) ( Figure 15 E) and rods ( Figure 15 D) (105–176 µm, mean 147 µm). Introvert with similar deposits ( Figure 15 F).

Paratypes range in size from 5–8 mm, all with retracted tentacles; body form, colouration and podial distribution (3–8 podia per row dorsally and 4–10 per row ventrally) as in holotype. Dissected paratype (male) also with eight tentacles (five large and three small). Internal anatomy as in the holotype; gonad with two pairs of unbranched tubules, each pair comprising three mature and one immature tubule. Spicules as in holotype.

Distribution

Type locality only.

Remarks

This species is clearly referable to the family Vaneyllidae as it corresponds well with the diagnosis of the family as amended by Thandar (1998). It is here assigned to the genus Psolidothuria , which was erected to accommodate only P. octodactyla Thandar , from considerable depths (2524–3255 m.) off the Cape Peninsula. In its body form, number and shape of tentacles, the structure of the calcareous ring and the form of the body wall, podial and tentacle deposits it comes very close to the latter species. However, it differs from P. octodactyla in its maximum size (8 mm cf. 28 mm), the distribution and nature of the podia, the absence of anal papillae, the form of the respiratory trees, the larger number of holes (up to 27 cf. 17) to the thecal plates, the smaller size of the holes (up to 50 µm cf. up to 100 µm) and the larger number of knobs on such plates. Further, the new species occurs in much shallower waters of the east coast.

Figures

FIGURE 15. Psolidothuria yasmeena sp. nov. Holotype. SAM­A 279134. A. scales from midlateral body wall; B. end­plate from ventro­lateral podium; C. plates and rod from ventro­lateral podia; D. rods from tentacle stalk; E. plates from tentacle tip; F. plates from introvert; G. internal anatomy; H. largest tentacle; I. calcareous ring. (CR—calcareous ring; pv—Polian vesicle). A scale a; B – F scale b; H – I scale c.