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Echinoderms from Southern New Zealand

Class Asteroidea

page 6

Class Asteroidea

Fam. Astropectinidae
Psilaster Sladen, 1885

Psilaster acuminates (Sladen, 1889)

  • Ten miles south of Cape Campbell, 50 fathoms, March, 1947; coll. F. Abernethy; 377 specimens.

The above record is notable for the evidence it provides of the abundance of the species on at least one portion of the New Zealand continental shelf. It has hitherto been regarded as a somewhat rare, mainly deep-sea form (ranging down to more than 900 fathoms). It was taken by H.M.S. Challenger in the Tasman Sea, and has since been proved to have a wide southern distribution, though the individual records of its having been found total only six occasions. These indicate its presence off South Africa, off South and Eastern Australia, and on the New Zealand shelf. In addition to the above record, one other unrecorded instance is known to me—a specimen taken off Napier, said to have been in deep water (a statement which probably means no more than in the sublittoral zone); it is now in the Napier Museum.

In the large sample studied, only a single six-rayed specimen was discovered—a fact indicating unusually high stability of pentamerism for an asteroid. The colour of both the paxillar area and of the marginal plates is salmon-pink. As it occurs in company with the following larger species, it resembles superficially the younger stages of the latter; in Psilaster, however, only the infero-marginals bear spines, whereas in Persephonaster both series of marginals are so provided. P. acuminatus proves to be an excellent species for dissection by university classes, and has been so employed both at Victoria University College and at the University of Otago. It is notable for the very large size of its polian vesicles, structures which students commonly fail to discover in species more usually studied.

Persephonaster Alcock, 1891

Persephonaster neozelanicus Mrtsn., 1925

  • Ten miles south of Cape Campbell, 50 fathoms, mud, March, 1947; coll. F. Abernethy; 70 specimens.

There were no meristic variants in the population-sample studied. The largest individual measures: R, 140 mm.; r, 35 mm.; R/r, 4. The number of marginals to the interbrachial semi-arc is 49 in the same specimen. The species thus reaches a larger size than was hitherto supposed. Mortensen (1925), in describing the type material, stated that there was no anus observable in his specimen. In the present material, the anus is usually placed on a prominence in the centre of the page 7 disc—some specimens have the rectal and pyloric portions of the intestine everted through it. Other new points that may be noted are: the sexes are separate; the gonopores open on the aboral inter-radii, near the margin. The colour in life is striking—the paxillar area salmon-pink, the marginals and underside cream.

Family Luidiidae
Luidia Forbes, 1839

Laidia neozelanica Mrtsn., 1925

  • East Marlborough coast, off Mount Benmore, 40 fathoms, mud, in trawl, February 5, 1952; coll. J, A. F. Garrick; two specimens.

Family Odontasteridae
Asterodon Perrier, 1891

Asterodon miliaris (Gray, 1847)

  • Off eastern coast of Canterbury and Otago, between Taiaroa and Timaru, 40 fathoms, January and November, 1951; P. M. Ralph; seven specimens.

Colour in life, orange-buff. The features which distinguish the species from others of the genus in New Zealand are discussed elsewhere (Fell, 1952).

Peridontaster Koehler, 1920

Peridontaster benhami Mrtsn., 1925

  • Off coast of east Canterbury, between Moeraki and Timaru, 40 fathoms, January, 1951; P. M. Ralph; one specimen.

Since Mortensen described the type specimen, the species does not, till now, appear to have been taken again. The type locality was east of the South Island, possibly the same area as that from which the new specimen originates. The latter was orange in colour in life, though now faded to pale cream. It measures: R, 32 mm.; r, 22 mm.; ratio R/r, 1·45.

In comparison with the relative abundance of the diplacanthid species of Asterodon, the two monacanthid forms, namely, P. benhami and Eurygonias hylacanthus, are rare. Indeed, whilst the above is only the third record of P. benhami, Eurygonias is so far known only from the unique genotype-holotype described by Farquhar forty years ago, now preserved at Victoria University College.

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Family Goniasteridae
Pentogonaster Gray, 1840

Pentagonaster pulchellus Gray, 1840

  • Alert station 20, three specimens; and station 23, one young specimen.
  • Off east coast of Canterbury and Otago, between Taiaroa and Timaru, 40 fathoms, January and November, 1951; P. M. Ralph; seven specimens.

