Plesiocolochirus dispar Lampert 1889
| Main Author: | Thandar, Ahmed S. |
|---|---|
| Format: | info publication-taxonomictreatment |
| Terbitan: |
, 2006
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/5674058 |
Daftar Isi:
- Plesiocolochirus dispar (Lampert, 1889) Figure 9 Colochirus dispar Lampert, 1889: 820, fig. 4; Ekman, 1918: 32. pl. 3, fig. 25, pl. 4, fig. 26. Pentacta dispar Clark & Rowe, 1971: 180 (dist.); Cherbonnier, 1988: 164, fig. 68. Colochirus gravieri Vaney 1905: 187. Pentacta gravieri Cherbonnier, 1955: 162, pl. 48, figs. k–s. Pentacta trimorpha Clark, H.L. 1921: 171, pl. 37 (1–8). Plesiocolochirus dispar Rowe (in Rowe & Gates 1995): 278 (syn.) Type Syntypes perhaps in Stuttgart, Germany. Type locality Mermaid Strait, northwest Australia. Previous southern African record None. Material examined SAM A 23175, Coconut Bay, Mozambique, 17.v. 1973, 1 spec. Description Form barrelshaped, with dorsal surface arched and ventral flattened, solelike, but sole not clearly defined; anterior end broad, posterior narrow and turned upwards. Length about 10 mm, diameter of anterior and posterior ends 5 mm and 2.5 mm respectively. Colour uniformly white, including podia and tentacles. Podia restricted to ambulacra in double rows but most of those of midventral ambulacrum retracted, except at anterior and extreme posterior ends; those of ventrolateral ambulacra mostly well extended; dorsal podia indistinct because of scales which envelope most of dorsum. Ventral podia with welldeveloped suckers. Mouth starshaped, boarded by five, distally calcified valves, especially the midventral one which appears as a toothlike structure. Tentacles 10, midventral two reduced. Anus terminal, surrounded by five teeth, each flanked by subterminal podia. Skin thin and rough to the touch. Calcareous ring (Figure 9 L) simple, well calcified, radial and interradial plates fused, radial plates with a bifid anterior prolongation for attachment of retractor muscle and a notched posterior surface; interradial plates shorter than radial plates, with a triangular anterior end and slightly indented posterior surface. Polian vesicle single, saclike; stone canal short, free; madreporite (Figure 9 K) spherical, grooved, lodged in the posterior notch of middorsal interrradial plate. Respiratory trees delicate, extremely transparent but well branched, right tree reaches about one third the body length from anterior end, left one shorter. Gonad not observed. Longitudinal muscles unpaired, thin, well developed anteriorly, fused to body wall for most of their length. Retractor muscles arise as single strands from the anterior third of the longitudinal muscles. Dorsal body wall invested in imbricating scales and, besides these, include deposits of four types: multilayered buttons with large knobs; simple buttons with small knobs; usually complete baskets; and developing spicules of various shapes and sizes. Scales (Figure 9 A) rather complex, oval, 105–875 μm long; smallknobbed buttons of various shapes and sizes (Figure 9 B), 48–65 μm (mean 56 μm); largeknobbed buttons (Figure 9 C), 58–71 μm (mean 63 μm), with four or more holes; baskets characteristic, flat (Figure 9 E), 39–65 μm (mean 51 μm), with four large and four smaller alternating holes, surface spinose. Dorsal podia supported by perforated rods and plates (Figure 9 F), 84–165 μm (mean 94 μm), some with marginal tuberosities (Figure 9 G) and reduced endplates, 90–145 μm (mean 132 μm). Ventral podia with similar deposits but larger endplates, 170–240 μm (mean 202 μm) (Figure 9 D). Tentacles supported by elongated, perforated rods, 42–258 μm (mean 107 μm), smaller in the branches (Figure 9 H) and larger in the stalk (Figure 9 J), as well as rosettes (Figure 9 I), 16–32 μm (mean 24 μm). Distribution Tropical IndoWest Pacific, up to 20 m. Remarks The single specimen was at first thought to represent Psolidium ornatum (E. Perrier, 1893). However, Dr Rowe (pers. comm.) drew my attention to Plesiocolochirus dispar (Lampert), a species which he thinks the specimen represents. I checked several descriptions of P. dispar and its synonyms and I concur with Dr Rowe without reservation. P. dispar has been recorded from the Red Sea and Somalia (see Clark & Rowe 1971) but this is its first record from southern Africa. However, the species was reported from Tuléar and Nosy Bay (Madagascar) by Cherbonnier (1988) who also provides a detailed description of the species. The current specimen agrees well with that material.
- Published as part of Thandar, Ahmed S., 2006, New species and new records of dendrochirotid and dactylochirotid holothuroids (Echinodermata: Holothuroidea) from off the east coast of South Africa, pp. 1-51 in Zootaxa 1245 on pages 28-30, DOI: 10.5281/zenodo.172917