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Echinoderms from Southern New Zealand

Family Amphiuridae — Amphiura Forbes, 1842

Family Amphiuridae
Amphiura Forbes, 1842

Amphiura magellanica Ljungman, 1866

  • Alert station 13, seven individuals.
  • Off Cape Campbell, 50 fathoms, April 4, 1947; coll. F. Abernethy; five individuals.

In fresh material of New Zealand examples of this species, the colour seems relatively invariable—the disc is grey above, cream below, the arms being entirely cream-coloured. In the field, therefore, it provides a useful diagnostic feature for separating the species from the very similar following one, where brilliant shades of various colours occur, often with banding on the arms.

In spirit material, it may be noted that in adult specimens of Amphiura magellicana the disc is usually tumid above, on account of the presence of embryos in the hursae—an additional difference to those already cited by Mortensen (1924) as distinguishing it from the following nearly-related form.

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Amphiura spinipes Mrtsn., 1924

  • Alert stations; 4, three specimens; 13, five specimens; 14, one individual; 20, about forty specimens.
  • Lochlan station 367/51, one specimen.

Amphiura spinipes is extraordinarily variable in respect to its coloration, even within populations of relatively restricted area—for example, Alert station 20 (Paterson Inlet, Stewart Island). On preliminary macroscopic sorting of the collection from the latter station, four distinct lots were isolated, on account of colour differences, which afterwards proved to be all of this species. Following are some of the major colour variants noted:—

(a)Purple-brown disc and arms—ten individuals from station 20.
(b)Pinkish-fawn above, arms pale fawn below—about twenty individuals from station 20.
(c)Grey, the arms banded with narrow black bars at 2 mm. intervals—one individual from station 4.
(d)Disc dark fawn, arms brilliant orange-vermilion—about twelve individuals from stations 13 and 20.
(e)Disc brownish-orange, arms fawn, with narrow black bands at 2 mm. intervals—two specimens from station 20.

Amphiura rosea Farquhar, 1894

  • Alert stations: 1, six specimens; 3, five young individuals; 6, three individuals.

In the present instance, all material was in spirit before it was examined, so the colours were not noted. Specimens from Alert station 3 are of typical form, but small. Those from station 1 have the radial shields separated by more scales than in the case of Farquhar's type.

Amphiura hinemoae Mrtsn., 1924

  • Station NGH 64A, one specimen.
  • Alert station 14, ten specimens.

Colour—hitherto unknown from fresh material—pale pink or orange, the disc naked below, the primaries prominently pigmented with grey spots.

The type locality—and, indeed, hitherto only known one—is White Island, 55 fathoms. Thus, again, as in the case of Peronella hinemoae, the southern range of the species is extended by some seven hundred miles, yet no occurrences are known in the intervening waters.

Amphiura amokurae Mrtsn., 1924

  • Paterson Inlet, Stewart Island, intertidal, under stones on seaward side of Point Anglem, January, 1951; coll. B. M. Bary; a single specimen.
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The species appears to be nowhere common, though isolated instances establish its presence throughout New Zealand from North Cape to Auckland Islands. Only one specimen was obtained by the Cape Expedition (at Auckland Islands).

Amphiura alba Mrtsn., 1924

  • New Golden Hind stations: 44, one specimen; 2, two young specimens. Alert stations: 18, two specimens; 20, one specimen.

The above specimens agree with A. alba in having one triangular tentacle-scale, no disc spines, the oral side of the disc completely scaled, spearhead-shaped oral shields, five or six pointed arm-spines, and the outer oral papilla large, flattened, and pointed distally. On the other hand, the six primary plates of the upper side of the disc are quite distinct—of rounded form—each separated from its fellows by smaller disc-scales. In Mortensen's type (from Colville Channel, 35 fathoms), the primaries are said to be "not very distinct." The difference, however, may be due only to age.

We have here yet another instance of a northern New Zealand species occurring seven hundred miles to the southward without known intervening records.

Amphiura abernethyi Fell, 1951

  • Alert stations: 10, six specimens; 26, one specimen.

These specimens are all only some two-thirds as large as the type material (from Cape Campbell). They are therefore more directly comparable with the related A. norae. Also, the number of mosaic platelets between the radial shields (about 18 to 20) is smaller than in the type A. abernethyi, though still considerably exceeding the corresponding number (5 to 7) in A. norae. The spacing between the radial shields is not so great in the present material as it is in the type, again a feature reminiscent of A. norae. It would not be surprising if eventually it should be found that A. abernethyi and A. norae are the two limiting forms of a cline.

Amphiura heraldica sp. nov. (Figures 5 to 7)

  • Dimensions: R, 8·0 mm.; r, 2·9 mm.; ratio R/r, 2·8.
Disc, circular, flattened, its aboral surface covered by scales of various sizes, amongst which the primaries and the radial shields are prominent. The scales partly imbricate and partly interlock. The six primary plates—namely, the dorso-central and the five radials—are large, contiguous, extend from the centre to halfway to the periphery, and shape the pattern of the English heraldic tudor rose. Adjoining the radial primaries, and interradial in position, occur five irregularly pentagonal plates, one to each iuterradius, and evidently also belonging to the primary system, Adjoining the radial distal border of each primary radial plate there are three small scales arranged as a trefoil, the middle leaflet of which is inserted between the proximal ends of the two adjoining radial shields. The radial page 17
Amphiura heraldica sp. nov.

Amphiura heraldica sp. nov.

Fig. 5.—Aboral view. Fig. 6.—Adoral view. Fig. 7.—Lateral view of arm-segment.

Figs. 5 and 7 to scale at left; Fig. 6 to scale at right.

Abbreviations: A, adoral plate. D, upper arm-plate. DC, dorso-central primary plate of disc. G, genital cleft. I, primary interradial plate of disc. L, lateral arm-plate. O, oral shield. PL, oral plate. R, primary radial plate of disc. S, radial shield. TE, tentacle-scale. V, lower arm-plate.

shields are polygonal, about as broad as long, mutually contiguous. The rest of the aboral surface of the disc is covered by rather large plates, smaller, however, than those already mentioned, and disposed in a less regular manner. The adoral surface of the disc is clothed in coarse, imbricating scales. Genital clefts extend to the Second arm-segment. Oral shields subtriangular, with a proximal acute angle and a distal convex base. Adoral plates subtriangular, larger than the oral shields, meeting broadly (or even overlapping) within. Three pairs of oral papillae, one pair infradental, one pair carried on the oral plates, the outermost borne on the adoral plates. All the oral papillae are large, leaf-shaped, and the two inner pairs have pointed tips.

Arms: upper arm-plates as broad as long, subquadrate, each with a convex distal border overlapping upon the next plate, all broadly contiguous. Lateral plates meeting neither above nor below, each bearing four, short, stout, subequal spines. Lower arm-plates similar to upper arm-plates, Save for the first one, which is more elongate. Tentacle-pores large, each having one large elliptical flat page 18 tentacle-scale, which is borne by the corresponding lower arm-plate. The pore itself is excavated within the lateral plate, and does not encroach much upon the margin of the lower plate.

Colour in spirit, white.

Type locality: Discovery station 2733, Chatham Rise, west of Chatham Islands, 30 metres, November 4, 1950; a single specimen.

Holotype: the unique specimen is in the Zoology Museum, Victoria University College.

The species is peculiar (amongst amphiurids) in respect of the large primary plates. The disc presents the aspect of an early post-larval stage, though its size is much larger than expected, and the arms present mature characters. It is, nevertheless, quite possible that this ophiuroid is a juvenile stage of some large species; but its distinctive features forbid our referring it to any known species.