Paracaudina australis ( Semper, 1868 )

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 : 51

Paracaudina australis ( Semper, 1868)

Figures 1b , 3 , 4

Molpadia australis Semper, 1868: 233–234 , 268, pl. 39 fig 14.— Théel, 1886: 55.

Caudina chilensis .—H. L. Clark, 1908: 175—176. (part non Molpadia chilensis Müller, 1850 ).

Pseudocaudina australis .— Heding, 1931: 283.

Paracaudina australis .— Heding, 1932: 455.— Heding, 1933: 127– 142, pl. 6 figs 5–7, pl. 7 figs 8–9, pl. 8 fig. 6.—H. L. Clark, 1935: 267– 284.—H. L. Clark, 1946: 45 (part).—A. M. Clark and Rowe, 1971: 193.— Pawson,1977:119 (part).— Rowe,1982:472 (part), fig.10.35b.— Cannon and Silver, 1986: 40, figs 8f, 10f. — Rowe and Gates, 1995: 264 (part).

Material examined. Queensland, Moreton Bay, Stradbroke Island, Dunwich , half buried on sandbar, 2 Dec 1978, AM J13583 (1) ; Port Denison District , AM J4145 (5).

Diagnosis. Paracaudina species up to 135 mm long, up to 35 mm diameter (preserved); thin, pliable, soft to firm smooth body wall; colour translucent pink to white live, off-white to pale brown preserved, lacking yellow colouration, at most slight yellowing anteriorly; posterior body with caudal taper to narrow rounded end, sometimes short tail; mid-body ossicles predominantly plates with bluntly spinous margin and surface, smooth plates, rods in deeper body wall; ossicles not thick buttons; spinous plates irregular, pointed marginal projections, surface knobs / blunt spines frequently joined by rods creating secondary layering, rods sometimes bridging a large central perforation as single rod or tripod or cross, rare chilensis -like plates with large central perforation bridged by box on one side and cross on the other side, up to 12 perforations, spinous plates up to 56 µm long; smooth plates irregular, up to 12 perforations, margin smooth, lacking marginal and surface spines and knobs, smooth plates up to 48 µm long; rods sparse, irregular, variably straight, bent, Y-shaped, C-shaped, J-shaped, some with node, rods frequently 24 µm long, up to 48 µm long.

Type locality. Rockhampton , Queensland .

Distribution. Northern Australia, Queensland, south-east coast; Singapore (?).

Remarks. Paracaudina australis ( Semper, 1868) is distinguished diagnostically by having in the body wall both irregular rods and spinous perforated plates with secondary layering, a body form with tapered caudal end but not long discrete tail, and an absence of distinct yellow or reddish-yellow colour. H. L. Clark 1908 included Paracaudina australis in his synonymy of Caudina chilensis , but subsequently (1935, 1946) rejected his own synonymy. Southern Australian specimens judged to be Paracaudina australis by H. L. Clark 1946, Rowe 1982 and Rowe and Gates 1995 are our new species Paracaudina cuprea O’Loughlin and Barmos (below). Mortensen 1925 based his discussion of Paracaudina australis on SAM specimens. Based on Mortensen’s figures we judge that these specimens were our new species Paracaudina cuprea O’Loughlin and Barmos (below). We note that Heding 1933 did not indicate what specimens he used to illustrate ossicles of Paracaudina australis .

David Lane (pers. comm. by Ria Tan) identified the common “See-through sea cucumber” in Singapore waters as Paracaudina australis . Ria Tan (pers. comm.) has observed the species only on the estuarine northern shores of Singapore near the mouth of the Johor River, floating or partly buried on sand bars near seagrass meadows, as shallow as the intertidal zone at low spring tide. We have to date not been able to confirm the determination as Paracaudina australis .

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 3. SEM images of ossicles from the mid-body wall of a specimen of Paracaudina australis (Semper, 1868) from Dunwich, Moreton Bay, south-east Queensland (AM J13583). Rarely occurring chilensis-like ossicle with cross and box bridging shown top right.

Figure 4. SEM images showing variation in form of ossicles from the mid-body wall of a specimen of Paracaudina australis (Semper, 1868) from Dunwich, Moreton Bay, south-east Queensland (AM J13583). Rarely occurring chilensis-like ossicle with cross and box bridging shown bottom right.