Spondylus leucacanthus Broderip, 1833
BRODERIP, W. J. 1833. Characters of new species of Mollusca and Conchifera, collected by Mr. Cuming. Proceedings of the Zoological Society of London, 1833 (1): 4-9, 52-56, 82-85. [p. 5]
1833 Spondylus leucacantha Broderip, 1833
1959 Spondylus ursipes S. S. Berry, 1959
1959 Spondylus ursipes S. S. Berry, 1959
Spondylus leucantha, Brod.; G. B. Sowerby II, 1847, Monograph of the genus Spondylus, Thesaurus conchyliorum; or, monographs of genera of shells, plate 87, figures 35, 36.
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«SPONDYLUS LEUCANTHA. Spond. testdârotundatâ, 6-costatâ, spinosâ, subcroceâ, spinis sublingulatis, subreflexis, longioribus, albis; interstitiis striatis; costis interstitialibus 3 (mediâ maximâ) spinosis, spinis brevioribus; intùs albâ, limbo angusto pallide subcroceo: Iong. 2 1/8, alt. 2 3/8, lat. 1 1/8 poll. (spinis haud inclusis).
Hab. ad Insulam Platam.
OBS. Spinis infrà subcanaliculatis.— W. J. B.» WILLIAM JOHN BRODERIP, 1833
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«Description: Spondylus leucacanthus Broderip, 1833 (figs. 1, 2). The original description is translated from the Latin as follows: Spondylus, romnd shell, 6 ribbed, spiny, sort of golden or yellow colored, with subtongue, sub-reflexed longer white spines; interstitial striae; 3 (more or less) interstitial spined ribs, shorter spined; interior white, narrow margin pale yellowish; length 2 1/8, height 2 1/8, width 1 1/8 inches (spines not included.
Waller (pers. comm. May 1996) notes that the species name is based on the masculine Latin noun canthus, and therefore the correct name should be leucacanthus rather than leucacantha. Additional description: Left valve with six primary rows of long, straight, narrow spines; spines on very young, small specimens (fig. 3) can be spatulate, rarely found on mature shells. Young shells with single row of small, sharp interstitial spines. Other rows of spines usually added after each resting stage. Interstitial spines on mature shell can vary from one to five rows; usually not seated on raised ribs as in Spondylus princeps. Color white through orange to coral red, rarely red-brown or peach. Right valve differing from left by foliaceous concentric ribs around small attachment area.
Discs of small, young specimens frequently orange. New growth most often white. Mature shell may have only the umbonal area orange (fig. 4), or major part of disc orange with white near margin. Occasionally shells all orange with all white spines or completely white. Completely orange or coral red (fig. 5) large shells relatively rare. Never dusty rose, or purple with orange spines. We have seen two shells with the major part of the disc yellow. Hinge teeth (fig. 6) white, diagonal to hinge line, except in gerontic specimens in which teeth become heavier and more perpendicular to the hinge line (fig. 7). Adductor muscle scar (figs. 7, 8) deep with pronounced callus on ventral edge. Interior most often white. Interior shell margin color band usually near hinge when present, matches the exterior shell color. An occasional shell with a narrow color band around entire margin. Length to 156 mm. Habitat: In the Isla Danzante area, S. leucacanthus is primarily a free-living species with occasional attachment of a small area to rocks or dead shells. Divers and dredgers report depths from 25 to 90 m, with a rare shell as shallow as 15 m. Colonies of 10,000 or more were seen on a sand bottom at 43 m. In previous years, large numbers were also seen on a sand bottom in the channel between the island and Baja California Sur at 32 m. The fact that only the deeper living shells remain today may be a function of the depth that can be reached by the Mexican hookah divers in their search for food.
