Zygothuria candelabri ( Hérouard, 1923 )

Gebruk, Andrey V., Solis-Marin, Francisco A., Billett, David S. M., Rogacheva, Antonina V. & Tyler, Paul A., 2012, Review of the genus Zygothuria Perrier, 1898 and the Atlantic group of species of the genus Mesothuria Ludwig, 1894 (Synallactidae: Holothuroidea) with description of the new species Mesothuria milleri sp. nov., Journal of Natural History 46, pp. 265-348 : 322-325

Zygothuria candelabri ( Hérouard, 1923)

( Figure 16 )

Mesothuria candelabri – Hérouard, 1923: 17–19, pl. 1, figs. 1–10; Madsen, 1953: 153. Non Mesothuria (Allantis) candelabri – Heding, 1940: 334–335, textfig. 3 [= Mesothuria (Penichrothuria) cathedralis ].

Zygothuria candelabri ( Hérouard, 1923) – Deichmann, 1930: 111.

Material examined

See Table 12.

Type material

Syntype (fragments), MOM, Princesse-Alice, St. 2986, 17 August 1910, 45 ◦ 7 ′ 30" N, 7 ◦ 6 ′ W, 4870 m .

Type locality

Atlantic Ocean, Bay of Biscay, 4870 m.

Diagnosis

Body ovoid, flattened, but with a well-differentiated sole; integument often wrinkled. Tubefeet arranged exclusively in single or double row along ventrolateral ambulacra, placed on sole margin, which often forms a fringe. Twenty tentacles. Calcareous ring well developed, with squarish radial pieces.

Ossicles tables with spire of three (rarely four) columns; arms of spire three rarely four, arms spinous or slightly spinous, longer than stem ( Figure 16 ); arm length 0.08–0.14 mm. Disks with seven or eight holes; several holes in outer circle may develop; disk diameter from 0.1 mm to 0.2 mm.

Remarks

The original description of Z. candelabri was based on fragments. It is a deep-living form recorded from 3757 to 4870 m in the north-east Atlantic ( Billett 1991). Ossicles similar to those in Z. candelabri occur in Mesothuria (Zygothuria) lactea var. spinosa ( Heding 1940) , size unknown, recorded from 5108 m in the south-east Atlantic ( Figure 6 ). The latter species is likely to be age variation of Z. thomsoni : the arms of the spire are shorter in this species. There is also a similarity between these forms and Z. connectens , 60 mm long, recorded off north-west Africa from 1975 to 2518 m. A difference occurs, however in that the arms of spire in the former are spinous, whereas they are smooth in the latter. Confusion is added by the variety Z. thomsoni var. hyalina (Théel, 1886) , 68 mm long, known from the Southern Ocean (off southern Australia) from 3294 m ( Figure 6 ), which differs from the type in the arms of the spire being less spinous. All these forms are closely related and they require further study. Records of

(Continued)

Z. candelabri from the Kermadec Trench (south-west Pacific) by Hansen (1975) need to be confirmed as well.

Distribution

North-east Atlantic, Bay of Biscay; off Morocco ( Figure 6 ).

Bathymetric range

Depth 3890–4870 m ( Hérouard 1923; Madsen 1953).

Figures

Figure 6. Distribution of a group of Mesothuria and Zygothuria species.

Figure 16. Zygothuria candelabri (Hérouard, 1923). Ossicles from Hérouard (1923), redrawn.