Pseudocnus intermedia Theel 1886
Creators: name: O'Loughlin, Mark
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Holothuroidea
Dendrochirotida
Cucumariidae
Pseudocnus
Pseudocnus intermedia

description: Pseudocnus intermedia (Théel, 1886)
Figure 2 d; table 1.
Cucumaria serrata var. intermedia Théel, 1886: 74, pl. 3 fig. 6, pl. 4 fig. 2.
Cucumaria laevigata (Verrill, 1876).— Ekman, 1927: 396 –403, fig. 15 (part non Pseudocnus laevigatus (Verrill, 1876)).
Material examined. Kerguelen Is, Bras Bossière, 4–5 m, BANZARE stn 6, SAM K2377 (8); Royal Sound, 2–20 m, BANZARE stn 49, SAM K2385 (4); Heard I., 85–93 m, ANARE HRD 0 0 2, NMV F84984 (1); 62– 80 m, ANARE HRD 0 0 7, NMV F84982 (1).
Diagnosis. Body fusiform, elongate, thin, up to 80 mm long, 12 mm maximum diameter, tapered posteriorly; 10 subequal dendritic tentacles; tube feet in single to zig-zag radial series that cross introvert, sometimes sparse dorsally, closer on ventral radii; 5 anal scales; ‘ring’ not calcified; 3 polian vesicles; sexes separate, small male genital papilla.
Ossicles in mid-dorsal body wall abundant pear shaped plates and knobbed buttons; pear shaped / pine cone shaped plates extensively knobbed on surface and margin, one narrow end spinous, typically 4 large central perforations, perforations small distally, plates up to 176 µ m long, commonly 120 µ m long; knobbed buttons irregularly oval, not narrowed and spinous distally, typically 4 large central perforations, knobbed on surface and margin, buttons up to 128 µ m long, typically smaller than spinous plates.
Distribution. Heard and Kerguelen Is, 2–275 m (Théel 1886).
Remarks. Ekman (1927) judged that Cucumaria serrata Théel, 1886 (and Théel’s varieties intermedia and marionensis) were junior synonyms of Cucumaria laevigata (Verrill, 1876). The consistent and exclusive form of the ossicles in the Heard and Kerguelen material examined here support the recognition by Théel (1886) of both Cucumaria serrata and Cucumaria serrata var intermedia, although Théel did not recognize the similarity of Cucumaria serrata with Pseudocnus laevigatus (Verrill, 1876). The status of Cucumaria serrata and the generic assignment of the species will be treated in a paper on Heard I. holothuroids. In this work Cucumaria serrata var. intermedia Théel, 1886 is raised out of synonymy, and the variety is raised to species status. The species is re-assigned to Pseudocnus Panning, 1949 on the basis of: 10 equal tentacles; weakly developed calcareous ring lacking posterior prolongations; pear shaped / pine cone shaped knobbed ossicles, spinous at the narrow end; oval knobbed buttons. It is distinguished amongst Pseudocnus species by radial only series of tube feet, and presence of both knobbed spinous pear-shaped ossicles and knobbed oval buttons, both shorter than 180 µ m long. The two ossicle forms are similar to the Magellanic species Pseudocnus dubiosus leoninus (Semper, 1868), but this latter species has a complete cover of tube feet.
The descriptive characters of the specimen of Pentactella laevigata Verrill, 1876 from only 22 m at Kerguelen I. raises the possibility that what is being described here as Pseudocnus intermedia is Verrill’s species. Verrill’s description of the size being 80 mm long by 24 mm diameter better describes what is judged here to be P. laevigatus than the thinner-bodied P. intermedia (80 mm long by 12 mm diameter).
description: Published as part of O'Loughlin, Mark, 2009, BANZARE holothuroids (Echinodermata: Holothuroidea), pp. 1-18 in Zootaxa 2196 on pages 7-8, DOI: 10.5281/zenodo.189493