Paracaudina championi 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 : 84-86

Paracaudina championi O’Loughlin & Skarbnik-López sp. nov.

Zoobank LSID. http://zoobank.org:act:86F7DB87-F210-4732-

9A77-2FC03915134B

Tables 1–3, 5, 6; figures 1, 11–13.

Molpadiidae sp. nov. (HOL 11).—Hibberd & Moore, 2009: 119, 145.

Material examined. Holotype. Southern Ocean , S Kerguelen Plateau, NE Heard Island, North-east Plateau, AAD Southern Champion cruise 46 haul 479, beam trawl, -50.67 74.62, 708 m, 30 Jul 2007, NMV F165736 ( UF tissue sequence code MOL AF666 ) ( AAD species code: HOL 11 ).

Paratypes ( AAD species code: HOL 11 ) . HIMI, Western Plateau , SC26(162), -52.44 72.67, 287 m, 30 Apr 2003, TMAG H3539 (3) ; SC26(165), -52.34 72.50, 462 m, 30 Apr 2003, TMAG H3434 (1).

Other material (AAD species code: HOL 11). Southern Shell Bank, SC26(264), -51.87 75.78, 779 m, AAD; Shell Bank MR, SC46(125), -51.69 76.19, 234 m, AAD; North-east Plateau, SC46(473), -50.48 74.60, 905 m, AAD; SC46(474), -50.46 74.79, 942 m, AAD.

Description. Preserved body up to 115 mm long (strongly contracted), tapering posterior body and tail 40 mm long, mid-body up to 30 mm diameter; body wall thick, leathery, wrinkled with transverse creases, pale brown to off-white to pale grey in colour; body form cylindrical, slight taper to blunt oral end, about one third of the body tapered to thin posterior tail (end of tail missing in holotype), tail not discretely delineated. Lacking anal scales or papillae. Tentacles 15, digitiform, lacking terminal digit or digits. Calcareous ring solid, plates fused; radial plates with two anterior projections, one with longitudinal muscle attachment and small anterior notch, separated by a bigger notch from the second lateral anterior projection, plates with tapered posterior projection with small bifid notch posteriorly; inter-radial plates with tapered anterior projection, wide rounded posterior indentation. Tentacle ampullae variable in length, up to twice the height of the ring in length. Single polian vesicle, tubular, long. Longitudinal muscles broad, flat, each divided along mid-line by narrow gap. Long, thin, un-branched gonad tubules.

Mid-body and caudal, but not peri-anal, ossicles are similar; some but not most are fairly regular, thick, knobbed cups with a basal distally-knobbed cross; most have no regular form and are thick, knobbed, often three-dimensional, and very irregular; ossicles predominantly up to 40 µ m long. Peri-anal body wall with irregular knobbed cups and irregular thick tables; knobbed cups as in mid-body wall; tables in smaller specimens with predominantly 3-pillar spires, one cross-bridge, few lateral blunt spines, 3 paired blunt spines apically, spires on tables in larger specimens complex with numerous distal blunt spines, spires up to about 170 µ m high; table discs indented centrally, raised marginally, irregular angular margins, predominantly 6 central perforations, 2 outer circles of irregular perforations, discs up to about 180 µ m across in small specimens, up to about 250 µ m across in large specimens.

Distribution. Southern Ocean, Kerguelen Plateau, N of Heard Island on North-east Plateau, Shell Bank, Western Plateau, 234– 942 m.

Etymology. Named championi for the fishing trawler Southern Champion that was commissioned by the AAD to serve this research expedition.

Remarks. The holotype was donated to NMV by the AAD. Initial preservation was by freezing, with subsequent transfer to 70% ethanol. The presence of peri-anal 3-pillared, large, thick tables is a significant morphological addition to the diagnostic characters of Paracaudina Heding, 1932 that was provided by O’Loughlin et. al. (2011). Caudal ossicles in Paracaudina specimens have been discussed and illustrated by O’Loughlin et al. (2011). No tables were observed in the mid-body wall or caudal region. In reporting on the New Zealand Caudinidae species, Davey & O’Loughlin (2013) discussed Hedingia Deichmann, 1938 , and the New Zealand occurrence of Hedingia albicans ( Théel, 1886) . In H. albicans there are abundant three-pillared tables with irregular discs in the caudal region, and rarely in the mid-body wall. Hedingia species lack thick, knobbed cup ossicles. The new caudinid species described here has the characteristic paracaudinid thick, knobbed cup ossicles throughout the body wall, but also has the characteristic tables of Hedingia in the posterior caudal region. We have provisionally assigned our new species to Paracaudina and await the evidence of molecular phylogenetic data for generic confirmation.

Apart from the significant diagnostic difference of presence or absence of caudal tables, Paracaudina championi O’Loughlin & Skarbnik-López sp. nov. is similar to Paracaudina alta Davey & O’Loughlin, 2013 with its very irregular ossicle forms. But the thick, knobbed cup ossicles are quite dissimilar to the more regular ossicles of all other species of Paracaudina . The illustration of P. alta body form ( Fig. 1B ) in Davey & O’Loughlin (2013) indicates that most of the body is cylindrical with a relatively short discrete tail, whereas for Paracaudina championi about one third of the body exhibits a long caudal taper. Body wall ossicles for P. alta are illustrated by Davey & O’Loughlin (2013) and also by O’Loughlin et al. (2011) for the earlier conspecific Paracaudina species. We judge that amongst the very irregular ossicles of both species a basal distally-knobbed cross is sometimes evident amongst the ossicles of P. championi but not amongst those of P. alta . Their respective occurrences north and south of the Antarctic Convergence, and considerable geographical separation, also discourage us from thinking that they are conspecific. We await molecular phylogenetic data for insight into these relationships of current Paracaudina species. TMAG paratypes have 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 1. Map of the southern part of the Kergulen Plateau detailing the Heard and McDonald Islands Territorial Sea, Exclusive Economic Zone, Marine Reserve and localities (map is courtesy of the Australian Antarctic Division © Commonwealth of Australia 2015). Names on the map in commas are used in this study but not formally recognized by the AAD.