Deep-Sea Echinoderms of New Zealand
Until now three genera of Goniasteridae have been recorded from New Zealand waters, namely Mediaster, Pentagonaster and Nectria. Three more genera can now be added to the fauna, namely Pseudarchaster, Hippasteria and Anthenoides. In view of this major change in the representation of Goniasteridae the following key to the genera may be useful.
|1.||Body covered by a membrane which obscures the outlines of the underlying plates and granules; inferomarginals projecting beyond the superomarginals||Anthenoides|
|Body not covered by a membrane which obscures the plates below; both marginal series similar||2|
|2.||Paxillae on the abactinal surface||3|
|No abactinal paxillae||5|
|3.||Abactinal plates with an elevated tabula, crowned with enlarged granules||Nectria|
|Abactinal plates with unspecialized paxillae||4|
|4.||An unpaired (but not recurved) median tooth to each pair of mouth-plates||Pseudarchaster|
|No median unpaired tooth||Mediaster|
|5.||No abactinal or marginal spines; terminal marginal plates enlarged||Pentagonaster|
|Abactinal and marginal spines present; terminal marginal plates not enlarged||Hippasteria|
Pseudarchaster Sladen, 1885
Abactinal plates paxilliform, extending far along the arm in several series, usually more than one series reaching the terminal plate. An unpaired median but not recurved tooth common to each pair of oral plates. Adambulacral armature comprising a palmate group of furrow-spines and a co-ordinate group of subambulacrals. Numerous actinal intermediate plates. Marginal plates thick, robust, paired, with fasciolar grooves between them.
Pseudarchaster, though widely distributed, has not hitherto been discovered in New Zealand or Australia ("Pseudarchaster" boardmani Livingstone, of New South Wales, must be referred to Mediaster, as H. L. Clark (1946) has already shown). One deep-water species can be recorded from Cook Strait, and, by an unusual coincidence, a second sublittoral species has become known at the same time from the same area. For the sake of clarity both species will be diagnosed here, though only one of them is so far known from below the continental shelf.
|Superomarginals, inferomarginals and actinal intermediate plates bearing granules, without enlarged spinules. Abyssal||P. garricki|
|Superomarginal plates bearing granules, but inferomarginal and actinal plates bearing both granules and coarse spines. Sublittoral||P. abernethyi|
Pseudarchaster garricki sp. nov. Plate 3, Figs. G, K, holotype.
Description: Abactinal paxillae in crowded hexagonal or polygonal groups, largest on the disc, comprising usually about 7 polygonal granules closely arranged around a central polygonal granule, and with small angular grains filling in the outer margins of the paxilla.page 9
A, B, Peribolaster lictor sp. nov.; A, abactinal skeleton and armature, midway along arm of holotype; B, oral, adambulacral and inferomarginal plates. C, Allostichaster insignis var. gymnoplax var. nov., supermarginal and inferomarginal plates. D, E, H, Cosmasterias dyscrita H. L. Clark; D, unguiculate (felipedal) pedicellaria from oral plate; E, adambulacral and actinolateral plates and their armature; H, oral plate, oriented so that the distal suboral spines are lowermost. F, Crossaster japonicus (Fisher), adambulacral plates and one inferomarginal, showing armature. G, I, Pteraster (Apterodon) bathami sp. nov.; G, oral plates and first three adambulacral wings, showing armature; I, paxillar spinules and webs of aboral surface.
Marginals broad and short, the proximal ones about four times as broad as long. About 40 marginals from the interradius to an arm-tip. Both superomarginals and inferomarginals covered in a uniform, dense granulation of more or less hexagonal granules. No scales or spinules on any of the marginals. Adambulacral plates with an armature of 5 or 6 truncate, compressed furrow-spines, and 7 or 8 truncate subambulacral spines, similar to the furrow spines, but not compressed. Distad to these is another line of finer spines, 4–5 in number. These form a postadambulacral fasciole, in conjunction with a still finer series of spines carried on the proximal margin of the proximal intermediate plate. The intermediate plates otherwise bear only granules, with no enlarged spines.
Material Examined: Only the holotype, which is from 550 fathoms in Cook Strait, VUZ Station 101.
Remarks: P. garricki is apparently distinguished from all other species of Pseudarchaster by the complete absence of spines or spinules from the uniformly granulated marginals and actinal intermediate plates.
Holotype: In the Department of Zoology, Victoria University of Wellington. R 82 mm, r 26 mm. Rays 5. Colour in life, orange above, cream below.
Pseudarchaster abernethyi sp. nov. Plate 3, Figs. I, J, holotype.
