Thyone comata Cherbonnier, 1988

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 : 7-12

Thyone comata Cherbonnier, 1988

Figure 2

Thyone comata Cherbonnier, 1988: 198 –190, fig. 80.

Type

MNHNP, 3592.

Type locality

Tuléar ( Madagascar), 8– 50 m.

Previous South African record None

Material examined

SAM­A27889, NE of Kosi Bay, KwaZulu­Natal, 26 52.8’ S, 32 54.8’ E, NMDP St. ZA 33, 3 vi 1990, 45 m., 1 spec.; SAM­A27890, 26 52.4’ S, 32 55.2’ E, NMDP St. ZA 38, 3 vi 1990, 45– 47 m., 1 spec.; SAM­A27891, Gypsy Hill, Leadsman Shoal, 27 49.7’ S, 32 38.2’ E, ‘Meiring Naude’ St. ZK 1, 8.vi.1988, 47– 50 m., 1 spec.

Description

Best preserved specimen (SAM­A27890) swollen anteriorly and in the middle, narrowing posteriorly, posterior end turned upwards. Length of ventral surface excluding turned up posterior end 22 mm (35 mm including posterior end), width of mid­body 8 mm. Largest specimen about 38 mm long along ventral surface, 10 mm broad in mid­body. All specimens whitish in colour, including podia. Podia elongated, evenly scattered and often not retracted, slightly more numerous ventrally, giving the skin a villose appearance, sucking discs small. Mouth anterior, anus dorsally directed and in at least two specimens encircled by minute calcareous teeth. Tentacles retracted, number and size variation could not be ascertained despite dissection of calcareous ring of two individuals.

Calcareous ring complex, tubular, with radial plates carrying long bifurcate processes, both ring and processes fragmented, the latter in a single series; fragmentation of radial and interradial plates more or less similar. Both radial and interradial plates triangular, the anterior process of each radial plate with shallow indentation for insertion of retractor muscle, that of interradial plates pointed. Anterior process of each plate flanked at tip by thickened alae, those of the radials not meeting, hence each radial plate appears anteriorly notched; in addition, each radial plate deeply incised posteriorly, i.e. bifurcating before the posterior border of the corresponding interradial plate. Calcareous ring, including processes, about 10 mm in length in the smaller specimen and about 15 mm in the distorted specimen. Polian vesicle single, elongated. Stone canal not detected in both dissected specimens.

Spicules of dorsal and ventral body wall (SAM­A27890) identical, comprising twopillared tables ( Figure 2 A,B & C) with an irregular disc, perforated by usually four central and a varying number of marginal holes of more or less equal size to the central holes. Spire of moderate height ( Figure 2 B), terminating in 4(–6) teeth. Length of dorsal table discs 80–130 µm (mean 98 µm) with 8–13 holes, spire height about 40 µm; length of ventral table discs 90–110 µm (mean 100 µm) with 7–14 holes, spire height 40–44 µm. Deposits of dorsal and ventral podia identical, comprising two­pillared tables with curved discs perforated by four large central holes and several small holes at each end. Spire usually terminating in a single tooth or rarely in two teeth. Tables of dorsal podia ( Figure 2 G) with discs 62–96 µm (mean 81 µm), spire height 27–46 µm (mean 34 µm); table discs of ventral podia ( Figure 2 F) 68–101 µm (mean 85 µm), spire height 22–36 µm (mean 29 µm). Endplates ( Figure 2 D & E) well developed with small central holes and 2–3 series of larger marginal holes with the most peripheral of marginal series always smaller than those within; diameter of endplates 102–135 µm (mean 120 µm). Anal region with broken periproctal plates and small tables similar to those of body wall. Introvert deposits include only two­pillared tables ( Figure 2 I, J) with multilocular discs (59–94 µm, mean 76 µm) of varying shapes and with short spires (30–40 µm), terminating in 4–6 teeth. Tentacle stalks with delicate, perforated rods ( Figure 2 K) (40–69 µm, mean 50 µm), tentacle tips with rosettes ( Figure 2 L) (23–32 µm, mean 27 µm). Longitudinal muscles with delicate, perforated and branching rods (45–81 µm, mean 67 µm) ( Figure 2 J). Dorsal table discs of largest specimen 89–132 µm long (mean 113 µm) with 9–15 holes, spire height 44–60 µm; ventral table discs 94–141 µm long (mean 114 µm) with 10–19 holes, spire height 41–50 µm. Largest specimen with table discs of dorsal podia 62–139 µm long (mean 100 µm), spire height 27–57 µm (mean 35 µm); table discs of ventral podia 65–128 µm long (mean 86 µm), spire height 24–41 µm (mean 32 µm); endplates 115–168 µm in diameter, larger in dorsal podia.

Longitudinal? absent? slender, slender,?

muscle perforated, perforated,

deposits branching branching rods rods

Distribution

Southwest Indian Ocean, 8– 50 m.

Habitat

Sand, fine sand, coral sand, algae.

