Cnemidaster sigsbeei (Perrier 1884)

Mammaster sigsbeei (Perrier)

Zoraster sigsbeei Perrier, 1881a:5.–Sladen, 1889:417, 418, 423, 790.

Mammaster sigsbeei.–Perrier, 1894:125. H. L. Clark, 1941:67.–Downey, 1970b: 12.

The arrangement of plates on the disc is definite and unmistakable: a centrodorsal plate, five interradial plates, then five larger radial plates. In each interradial arc are two large somewhat crowded-looking plates, and over the base of each arm are three large, tumid plates. All these plates are raised, tumid, round, and somewhat bare (although they may have small spinelets around the edge). The madreporite is small and inserted between the two interradial arc plates and the interradial primary plates. The jaws bear three transverse rows of 2, 2, and 3 or 4 long, acute spines, and inside the mouth, not visible without dissection, are two more pairs, the central pair short and blunt, and the outer pair curved away from the jaws like cow’s horns, both pairs covered with small pedicellariae. Both small and large straight pedicellariae are present in the ambulacral groove and on the dorsal surface, especially on the disc.

The number of rows of tube feet diminishes from four to two about half to three quarters of the way down the arm. Only the carinal plates and one row of plates on each side extend all the way to the end of the arm. The terminal plate is as broad as long, with an indentation on the proximal side. The carinals are overlapped on each side by the plates of the next adjoining row. These three rows of plates are comparatively bare, with only a few spinules on the distal edges of the plates, and are probably covered by a thin skin. The next row of plates is covered with tiny spinules, is overlapped by the adradials, and in turn overlaps the similar row of plates below it. Both of these rows diminish and disappear before reaching the end of the arm, the lower row first, then the upper. Next come two rows of narrow elongate plates which disappear distally before the rows above. Each of the plates in these four spinose rows bears one larger spine on a tubercle. The adambulacral plates are alternately carinate and noncarinate, with every other one projecting strongly into the furrow and bearing four stout, movable spines in a transverse row. These spines are frequently curved and the first or second often bears one or two large pedicellariae. The adambulacral plates between do not project into the furrow and have no furrow spines, but bear two to four somewhat flattened spines distally, side by side in pairs. The difference between the alternating adambulacrals becomes less distinct distally.

JUVENILE.–A specimen from Combat Station 450 has a major radius of 9 mm. The centrodorsal plate is by far the largest plate and bears a blunt tubercle. There are only two rows of plates on the arms beyond the carinals proximally, and only one row distally. There is no appreciable alternation of the adambulacral plates. There are only two rows of tube feet the whole length of the arm. The primary plates of the disc, except for the centrodorsal plate, are not appreciably raised and tumid. There are no pedicellariae.

This species apparently occurs throughout the West Indies, from Key West to Trinidad, in 195–350 fathoms.

MATERIAL EXAMINED.–Combat Station 450 (10) [R=47 mm, r=8 mm, Rr=1:6]; juvenile, [R=9 mm, r=2 mm, Rr=1:4.5]. Oregon Stations: 2775 (1) [R=29 mm, r=5 mm, Rr=1:6]; station unknown, Florida Keys, 200 fms (5) [R=60 mm, r=9 mm, Rr=1:6].

Zoroaster Thomson

Zoroaster Thomson, 1873: 154. [Type, by original designation, Z. fulgens Thomson.]

All of the Zoroasters in the western Atlantic appear to belong to one species (see Downey, 1970b).

Mammaster sigsbeei (Perrier, 1880)

In view of the fact that some specimens of Doraster constellatus have previously been misidentified as Mammaster sigsbeei (Perrier), it may be helpful to include here a brief redescription of M. sigsbeei.

DESCRIPTION.—The arrangement of plates on the disc is definite and unmistakable: a centrodorsal plate, next, 5 interradial plates, then 5 larger radial plates. In each interradial arc are 2 large somewhat crowded-looking plates, and over the base of each arm are 3 large tumid plates. All these plates are raised, tumid, round, somewhat bare (although they may have small spinelets around the edge). The madreporite is small and inserted between the 2 interradial arc plates and the interradial primary plate.

The jaws bear 3 transverse rows of 2, 2, and 3 to 4 long acute spines, and inside the mouth, not visible without dissection, are 2 more pairs, the central pair short and blunt, and the outer pair curved away from the jaws like cow's horns, both pairs covered with small pedicellariae. Both small and large straight pedicellariae are present in the ambulacral groove and on the dorsal surface, especially on the disc.

