Heteromolpadia joyceae, Pawson, David L. & Vance, Doris J., 2007

Pawson, David L. & Vance, Doris J., 2007, Heteromolpadia joyceae, a new species of sea cucumber from New Zealand, with a key to New Zealand Molpadiidae (Echinodermata: Holothuroidea: Molpadiida), Zootaxa 1608, pp. 35-39 : 36-38

Heteromolpadia joyceae , new species

Figure 1 A–F

Molpadia ? n.sp. Pawson, 1965a: 13; 1977: 98.

Diagnosis: Body gray, typically with very numerous reddish spots approximately 1 mm in diameter. Body wall ossicles in young specimens three-armed anchor plates, anchors, and three-pillared tables 100µm in average diameter with three larger perforations and often three additional smaller perforations. Body wall ossicles almost completely disappear as individuals grow. Tables in tail approximately 300Μm long, with 15–20 perforations.

Material Examined: HOLOTYPE, Bay of Plenty, North Island, New Zealand, NZOI Station Z9005, 21 January 1998, 37 °37.00’S– 37°39.00’S, 176°48.49’E – 176°44.73’E, 360–367m, 1 specimen. PARATYPES, 17 specimens: NZOI Station Z8999, 20 January 1998, 37 °36.79’S– 38°47.00’S, 177°12.10’E – 177°12.90’E, 460– 467m, 5 specimens. NZOI Station Z9008, 22 January 1998, 37 °09.87’S– 37°12.67’S, 176°21.73’E – 176°22.96’E, 518–536m, 9 specimens. NMNZ Station BS754, 23 January 1979, 37 °08.8’S 176°21.8’E to 37°09.4’S 176°23.8’E, 512–632m, mud, 1 specimen. NMNZ Station BS772, 27 January 1979, 39 °17.2’S 178°12.7’E to 39°19.3’S 178°11.3’E, 258–306m, mud, 2 specimens.

Additional material: 67 specimens from 16 NZOI stations.

Description: Specimens typical of the Family Molpadiidae , although the tail is relatively long, occupying 17–30% of the total length of the body. Holotype ( Figure 1 A) 86mm in total length, of which the tail occupies 16mm. In all specimens, total length is 48–120 mm. Body wall smooth to touch, thin, but tough and leathery. Color in alcohol gray to dirty white, with very numerous light to dark red irregularly shaped spots ( Figure 1 A), which are aggregations of phosphatic deposits, each spot approximately 1mm in diameter. Spots closely aggregated towards anterior end of body, more scattered posteriorly. Tail grayish-white, lacking red spots. Oral disk typical, with 15 tentacles, the disk diameter approximately 10% of body length.

In a 90mm long Paratype, calcareous ring with interradial pieces 5mm high, radial pieces 7mm high, of which relatively short posterior projections occupy 2mm. Posterior projections with narrow notch 0.5mm deep. Polian vesicle single. Stone canal in mid-dorsal interradius whitish, approximately 7 mm long, madreporite approximately spherical, 0.5mm in diameter. Pore canal 1mm long extends from madreporite to attach to mid-dorsal body wall. Pore canal opens to exterior in an area distinguished by a bare gray patch approximately 10mm posterior to oral disk. Gonad with few branches, genital duct opens to exterior in middorsal interradius, 1mm posterior to oral disk. Gonad without ossicles. Course of intestine, and respiratory trees, typical.

Body wall in all specimens contains primarily clusters of phosphatic deposits ( Figure 1 B), derived from dissolution of calcareous ossicles. Rare remaining fragments of ossicles ( Figures 1 C–D) indicate that young specimens of this species carry in their body wall single anchor-plates that are apparently three-armed, along with typical molpadiid anchors. Fragments show that three-pillared tables of 100µm average diameter with three major perforations and often three smaller perforations are scattered in the body wall. Tail contains spired tables ( Figure 1 E–F) of average length 300µm, with an oval central area with 15–20 perforations, and two rod-like extensions, usually imperforate. The three-pillared spire averages 60ìm in height.

Distribution: Off the east coast of the North Island, and the northeast coast of the South Island, and the Chatham Rise, in 258–632 meters. Apparently this species is confined to the bathyal zone.

Ecology: Like all other molpadiids, prefers mud substrates. In all specimens, the intestine is packed with mud.

Etymology: It is our pleasure to name this species for Mrs. Joyce McCullough of China Grove, North Carolina, as a small token of appreciation of her untiring, endlessly cheerful, volunteer assistance in the field and in the laboratory over the past several years.

Remarks: Pawson (1965a) suspected that the two specimens he named “ Molpadia ? n.sp. ” represented a new species, but noted that more material was needed in order to properly characterize the species. The abundant material now available confirms the validity of this new taxon. In having single three-armed anchor plates in the body wall, this species falls into the genus Heteromolpadia Pawson, 1963 . From the Indonesian species H. tridens ( Sluiter, 1901) , H. joyceae differs in possessing spired tables in the body wall. Furthermore, in H. tridens the three-armed ossicles and anchors are retained to some extent as the animal grows, and apparently do not undergo extensive dissolution. H. joyceae differs from the other New Zealand congeners H. marenzelleri ( Théel, 1886) and H. pikei Pawson, 1965 b, in the nature of the ossicles in the tail; these are generally larger in H. joyceae , with far more numerous perforations (see key above).

Figures

FIGURE 1. Heteromolpadia joyceae new species. A, Holotype, whole animal, total length 86 mm. B, scattered phosphatic deposits derived from dissolution of skin in liquid household bleach. C, Remnants of a spired table with three larger perforations and three smaller. D, Fragments of three-armed anchor plate. E, Spired tables from tail. F, spired tables from tail, higher magnification. Scale line in Figures 1 B-F = 100 Μm.