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Sea-Stars (Echinodermata: Asteroidea) from "Eltanin" Cruise 26, with a Review of the New Zealand Asteroid Fauna

Suborder Cribellina Fisher, 1911

page 14

Suborder Cribellina Fisher, 1911

Family Porcellanasteridae Sladen, 1883
Porcellanaster Wyville Thomson, 1877
Porcellanaster caeruleus Wyville Thomson (Pl. 1, c-f).

Porcellanaster ceruleus Wyville Thomson, 1877, p. 378, figs. 97, 98.

Porcellanaster caeruleus Sladen, 1889, p. 134, pl. 20, figs. 1–7, pl. 20A, figs. 1–10; Clark, H. L., 1923, p. 239; Madsen, 1961, p. 126, figs. 22–24.

Material Examined:

6 specimens, Sta. 1837 (2); 1844 (1); 1846 (3).

Size:

R = 18–5 mm., average 11 mm.; r = 6–2 mm., average 4 mm.

Remarks:

The present specimens show considerable variation; however, these come within the limits described previously (Madsen, 1961). In several small specimens the apical appendage is well developed and paved with small overlapping porous plates; in the 3 larger specimens (Sta. 1846, R = 18—13 mm.) it is inconspicuous. The supermarginals of all these 3 larger specimens bear distinct spines and the abactinal spines of the disc are well developed and conspicuous in all but the interradial areas; actinally, the interradial areas are paved with plates (in small specimens these areas are naked except for a few, small, scattered, isolated plates near the margins). In one small specimen (Sta. 1837, R/r = 7/3 mm.) 3 straight pedicellariae are present abactinally, near the marginal plates in each interradius.

Colour:

Blue-grey.

Geographical Distribution:

World-wide, in deeper waters from Greenland to Antarctica.

Depth Range:

1158–6035 m.

Type Locality:

"Challenger" Sta. 45, south-east of New York, 38° 34′ N., 72° 10′ W.

Location of Type:

British Museum (Nat. Hist.).

Eremicaster Fisher 1905
? Eremicaster sp.
Material Examined:

One specimen, Sta. 1844.

Size:

R/r = 11/4 mm.

Remarks:

This specimen is much damaged, especially actinally, but the presence of 3 cribriform organs in each interradius suggests its inclusion in Eremicaster. It is conceivable that damage to the arms in life could result in abnormalities in development of the cribriform organs; if this is so in the present specimen, then it probably belongs in Porcellanaster. In each interradius there is one conspicuous, large central cribriform organ which is flanked by a small inconspicuous organ on either side. The latter are more or less V-shaped, with the open part of the V bordering the disc and the organs scarcely reach the inferomarginals. The abactinal surface, especially near the arm bases, is paved by pitted embryonic plates; centrally on the disc and extending interradially there are small, round or oval, isolated, tumid, conspicuous plates superimposed on the pitted plates which bear short spines interradially. page 15Distally, the one intact arm tip is protected by a saddle-shaped plate with 3 broken spines.

Colour:

Blue-gray.

Geographical Distribution:

World-wide including Antarctica but as yet not known from north of 60° N.

Depth Range:

750–7245 m.

Location of Specimen

United States National Museum.

Styracaster Sladen 1883
Styracaster horridus Sladen (Fig. 1, e; Pl. 1, g, h)

Styracaster horridus Sladen, 1889, p. 150, pl. 23, figs. 5–7, pl. 27, figs. 17–20; Madsen, 1961, p. 93, text-figs. 12–17, pls. 7, 8.

Chunaster scapanephorus Ludwig, 1907, p. 316; Madsen, 1961, p. 94.

Material Examined:

One specimen, Sta. 1844.

Size:

R/r = 44/8 mm.

Remarks:

The present specimen, although somewhat damaged, agrees well with the type description. The marginals join medially at about the fourth plate and there are 9 or 10 strong spines present to the arm tips; the abactinal paxillae are composed of from 3–7 short spines. Only 7 oral furrow spines are present and although the plates are damaged there appears to have been one suboral spine situated midway along the median suture. Both the adambulacral plates and the actinal plates (fig. e)—the latter with from one to 3 small inconspicuous granules—are similar to those described for the type material.

Colour:

Abactinal surface—disc cream, marginal plates and spines white, cribriform organs pale yellow; actinal surface—interradially, grey-blue (probably due to ingested mud) with adambulacral and oral plates white; faint pink ?gonads in 2 interradi. Tube feet and actinostomial ring yellow.

Geographical Distribution:

Northern Hemisphere—Bay of Biscay south to Gulf of Guinea and from the Indian Ocean; south of the equator it has been collected from near Madagascar, Sumatra, the Kermadec Trench and, this report, at 46° S.

Depth Range:

2470–5610 m.

Type Locality:

"Challenger" Sta. 346, 2° 42′ S., 14° 41′ W., Eastern Atlantic.

Location of Type:

British Museum (Nat. Hist.).

Family: Benthopectinidae Verrill, 1894
Benthopecten Verrill, 1884
Benthopecten pikei H. E. S. Clark var. australis var. nov. (Fig. 1, f, g; pl. 1, i, j).
Material Examined:

2 specimens, "Eltanin" Sta. 1846.

page 16
Size:

Larger specimen R/r = —150/20 mm.; smaller specimen (arms broken) R/r = -35/5 mm.

