“Cladaster analogus sp.nov.
(Fig. D, 2; Plate IV, figs. 1-3)
DIAGNOSIS. Closely related to Cladaster validus Fisher; stellato-pentagonal with short rays, thick disk, block-like marginals and unequal, spaced granulation on surface of plates; madreporite larger than any abactinal plate; pedicellariae very broadly spatulate with flat jaws, arising from a pit on the plate but without a differentiated depression for the opened jaws; superomarginals 11; adambulacrals with 2, sometimes 3, heavy, compressed round-tipped furrow spines; one major subambulacral and a secondary smaller one on outer end of plate independent of the small marginal granules. R 57 mm., r 34 mm., br (interradius) 35-37 mm.
DESCRIPTION. The abactinal plates are fairly regularly arranged on the radial areas in series parallel to the midradial, in which the largest plates are situated about one-third R from the conspicuous subcircular central plate. Across the ray from interradius to interradius and passing the midradial series at about mid R are 13 plates. The radial plates are subcircular to subhexagonal, the others mostly subcircular. They are separated by a shallow furrow covered normally by the close-set, peripheral granules which are superficially 4-sided, round-tipped, convex, and deciduous. The exposed surface really constitutes a very low tabulum and is nearly plane. It normally carries, spaced unequal, deciduous subspherical granules, the largest of which are slightly larger than the peripheral, the smallest (more round-tipped cylindrical to thimble-form) decidedly smaller than the peripheral. A majority of these granules have been rubbed off the plates. Here and there is a small tongs-shaped pedicellaria arising from a depression of the plate. The jaws are spatulate, constricted at middle, and about 0.5 mm. wide by 0.5 mm. high. The large flat madreporite is one-third r from centre; diameter 5 mm. Papulae very small, apparently about 6, around plates of radial area.
The marginal plates are block-like, wider than long, convex, and form a thick, rounded border. Both series regularly diminish in size distally. Superomarginals 11, the last plate of one series meeting 1 or 2 of opposite side of ray medially. The plates are bordered by squarish granules similar to the abactinal while the surface is covered with very deciduous, slightly spaced, subspherical granules which increase in size to small tubercles in centre of plate, especially toward end of ray. The inferomarginals are similarly provided with granules which are slightly more uniform in size.
A single row of actinal plates extends the length of 5 or 5 ½ inferomarginals; the next row, 2 ½ or 3; the third, 2; the fourth, 1 ½; while the remaining 2 chevrons are in the span of the interradial pair of plates. The actinal plates are rather ornate with 1-3 central granules; or, on inner 3 series, a central broadly spatulate pedicellaria, with jaws about twice the height and breadth of the abactinal. The peripheral granules are regularly much larger on the side toward margin and end of ray.
The adambulacral armature is essentially that of Hippasteria, consisting of 2, sometimes 3, heavy, compressed, round-tipped furrow spines about as long as width of plate. On centre of plate is a much heavier subcylindrical round-tipped tubercle (with a smaller adoral companion on first 4 or 5 plates). Near outer end of plate is a tapered tubercular spine about half as long, or sometimes 2, side by side. The margin of plate (except the furrow) is occupied by prismatic granules like those of adjacent actinals, which elongate into coarse prismatic spinelets toward furrow. I find only one subambulacral spatulate pedicellaria. Marginal oral spines 6, coarse, compressed and prismatic ; suborals crowded, about 6 to an oral angle.
TYPE LOCALITY. St. WS 86. Falkland Islands, 53° 53' 30" S, 60° 34' 30" W, 151-147 m., shell and stones, 1 specimen.
REMARKS. This species is very closely related to C. validus Fisher1. from Amukta Pass, Aleutian Islands, 52° o6' N, 171° 45' W, 283 fathoms, rocks, black sand, hydrocorals. The only known specimen of validus has R 17 mm., r 10 mm., and is probably young. It differs from analogus in minor details such as a definite tumid naked area on the superomarginals. Although most of the superomarginals of analogus have lost their granules, the scars are discernible and there appears to be nothing like a specialized area. In analogus the madreporite is larger than any abactinal plate; in validus it is distinctly smaller than the radials, although this may well be associated with immaturity. In validus the pedicellariae are abactinally a trifle larger (relative to size of plate) than in analogus and the jaws have more distinctly incurved ends. The actinal pedicellariae of analogus have broader jaws. Considering the difference in size of the two specimens, the adambulacral armature is remarkably alike. In validus the second or outer subambulacral tubercle (distinct from the marginal series of granules) is not developed, although on the margin of plate there are 1 or 2 granules larger than the immediately adjacent actinal granules. In analogus these outer marginal granules are subequal to the adjacent actinals.
The disparity in size of the peripheral granules of actinal plates occurs also in validus.
In Cladaster rudis Verrill2 the only example has R 25 mm., r 12 mm., and 4 distal superomarginals in contact medially. The pedicellariae have narrower jaws of a different form to those of validus and analogus. In rudis there is no specialized naked area on the superomarginals, the granules being scattered. The dark spots shown in Verrill's fig. 2 (which might be interpreted as specialized areas) I was unable to observe with a strong lens. The adambulacral armature of rudis lacks the second subambulacral spine, there being, as in validus, 2 enlarged marginal granules just external to the subambulacral spine.
In C. macrobrachius Clark3 from Cape of Good Hope (R 40 mm., r i6 mm.) the 5 distal pairs of superomarginals meet medially, and in spite of its smaller size most of the adambulacrals have 3 furrow spines, while the subambulacrals are generally in 3 longiseries of 3 spines each, the aboral of the first series and the median of the outer being really spines - the rest scarcely more than granules.
Hippasteria imperialis Goto,4 a large species from 640 m. off Misaki, Japan, is possibly a Cladaster but hardly a Hippasteria.”
1 Fisher, 1911, p. 222, pl. 41, figs. 1, 2.
2 Verrill, 1899, p. 176, pl. 28, figs 2-2c.
3 Clark, 1923, p. 268, pl. 13, figs. 1, 2.
4 Goto, 1914, p. 338, pl. 12, figs. 178-193.
(Fisher, 1940: 123-125)
