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The Bathyal Holothurians of the New Zealand Region

Order Molpadida Haeckel, 1896

Order Molpadida Haeckel, 1896

For diagnoses and remarks on included families see Pawson (1963, pp. 10, 16).

Family Molpadiidae Müller, 1850

Key to the New Zealand Genera of the Molpadiidae
1 (2) Calcareous deposits include anchors and three-armed anchor plates, and spired tables Heteromolpadia Pawson (p. 10)
2 (1) Calcareous deposits may include anchors and rosettes of racquet-shaped plates, fusiform rods, spired tables. Single three-armed anchor plates lacking Motpadia Risso (p. 10)

Heteromolpadia Pawson, 1963

Diagnosis: Calcareous deposits include two-armed anchors associated with single perforated anchor plates of varying shapes, which usually have three marginal projections. No rosettes of racquet-shaped plates; no fusiform rods. Phosphatic bodies present, at least in adult specimens.

Type Species: Ankyroderma marenzelleri Theel.

Remarks: This genus was erected (Pawson, 1963) to accommodate those molpadiids with peculiar triradiate anchor plates, and two species, the type species and Ankyroderma tridens Sluiter, were included.

Heteromolpadia marenzelleri (Theel)

For synonymy, see Pawson (1963, p. 11).

Material Examined: Marine Dept., Stn. 2, 2 specimens; Stn. 3, 6 specimens; Stn. 5, 5 specimens; Stn. 16, 2 specimens.

Remarks: Typical specimens, ranging in length from 19mm to 45mm. Colour in alcohol grey, body-wall thin and prickly to the touch. Characteristic anchors, anchor-plates and tables are abundant, and phosphatic deposits are consequently rare.

Distribution: From New Zealand waters in depths ranging between 25 and 720 metres.

Heteromolpadia pikei Pawson

Heteromolpadia pikei Pawson, 1965b, p. 79, Text-fig. 1, figs. 4–6.

Material Examined: Marine Dept. Stn. 2, 1 specimen; Stn. 21, 1 specimen; Stn. 25, 2 specimens.

Molpadia Risso, 1826

Diagnosis: Calcareous deposits include tables, anchors and rosettes of racquet-shaped plates and large fusiform rods in various combinations. Tail deposits elongate to fusiform.

Type Species: Molpadia musculus Risso.

Remarks: Attempts to subdivide the genus Molpadia by Heding (1931, 1935) have proved unsuccessful, as some genera were based on extremely variable page 11 characters of doubtful diagnostic importance. Our knowledge of the species in this heterogeneous assemblage is far from complete, and the matter is complicated by the changes which take place in the calcareous deposits during the life histories of so many of the species. Deichmann's (1936) stopgap proposal of "groups" of species seems a logical approach to the problem, at least until the life histories of a few typical species have been worked out.

Key to Species of Molpadia Known from New Zealand
1 (4) Calcareous deposits include large fusiform rods, which are present in the bodywall and in the tail.
2 (3) Anchors and rosettes of racquet-shaped plates present M. musculus (Risso)
3 (2) Anchors and rosettes lacking M. violacea (Studer)
4 (1) Fusiform rods lacking from bodywall and tail. Deposits spired tables M. antarctica (Theel)
Molpadia musculus (Risso) Text-fig. 3, figs. 1–4, 6

Molpadia musculus Risso, 1826, p. 293; Clark, 1907, p. 165 (complete list of references); Herouard, 1923, p. 132, Pl. 5, fig 1; Deichmann, 1930, p. 198, Pl. 23, figs. 4–7; Heding, 1931, p. 279; Deichmann, 1940, p. 225, Pl. 40, figs. 1–15.

Ankyroderma loricata Perrier, 1902, p. 535, Pl. 33, figs. 23–28; Herouard, 1923, p. 135.

Molpadia holothurioides Clark, 1920, p. 129.

Eumolpadia asaphes Heding, 1935, p. 42, Pl. 5, figs. 9–10, Pl. 7, fig. 2, Pl. 8, fig. 3, Text-fig. 9.

Material Examined: N.Z.O.I. Stn. 0609, 1 specimen.

Description: Single specimen strongly contracted anteriorly; total length 23mm (probably more in life); oral disc 3mm in diameter; tail 3mm in length (broken, probably about 6mm long in life). Shape typical of the species, skin thin, prickly to touch. Colour in alcohol grey, anterior end slightly lighter.