Description: Abactinal paxillae in crowded hexagonal or polygonal groups, largest on the disc, tending to become transversely rectangular at the bases of the arms. On the disc the paxilla comprises usually about 30 granules, the central ones more markedly polygonal than the outer ones, which tend to be rounded, and are packed less tightly. Marginals broad and short, the proximal ones about three times as broad as long. About 42 marginals from the interradius to the arm-tip. The superomarginals covered in a rather fine, more or less uniform granulation, somewhat coarser toward the outer edge, and with the fascioles between the plates formed by finer granules in linear series. The inferomarginals densely covered in a scaly granulation, with occasional lanceolate, flattened spines directed distally from short stalks. Adambulacral plates with an armature of 3–6 (usually 4 or 5) cylindrical truncate furrow-spines, and about 12–16 truncate, cylindrical or compressed subambulacral spines; one of the subambulacral spines is usually much expanded into a flattened, or bifurcate, or sometimes lanceolate spine. Postambulacral fascioles indistinct. Intermediate plates armed with irregular granules, spines and occasional enlarged lanceolate spines, the borders defined by delicate spinules, arranged too irregularly to form obvious fascioles.
Material Examined: Fourteen specimens, including the holotype, from 55–63 fathoms, 10 miles E. by S. of Cape Campbell, March, 1957. Coll. F. Abernethy.
Remarks: From P. garricki this species is easily distinguished by the spines on the inferomarginal and actinal plates. P. abernethyi does present some close parallels to some other species, however. In particular it appears to fall close to P. parelii (Düben & Koren), a circumpolar north Pacific and north Atlantic species. To judge by Fisher's (1911) account, P. parelii has smaller paxillae, since the larger ones described by him have only half the number of granules found in P. abernethyi; this difference is further confirmed by Plate 31 in Fisher's book, a photographic plate which is clear enough to enable the granules in the paxillae to be counted. The material of P. abernethyi at my disposal shows considerable variation, especially as regards the adambulacral and actinal intermediate armature, but all specimens agree in having the larger type of paxilla which is present in the holotype. I therefore regard this as a primary diagnostic character. Pseudarchaster discus Sladen, from the Magellanic area, also invites comparison, but here again the paxillae are even smaller, having only "about a dozen" polygonal granules, according to Sladen (1889, p. 111). From P. dissonus Fisher the absence of bivalved postadambulacral pedicellariae provides a distinguishing feature, and the furrow-spines of P. dissonus are sharp, not truncate.
Holotypes In the Department of Zoology, Victoria University of Wellington. R 110 mm, r 32 mm. Rays five. Colour in life, orange above, the actinal surface cream.
Mediaster Stimpson, 1857
Mediaster sladeni Benham
- Benham, W. B., 1909. Rec. Cant. Mus. 1 (2), p. 94–7, Pl. VII.
Material Examined: Thirteen specimens from the following archibenthal stations: 250–300 fathoms, Canyon B, off east Otago, Dom. Mus. Station B.S. 191, page 112 specimens; 125 fathoms, Chatham Rise, Station 51 of the Chatham Islands 1954 Expedition, 11 specimens.
The species is known also from the Cook Strait shelf as a somewhat rare form at depths greater than 40 fathoms. Benham's holotype was a unique specimen from 25–30 fathoms off Oamaru, and apparently the species has not been recorded from any other locality till now. The Chatham Rise material presents some considerable variation in form, and this will be illustrated photographically in the official report of the Chatham Islands Expedition.
Hippasteria Gray, 1840
Hippasteria trojana sp. nov. Plate 1, Figs. A, G, holotype.
Diagnosis: Large pentagonal body, defined by conspicuous, naked marginal plates, each of which carries one prominent conical spine, 35 or 36 marginals in the entire interbrachial arc from arm-tip to arm-tip. There may be one or two large bivalved pedicellariae on the more proximal superomarginals and inferomarginals, and exceptionally there may be two sub-equal spines instead of one. The abactinal plates carry a single erect conical spine or a large bivalved pedicellaria, and they are surrounded by smaller platelets or granules. Actinal area large, with numerous large bivalved pedicellariae, each surrounded by a circle of granules. The pedicellariae form a row parallel to each furrow margin, on the adjoining intermediate plates. Adambulacral armature comprising 3 robust furrow-spines, which are flattened distally, and 1 to 3 robust, erect subambulacral spines, the number depending upon the size of the adambulacral pedicellariae. Typical patterns are illustrated in Fig. A, which shows the 5th to 7th adambulacral plates of a ray of the holotype.
Material Examined: The unique holotype, taken at a depth of 220 fathoms on the Chatham Rise, at Station 6 of the Chatham Islands 1954 Expedition. The full description and photographic figures of this species will be given in the official report of that expedition.
