Lindapecten exasperatus (G. B. Sowerby II, 1842)
SOWERBY II, G. B. 1842. Monograph of the genus Pecten. In: G. B. Sowerby II (Ed.), 1842-1847, Thesaurus conchyliorum; or, monographs of genera of shells, 1 (2): 45-78, pls. 12-20. London. [p. 54, pl. 18, figs. 183-186]
1842 Pecten exasperatus G. B. Sowerby II, 1842
1860 Pecten schrammi Fischer, 1860
1906 Pecten (Chlamys) tamsi Bavay, 1906
1925 Pecten (Aequipecten) acanthodes Dall, 1925
1860 Pecten schrammi Fischer, 1860
1906 Pecten (Chlamys) tamsi Bavay, 1906
1925 Pecten (Aequipecten) acanthodes Dall, 1925
G. B. Sowerby II, 1842, plate 18.
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«T. rotundato-sub-quadratâ, sub-ventricosâ, scabrâ; auriculis magnis, scabroso-striatis; costis octodecim, sub-angulatis, angulis serratis, lateribus serratim striatis, interstitiis scabroso-striatis; colore vario. Long. 0.95.; lat. 0.55.; alt. 1.; poll.
In the character of the ribs this species resembles the last [P. sub-rufus Pennant], they are, however, rather thicker, the shell is more ventricose, less oblique, and has broader auricles. The variations in colour are similar to those of the last species. Mediterranean.» GEORGE BRETTINGHAM SOWERBY II, 1842
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«Although Lindapecten muscosus and L. exasperatus have long been recognized as distinct taxa in the shell literature of the western Atlantic region, there has been persistent controversy whether these are good species or merely ecophenotypes adapted to different benthic habitats. Abbott (1974: 445) regarded them as distinct species having overlapping geographic ranges but differing in habitat preferences. Lindapecten muscosus was said by Abbott to range from "North Carolina to Florida and Texas to Brazil [and] Bermuda" and to be "moderately common just off shore to 90 fathoms [165 m]." The range for L. exasperatus was given as "Bermuda, southern Florida to the lower Caribbean ... common in shallow water on turtlegrass in soft sandy mud areas."
Study of all specimens of Lindapecten muscosus and L. exasperatus in the USNM collections as well as field work by the present author have corroborated Abbott's (1974) observations, but with some further elaboration of geographic ranges. Specimens of L. muscosus that were either alive or are represented by unweathered paired valves are present along the southeastern Atlantic coast of the United States from Cape Lookout southward to the Florida Keys in off shore localities ranging from 18-42 m; dead young shells have been dredged off shore from as far north as Cape Hatteras. Along the Florida Keys, L. muscosus is present generally as young shells on the outer (Hawk Channel) side of the Keys in depths from 5-73 m. In the Gulf of Mexico, L. mucosus ranges from southwest of Key West, Florida, northward and westward on the continental shelf to Texas and as far south as Campeche, Mexico, in depths ranging from 11-55 m, most commonly in 30-50 m. Only one specimen is present in USNM collections from the Caribbean, from St. Thomas, U.S. Virgin Islands (USNM 103039, depth not given). The species has also been reported from Brazil (Abbott, 1974: 445; Ríos, 1975: 206). Lindapecten exasperatus along the eastern coast of the United States is rare north of Jupiter Inlet, Florida, but common to the south in inshore areas of eastern Florida and the Florida Keys. The species is common in Bermuda, the Bahamas, and throughout the Antilles. It extends southward along the Caribbean coasts of Central America and along the Caribbean coasts of Colombia and Venezuela. Although the geographic range of L. exasperatus partially overlaps that of L. muscosus in southern Florida, habitat preferences of the two species differ in the manner noted by Abbott (1974: 445). Along the Atlantic coast of the Florida Peninsula, L. muscosus occurs mainly off shore, commonly associated with coral, whereas L. exasperatus occurs inshore, commonly