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Deep-Sea Echinoderms of New Zealand

Subgenus Aspidocidaris Mortensen, 1928

Subgenus Aspidocidaris Mortensen, 1928

Basal disc on primary radioles more or less developed, and terminal disc usually well developed, often forming large round discs which cover the whole apical side. Secondary spines flattened, with a straight-cut end.

The subgenus has not hitherto been reported from New Zealand. One species, Goniocidaris (Aspidocidaris) australiae Mortensen, is known from Australia, three occur in the Indonesian-Philippines region, and two others in Japanese waters. The New Zealand form is apparently different from any of those.

Goniocidaris (Aspidocidaris) parasol sp. nov. Plate 3, Fig. B, Plate 5, Fig. b; (both holotype).

Diagnosis: Test flattened above and below, the sides arched, ambitus rounded, apical system ca. half h.d., peristome one third h.d. Ambulacra weakly sinuate, ca. 16% IA. At the ambitus about seven amb plates occur opposite an IA plate. Interporiferous area 3–4 times broader than the poriferous area. Pores oblique. Marginal tubercles in vertical linear series.

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Plate 5

Plate 5

a, Pseudechinus flemingi sp. nov., immature paratype of ca. 25 mm h.d., showing relatively long primary spines at that stage, b, Goniocidaris (Aspidocidaris) parasol sp. nov., holotype, partly denuded. Both echinoids to the same scale, as shown.

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Internal tubercles 2 or 3 to each plate, in more or less vertical linear series. The median area is sunken, completely naked, and forms a conspicuous, vertical furrow, weakly sinuous but not following a zig-zag course, and with no abrupt changes in its width from plate to plate. About 7 IA plates. Primaries cylindrical, slender, developing a wide distal disc in the case of the adapical radioles; the disc is somewhat excentric, the adapical side being larger. In the adult, a fully-formed disc is almost as large as the apical area, and about 15 to 20 such discs may be present, forming a complete shielding system over the aboral surface. Oral primaries more or less spearhead-shaped, with lateral teeth sometimes evident near the base.

Material Examined: Five specimens from 130 fathoms, Station 34, Chatham Islands Expedition 1954.

Holotype: In the Canterbury Museum, Christchurch, H.d. 27 mm, ht. 17 mm. Colour in life, radioles pale purple or mauve, the secondaries and miliaries a rich red-brown. Test, when cleaned, creamy white.

Remarks: A fuller description, with photographic figures, will be given in the official report of the Chatham Islands Expedition. From the diagnosis above, it will be evident that the two species most similar to G. parasol are G. australiae Mortensen and the Japanese G. clypeata Döderlein. G. parasol is distinguished from both species by the greater development in the adult of the apical discs, by the broad, almost straight, sunken, naked furrow in the interporiferous area, with no trace of zig-zag furrows, by the colour of the primary radioles, and the arrangement of the internal tubercles on the ambulacral plates. From G. clypeata it is further distinguished by lacking the deckled edge to the disc, and by having the adapical side of the disc larger than the abapical side.