“Pentagonoster patagonicus, n. sp. (Pl. XLVI. figs. 3 and 4; Pl. XLIX. figs. 3 and 4).
Rays five. R = 68 mm.; r = 43 mm. R =1.58 r. The minor radius is thus in the proportion of about 63 per cent.
Body of large size. General form depressed and flat. Abactinal area slightly inflated in the central region and flexible. Marginal contour pentagonal with a slight stellate tendency, the extremities of the rays being pointed and slightly produced. Interbrachial arcs forming a distinct curve sweeping from tip to tip. Margin thick and more or less vertical, the rounding more bevelled on the abactinal surface than on the actinal.
The whole abactinal paxillar area is covered with small, regular, polygonal tabula or patinas, those in the radial areas regularly hexagonal and larger than those in the intermediate regions, which are rhomboid, and all diminish in size as they approach the margin. The larger paxillae in the radial regions do not actually touch one another but are slightly spaced apart. These paxillae consist of a hexagonal tabulum on a low broad base, and the tabulum is covered with low truncate granules, the marginal series of which are slightly larger than the rest and sub-prismatic or polygonal; all the granules are uniformly truncate so as to form a smooth upper surface to the tabulum, which is also slightly convex; and the edges of the patinas are sharply cut as if "dressed" with a knife. Occasional patinas at wide intervals apart bear a single small excavate pedicellaria, having two chisel-shaped or spatulate jaws, which can be drawn down more or less into the pit or cavity; the form of the jaws varies considerably, sometimes being narrow and elongate, sometimes much broader and more lamelliform; occasionally three jaws may be present. The email rhomboid tabula in the interradial regions, which are crowded and fit close to one another, have a much lower base; indeed the base appears to gradually diminish and the paxillar character to disappear as the tabula approach the margin. In the marginal region, where the tabula are smaller, faintly indicated lines may be seen to proceed inwards from the sutures of the supero-marginal plates, which have the appearance of dividing up this marginal series of small tabula into band-like series corresponding in breadth to the length of the marginal plates, four or five rows of tabula being in each band; this character is lost, however, as soon as the large hexagonal and separated paxillar are reached. There are six papulas round each tabulum, corresponding in position to the angles of the hexagon, and they are separated from one another by the stellate prolongations between the plates. The five primary interradial plates (basals) are clearly discernible and are distinctly larger than any of the other tabula. They are all equidistant from the centre, being from four to five times their own diameter distant. One bounds the adcentral side of the madreporiform body and is larger than the others. The dorso-central plate may also be distinguished.
The supero-marginal plates are fifteen in number, counting from the median interradial line to the extremity. They form a conspicuous border to the abactinal area and their breadth and length are subequal, except at the extremity, where they gradually diminish in size, and the breadth is in excess of the length; the plates are slightly convex and form a bevelled edge to the paxillar area. Their surface is covered with small, low, truncate, crowded granules, excepting a small irregular oval naked space on the abactinal surface. A number of the plates bear one of the small excavate pedicellariae, similar to those already described above, and these are frequently situated in the naked oval space.
The infero-marginal plates correspond to the superior series, and are similarly covered with small, low, crowded granules. Only five or six plates on each side of the median interradial line have small naked areas on the actinal side, which are very much less than those on the superior aeries and gradually diminish as they proceed along the ray. It would appear that pedicellariae are normally not present on the infero-marginal plates. In the example under notice I have only found one plate thus furnished.
The adambulacral plates are a little broader than long, and their armature consists of a marginal series of four or sometimes five short equal spinelets, irregularly cylindrical or often more or less subprismatic, with roundly truncate tips, frequently subclavate, and on the outer half of the ray more or less compressed in the direction of the axis of the ray. At a short distance behind these are normally three low, thick, dumpy, subclavate, papilliform spinelets forming a slightly arched line traversing the plate diagonally, the aboral end of the series being nearest the marginal or furrow spinelets. External to these are a few (about five to seven) low, truncate, prismatic granules, which may either form two subregular parallel lines, or a diagonal line subparallel with the second series of dumpy papillae, with one or more granules filling in the vacant spaces at the corners left by the obliquity of the line. These outer granules are scarcely distinguishable from those on the adjacent actinal intermediate (ventral) plates to be described below. In two or three rare instances an incipient pedicellaria is present on the adambulacral plates, but not more than that number occur in the whole of the adambulacral plates of the example under description. Pedicellariae may therefore be said to be not present normally. Near the extremity of the ray there are not more than three furrow spinelets on each plate, and finally only two. And the second row of dumpy papilliform spinelets is at the same time represented by only two, one of which is much larger than the other, and on the terminal seventeen or eighteen plates the larger one only is present, and is relatively increased in size and prominence in proportion to the size of the plate and the accompanying spinelets.
The mouth-plates are elongate and triangular, slightly truncate posteriorly; and the free margin of each plate forms a straight line in continuation of the series of adambulacral plates which border the furrow, the united pair thus completing conformably the apex of the rectilineal angle of the actinal interradial area which is bounded by the two adjacent furrows. The actinal surface of the plates is plane and presents no prominence or convexity. The armature of each plate consists of a marginal series of eight or nine short, subprismatic, roundly truncate spinelets, exactly similar to those on the adambulacral plates. Behind this on the actinal surface of the plate are five or six thick, coarse, sub-prismatic papillae, the foremost three standing in a line parallel to the median suture, and this line is continued to the outer extremity of the plate by about half a dozen small, low, prismatic granules; the outermost three stand parallel to the marginal spines, and a few small granules extend from this point along the margin contingent with the adjacent adambulacral plate; and occasionally one or two stand in the intervening space between the line thus formed and the line of granules parallel to the furrow above noticed.
