Ohshimella ocula ( Cherbonnier, 1988 ) 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 : 22-25

Ohshimella ocula ( Cherbonnier, 1988) comb. nov.

Figure 7

Phyllophorus (Urodemella) oculus Cherbonnier, 1988: 222 –224, fig. 97 (A–G).

Type

MNHNP, 2978.

Type locality

Mozambique Channel, 20– 25 m.

Previous South African record

None.

Material examined

SAM­A27905, off Sodwana Bay, KwaZulu­Natal, 27 32.8’ S, 32 42.8’ E, NMDP, St. ZH 19, 2 vi 1990, 77 m, 1 spec.; SAM­A27906, S.E. of Lala Nek, KwaZulu­Natal, 27 14.1’ S, 32 49.2’ E, NMDP, St. ZDD 8, 8 vi 1990, 84– 97 m, 1 spec.

Description

Both specimens barrel­shaped; colour in alcohol dirty off­white, slightly darker dorsally. Larger of the two specimens (off Sodwana Bay) approximately 45 mm in length and 23 mm in breadth; smaller specimen (Lala Nek) approximately 20 mm in length and 10 mm in breadth. Podia well developed and of same colouration as body wall — those of the larger specimen scattered in both ambulacra and interambulacra, more numerous ventrally; those of smaller specimen mostly confined to ambulacra in 2–3 rows with a few also in the interambulacra. Mouth anterior, anus posterior. Anal teeth absent, no special anal papillae. Tentacles 20, in two rings of 15+5; those of outer ring large but of unequal size (ventral ones slightly reduced), largest tentacle 10 mm in length; those of the inner circle small. Smaller specimen also with 20 tentacles, those of outer ring comprising 10 large and five small tentacles, the latter alternating with and of same size as the five of inner ring, giving the impression that there are 20 tentacles in two rings of 10+10; large tentacles beige­brown with darker basal branches and tips, smaller tentacles uniformly beige­brown. Body wall soft, slightly rough to the touch.

Calcareous ring complex, both radial and interradial plates well developed, somewhat fused basally and not fragmented, the former with a deep anterior notch for the attachment of retractor muscle; interradial plates triangular, slightly shorter than radial plates and slightly concave posteriorly. Posterior prolongations of radial plates short, fragmented but fragmentation often obscured by thick membrane. Calcareous ring of larger specimen, including processes, about 12 mm long. Polian vesicle single, well developed, saccular, 5 mm long. Stone canal single about 3 mm long, straight, anteriorly directed and partially attached to dorsal mesentery. Madreporite spherical and yellowish. Respiratory trees well branched, right one reaching anterior end of body, left one shorter, about half the length of the right one, both uniting before entering cloaca. Cloaca elongate, suspensors well developed. Most gonadal tubules lost in larger specimen, the remaining ones branched. Longitudinal muscles unpaired. Retractors short, arising anteriorly from longitudinal muscles and may or may not bifurcate before inserting on radial plates.

Spicules of dorsal and ventral body wall of same form, slightly larger ventrally, comprising numerous rosettes ( Figure 7 C) and relatively few spinous rods ( Figure 7 A, B, D), the latter developed as crosses with or without holes, holes when present usually two, rarely one. Spines developed only on arms of cross or only on its main body, or both.

Rosettes rounded, mulberry­like. Rods of the dorsal body wall of larger specimen 55–82 µm long (mean 69 µm), ventral rods 52–85 µm (mean 65 µm). Dorsal rosettes of larger specimen 23–45 µm (mean 32 µm), ventral rosettes 19–33 µm (mean 29 µm). Podial deposits include rosettes, scarce tables and multilocular plates, the latter surrounding large endplates. Rosettes ( Figure 7 F) 16–40 µm (mean 28 µm); multilocular plates ( Figure 7 E) 145–250 µm (mean 210 µm), of variable form, perforated by 8–35 holes; endplates 400–500 µm in diameter ( Figure 7 G), with no regular arrangement of large and small holes. Tables rare, delicate ( Figure 7 H), reduced, only four observed in about 10 preparations of podial deposits. Tentacle deposits include rosettes ( Figure 7 J) and slightly curved rods ( Figure 7 I). Rods 48–145 µm (mean 98 µm) long, with usually one, sometimes more, terminal perforations, larger ones with also terminal digitations/ tuberosities; larger rods in tentacle shaft, smaller ones in the terminal branches where rosettes predominate. Rosettes 22–58 µm (mean 42 µm). Introvert deposits include minute rods ( Figure 7 K), 38–90 µm (mean 63 µm) and rosettes ( Figure 7 L), 30–40 µm (mean 36 µm). Smaller specimen with identical spicules but no introvert deposits.

Distribution

South­West Indian Ocean.

Habitat

Dead coral and rubble; coarse sand, muddy sand.

Remarks

The two specimens described above correspond well with Cherbonnier’ s (1988) description of the type of Phyllophorus (Urodemella) oculus from the Mozambique Channel. On the basis of its spicules the species clearly falls in the genus Ohshimella and not Phyllophorus as it lacks table deposits of the type found in the latter genus. This is supported by Yves Samyn (pers. com.). Perhaps Cherbonnier was misled by some similarities in the spicules of his new species with that of P. (U.) brocki (Ludwig) , which precedes his description of P. oculus . However, in the former species the deposits are clearly tables or table derivatives, which is not the case in O. oculus . Incidentally, both species have a more or less similar calcareous ring, rosettes and tentacle rods. What is more surprising is that Cherbonnier states that his new species bears some affinities with Phyllophorus purpureopunctata ( Sluiter, 1901) . However, the spicules of both these species are remarkably different. Regrettably Cherbonnier did not compare his P. oculus with his Ohshimella castanea Cherbonnier, 1980 from New Caledonia. Although both these species may not be synonymous there is a striking resemblance in their body wall, podial and tentacle spicules. In fact, the podial and tentacle deposits of both are identical. I examined the holotype of O. castanea , received from MNHNP, and am of the opinion that there are sufficient differences between the two species to keep them separate. However P. (U.) oculus is here transferred to the genus Ohshimella .

Figures

FIGURE 7. Ohshimella ocula (Cherbonnier, 1988). SAM­A 27906. A. rods from body wall; B. rods / crosses from same; C. rosettes from ventral body wall; D. side view of cross from body wall; E. plates from dorsal podia; F. rosettes from dorsal podia; G. part of dorsal end­plate; H. table from ventral podium; I. rods from tentacles; J. rosettes from tentacles; K. rods from introvert of SAM­ A 27905; L. rosettes from introvert of SAM­A 27905. A – F & H – L scale a; G scale b.