Cladolabes arafurus O’Loughlin, 2014

P. Mark O’Loughlin, Melanie Mackenzie & Didier Vandenspiegel, 2014, New dendrochirotid sea cucumbers from northern Australia (Echinodermata: Holothuroidea: Dendrochirotida), Memoirs of Museum Victoria 72, pp. 5-23 : 6-7

Cladolabes arafurus O’Loughlin , sp. nov.

Zoobank LSID. http://zoobank.org:act:AB27AA20-F074-4C3B-

BABE-242616AD4A2F

Figures 1 , 2 .

Material examined. Holotype. N Australia, Arafura Sea, GA cruise SS 2012t 07, stn/site 01BS01, sample 110, 11.23°S 134.73°E, RV Southern Surveyor, benthic sled, 31 m, B. Alvarez de Glasby et al., 16 Oct 2012, NMV F202989 (UF tissue lot MOLAF1530 ).

Paratype. NE Australia, Queensland, Yeppoon, dredged off Middle Island , 23.13°S 150.74°E, 9–37 m, B. J. Smith, 6 Sept 1967, NMV F204070 (1).

Description. Form sub-spherical, up to 63 mm long (preserved), slightly convex dorsally, deeply convex ventrally, mouth anterior dorsal, anus posterior dorsal, slightly developed oral and anal cones (preserved); dorsal body wall thicker than ventral wall, creased, covered closely with numerous tube feet, diameters about 0.5 mm; ventral body wall thin, scattered cover of tube feet; lacking anal scales; 20 dendritic tentacles, 15 large (variable sizes) in outer circle, 5 smaller (not significantly smaller) in inner circle (proximal peri-oral); calcareous ring not composite, radial and inter-radial plates of ring high, narrow anteriorly, posterior paired radial prolongations distinct, short, not fragmented; single polian vesicle; gonad tubules branched basally; respiratory trees extending throughout coelom.

Ossicles sparsely scattered in mid-body dorsal and ventral body wall, small plates, rods and rosettes; plates frequently regular, oval with 2 large central perforations and single smaller perforation at each end (judged to be reduced table discs), short blunt pillar frequently projecting from centre of plate (judged to be reduced spires), plates 56–90 µ m long; rods related to plates, 1 or 2 perforations, sometimes with central short pillar, up to 70 µ m. Peri-anal body wall ossicles plates, rods, rosettes and small scales; plates similar to midbody wall (judged to be reduced tables); rods irregular, many branched, distal ends of rod and branches widened and perforate, up to 120 µ m long; multi-layered anal scale about 320 µ m long. Tube feet endplate diameters up to 400 µ m, tube foot and endplate support ossicles elongate perforated curved plates up to 160 µ m long. Tentacles with rod ossicles and rosettes; rods fine to thick, ends widened with few perforations, rods up to 400 µ m long. Oral disc and introvert with abundant rosettes, rosette rods and rare plates.

Preserved body colour off-white with fine brown flecking and spotting, tube feet brown.

Distribution. N Australia, Arafura Sea to Yeppoon, 9– 37 m.

Etymology. Named for the Arafura Sea from which the type specimen was collected.

Remarks. We had considerable difficulty in finding a genus to which we should refer this new species, but we did not feel justified in establishing yet another new dendrochirotid genus. We refer the new species to Cladolabes with major reservations. We judge that the plates with short central pillars of Cladolabes arafurus O’Loughlin sp. nov. are related to table discs and spires, the latter very reduced. This would account for the unusual ossicle forms. We have emended the diagnosis of Cladolabes to include this character. But we recognize that the reduced tables in species currently referred to Cladolabes are generally characterized by a rod-like spire and reduced disc, the opposite to Cladolabes arafurus . The forms of the calcareous ring in species currently referred to Cladolabes are quite variable but generally the inter-radial plates have posterior prolongations and are not truncate posteriorly as in Cladolabes arafurus . We anticipate that emerging genetic data will result in a major revision of family Cladolabidae and await this evidence as to where the new species belongs generically. The form of the ossicles is distinctive, especially what we judge to be the reduced tables, and distinguishes Cladolabes arafurus from all other species in the genus.

Figures

Figure 1. Photos of preserved and collapsed specimens of Cladolabes arafurus O’Loughlin sp. nov. A, dorsal view of holotype (NMV F202989, 50 mm long); B, ventral view of holotype; insert with sketch of the calcareous ring of the holotype; C, dorsal view of paratype (NMV F204070, 63 mm long); D, ventral view of paratype; insert with photo of the calcareous ring of the paratype.

Figure 2. SEM images of ossicles from the holotype of Cladolabes arafurus O’Loughlin sp. nov. (NMV F202989). A, mid-dorsal body wall and tube feet small plates (reduced table discs), some with central short pillar (reduced spires), rosettes, and tube feet support plates (large, right) (scale bars 10 µm); B, ventral mid-body wall reduced tables (scale bars 10 µm); C, peri-anal body wall small endplate (top left), reduced tables with central short pillar, rods, and rosettes (scale bars 10 µm); D, ventral tube foot endplate (top right, scale bar 100 µm), and tube foot support plates (scale bars 20 µm); E, tentacle rods (scale bars 20 µm).