The epifauna on S. leucacanthus is distinctive. Many of the smaller shells are almost clean when brought up in the dredge or by divers. If there is growth on the shells, it tends to be bryozoans and sponges, rather than the coralline algae usually found on S. princeps. Discussion: Spondylus leucacanthus Broderip, 1833, was described from Isla La Plata, Ecuador, without being figured. Both Sowerby (1847b) (fig. 9) and Reeve (1856) (fig. 10) figured the shell. Olsson (1961) figured the holotype and made it a subspecies of S. princeps Broderip, 1833, which was described from the same type locality. Olsson repeated that its distribution was confined to the coast of Ecuador. Keen (1971) made S. leucacanthus one of three synonyms of Spondylus princeps Broderip, 1833. Shasky (1980) reported taking S. princeps from Isla La Plata at a depth of 33 to 40 m. Of the five shells collected by him now at the SBMNH, four are actually S. leucacanthus.
Spondylus victoriae Sowerby, 1859, was originally described from the Golfo de California. Durham (1950) used the name without having seen Sowerby's original figure. However, it is an Australian species (E.A. Smith, 1884; Lamprell, 1987). The figure of Durham's hypotype (15418) appears to be Spondylus leucacanthus. Bernard (1983) reported S. victoriae to be widespread in the Golfo de California and well represented in the Allan Hancock Foundation material at the LACM. None of the LACM material had any notations by Bernard to confirm which shells he considered to be S. victoriae, and all appeared to be either S. leucacanthus, S. princeps or S. calcifer. Spondylus ursipes was described by Berry in 1959 (fig. 11). The holotype (CASIZ 043984) does not have the interior encircling orange-brown band noted in the original description of the species, but does have traces of color near the hinge Une. The hinge teeth, not mentioned in the original description, are white, massive and perpendicular to the hinge line (figs. 12, 13). The adductor muscle scar is deep and has the pronounced callus characteristic of S. leucacanthus. The elongate appearance of the holotype (Keen, 1971, fig. 213; Hertz, 1984, fig. 34) and two paratypes (SBMNH 34011, 34012) is due to the growth of the ligamental area, and not the shape of the disc (fig. 12). One paratype has the interior color band noted by Berry. The other has traces of interior color near the hinge. Shells taken from the more northern part of the range at Bahia de los Angeles and off Isla Angel de la Guarda in the Golfo de California, including the holotype and paratypes, are heavier than usual, with dirty white color and broken spines covered with heavy incrustation. Of the many hundreds of shells seen, only the heavy, ponderous ones have the teeth large and perpendicular to the hinge line. No small or lighterweight shells of the same size were seen with this kind of tooth arrangement. All of the lighter-weight shells of the same size have much more delicate teeth set diagonally to the hinge line. Our assumption is that the heavy shells are gerontic S. leucacanthus, which by continually depositing material over the inner surface of the shell, have also required the migration of the massive teeth to a more upright position. J. Smith (1989) figured S. ursipes (SBMNH 27380) from Bahia Adair, Sonora, Mexico, which would be the northern-most record in the Golfo de California. Since the single valve was found intertidally at Cholla Cove (Bahia la Cholla), which is often used by shrimp boats to clean their decks and because the surrounding water is relatively shallow, we hesitate to include the record in the distribution of the species. The same can be said for a single specimen taken intertidally at Puertecitos, Baja California (SBMNH 21975). DuShane & Poorman (1967) reported a specimen of S. ursipes from the Berry collection as occurring off Bahia San Carlos, Mexico. A search of the Berry collection, now housed at the SBMNH, failed to locate the shell. Lamprell (1987; figs. 2a, b) thought S. ursipes was similar in texture to S. calcifer Carpenter, 1857, and might be a form of that species. He had not seen the type material, and his figures appear to be typical S. leucacanthus. Spondylus pictorum Schreibers was the name used by Abbott (1954) for four figured specimens. Distribution was given as the Golfo de California to Panama. Two of the four are easily recognizable as S. leucacanthus.» SKOGLUND, C. & D. K. MULLINER. 1996. The genus Spondylus (Bivalvia: Spondylidae) of the Panamic Province. The Festivus, 28 (9): 93-107, pla. 1-4. [p. 96, 97]
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Spondylus leucacanthus Broderip, 1833; Skoglund, C. & D. K. Mulliner, 1996, The genus Spondylus of the Panamic Province, figures 1, 2 (Holotype (BMNH 1950.8.28.5), 3-13.
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