The actinal interradial areas are covered with a great number of small, regular, quadrangular intermediate plates. The largest are adjacent to the adambulacral plates; and these as well as the next two or three longitudinal series are a little broader than long, the breadth diminishing in each row away from the furrow; the remaining intermediate plates have the length and breadth subequal, and all diminish in size as they approach the margin, where some small and irregular plates are found. The plates fit close together, forming a compact pavement. The surface of the plates is covered with coarse, uniform, subprismatic granules, those forming the marginal series on each tabulum being a shade larger than the others, and always presenting a straight side to the margin, as if the outer edge of the whole series had been trimmed with a knife. The granules are closely placed, but do not touch one another. On a few of the plates is an excavate pedicellaria of similar character to those on the abactinal surface already described, but much larger and with broader jaws; the largest ones are nearest the mouth, and pedicellariae generally are also of more frequent occurrence on the inner third of the area. Sometimes the pedicellariae appear as if formed of two pedicellariae closely juxtaposed, with the jaws either opening in the same plane or at an angle. In this case the pedicellarian apparatus of the plate has four jaws; in others there may be three jaws. The breadth of the jaws varies considerably, and there is no regularity in the orientation of the pedicellariae. The pedicellariae nearest the margin are much smaller, and nearly of the same character as those on the abactinal surface.
The anal aperture is subcentral, and is on the right posterior area of the dorso-central plate, when the madreporite is placed in the right anterior interradium.
The madreporiform body is rather small, subpolygonal in form, and flatly convex; it is situated at about one third of the distance from the centre to the margin. It is remarkable for only showing convoluted striae on the bevelled margins of the body, the whole of the central area being covered with very numerous small oblong pits.
Colour in alcohol, a bleached yellowish white, with a slight brownish shade.
Individual Variation.—In a rather smaller example than that described above, R=56 mm., and from the same locality (Station 313), it is noteworthy that all the infero-marginal plates, excepting only the last two or three, have a well-developed oval naked space. In this specimen there is some irregularity both in the size and in the position of the large papilliform granules on the adambulacral plates which immediately succeed the furrow series, and sometimes only two are present.
Locational Variation.—A series of specimens from Station 311 are all much smaller in size than the type described, the largest measuring only R=37 mm. In these the tips of the rays are slightly more definitely pointed, and all the infero-marginal plates have naked spaces, excepting only in some instances two or three plates at the tip. The naked spaces appear to be relatively larger in some of the smaller examples, but considerable variation is shown in the series in this respect; and I am therefore unable to say definitely that the size of this area diminishes with age, although I am disposed to think that such is the case. It is remarkable that none of the specimens from this locality (Station 311) have any pedicellariae, on the actinal surface. In the smallest example, which measures R = 26, r = 15 mm., there are eleven supero-marginal plates, counting from the median interradial line to the extremity.
Localities.—Station 313. Near the Atlantic entrance to the Strait of Magellan. January 20, 1876. Lat. 52° 20' 0" S., long. 67° 39' 0" W. Depth 55 fathoms. Sand. Bottom temperature 47.8° Fahr.; surface temperature 48.2° Fahr.
Station 311. Off the entrance to Smyth Channel. January 11, 1876. Lat. 52° 45' 30" S., long. 73° 46' 0" W. Depth 245 fathoms. Blue mud. Bottom temperature 46.0° Fabr.; surface temperature 50.0° Fahr.”
(Sladen, 1889: 269-272)
Ceramaster patagonicus, the cookie star, is a species of sea star. It is bright orange or yellow in colour. Its arms are short and it has no spines. It is a deep water species and lives on rocky sea beds. Its diet includes sponges.
The World Register of Marine Species lists four subspecies:[1]
The cookie star is roughly pentagonal in shape with a diameter of up to 16 centimetres (6.3 in). It has a slightly inflated, broad central disc and five short rays. The aboral (upper) surface is covered with neatly arranged flat-topped scales, polygonal in the central area and hexagonal on the rays. Between the rays the scales are small and crowded together. There is a marginal row of distinctive larger scales forming a bevelled edge. Sometimes the disc and ray areas are swollen with sunken inter-radial areas between. This may happen when the starfish has recently fed or when its gonads are enlarged prior to spawning. The general colour is yellow, orange or pink.[2][3] It is larger than the rather similar Arctic cookie star (Ceramaster arcticus) and does not have red patches on the aboral surface as that species often has.[4]
The cookie star is found in the Southern Ocean, the Strait of Magellan and in Australian and New Zealand waters.[1] It is also found on the west coast of North and South America from Alaska southwards to Cape Horn.[3] It is a deep water species, in the Southern Ocean being found at depths varying between 100 and 5,000 metres (330 and 16,400 ft) but is commonest at depths less than 250 metres (820 ft).[2]
The cookie star feeds on sponges such as the cloud sponge (Aphrocallistes vastus ) and the chocolate puffball sponge (Latrunculia austini).[3] The Morning sun star (Solaster dawsoni) is a predatory starfish that feeds on other starfish. If approached by a morning sun star, a cookie star does not attempt to flee, although this would be a pointless strategy as the cookie star is a very slow crawler. The morning sun star climbs on top in its usual attacking position but soon gives up and looks very sick, apparently repelled by a toxic chemical substance. In an experiment, four cookie stars were kept in a tank with a number of hungry morning sun stars for a period of two months, but none were harmed.[3]
Ceramaster patagonicus, the cookie star, is a species of sea star. It is bright orange or yellow in colour. Its arms are short and it has no spines. It is a deep water species and lives on rocky sea beds. Its diet includes sponges.
