“Lophaster stellans, n. sp. (P1. LXXI. figs. 4 and 5; P1. LXXII. figs. 11 and 12). Rays five. R= 32 mm.; r = 11 mm. II< 3 r. Breadth of a ray at the base, 12 to 13 mm.
The rays are broad at the base, and taper gradually therefrom up to the extremity. The abactinal surface is convex over the disk and upon the rays, and tapers regularly to the extremity. The actinal surface is plane. The interbrachial arcs though wide are angular; and in consequence of the height and convexity of the disk, the declivity there at the summit of the arc is rapid.
The abactinal surface is beset with well-developed paxillae, which are widely spaced and arranged with more or less regularity in longitudinal lines along the rays. The paxillae have a thick, robust, skin-covered pedicle, and are surmounted by a crown of five to eight moderately robust subequal spinelets, with denticulate tips, usually shorter than the pedicle, which radiate widely apart, and, when well preserved, have a strongly marked stellate character; whence the name of the species. Numerous papulae are present in the interspaces, usually in groups of four or five, or more.
The supero-marginal plates are well developed, and bear robust paxillae with long pedicles, similar to those on the abactinal surface, excepting that the pedicles are longer and thicker. The infero-marginal plates bear still larger paxillae, which are surmounted by a crown of rather more numerous spinelets. The rotundity of the pedicle is maintained, and there is no modification in the form of the paxillae. The parillae are well spaced, and there are about eighteen between the median interradial line and the extremity.
The adambulacral plates are large, and are separated superficially by channels or wrinkles in the membrane with which the whole actinal surface is invested, passing obliquely from the furrow to the margin. Their armature consists of two series of spines. (1.) A furrow series of rather large but delicate, tapering, skin-covered spines, which radiate apart, and are partially united by web, forming a fan parallel to the furrow. Near the mouth five spinelets are present in each comb, but the number is successively reduced to four, three, and two, as they proceed along the ray, and probably only one spine is present at the extremity. (2.) On the actinal surface of the plate is a lineal transverse series of three (occasionally four near the mouth) large, robust, tapering, skin‑ covered spinelets, the innermost one of the series being sometimes out of line and more aboral in position than the rest.
The mouth-plates are large, spade-shaped, and prominent actinally. Their armature consists of a marginal series of nine rather short skin-covered spinelets, which decrease in size gradually as they recede from the mouth. The spinelets are united for a short distance above their base by a membranous web, and their posture has a slight trend downward, which causes the mouth-plates to assume a scoop-like appearance. On the actinal surface of each plate are about four erect, tapering, skin-covered spinelets, usually in a closely placed lineal series, but sometimes subject to irregularity, those nearest the mouth being largest. The fan on the furrow margin of the adambulacral plate next the mouth-plate is usually semicircularly curved and more prominent than the others, appearing to form a kind of supplementary appendage to the mouth-plate armature, which adds greatly to the ornate character of the actinal aspect of this species.
The actinal interradial areas are very small, and do not contain more than eight or ten small intermediate plates, probably fewer, and seven or eight of these bear small tufts of three or four short, tapering, skin-covered spinelets, the groups or tufts being widely spaced.
The madreporiform body, which is oval in outline and rather small, is situated about midway between the centre of the disk and the margin. Its surface is convex and is marked with rather coarse striae.
The ambulacral tube-feet are large, and have well-developed fleshy terminal disks.
Colour in alcohol, a bleached ashy or yellowish white.
Localities.—Station 303. Off the Chonos Archipelago, western coast of South America. December 30, 1875. Lat. 45° 31' 0" S., long. 78° 9' 0" W. Depth 1325 fathoms. Blue mud. Bottom temperature 36.0° Fahr.; surface temperature 54.8° Fahr.
Station 308. South of Wellington Island, west coast of Patagonia. January 5, 1876. Lat. 50° 8' 30" S., long. 74° 41' 0" W. Depth 175 fathoms. Blue mud. Surface temperature 51°1 Fahr.
Station 309. Off Puerto Bueno. January 8, 1876. Lat. 50° 56' 0" S., long. 74° 15' 0" W. Depth 40 fathoms. Blue mud. Bottom temperature 47.0° Fahr.; surface temperature 50.5° Fahr.
Remarks.—This species is readily distinguished from Lophaster furcifer by the general form, by the structure of the abactinal paxillae, and by the character of the armature of the adambulacral plates.”
(Sladen 1889: 460-461)
