Paracaudina ambigua O’Loughlin and Barmos, 2011

O'Loughlin, P. Mark, Barmos, Shari & VandenSpiegel, Didier, 2011, The paracaudinid sea cucumbers of Australia and New Zealand (Echinodermata: Holothuroidea: Molpadida: Caudinidae), Memoirs of Museum Victoria 68, pp. 37-65 : 39

Paracaudina ambigua O’Loughlin and Barmos sp. nov.

Figure 1a , 2

Material examined. Holotype. Western Australia, Shark Bay, FWA– WAM RV Naturaliste Shark Bay Survey II Feb / Mar 2003, stn 13/173/P, 24º47.02'S 113º21.97'E to 24º46.48'S 113º22.08'E, 24 m, 6 Mar 2003, S. Morrison and S. M. Slack-Smith, WAM Z29767 .

Paratype. Western Australia, Ningaloo Marine Park , AIMS RV Solander, stn RVS 4545–D069, 23º48'S 113º30'E, 33 m, 1 Feb 2008, M. Salotti and S. M. Slack-Smith, WAM Z23331 (1).

Diagnosis. Paracaudina species up to 45 mm long (holotype, caudal taper but anal end and valves missing), body up to 15 mm high (body flattened laterally); body wall thick, soft to semi-gelatinous, white (preserved); posterior body with caudal taper to short discrete tail (evident in paratype); ossicles different mid-body and caudally; mid-body ossicles predominantly small irregular rods, frequently forming a single loop, or small plates with up to 4 perforations, these ossicles up to 40 µm long; rare mid-body irregularly oval perforated plates with spinous margin and some secondary bridging, about 64 µm long; caudal ossicles irregularly oval to round to octagonal perforated plates, long pointed spinous margin, surface spines and bridges and secondary development, some plates chilensis -like with box and cross bridges over central perforation, caudal ossicles typically 56–64 µm long.

Type locality. Central Western Australia, Shark Bay .

Distribution. Central Western Australia, Shark Bay, Ningaloo Marine Park; 24– 33 m.

Etymology. From the Latin ambiguus (of double meaning, uncertain), feminine ambigua , referring to the generic uncertainty created by the presence of Acaudina -like ossicles mid-body and Paracaudina -like ossicles posteriorly.

Remarks. Paracaudina ambigua O’Loughlin and Barmos sp. nov. is distinguished diagnostically amongst Paracaudina species by having fine irregular rod and loop ossicles in the mid-body wall and marginally spinous chilensis -like plate ossicles in the caudal region, some with the characteristic cross and box bridges over a central perforation. Both specimens are in poor condition, but the ossicles are in excellent condition and characterise the new species. Distal pairs of digits are evident on a few tentacles of the holotype, but the condition of the tentacles is such that a second pair is not clearly evident on any tentacle. The caudal part is missing from the holotype, but a distinct narrow tail and soft anal valves are present on the paratype (18 mm long).

Figures

Figure 1. Photos of preserved specimens of species of Paracaudina Heding, 1932: a, holotype of P. ambigua O’Loughlin and Barmos sp. nov. (insert with drawings of rod and loop ossicles from the mid-body wall; WAM Z29767); b, P. australis (Semper, 1868) (insert with drawings of rod ossicles from the mid-body wall; AM J13583); c, P. chilensis (Müller, 1850) (WAM Z5638); d, P. coriacea (Hutton, 1872) (NIWA 70955); e, P. coriacea (Hutton, 1872) (AM J12290); f, mouth and tentacles of P. coriacea (Hutton, 1872) (NIWA 70954).

Figure 2. SEM images of ossicles from the holotype of Paracaudina ambigua O’Loughlin and Barmos sp. nov. from Shark Bay, central Western Australia (WAM Z29767): upper, forms of predominant ossicles from the mid-body wall; lower, forms of ossicles from the caudal body wall (rarely occurring chilensis-like ossicles with cross and box bridging shown lower top right and lower bottom left).