Remarks

The specimens here studied come very close to Thyone villosa Semper, 1868 , from Cebu ( Philippines), re­described from the type by Panning (1949), T. comata Cherbonnier, 1988 from Tuléar ( Madagascar) and Mayotte Island ( Comores) and, on the bases of body wall deposits alone, to T. pedata Semper, 1868 , recently described by Liao (in Liao & Clark 1995) from new material collected from the Gulf of Tonkin, South China Sea. In fact, so much is the resemblance of the present material to the above three species that I was at first inclined to consider T. pedata and T. comata to be junior subjective synonyms of T. villosa , a species not encountered since its original description. However, judging from an examination of the holotype of T. villosa , received by courtesy of the Hamburg Museum, and from Cherbonnier’ s description of T. comata and that of Liao’ s of T. pedata , there is some justification in keeping the three species separate. The southern African material comes very close to T. comata , to be almost indistinguishable. It differs from T. villosa in the form of the tentacle deposits, the thinness of the longitudinal muscles and the presence therein of slender branching rods (absent in T. villosa ) and from T. pedata in the presence of anal teeth and slender rods and rosettes in the tentacles and only tables (instead of rosettes) in the introvert.

It is a pity that Cherbonnier (1988) compared his T. comata only with T. pedata while his T. crebrapodia , also from Tuléar, he compared with T. villosa Semper and T. dura Koehler & Vaney. The latter species, described from the deep Arabian Sea (at 264 m), according to Koehler and Vaney (1908), shares some similarities with T. pituitosa Sluiter, 1901 from the deep tropical West Pacific (at 310 m). An examination of the holotype of the latter species at the ZMUA, showed that its calcareous ring is different from typical members of Thyone in being of the sclerodactylid rather than the phyllophorid type (see Thandar 1989c). This is also true for the calcareous ring of T. dura , judging from the figure given by Koehler & Vaney. Thus, Cherbonnier’ s T. crebrapodia cannot be compared with either T. pituitosa or T. dura . In fact, his T. comata resembles T. villosa more than does his T. crebrapodia . The latter species differs from the former two in the smaller size of its body wall and podial tables and in its tentacle deposits. Table 1 lists the characters of the above four nominal species of Thyone as well as those of the southern African material. The body wall, podial, tentacle and introvert spicules of the holotype of T. villosa are illustrated in Figure 3 .

Semper (1868) separated his T. pedata from T. villosa on the basis of the absence of anal teeth and this system was adopted by both Lampert (1885) and Théel (1886a). Regrettably, Panning (1949) overlooked T. pedata in his revision of the Cucumariidae . However, as shown above and in the table below, there is enough justification in maintaining the distinctiveness of both these species.

Figures

FIGURE 2. Thyone comata Cherbonnier, 1988. SAM­A 27889. A. tables from antero­dorsal body wall; B. tables from side; C. tables from postero­ventral body wall; D. end­plate from dorsal podium; E. end­plate from ventral podium; F. tables from ventral podia; G. tables from dorsal podia; H. tables from proximal introvert; I. tables from distal introvert; J. rods from longitudinal muscles; K. small perforated rods from tentacle stalk; L. rosettes from tentacle tip. A – K scale a; L scale b.

FIGURE 3. Thyone villosa Semper, 1868. Holotype. A. body wall tables; B. podial tables; C. tables from distal introvert; D. rods from tentacle tip; E. plates from tentacle tip. A – C scale a; D & E scale b.

Tables

TABLE 1. Distribution, depth records and morphological characters of four related species of Thyone, including the two South African specimens of T. comata.

	T. pedata (ex Liao 1995)	T. villosa (holotype)	T. comata T. comata T. comata (ex Cherb. ( A27889 ) ( A27890 ) 1988)	T.crebrapodia (ex Cherb. 1988)
Distribution	China Sea	Philippines	Madagascar East coast East coast & Comores South South Africa Africa	Madagascar
Depth (m)	55	26	8–32 45 45–47	shallow
Length (mm)	18–22	20	5–27 27 18	12–24
Anal teeth	absent	present	present present undetected	?
Body wall tables disc length (m)	119–128	93–122	100–130 89–141 79–128	55–60
spire heigth (m)	?	37–56	35–45 41–60 39–44	35–40
Podial tables disc length (m)	81–106	93–194	80–100 62–139 62–101	65–85
spire heigth (m)	31–41	37–59	20–35 24–57 22–46	20–30
Introvert deposits	rosettes (in heaps)	tables, discs (90–103 m), multilocular	tables, discs tables, tables, discs multilocular discs (59–94 m), multilocul multilocular ar	tables, discs 70–100 m), multilocular
Tentacle deposits	stout rods	irregular branching perforated rods and plates	slender slender slender rods, rods, rods, perforated at perforated perforated ends and at ends and at ends rosettes rosettes and rosettes	branched rods, perforated at ends, some rosette­like and rosettes
Longitudinal muscles	?	thick, conspicuous	thin to thick thin, thin, inconspicu inconspicuous ous	?