Paracaudina Heding, 1932

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 Heding, 1932

Figures 1f , 5c–e , 7 , 8 , 12a, b

Pseudocaudina Heding, 1931: 283 .

Paracaudina Heding, 1932: 455–456 .

Type species. Molpadia chilensis Müller, 1850 (subsequent designation by H. L. Clark 1935).

Other included species. Paracaudina ambigua O’Loughlin and Barmos sp. nov.; P. australis ( Semper, 1868) ; P. bacillis O’Loughlin and Barmos sp. nov.; P. coriacea ( Hutton, 1872) ; P. cuprea O’Loughlin and Barmos sp. nov.; P. delicata Pawson and Liao, 1992 ; P. keablei O’Loughlin and Barmos sp. nov.; P. luticola Hickman, 1962 ; P. chilensis obesacauda (H. L. Clark, 1908) ; P. tetrapora (H. L. Clark, 1914) ; P. tripoda O’Loughlin and Barmos sp. nov.

Diagnosis. Cylindrical form, smooth or wrinkled body wall; tentacles 15, each with 2 pairs of digits (figs 1f, 5c); posterior end of body with caudal taper or discrete thin tail; tail may be short or long; 5 radial triangular non-calcareous anal valves, each with up to 4–5 pairs of marginal digitiform papillae, terminal ones longest (fig. 5d); radial plates of calcareous ring with two anterior lateral low blunt projections, one with small notch, posterior digitiform prolongation about half the length of the plate, prolongation divided by terminal notch of variable depth or deeper division (fig. 12a); interradial plates with anterior central blunt point, posterior end truncated (fig. 12a); dorsal short to long tubular stone canal with terminal madreporite, free in coelom or attached to pyloric mesentery (specimen NMV F174894); single ventral, elongate, tubular to globular polian vesicle, usually with dark reddish-brown colouration; longitudinal muscles broad, flat, with distinct longitudinal division (fig. 5e); retractor muscles formed by pair of in-turned outer margins of divided longitudinal muscles (fig. 5e); gonad tubules usually branched, in tufts on each side of dorsal mesentery (fig. 5e); right branch of respiratory tree extending in the coelom to the calcareous ring; ossicles may be concave or flat, thick crossed and knobbed cups, thick knobbed perforated plates, octagonal plates with large central perforation and cross or tripod bridging one side and sometimes square the other side (figs 7, 8, 12b), perforated smooth and knobbed and spinous plates with variably developed secondary layering, and irregular rods; ossicles never tables; phosphatising of ossicles and calcareous ring may occur, and a red to brown to yellow pigment may occur in the body wall.

Remarks. A comprehensive diagnosis of genus Paracaudina Heding, 1932 is provided to avoid diagnoses of species with repetition of characters that all have in common. We recognise that some of the characters listed in this diagnosis of Paracaudina are shared with other genera and at family and possibly order level.

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 5. Photos of Paracaudina bacillis O’Loughlin and Barmos sp. nov.: a, preserved holotype specimen (insert with drawings of rods from the mid-body wall; NMV F151853); b, photo of live holotype (oral end right; photo by L. Altoff and A. Falconer); c, mouth and tentacles of paratype (NMV F174894); d, anal valves and papillae (holotype); e, dorsal mesentery with tufts of gonad tubules on both sides, divided flat longitudinal muscle with thin retractor muscle (holotype); f, live specimen spawning, Port Phillip Bay, Rye Pier, 4 m, 10 Nov 2007 (photo by D. McKenzie).

Figure 7. SEM images of ossicles from the mid-body wall of a specimen of Paracaudina chilensis (Müller, 1850) from Eighty Mile Beach, NW Australia (WAM Z5640).

Figure 8. SEM images of ossicles from the mid-body wall of a small specimen of Paracaudina chilensis (Müller, 1850) from Tasman Bay, South Island, New Zealand (NIWA 70956).

Figure 12. a, Calcareous ring of a specimen of Paracaudina cuprea O’Loughlin and Barmos sp. nov. from Portland Bay, Victoria (NMV F174890) (insert with drawing of two radial plates and one interradial plate typical of Paracaudina species); b, SEM images of ossicles from a specimen of Paracaudina chilensis obesacauda (H. L. Clark, 1908), judged here to be typical of Paracaudina chilensis (Müller, 1850) (copied from Pawson et al. 2001).