The number of rows of tubefeet diminishes from 4 to 2 about half to three quarters of the way down me arm. Only the carinal plates and 1 row of plates on each side extend all the way to the end of the arm. The terminal plate is as broad as long, with an indentation on the proximal dorsal side. The carinals are overlapped on each side by the plates of the next adjoining row. These 3 rows of plates are comparatively bare, with only a few spinules on the distal edges of the plates, and are probably covered by a dun skin. The next row of plates is covered with tiny spinules, is overlapped by the adradials, and in turn overlaps the similar row of plates below it. Both of these rows diminish and disappear before reaching the end of the arm, the lower row first, then the upper. Next come 2 rows of narrow elongate plates which disappear distally before the rows above. Each of the plates in these 4 spinose rows bears 1 larger spine on a turbercle. The adambulacral plates are alternately carinate and noncarinate, with every other one projecting strongly into the furrow and bearing 4 stout movable spines in a transverse row. These spines are frequently curved and the 1st or 2nd often bears 1 or 2 large pedicellariae. The adambulacral plates between do not project into the furrow, and have no furrow spines, but bear 2 to 4 somewhat flattened spines distally side by side in pairs. The difference between the alternating adambulacrals becomes less distinct distally.

JUVENILE.—A specimen from Combat station 450 has R=9mm. The centrodorsal plate is by far the largest plate and bears a blunt tubercle. There are only 2 rows of plates on the arms beyond the carinals proximally and only 1 row distally. There is no appreciable alteration of the adambulacral plates. There are only 2 rows of tubefeet the whole length of the arm. The primary plates of the disc, except for the centrodorsal plate, are not appreciably raised and tumid. There are no pedicellariae.

MATERIAL EXAMINED.—MCZ 876, cotype, 1 dry, off St. Kitts, 208 fms., Blake collection; MCZ Ex. 877, cotype, 1 dry, 28°42′N, 88°40′W, 321 fms., Blake collection; MCZ 4048, 8 dry, Cuba, Old Bahama Channel off Punta Alegra, 195–230 fms., Atlantis stations 2981B, 2982B, 2982C, March 1938; MCZ 4049, 7 dry, west end of Old Bahama Channel, 235–260 fms., Atlantis stations 2983, 2983A, March 1938; MCZ 4053, 1 dry, Cuba, off Puerto Tanama, 295 fms., Atlantis station 3371, April 1938; MCZ 4054, 4 dry, Cuba, Old Bahama Channel off west end of Cayo Romano, 245– 255 fms., Atlantis stations 3387, 3388, April 1939; MCZ 4057, 3 dry, Cuba, off Bahia de Matanzas, 285 fms., Atlantis station 3483, May 1939; MCZ 4050, 4 dry, south end of Santoren Channel, southeast of Cay Sal Bank, 250 fms., Atlantis station 2985; MCZ 4051, 3 dry, Nicholas Channel south of Cay Sal Bank, 280– 300 fms., Atlantis station 2987, March 1938; MCZ 4056, 1 dry, Nicholas Channel south of Cay Sal Bank, 325 fms., Atlantis station 3443, May 1939; MCZ 4055, 13 dry, Cuba, off Caibarien, 245-265 fms., Atlantis stations 3431, 3434, 3435, 3436, 3437, 3438, April 1939; MCZ 4052, 1 dry, Cuba, off Bahia Matanzas, 170-255 fms., Atlantis station 3000, March 1938; MCZ 880, cotypes, 2 wet, same as MCZ 876; USNM E3967, 1 dry, Smithsonian-Johnson expedition station 23, 18°322032;N, 66°21′W, 260 fms., 1933; Combat station 450, 10 dry, 23°59′N, 79°43′W, 350 fms., July 1957; Oregon, 5 dry, no station, Florida Keys, 200 fms.; Oregon station 2775, 1 dry, 11°35′N, 62°37′W, 220–230 fms., April 1960.

The Genera and Species of Zoroasteridae

The characters of the other genera of Zoroasteridae are firmly established by the original authors and by H. L. Clark (1920) and W. K. Fisher (1919a, b). I see no need to redescribe any of them here. A list, however, of the genera and species and their known distribution follows.

GENERA AND SPECIES DISTRIBUTION

Zoroaster Thomson, 1873

fulgens Thomson, 1873 North Atlantic, 120–1600 fms.

actinocles Fisher, 1919 Aleutians, 1217 fms.

adami Koehler, 1909 Bay of Bengal, 569 fms.

alfredi Alcock, 1893 Bay of Bengal, 1300–1380 fms.

angulatus Alcock, 1893 Indian Ocean, 597–705 fms.

barathri Alcock, 1893 Bay of Bengal, 1520 fms.

carinatus Alcock, 1893 Andaman Sea, 130–250 fms.

carinatus philippinensis Fisher, 1916 Borneo, 415 fms.

evermanni Fisher, 1905 Southern California, 216– 510 fms.

evermanni mordax Fisher, 1919 Washington to California, 275–815 fms.

gilesii Alcock, 1893 Andaman Sea, 400–500 fms.

hirsutus Ludwig, 1905 Acapulco, Mexico, 1878 fms.

longispinus Ludwig, 1905 (?juv.) Eastern Tropical Pacific, 780–1320 fms.

macracanthus Clark, 1916 Australia, 250–450 fms.

magniftcus Ludwig, 1905 Gulf of Panama, 1671 fms.

microporus Fisher, 1916 Moluccas, 700 fms.

ophiactis Fisher, 1916 Celebes, 834 fms.

ophiurus Fisher, 1905 California, 1059 fms.

orientalis Hayashi, 1950 Japan, 105–475 fms.

perarmatus Clark, 1920 Peru, 536 fms.

planus Alcock, 1893 Laccadive Sea. 1200 fms.

spinulosus Fisher, 1906 Hawaii, 328–558 fms.

tenuis Sladen, 1889 (?juv.) New Guinea, 1070 fms.

