Pseudostichopus langeae Thandar, 2009

Thandar, Ahmed S. & Rambaran, Ryan, 2015, On some sea cucumbers (Echinodermata: Holothuroidea) from off the south and west coasts of South Africa collected by the South African Environmental and Observation Network (SAEON), Zootaxa 3999 (1), pp. 41-61 : 44-46

Pseudostichopus langeae Thandar, 2009

( Figure 3 )

Pseudostichopus langeae Thandar, 2009: 30 –33, figs. 1 and 2.

Diagnosis (see Thandar 2009)

Material examined. A31419 , West Coast Survey 2011, just north of Lambert’s Bay, 31° 51.325'S, 16° 27.789'E, Demersal Trawl 060-4080, Cruise 270, 368 m, 29/01/2011, 2 specs.

Description. Body sub-cylindrical, slightly flattened ventrally, slightly arched dorsally, length up to 55 mm, width of mid-body up to 5 mm; encrusted predominantly with sand grains, but Foraminifera and shell debris also present. Skin with longitudinal ridges and depressions, mostly concentrated in extremities of ventro-lateral regions, encrustations more abundant in depressions. Mouth ventral, anus sub-ventral. Colour in live state white, off-white to grey in alcohol. Tube feet very reduced (0.5–1.5 mm), fine, in paired longitudinal rows dorso- and ventrolaterally, more common dorsally; mid-ventral and mid-dorsal regions naked, tube feet reach level of mouth and anus. Papillae and anal teeth absent. Both specimens with part of gut protruding through anus. Pygal furrow distinct. Tentacles 20, peltate, crown 1 mm in diameter.

Calcareous ring fragile, radial and inter-radial plates notched posteriorly, radial plates larger and more deeply notched; inter-radial plates each with triangular anterior projection; radial plates undulating anteriorly. Gut filled with sediment. Stone canal and madreporite not detected. Polian vesicle single, 5 mm, saccular. Respiratory trees yellow, well-branched, left tree spans just over half the body length, right tree extends throughout length of body, attached to body wall, both trees originate from single stem posteriorly. Gonad large, single tuft, unbranched. Longitudinal muscles thick, paired, appear cylindrical.

Ossicles only present in tentacles, tube feet, respiratory trees and gonad. Tentacles with straight or slightly curved rods (124–220 µm), usually with smooth margins or sometimes adorned with few spines, extremities may be branched, toothed, truncate, rarely perforate. Tube feet rods similar in form but smaller (98–152 µm) and with greater curvature due to their concentric arrangement within each podium. Respiratory trees with very small (74– 92 µm), usually x-shaped rods formed from dichotomously branching arms which may sometimes branch more than twice, rods thickened centrally, usually before branching of arms. Arms taper into extremities forming sharp, pointed ends which may be adorned with one or two spinelets. Gonad with small y-shaped or straight rods, variable in size (32–84 µm), centrally thickened, arms tapering into extremities forming sharp, pointed ends; often as c- or s-shaped bodies, sometimes irregularly branched, also present. Pygal lobes without ossicles.

Distribution. South and west coasts of South Africa, 186– 368 m.

Remarks. The most comprehensive revision of pygal-furrowed synallactids is by O’Loughlin and Ahearn (2005). In this revision, the authors described new species, presented new combinations and provided a wellconstructed key to the group ( Thandar 2009). According to Thandar this species comes close to Pseudostichopus occultatus von Marenzeller, 1893 and P. peripatus (Sluiter, 1901) .

P. occultatus occurs in the Mediterranean Sea at depths of 415–1445 m and in the north Atlantic, off the coast of Spain, at depths of 363– 510 m. The specimens in the current collection, as well as those described by Thandar (2009), have not been recorded at depths greater than 368 m, thus excluding them from the bathymetric range of the Mediterranean species while reaching the lower limit of the bathymetric range of the north Atlantic species. There are, however, major differences between P. occultatus and the current species in that no ossicles are present in the pygal lobes, nor any sponge spicule encrustations, absence of body epibiotes, as described by O’Loughlin (2002), and no end-plates in the tube feet as described by O’Loughlin and Ahearn (2005).

\ P. peripatus (Sluiter, 1901) on the other hand, with its long list of synonyms, is virtually a cosmopolitan species ( Thandar 2009). This, together with its considerable variety of ossicles and body forms, indicates that it is a polymorphic species. It, however, differs from P. langeae in its dorso-ventrally depressed body, serrated ventrolateral margins created by strong wrinkling and transverse creases, and different form of the gonad rods (see O’Loughlin and Ahearn 2005).

The current material is identical to the type described by Thandar (2009) but with minor variations. These include the absence of broken shells, coral debris and echinoderm spines in the encrustations. While the x- and yshaped rods are present in both the respiratory and gonad, in the current specimens the former are almost exclusively confined to the respiratory trees and the latter to the gonad. Thandar’s type contained a mixture of both x- and y-shaped rods in both the respiratory trees and the gonad. The ossicles of the tentacles and tube feet of the current material fall within the range mentioned by Thandar (2009) (300 Μm for tentacle rods, 200µm for tube feet deposits), however the gonad rods are noticeably smaller (120µm in the type). This is the second record of this species. The depth range recorded herein increases the bathymetric range by only 35 m and the horizontal range from off Cape Peninsula to just north of Lambert’s Bay. The coordinates recorded for Paratype SAM-A28043 by Thandar (2008) is inaccurate and should read 34° 46' S, 17° 98' E.

Figures

FIGURE 3. Pseudostichopus langeae Thandar, 2009. A 31419, A. Tentacle rods; B. X-shaped rods from respiratory trees; C. Yshaped rods from gonad; D. Tube feet rods; E. Calcareous ring; F. Specimen entire, courtesy Lara Atkinson. (Figures A-D, scale a; Figure E, scale b).