Cladodactyla Brandt, 1835

O’Loughlin, P. Mark, Mackenzie, Melanie, Paulay, Gustav & VandenSpiegel, Didier, 2014, Four new species and a new genus of Antarctic sea cucumbers with taxonomic reviews of Cladodactyla, Pseudocnus, Paracucumidae and Parathyonidium (Echinodermata: Holothuroidea: Dendrochirotida), Memoirs of Museum Victoria 72, pp. 31-61 : 34-37

Cladodactyla Brandt, 1835

= Dendrelasia O’Loughlin (in O’Loughlin et al., 2013): 69–70 (new synonymy)

Table 1; figure 2

Diagnosis (sensu stricto – see Remarks). Ten equal tentacles; calcareous ring calcified and evident in small specimens but de-calcified and no longer evident in larger specimens; tube feet restricted to radii; dorso-lateral radial body wall thick, soft, “spongy”; external dorsal marsupium created by elongate indentation / invagination between dorso-lateral radii, radial edges may close over a protective chamber, anterior mid-dorsal gonoduct opening in marsupium; hermaphroditic; tube feet on bivium smaller and more numerous than on trivium; respiratory trees arise from 3–4 basal sources, each with dendritic branches; mid-body wall ossicles absent in larger specimens; peri-anal ossicles include prominently spinous, single-layered, perforated plates.

Type species. Holothuria crocea Lesson, 1830 (type locality Falkland Islands ( Malvinas)) (by subsequent designation ( Panning 1940: 170))

Remarks. The availability of numerous larger specimens of “ Dendrelasia” sicinski from the South Shetland Islands has enabled us to judge that Dendrelasia is a junior synonym of Cladodactyla (see below). We formalize the synonymy here. We base our sensu stricto diagnosis of Cladodactyla on the two species that we consider to be Cladodactyla in confidence: C. crocea and C. sicinski . The differences ( Table 1) in the presence or absence of a dorsal external marsupium, tentacle arrangement, calcification in the calcareous ring, and ossicle forms, and the broad geographic distribution of the other included species, lead us to suspect that Cladodactyla as currently circumscribed may not be monophyletic.

COI sequence data from several hundred dendrochirotids (Michonneau et al. in prep.) recovers these two species of Cladodactyla in a clade with Staurocucumis (including Abyssocucumis , considered generically distinct by some ( Hansen 1988, O’Loughlin 2002) but not others ( Massin & Hendrickx 2011)) and Heterocucumis , with modest support. An analysis of this clade ( Fig. 2 ), including samples of the type species of all four genera: Cladodactyla crocea , Staurocucumis liouvillei , Abyssocucumis abyssorum , Heterocucumis steineni , fails to recover these genera as monophyletic, and includes a subclade with 96% bootstrap support that has species of Staurocucumis , Heterocucumis , and Cladodactyla intermixed. Revising the generic limits of this lineage is beyond the scope of this paper. We note however that Cladodactyla , as the senior generic name in this assemblage, is clearly appropriate for C. crocea and C. sicinski .

Figures

Figure 2. Maximum likelihood tree for Cladodactyla–Heterocucumis–Staurocucumis clade, based on COI sequences, T92+G+I model, 100 bootstrap replicates, Laevocnus laevigatus as outgroup. Filled circles>0.95 bootstrap support; hollow circles>0.70 bootstrap support.