Remarks: H. trojana resembles H. spinosa armata Fisher in having naked marginals armed with 1 or 2 spines and pedicellariae, but differs in having 3 furrowspines (as against a single one in H. spinosa armata), and 1–3 subambulacral spines (as against 1 only). From H. heathi and H. falklandica, both described by Fisher, the New Zealand form is at once distinguished by the marginal plates, which are inconspicuous and granulated in the two species named, and carry up to 5 spines. The species to which H. trojana appears most closely related is the one which is most remotely situated, in the Atlantic Ocean—namely, H. phrygiana (Parelius). Both species have conspicuous, naked marginals; H. phrygiana 2–3 furrow-spines, not unlike the condition in H. trojana. However, a specimen of H. phrygiana in my collection can be distinguished by its blunt, cylindrical furrow-spines, which are not at all flattened distally. H. phrygiana also tends to have more than one spine on each marginal plate, whereas this is exceptional in trojana. A still more striking difference is the complete absence of pedicellariae from the marginals in H. phrygiana. It does seem evident, though surprising, that the New Zealand species is closer to the Atlantic species than to the Pacific or Magellanic ones, and it may appropriately take the specific name trojana, the Phrygians and Trojans having been close allies (Iliad Bk. 2).
Although no living species of Hippasteria has hitherto been recorded from Australia or New Zealand, it is relevant to note that a fossil form, Hippasteria antiqua Fell, was described from upper Cretaceous sediments in Canterbury (Fell, 1956), only 600 miles west of the position in which the living species has been found. Hippasteria antiqua carries a single robust conical spine on each superomarginal. The condition of the adambulacrals and inferomarginals cannot be determined, but one obvious difference from H. trojana lies in the prominent carinal abactinal plates, lacking from the latter species.
Holotype: In the Canterbury Museum, Christchurch. Rays five, R 105 mm, r 62 mm.
Anthenoides Perrier, 1881
Body covered by a membrane which is superficially smooth and rather thick, obscuring the underlying granules during life, though these become visible after drying. Secondary small abactinal plates on either side of the median carinal series. Actinal intermediate areas large, the intermediate plates polygonal. Adambulacral armature comprising a furrow-comb, plus granules or subambulacral spines and pedicellariae. No abactinal or actinal spines.
This striking Indo-Pacific genus, though new to the fauna of New Zealand, is already known to be represented in Western Australia, where a small species, A. dubius H. L. Clark, has been taken. The New Zealand representative, on the other hand, is a large and handsome form, rivalling Dipsacaster magnificus.
Anthenoides granulosus Fisher Plate 1, Fig. B.
- Fisher, W. K., 1919. Bull. U.S. Nat. Mus., p. 328, Pl. 88 and 94.
Material Examined: One specimen, taken in 270 fathoms, off Mayor Island, Bay of Plenty, by Dr. R. K. Dell, at Dom. Mus. Station B.S.209. It is now in the collection of the Dominion Museum, No. Z Ech. 567.
Remarks: The specimen, the only one so far discovered in New Zealand waters, appears to be an adult and has 31–33 marginals in either series, from the IR to the arm-tip. The holotype of the species was taken in 265 fathoms off Mollucca Islands. The New Zealand specimen has relatively longer arms, R 135 mm, r 50 mm, R = 2 6 r (as against R = 2 r in the holotype); this difference is, however, probably due to the greater size of the New Zealand specimen, for in other respects there is close agreement.
The marginals are densely granulated, with coarser granules on the lateral margins of the proximal inferomarginals. The ambitus is defined by the projecting inferomarginals alone. The pedicellariae are largest on the proximal adambulacral plates, and smallest on the abactinal plates, where they resemble cleft granules. The adambulacral armature is characteristic of the species as described by Fisher, comprising (a) a furrow-comb of 6–9 uniform, delicate spines, deeply placed in the narrow furrow, (b) 2 or 3 coarse sub-ambulacral spines, one or two of which become enlarged on the distal half of the arm, (c) scattered granules and pedicellariae. The enlargement of the subambulacral spines on distal adambulacral plates, though mentioned by Fisher (1919), was not figured by him, and so an illustration of the condition in the New Zealand specimen is given here (Fig. B). From A. epixanthus Fisher, of Hawaii, the present specimen differs in possessing abactinal pedicellariae and in its adambulacral armature.
The presence of this Indonesian sea-star in the Bay of Plenty gives further ground for regarding the area as falling within the Aupourian marine province, where northern elements of the fauna are most evident.
Pentagonaster Gray, 1840
Pentagonaster pulchellus Gray
- Gray, J. E., 1840. Ann. Mag. Nat. Hist. VI, p. 280.
Material Examined: Although this beautiful sea-star is well-known from quite shallow water, 3–40 fathoms, it has not previously been taken from the continental slope. Seven specimens now in the Dominion Museum were taken by Dr. R. K. Dell from the edge of Canyon A, off East Otago, at Dom. Mus. Station B.S.189 in 120 fathoms. Dell (personal communication) considers it not unlikely that they had fallen into the canyon, as some shelf mollusca were found to be living under similar circumstances.