Echinocucumis ampla O’Loughlin & Skarbnik-López, 2015

O'Loughlin, P. Mark, Skarbnik-López, Jessica, Mackenzie, Melanie & VandenSpiegel, Didier, 2015, Sea cucumbers of the Kerguelen Plateau, with descriptions of new genus and species (Echinodermata: Holothuroidea), Memoirs of Museum Victoria 73, pp. 59-93 : 77-80

Echinocucumis ampla O’Loughlin & Skarbnik-López sp. nov.

Zoobank LSID. http://zoobank.org:act:7147741A-1BFE-48DC-

A351-FBF5A53B8539

Tables 1, 2, 5, 6; figures 1, 7, 8.

Dactylochirotida sp. nov. (HOL 10).—Hibberd & Moore, 2009:

119, 146.

Material examined. Holotype. Southern Ocean , S Kerguelen Plateau, NE Heard Island, North-east Plateau, AAD Southern Champion cruise 46 haul 479, beam trawl, -50.68 74.62, 708 m, 30 Jul 2007, NMV F165735 ( AAD species code: HOLO 10 )

Paratypes. Holotype locality and date, NMV F198492 (2) ( UF tissues sequence codes MOL AF663, 664, 665); HIMI, southern Shell Bank , SC26(264), -51.87 75.78, 779 m, 9 May 2003, TMAG H3431 .

Other material (AAD species code: HOL 10). HIMI, southern Shell Bank, SC26(263), -51.80 75.50, 628 m, AAD; SC46(115), -51.81 75.98, 557 m, AAD; North-east Plateau, SC46(471), -50.38 74.54, 970 m, AAD; Pike Bank, SC50(016), -51.45 71.84, 756 m, AAD.

Description. Preserved body up to about 65 mm long lateral width (tentacles withdrawn), up to 30 mm high mid-body, tapered anteriorly to partly up-turned rounded oral end, prominent belly mid-body, tapered posteriorly into long up-turned tail; body wall off-white to pale brown, thin, brittle, parchment-like, completely covered with a test of imbricating spined scales, spines more dense ventrally than dorsally. Five inconspicuous anal scales, thick columnar, comprising thick mesh of branched rods, anal scales about 700 µ m long. Five elongate, thin anal papillae, walls supported by rod ossicles, papillae up to about 600 µ m long. Calcareous ring cucumariid-like, ring narrow, prominent anterior mid-plate radial and inter-radial prolongations, lacking posterior prolongations. Tentacles 10, digitiform, flexible, irregularly long and short. Tube feet absent from the body. Longitudinal muscles cylindrical, thin. Multiple-branching thin gonad tubules.

Body wall ossicles imbricating spined plates; plates irregularly oval in form, single-layered, thick, perforated, perforations predominantly relatively small and spaced, up to about 16 perforations across the diameter, plates up to 1.2 mm long ventrally, slightly smaller dorsally; spines variably near margin of plate to near center, long to short, thick to thin, pillars comprising dendritic branching rods, predominantly one spine per scale, rarely a cluster of up to three, spines rounded and rugose distally with short blunt spinelets; spines dorsally up to 720 µ m high (fine spinous distal point frequently lost), up to 200 µ m diameter mid-height; spines ventrally more coarse, more than 680 µ m high (with fine spinous distal point lost), up to 280 µ m diameter mid-height. Distal tail with large thick plates, not multilayered, not closely perforated, small spaced perforations variably present around margin, large central perforation, plates up to 600 µ m diameter. Tentacles supported by close, transversely aligned, curved rods; rods irregular in form, variably perforated distally, variably bluntly spinous to short digiform projections laterally, rods up to 300 µ m long.

Distribution. Southern Ocean, S Kerguelen Plateau, N of Heard Island on North-east Plateau, Pike Bank, southern Shell Bank, 557– 970 m.

Etymology. Named from the Latin ampla (feminine), meaning large, to indicate the relatively large size of this species.

Remarks. Type specimens were donated to NMV by the AAD. Initial preservation was by freezing, with subsequent transfer to 70% ethanol. In spite of a close examination no tube feet were detected. But in a body wall ossicle sample some small curved thin rods (up to 80 µ m across) were found that were probably residual tube foot support rods. And we note the perforation in the upper left scale in Figure 8b that might be a perforation for a tube foot. Echinocucumis ampla O’Loughlin & Skarbnik-López sp. nov. is distinguished from all other species of Echinocucumis by the combination of: large size; absence of a distinctly tapered up-turned oral end; tube feet not detected; spines variably marginal to central on plates; spines comprising composite, columnar, branched rods. Pawson (1964) referred two specimens from New Zealand to Echinocucumis hispida ( Barrett, 1857) , with some reservations. The larger has a greater curvature length of only 50 mm, distinctly upturned oral and anal ends, single spines arising from the margin only of the scales, and tube feet present. Based on some differences in morphology, and the fact that very few HIMI species have been found north of the Antarctic Convergence, we judge that the New Zealand species is not E. ampla . The TMAG paratype has been confirmed by direct observation of TMAG loan material. “Other material” refers to lots that were identified in the AAD by comparison with voucher specimens that were identified by Mark O’Loughlin. These lots are held (unregistered) in the AAD and the determinations not confirmed by Mark O’Loughlin.

Figures

Figure 8. SEM images of ossicles from a paratype of Echinocucumis ampla O’Loughlin & Skarbnik-López sp. nov. (NMV F198492). a, spined plate from the mid-dorsal body wall; b, spined plates and spines from the mid-ventral body wall; c, part-perforate plate fragments from the perianal body wall; d, rods from a tentacle.