Bright orange-red in life, the large marginals coloured in the same way as the rest of the upper surface, paler below. In young individuals, the penultimate marginals are not yet enlarged; in the case of one of the east coast specimens, even at the stage having the major radius of 30 mm., the penultimate marginals are still not enlarged—an unusual circumstance which gives the specimen a very different appearance from normal.

Family Asterinidae
Asterina Nardo, 1834

Asterina regularis Verrill, 1867

  • New Golden Hind stations NGH L14, one specimen, and NGH L15, two specimens.
  • Alert stations 2, three specimens; 6, one specimen; 19, three specimens; 24, one specimen.

These do not differ from the common form, and are similarly coloured.

Family Echinasteridae
Henricia Gray, 1840

Henricia ralphae sp. nov. (Figures 1 to 4)

Dimensions: R, 53 mm.; r. 15 mm.; breadth of arm at base, 17 mm. R, 54 mm.; r, 17 mm.; br., 23 ram. R, 64 mm.; r, 14 mm.; br., 13 mm. (syntypes). R, 72 mm.; r, 16 mm.; br., 18 mm. (holotype).

Arms, five. Abactinal and actinal surfaces of the arms covered by a thin ectoderm through which can be seen a meshwork of interlocking plates. These enclose papular areas of varying size, in most cases exceeding the area of an individual plate by at least five times. Papular areas polygonal, dark in colour (reddish-brown) when dried, bearing from one to five separate papulae. Some of the abactinal and lateral plates bear small, slightly raised pseudopaxillae which carry spines. They vary in number and arrangement as follows: On the disc, the majority of the plates are paxillose, and carry fascicular bundles of short, slender spines, from two to eight in number, but mostly four or five. Over the greater part of page 9
Henricia ralphae sp. nov.

Henricia ralphae sp. nov.

Fig. 1.—Actinal surface of arm, the furrow lying to the left. Fig. 2.—Abactinal surface of arm. Fig. 3.—Abactinal surface of disc in region of periproct and madreporite. Fig. 4.—Part of syntype, showing the inflated type of arm, abactinal view.

Abbreviations: A, anus. AB, abactinal plate. ACT, actinal spines. AD, adambulacral spines. FU, furrow-spine of adambulacral plate. MADP, madreporite covered by spines. MAG, marginal spines, arranged in comb. PAA, papular area. PAP, papula (or dermal branchia). PP, periproct.

Figs. 1 to 3 are to the lower scale; Fig. 4 to the upper scale.

page 10 the abactinal and lateral surface of the arms, however, only about one-third of the plates are paxillose, and here the fascicles comprise from two to four spines, with occasional isolated spines. The anus, lying somewhat excentrically on the disc, is surrounded by a periproctal membrane, rather larger than the largest papular areas, and studded with spines similar to those of the psendopaxillae. The madreporite lies nearby, in one interradius, and is likewise almost completely covered by spinules, which also surround it and almost obscure it.

On the actinal surface, three regular, longitudinal series of plates are present—namely, an adambulacral series bordering the furrow, next to it an actinal series, and next to this a prominent marginal series. The actinal, or middle, series extends from near the mouth to only about half-way along the arm. Papulae occur singly in the depressions between the adambulacral and actinal series, and between the actinal and marginal series. The armature of the plates is as follows: Each adambulacral plate bears a furrow-spine, which is placed deep in the furrow and is somewhat curved; it also bears subambulacral spines, two or three large ones at or near the furrow border, and beyond these three or four smaller spines occur. All these adambulacral spines are arranged in a more or less monoserial, transverse line. The actinal plates each bear a compact cluster of four or five similar slender spines. The marginal plates are transversely elongated; each of them carries a transverse monoserial comb of seven to ten slender, rather glassy spines with thorny tips. There are distinct intervals without spines between all these plates, so that in no case are there continuous transverse rows of spines extending from the furrow up the sides of the arm, such as occur in the other two New Zealand species, H. lukinsii and H. compacta.

Colour in life, brilliant orange-vermilion.

Holotype in the Zoology Museum, Victoria University College.

Type Locality.—Off east coast of Otago, between Taiaroa and Moeraki, three specimens trawled from 40 fathoms, collected by Miss P. M. Ralph in November, 1951. Syntypes from east coast of Canterbury, between Moeraki and Timaru, 40 fathoms, collected also by Miss Ralph in January, 1951.

