The paracaudinid sea cucumbers of Australia and New Zealand (Echinodermata: Holothuroidea: Molpadida: Caudinidae) 
39 
Remarks. Rods may be present with perforated plates, as in 
Paracaudina australis (Semper, 1868), and rods are not 
necessarily fusiform (spindle-shaped). We have emended the 
diagnosis of Pawson and Liao 1992 in these two respects. 
Family Caudinidae Heding, 1931 
Diagnosis (emended from Pawson and Liao 1992). Tentacles 
without a terminal digit, and with one or two pairs of lateral 
digits; tail sometimes inconspicuous; ossicles may include 
large tables, crossed cups, perforated plates and irregular rods; 
phosphatic bodies usually absent. 
Remarks. We have emended the statement concerning which 
ossicles may be present, but we have not changed the ossicle 
types listed. 
Paracaudina Heding, 1932 
Figures If, 5c-e, 7, 8, 12a, b 
Pseudocaudina Heding, 1931: 283. 
Paracaudina Heding, 1932: 455-456. 
Type species. Molpadia chilensis Muller, 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 If, 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-tumed 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. 
Paracaudina ambigua O’Loughlin and Barmos sp. nov. 
Figure la, 2 
Material examined. Holotype. Western Australia, Shark Bay, FWA- 
WAM RV Naturaliste Shark Bay Survey II Feb / Mar 2003, stn 
13/173/P, 24°47.02'S 113°21.97'E to 24°46.48'S 113°22.08'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, 23°48’S 113°30'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 pm long; rare mid-body irregularly oval 
perforated plates with spinous margin and some secondary 
bridging, about 64 pm 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 pm 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). 