Calcareous deposits in bodywall (excluding tail), anchors and rosettes of racquet-shaped plates, with perforated plates, closely aggregated, often overlapping. Racquet-shaped plates (Tex-fig. 3, fig. 4) 0.4–0.7mm in length, with 10–25 perforations at broad end; handle usually imperforate. Racquets always aggregated into rosettes of five or six, with broad ends overlapping, diameter of each rosette approximately 1.3mm. Each rosette supports at its centre a single anchor, with a saucer-shaped base and a smooth cylindrical shaft of average length 0.6mm. Distal end of shaft with two anchor arms (Text-fig. 3, fig. 6), smooth, or with one to two serrations near tips. Anchors project above level of bodywall, visible with naked eye. Rosettes and anchors numerous, scattered regularly in skin. Spaces between rosettes completely filled by large perforated plates.

Plates of variable shape (Text-fig. 3, fig. 2), with three large perforations, and often some smaller holes; spires lacking. Some plates tend to become fusiform in shape. Length ranges from 0.3mm to 1.0mm. Tables with three perforations (Text-fig. 3, fig. 3), and their developmental stages, are present. These bear a spire composed of a single rod, with a small distal crown of spines. Average diameter of tables 0.3mm; height of spire 0.15mm.

Phosphatic deposits extremely rare, scattered in very small numbers, light orange in colour. No calcareous deposits in process of dissolution into phosphatic material present.

Tail with great numbers of fusiform rods with two to four small, angular central perforations (Text-fig. 3, fig. 1). Length of rods ranges from 0.55mm to 0.81mm, average length 0.73mm.

Remarks: There is little doubt that this species falls into the M. musculus group as defined by Deichmann (1936). As the rosettes of racquets and the fusiform deposits of the bodywall and tail are characteristic of the species M. musculus, I have assigned the present material to that species. This constitutes page 12 the first definite record of M. musculus from the New Zealand region. M. musculus is cosmopolitan, and has been taken from depths between about 100 and 900 metres.

Text-fig. 3.—Molpadia musculus (Risso): Fig. 1, tail deposits; Fig. 2, perforated plated from the bodywall; Fig. 3, tables; Fig. 4, racquets; Fig. 6, anchor arms. Molpadia antarctica (Theel): Fig. 5, tail deposits; Fig. 7, tables from the bodywall. Molpadia ?n.sp.: Fig. 8, table in process of transformation into phosphatic material; Fig. 9, tail deposits.

Text-fig. 3.—Molpadia musculus (Risso): Fig. 1, tail deposits; Fig. 2, perforated plated from the bodywall; Fig. 3, tables; Fig. 4, racquets; Fig. 6, anchor arms. Molpadia antarctica (Theel): Fig. 5, tail deposits; Fig. 7, tables from the bodywall. Molpadia ?n.sp.: Fig. 8, table in process of transformation into phosphatic material; Fig. 9, tail deposits.

Molpadia violacea (Studer)

For synonymy and diagnosis, see Pawson (1963), p. 15.

Material Examined: None.

page 13

Remarks: Molpadia violacea is known from Kerguelen Island (Theel, 1886a) and the New Zealand region (Theel, 1886a; Pawson, 1963), from depths of 36–126 metres (Kerguelen Island) and 720–1,260 metres (New Zealand).

This species is considered a synonym of M. musculus by Deichmann (1940), but while the typical M. musculus has well developed anchors and rosettes of racquet-shaped plates, no trace of these deposits has been found in material of M. violacea from the New Zealand region (Pawson, 1963). Unfortunately no further material of M. violacea has come to hand, and unless it can be shown that M. violacea did at some stage of its life history have anchors and rosettes, I must regard the species as distinct from M. musculus.

Molpadia antarctica (Theel) Text-fig. 3, figs. 5, 7

Trochostoma antarcticum Theel, 1886a, p. 44, Pl. II, fig. 7; Theel, 1886b, p. 16; Herouard, 1901, p. 42; Augustin, 1908, p. 35, Text-fig. 22 a-o.

Molpadia antarctica: Clark, 1907, p. 32, 168; Ohshima, 1915, p. 252.

Material Examined: N.Z.O.I. Stn. 604, 1 specimen.

Description: Total length 20mm, diameter of oral disc 3mm. Tail broken off near base; its length cannot be determined. Bodywall thin, prickly to touch. Colour in alcohol uniformly grey.

Calcareous deposits exclusively tables of average diameter 0.28mm, usually with six or more large perforations (Text-fig. 3, fig. 7); three central perforations usually largest. From centre of each table arises a tall three-pillared spire, pillars united by three or four crossbars. Spires project above level of bodywall, barely visible to naked eye. Tables very closely crowded together, often overlapping. Anchors and anchor plates or rosettes lacking.

Tail with great numbers of elongate three-pillared tables (Text-fig. 3, fig. 5) bearing 4–10 perforations and complex spinous spire. Average length of tables 0.16mm.