Bythiolophus Fisher, 1916

acanthinus Fisher, 1916 Celebes, 559 fms.

Cnemidaster Sladen, 1889

wyvillei Sladen, 1889 Philippines, 761–1089 fms.

nudulsLudwig, 1905 Gulf of California, 998 fms.

squameus Alcock, 1893 Laccadive Sea, 1043 fms.

zea Alcock, 1893 Indian Ocean, 597–1200 fms.

Doraster, new genus

constellatus, new species Caribbean, Gulf of Mexico, 190–350 fms.

Mammaster Perrier, 1894

sigsbeei (Perrier, 1880) Caribbean, 200–450 fms.

Myxoderma Fisher, 1905

sacculatus Fisher, 1905 West coast of North America, 284–916 fms.

platyacanthus Clark, 1913 Lower California, 284 fms.

platyacanthus rhomaleum Fisher, 1919 Oregon to California, 223– 550 fms.

Pholidaster Sladen, 1889

squamatus Sladen, 1889 Philippines, 100 fms.

distinctus Fisher, 1919 Banda Sea, 140 fms.

Prognaster Perrier, 1891 (genus doubtful)

grimaldii Perrier, 1891 (? see page 14) Azores, 1568 fms.

The Atlantic Species of Zoroaster

In the course of this study, I examined critically the Atlantic species of the genus Zoroaster. Unfortunately, the types of many species from other parts of the world were not available to me, and a complete revision of the genus was neither possible nor, at this point, particularly necessary. It is appropriate, however, to include here my conclusions regarding the species found in the Atlantic.

The characters used to distinguish the species of Zoroaster are, on the whole, unsatisfactory. Degree of development of the adradial plates is more a function of growth than a firm taxonomic character; presence of a central spine on certain plates is untrustworthy, because of the weakness of attachment (presence or absence of a tubercle is not necessarily indicative of presence or absence of a spine) and also because this, too, may be a function of growth. Large duck-billed pedicellariae are lacking in Pholidaster and sometimes in Mammaster, but their number and placement are variable within the species of Zoroaster. The armature of the actinolateral plates apparently is also variable within a species.

As with most asteroids, the number of furrow spines is a dependable character. Armature of the disc plates, degree of ensacculate spinulation, and tumidity of disc plates are mostly useable but less dependable specific characters. The ratio of minor to major radius may prove useful and if so, I would be inclined to separate Perrier's longicaudus from the rest of the Atlantic Zoroasters. Long slender arms also characterize ackleyi and seem to set it apart from trispinosus, fulgens, and diomedeae; however, gradations between ackleyi and these last three “species” lead one inevitably to the conclusion that R/r is an environment-dependent factor. Size and placement of papular pores should, perhaps, be given more attention, but are probably a function of R/r.

The synonymizing of diomedeae, ackleyi, and trispinosus (and possibly longicaudus)with fulgens has the unfortunate effect of rendering H.L. Clark's (1920) key to the species of Zoroaster practically useless. With the types, however, of many of the species he listed unavailable to me for study and comparison, I feel it would be unwise to attempt a revised key here. As this is mostly a deep water family, I am sure that further synonymizing among the Zoroasteridae, particularly in the genus Zoroaster, is inevitable with further study on a worldwide basis.

H.L. Clark (1920) indicates that Prognaster longicauda Perrier is a Zoroaster; in this he is quite correct. It is probably Zoroaster fulgens. Neither Clark nor myself, however, had an opportunity to examine Prognaster grimaldi Perrier, the type species of the genus. P. grimaldi is known only from the type specimen (Azores, 1568 fms.), and I suspect, as did Clark, that it, too, is a Zoroaster, probably fulgens. The only character on which Prognaster is separated from Zoroaster is that the former has all adambulacral plates alike, the latter has the usual zoroasterid alternate carinate and noncarinate adambulacrals. Adambulacral plates alike would be a very important and unusual character in this family, but I doubt that it really exists in Perrier's specimen. Perrier's figures in his Monaco report (1896) show an unusually wide area between the carinate adambulacrals and the figures look, in every respect, like Zoroaster fulgens; Perrier, however, states that he did not observe two kinds of adambulacral plates. As he had only one specimen, he was probably reluctant to dissect it sufficiently to determine this character.