Remarks:

Both the present specimens differ from B. pikei in having more numerous (3–6) spines (fig. f) on the abactinal plates of the disc and from 4–6 small, very thorny spines on the arm plates which give a distinctly "hairy" appearance, especially proximally. In B. pikei there are seldom more than three spines on the abactinal plates and these are reduced to one distally; the distinct V-shaped arrangement of abactinal plates seen in B. pikei is absent in both the present specimens. In the larger of the 2 specimens discussed here, the enlarged central spines of the disc are more numerous, thicker and almost bulbous when compared with similar spines in B. pikei; this difference can probably be attributed to the larger size of the present individual. Another difference is in the unpaired superomarginal plate (fig. f). In the larger specimen there is a single enlarged spine surrounded basally by a half circle of 6 or 7 smaller spines with scattered spinules basally; in B. pikei only one unpaired plate bears an enlarged spine (the others may have been lost through injury) and there is no distinct half circle of smaller spines. The curious pectinate pedicellariae shared between the adambulacral and inferomarginal plates (fig. g.) (one such pedicellaria is present in the holotype of B. pikei) are very distinct in the larger of the 2 present specimens, especially midway along the arms; these pedicellariae consist of from 4–7 small, slender inferomarginal spines which interlock with similar adambulacral spines; no pedicellariae are present in the smaller specimen.

The smaller specimen lacks a conspicuously enlarged second inferomarginal spine on most of the plates, the adambulacral furrow spines are 6 in number and there are generally only 2 subambulacral spines on any plate; the actinal plates are few with an indication of pedicellariae in 2 interradii only and there are 4 or 5 oral furrow spines.

Both B. pikei and the new variety can be distinguished from B. munidae H. E. S. Clark (in press) by the fewer oral furrow spines and differences in the armature of the inferomarginal plates.

Colour:

Large specimen red, smaller specimen "lighter".

Geographical Distribution:

Known only from "Eltanin" Sta. 1846, 43° 54′–43° 48′ S., 167° 43–167° 46′ E., off the West Coast of the South Island of New Zealand.

Depth Range:

1647–1693 m.

Locality:

"Eltanin" Sta. 1846, 43° 54′–43° 48′ S., 167° 43′–167° 46′ E., off the West Coast of the South Island, New Zealand; 1647-1693 m.

Location of Specimen

United States National Museum.

Pectinaster Perrier, 1885
Pectinaster mimicus (Sladen) (Pl. 2, a-d).

Pontaster mimicus Sladen, 1889, p. 48, pl. 6, figs. 1, 2, pl. 7, figs. 5, 6.

Pectinaster mimicus Ludwig, 1910, p. 449; Fisher, 1919, p. 182, pl. 49, fig. 1.

Material Examined:

81 specimens, Sta. 1846.

page 17
Size:

R = 68–11 mm., average 43 mm.; r = 12–13 mm., average 7 mm.

Remarks:

This species has been well described previously and is highly variable as Fisher (1919, p. 183) shows. The present specimens, when compared with 2 specimens of P. mimicus (Sladen) from Macassar Straits (U.S. National Museum, 53256) differ in having generally more abundant and stouter pedicellariae, especially abactinally, and in having rather fewer abactinal spines surrounding enlarged central spines; other differences include the more robust and stouter marginal spines and the rather more dense covering of the marginal plates—all these characters are very variable and all degrees are to be seen in the material at hand.

The accompanying table shows the variations observed in 12 specimens:

TABLE: Variations in 12 specimens of Pectinaster mimicus (Sladen)

TABLE: Variations in 12 specimens of Pectinaster mimicus (Sladen)

This table is interesting when compared with that given by Fisher (1919, p. 183) as both the number of proximal adambulacral furrow spines and the number of adambulacral plates corresponding to the first 10 inferomarginals seem more stable in the present material.

page 18

Several specimens in the present collection are of particular interest. In one specimen, R/r = 34/7 mm. the enlarged central spines of the abactinal paxillae are missing from all but a few paxillae; abactinal pedicellariae are numerous, especially centrally on the disc; between the 2 most proximal superomarginals there is a single, large, pectinate pedicellaria and indications in several interradii of flanking pedicellariae; similar pedicellariae may be present between the inferomarginal plates, and occasionally indistinct pedicellariae are present between the supero—and inferomarginal series; actinal pedicellariae are few and indistinct and none is present between the inferomarginals and adambulacrals; there are 5–7 adambulacral furrow spines, one enlarged subambulacral spine and the oral plates have a furrow series of 7 or 8 spines.

In another specimen, R/r about 45/8 mm., the enlarged subambulacral spine is very sturdy and slightly recurved towards the arm tip; it is accompanied by a second slightly shorter and finer, but similarly recurved, spine.

Small specimens (R = 25 mm. or less) appear distinctly "hairy" abactinally, as the enlarged central spines of the abactinal paxillae are particularly long, especially near the papulae; abactinal and intermarginal pedicellariae are often absent. In one specimen, R/r = 24/4 mm., one arm is forked, probably due to an injury, the fork beginning about one quarter of the way from the base of the arm and the ambulacral groove also forks.

Ten specimens were dissected; in all the gonads were interradial in position and well developed; in one specimen (R about 60 mm.) a branching copepod was present overlying the ambulacral plates and extending from the mouth well into the base of one arm; this arm was slightly broader and disfigured.

Colour:

Abactinal surface ranges from pale pink (R = 25 mm. or less) to darker pink, papularia cream or white; actinal surface dark pink, tube feet yellow-orange, actinostomial membrane grey-yellow.

Geographical Distribution

Known from the Philippines and Indonesian area and possibly also from the Laccadive Sea and, this report, off the West Coast of the South Island of New Zealand.

Depth Range:

692–1693 m.

Type Locality:

"Challenger" Sta. 191, 5° 41′ S., 134° 04′ 30″ E., Arafura Sea.

Location of Type:

British Museum (Nat. Hist.).