Panningia pseudocurvata, 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 : 11-14

Panningia pseudocurvata n. sp.

Figures 6 & 7

Diagnosis. A small, U-shaped species (holotype 12 mm), beige-yellow in alcohol. Tentacles 10, of more or less equal size. Anal teeth poorly calcified. Tube feet restricted to ambulacra, in 1–2 single/double zigzag rows; end-plates present; interambulacra naked. Calcareous ring simple, radial plates anteriorly broad, bifid, posteriorly narrow, with short paired posterior prolongations. Polian vesicle single, stone canal short, madreporite bean-shaped. Body wall deposits as large, imbricating, smooth, multilocular plates, often with one end narrowed, roughened and slightly turned up as a short, elevated projection; other plates smaller, without projection. Tube feet deposits as elongated rods. Tentacle with mostly curved, spanner-like rods. Introvert with rosettes and rosette-like multilocular plates.

Etymology. This species is so named because of its obvious resemblance, in form and ossicles, to P. curvata Cherbonnier, 1958 .

Material examined. Holotype SAM A28098, AHAB-9, stn. -88, Dredge, Angola, 7.235° S, 12.684° E, 11.17, 28.v.2004, 41 m, Forster & Zettler; Paratype SAM A28099, same data as holotype; SAM A28100, (juvenile), AHAB-9, stn. -66, Dredge, Angola, 9.562° S, 13.100° E, 25.v.2004, 26 m, Forster & Zettler.

Description of holotype. Specimen small, U-shaped, anus situated above level of mouth ( Figure 6 A). Length along ventral surface 12 mm, width in mid-body 1.5 mm. Colour in alcohol beige-yellow, uniform. Tentacles 10, retracted, of more or less equal size, well branched. Anus encircled by five slightly calcified anal papillae. Tube feet restricted to ambulacra, mostly in a single zigzag row per dorsal ambulacrum and in two zigzag rows per ventral ambulacrum, better developed ventrally, especially in middle of mid-ventral surface, becoming smaller in size both anteriorly and posteriorly, few reaching level of mouth and anus. Tube feet generally thin, some filamentous, suckers present, better developed ventrally, both sucker and tube foot of equal diameter. End-plates present (Figure 7B). Interambulacra naked. Skin thin, slightly translucent, covered with imbricating plates/scales.

Calcareous ring ( Figure 6 B) delicate, simple. Radial plates anteriorly bifid with anterior part narrow proximally, distally broad with short paired, undivided, posterior prolongations, each plate with a deep groove/depression for attachment of retractor muscle. Interradial plates triangular with a slight anterior indentation and a slight posterior concavity. Stone canal short, slightly curved, madreporite bean-shaped ( Figure 6 C). Polian vesicle single, slightly elongate, ventral. Left respiratory tree longer, reaching two-thirds body length, right one short, reduced to few branches. Gonad mature, tubules unbranched, full of ripe and developing eggs. Longitudinal muscles as single strands; retractor muscles arise in anterior third of body, more anteriorly in the ventral ambulacra, inserting without branching on the middle portion of the radial plates.

Body wall ossicles as imbricating multilocular plates (136–184 µm, mean 155 µm, SD ± 25, n = 10), slightly smaller ventrally; plates always smooth, often with one portion narrowed, roughened and turned slightly up as a short, elevated projection ( Figure 6 D); other plates smaller ( Figure 6 E), also smooth, multilocular, oblong without projection (80–175 µm, mean 137 µm, SD ± 32, n = 10), the latter as the only deposits in the anal region. Pedicel deposits (Figure 7A) in the form of elongated rods, usually swollen and perforated at both ends and sometimes also in the middle (47–92 µm, mean 73 µm, SD ± 14, n = 10). Tentacle ossicles (Figure 7C & D) as rods of various form, mostly curved, spanner-like with one or more perforations at one or both ends (29–55 µm, mean 41 µm, SD ± 8, n = 20); some rods with a third arm or cross-like, such rods often elaborate with swollen multilocular ends (33–57 µm, mean 42 µm, SD ± 6.5, n = 20). Introvert deposits as rosettes (Figure 7E) arising from branched rods (Figure 7F), and rosette-like multilocular plates (23–47 µm, mean 35 µm, SD ± 5.6, n = 20).

Distribution. Known only from the type locality, 26– 41 m.

FIGURE 7. Panningia pseudocurvata n. sp. Holotype, SAM A28098. A. rods from tube feet; B. endplate; C. tentacle deposits; D. larger rods from tentacles; E. introvert deposits; F. developing rosettes from introvert.

Habitat. Medium coarse sediments with median grain size of 356 µm in water depth of 26 m. At 41 m, sandy substrate.

Remarks. Of the five nominal species of Panningia , the new species comes quite close to only Panningia curvata Cherbonnier, 1958a from Sierra-Leone, differing from it in the smoothness of the plates, their less pronounced projection and the abundance of spanner-shaped deposits in the tentacles. In Cherbonnier’s species the tentacle deposits are said to be rare and no spanner-like rods are described. Cherbonnier illustrates a rosette-like deposit from a tentacle but he mentions that this is also rare. It is possible that this might have come from the introvert of his specimen. Like the family Rhopalodinidae , the genus Panningia appears to be restricted to the East Atlantic waters and perhaps close to the form from which the rhopalodinids might have originated.

Figures

FIGURE 6. Panningia pseudocurvata n. sp. Holotype, SAM A 28098. A. Specimen entire; B. calcareous ring; C. madreporite; D. dorsal body wall plates; E. ventral plates.