Remarks.—This large and striking species of Henricia can easily be differentiated from the other two species of the genus occurring in New Zealand waters (H. lukinsii and H. compacta) by its sparse abactinal spinulation, its distinctive actinal and adambulacral armature, and by its large size. Of other species of Henricia known from the Southern Ocean, H. obesa (Sladen) resembles H. talphae in general form, including the occasional inflation of the base of the arm (cf. dimensions of second syntype listed above with those of the holotype)—but it has a different spinulation. The same may be said of the Australian "Henricia page 11 hyadesi" (Perrier), which supposed species Fisher (1940) has merged with obesa partim, and with H. sufflata and H. compacta partim. H. sufflata (Sladen) is as yet known only from the Challenger station 170, off the Kermadec Islands, 520 fathoms; it, too, has the base of the arm inflated in the type material, but the spinulation is quite different. H. simplex (Sladen) has a sparse abactinal spinulation, but its subambulacral armature differs from that of H. ralphae. H. pagen-stecheri (Studer) presents one resemblance to H. ralphae, as also does H. lukinsii, in the presence of an inter radial abactinal depression—an inconstant feature in the two former species, however—but that is the only similarity. H. diffidens (Koehler) is of the North Pacific "longispina" type, and so is not comparable.

The foregoing comparisons are given in view of the notoriously difficult systematics of Henricia. General body shape is variable and of no guide in separating species. The variation is well shown in the dimensions quoted for the present species. The pronounced inflation of the arm in one syntype is illustrated in Fig. 4.

In 1909, Benham described Echinaster farquhari from almost the same locality, namely, off Otago Heads, in 18 to 28 fathoms; only one specimen was obtained. In general facies it presents, to judge by Benham's account, a remarkable similarity to H. ralphae; in size and colour, it is similar. The conjunction of the localities caused me to wonder at first if he might have mistaken a Henricia for an Echinaster, and if the two might really be identical. It seems, however, that Benham's species must be a true Echinaster, as I think the following considerations show: Benham states that in Echinaster farquhari the abactinal armature of the plates of the arms comprises ... "here and there an isolated, short, blunt, apparently immovable spine" which ... "springs from a node in the network." His figures support the statement—which, of course, points to Echinaster. Again, although he refers to papulae on other parts of the body, he makes no reference to any between the actinal plates—a condition also diagnostic of Echinaster. There are a number of other differences between E. farquhari and H. ralphae, such as the distinctive arrangement of the spines on the lower plates, the fact that spines are sparse on the abactinal surface but become more numerous near the arm-tips; the madreporite in E. farquhari is prominent, projects above the abactinal surface, and is not surrounded by spines. We are forced to conclude that the two forms cannot be extreme variants of one and the same species, and that therefore the two related genera, Henricia and Echinaster, occur in the same area. An analogue is presented perhaps by Persephonaster and Psilaster, two related genera each represented by one species off Cape Campbell, and as yet known to be common only in that one place.

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Family Asteriidae
Sclerasterias Perrier, emend. Fisher, 1924

Sclerasterias mollis (Hutton, 1872)

  • Station NGH 3, one small individual.
  • Otago Harbour. November, 1951; coll. E. Batham; one specimen.
  • Ten miles south of Cape Campbell, mud bottom, 40 to 50 fathoms, March. 1947; coll. F. Abernethy; 10 specimens.

The species is abundant at Cape Campbell, and the hundred specimens taken there comprise only a representative sample of what came up in the trawl of the Phyllis. Of the hundred. 99 were five-armed, one alone six-armed. Two only showed regenerating arms, one of them in the so-called "sea-comet" condition. The colour in life is a bright brick-red, marked by longitudinal yellowish bands which correspond in position to the longitudinal rows of spines. The largest specimen has R, 120 mm.; r, 18 mm. The majority have arms exceeding 10 mm. in length. This is the only large Asterias-like starfish of New Zealand to have five arms. As the specific name indicates, it is very fragile, owing to weak regions of the body-wall where the arms enter the small disc.

Coscinosterias Verrill 1867

Coscinasterias calamaria (Gray, 1840)

  • Alert stations: 2, one specimen; 6, one specimen.
  • Off east Otago coast, 40 fathoms, two specimens.

The common eleven-armed starfish.

Allostichaster Verrill, 1914

Allostichaster insignis (Farquhar, 1895)

  • Alert stations: 23, fourteen specimens; 25, one specimen.

The widely-distributed, six-armed, fissiparous starfish of New Zealand. As it has already been recorded from Wellington, the Snares Islands, and Auckland Islands, its presence in the Fiords was to be expected. There, however, it was found only in Dusky Sound.