Phosphatic deposits present, exceedingly scarce. A small number of tables are in first stages of dissolution into phosphatic material which is very light yellow, therefore easily overlooked.

Remarks : This specimen represents the species as originally described by Theel (1886). Ohshima (1915) recorded the same species from off Japan, noting that the average diameter of the tables in the bodywall is 0.185mm (as against 0.3mm in the present specimen). Also the tail deposits in Ohshima's material are smaller (0.04–0.11mm diameter) compared with 0.16mm length. However, Ohshima gave no indication of the shape of the tail deposits in his material, and mentioned the "disc diameter", which may perhaps be interpreted as the dimensions of the perforated area of the tail deposit.

Ohshima's specimen was 33mm in length, and phosphatic deposits were entirely absent, but he noted some tables undergoing a change in colour.

Molpadia antarctica is known from off Chile (Theel, 1886a), between Florida and Cuba (Theel, 1886b), off Alexander Land, Antarctica (Herouard, 1901), and from various localities off Japan (Augustin, 1907; Ohshima, 1915). Thus it is a widespread species in depths ranging from about 80 metres to 1,218 metres.

Molpadia ? n.sp. Text-fig. 3, figs. 8, 9

Material Examined: N.Z.O.I. Stn. B.291, 2 specimens.

Description: Total length of specimens, 38mm and 61mm; body of typical molpadid shape. Colour in alcohol grey, with large numbers of small light red spots, more closely aggregated in smaller specimen. Tail grey.

Calcareous deposits almost completely transformed into phosphatic material (Text-fig. 3, fig. 8), and comprise only tables. No anchors, rosettes or anchor plates. Original shape of tables cannot be accurately determined, but fragments indicate page 14 that they may have been similar to those in Molpadia antarctica (Theel). Phosphatic bodies vary greatly in size and shape, aggregated into small, scattered clusters (replacing calcareous deposits), forming red spots visible to naked eye.

Tail with elongate tables bearing three-pillared spires (Text-fig. 3, fig. 9), and numerous (10–16) small perforations. Average length of tail deposits 0.22mm.

Remarks: These specimens clearly represent a species in which the calcareous deposits (apart from those in the tail) are entirely transformed into phosphatic material, probably early in life. It is possible that these are representatives of an undescribed species, closely allied to M. antarctica, although the latter has smaller (0.16mm) tail deposits with fewer perforations (6–10). Clark (1907, p. 32) notes that calcareous deposits tend to disappear from the bodywall of M. antarctica with growth but makes no mention of phosphatic deposits. Further the bodywall in present material is quite thin, but not delicate, as in M. antarctica.

Without a better knowledge of the calcareous deposits of the bodywall, it is felt that these specimens should not be assigned to a new species, and for the present they must remain unnamed.

Family Caudinidae Heding, 1931

Diagnosis: Tentacles with two pairs of digits. Caudal appendage usually long and slender. Deposits not tables but cups (buttons), perforated plates or irregular rods. (Heding, 1931, in part.)

Type Species: Paracaudina chilensis (Müller).

Paracaudina chilensis (Müller)

For synonymy, see Pawson, 1963, p. 18.

Material Examined: None.

Remarks: A circum-Pacific species, bathymetric range from 0 to more than 900 metres.

Hedingia Deichmann, 1938

Diagnosis: Tentacles with two pairs of digits. Deposits large tables (0.15–0.27mm diameter), with high spires composed of three converging rods.

Type Species: Trochostoma albicans Theel.

Hedingia albicans (Theel)

Trochostoma albicans Theel, 1886a, p 44, Pl. XI, fig. 3.

Trochostoma albicans var. glabra Theel, 1886a, p. 46; Koehler and Vaney, 1905, p. 89; Perrier, 1902, p. 526, Pl. 22, figs. 7–8.

Caudina arenata var. armata Theel, 1886b, p. 17; Gerould, 1897, p. 19, Pl. III, figs. 34–37.

Caudina albicans: Clark, 1907, p. 174, Pl. X, fig. 12; Deichmann, 1930, p. 201, Pl. 24, fig. 1; Heding, 1931, p. 283.

Haplodactyla albicans: Heding, 1935, p. 65, Pl. IV, fig. 9, Pl. V, fig. 17, Pl. VIII, fig. 10.

Hedingia albicans: Deichmann, 1938, p. 112; Madsen, 1953, p. 167; Deichmann, 1940, p. 216.

Material Examined: None.

Remarks: Occurs off New Zealand, south of Iceland, off the north-east coast of U.S.A., the Cape Verdes, Mediterranean Sea, Bay of Bengal in depths ranging from 500 metres to 3,200 metres (Madsen, 1953).