associated with grassy areas. Along the Florida Keys, L. muscosus occurs mainly on the deeper Hawk Channel side, whereas L. exasperatus again favors inshore habitats. So far as determined from the collections examined, only L. muscosus occurs in the northern Gulf of Mexico, where it can extend to considerable depths. The specimens from greater depths commonly have longer spines than those from shallower depths, and this difference can already appear in early ontogeny. Petuch's (1995) L. lindae represents this kind of variant. The extreme spininess of some Lindapecten muscosus is commonly associated with cover by epifaunal sponges. It has been demonstrated that some scallops develop a mutualism with sponges, whereby the sponge benefi ts from an attachment site and the scallop benefi ts from becoming less attractive to predators because of the sponge [Bloom, 1975, with reference to Chlamys hastata hericia (Gould, 1850) and C. rubida (Hinds, 1845)]. Furthermore, Beu (1965) and Dijkstra & Marshall (2008: fi gs 42, 53) found that spininess increases when sponges are present on the shell surface of some New Zealand species. If the morphological differences between L. muscosus and L. exasperatus were due entirely to the presence or absence of sponge cover, however, one would expect a broader overlap of geographic ranges and more frequent cooccurrences of the two species.» WALLER, T. R. 2011. Neogene Paleontology of the Northern Dominican Republic. 24. Propeamussiidae and Pectinidae (Mollusca: Bivalvia: Pectinoidea) of the Cibao Valley. Bulletins of American Paleontology, 381: 1-197, pls. 1-18. [p. 80, 81]
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Aequipecten exasperatus (Sowerby II, 1842); B. K. Raines & G. T. Poppe, 2006, A Conchological Iconography, The Family Pectinidae, plate 245, figures 1-3, 5, 6.
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«Shell thin, moderately convex, usually with 17 ribs and radially sculptured with fine scabrous threads. Auricles unequal, with radiaI sculpture of fine scaly threads, which are markedly stronger on the byssal auricle. Fasciole conspicuous. CtenoIium of four to six dentides. An specimens have microscopic provincula.
Young shells are more rotund and convex than adults, with aurides proportionately more conspicuous. They lack intercostals and have camptonectes marking in the flat interspaces. It varies among individuals from Sanibel Island, FIa.;. it appears to be rare on adult valves and more common on recent than on fossil shells. Usually it occurs only on the submargins, but appears in the interspaces of some adults. Most adults have one or several scabrous intercostals. Fasciole wide, notch narrow, shell internally lirate. Recent shells range brown, white, pink and yellow to shades of red; and are unicolored or mottled. Dimensions.— Hypotypes: Right valve, height 18, width 14 mm.; left valve, height 16, width 12 mm.; (Ft. Denaud, Fla.); tight valve, height 38, width 28 mm., (Port Mayaca, Fla.). Localities.— Costa Rica, [Gabb]; Shelf Creek, Fla., [Willcox]; Simmons Bluff, S. C., and Antilles, [Dall]; living from Cape Hatteras, N. D. to GuadeIupe Island, W. I., and on Gulf coast of Florida; [Dall]; Sanibel IsIand, Moore Haven, Ft. Denaud, Prairie Creek, Port Mayaca, and Acline, Fla. Horizon.— Pliocene to Recent. Hypotypes.— Collection H. I. Rowland. Syntypes.— Collection British Museum of Natural History» TUCKER-ROWLAND, H. I. 1936. The Atlantic and Gulf Coast Tertiary Pectinidae of the United States. II. Systematic descriptions, Continued. The American Midland Naturalist, 17: 985-1017, pls. 5-10 [Under H. I. Rowland]. [p. 1011]
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Chlamys (Chlamys) exasperatus (Sowerby); H. I. Tucker-Rowland, 1936, The Atlantic and Gulf Coast Tertiary Pectinidae of the United States, II. Systematic descriptions, plate 8, figures 1, 2, 11.
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