Spondylidae J. E. Gray, 1826
GRAY, J. E. 1826. On a recent species of the genus Hinnita of De France, and some observations on the shells of the Monomyaires of Lamarck. Annals of Philosophy [new series], 12: 103-106. [p. 104]
«In the list of species of shells not taken notice of by Lamarck, which was published in a former number ofthe Annals of Philosophy, I described as a new species of the genus Lima a shell, of which I had observed an old very much worn specimen, in the British Museum; having, since that period, observed two specimens of a fossil species, which agreed with all the characters that were peculiar to my Lima ? gigantea, I therefore was inclined to consider them as forming together a distinct genus, and I was farther confirmed in this opinion when I re-examined the other allied genera, for I found, by the assistance that the fossil specimens afforded me, that the recent shell was most probably attached (immediately) to the marine bodies, and that it was certainly much more nearly allied to the genus Spondylus of Linnaeus, than to the genus which I had from the examination of the mutilated recent specimen referred it to.
Thinking that perhaps the fossil shells had been described, I compared the specimen with the characters and observations which De France has given for his genus Hinnites, which he established for two species of fossil shells, and to which he observes there are no recent species known. I found that it agrees in every particular with his remarks, and therefore I feel myself perfectly satisfied that it may be considered as the recent type of that genus; thus, at the same time, adding the genus Hinnita (for now the name must be changed, as the termination ites is only used in those genera where the species have only hitherto been found in a fossil state), to the list of recent shells, and erasing it from the catalogue of those genera which are considered by geologists as only to be found in a fossil state. The following character may be given to the genus, which should be referred to the family Spondylidae (nob.)» JOHN EDWARD GRAY, 1826
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Spondylus species. G. B. Sowerby II, 1847, Monograph of the genus Spondylus, Thesaurus conchyliorum, plate 88.
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Spondylidae; H.H. Dijkstra & B. A. Marshall, 2008, The recent Pectinoidea of the New Zealand region (Mollusca: Bivalvia: Propeamusiidae, Pectinidae and Spondylidae), figures 64A-64K.
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«Family SPONDYLIDAE Gray, 1826
Diagnosis
Most species inaequivalve, auriculate, radially ribbed, with spines of irregular shape and size, right (cemented) valve with external triangular area at apical end; monomyarian with posterior adductor muscle; ligament alivincular, resilium deep in triangular pit; adult hinge with two isodont crura in each valve, those on lower valve adjoining resilium. Remarks
Extant members of the genus have been recently monographed by Lamprell (1987, 2006).» DIJKSTRA, H. H. & B. A. MARSHALL. 2008. The recent Pectinoidea of the New Zealand region (Mollusca: Bivalvia: Propeamusiidae, Pectinidae and Spondylidae). Molluscan Research, 28 (1): 1-88, figs. 1-70. [p. 74]
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T. R. Waller, 2006, Phylogeny of families in the Pectinoidea (Mollusca: Bivalvia): importance of the fossil record, figure 11.
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«The family Spondylidae at present consists of approximately 70 living species distributed throughout the world in tropical and subtropical oceans. Most authors place all of these species in the genus Spondylus Linnaeus, 1758. A monotypic subgenus Spondylus (Corallospondylus) Monterosato, 1917 (type species Spondylus gussonii Costa, 1829) differs from Spondylus s.s. in lacking a pectiniform early growth stage and instead having a non-auriculate early dissoconch without any trace of a byssal notch. It lives at a greater depth range [approximately 70 to > 1800 m according to Lamprell (1987: 87)] than Spondylus s.s. and is restricted to the Atlantic and Mediterranean.
Extant and fossil Spondylidae have an extensive inner commarginal crossed-lamellar aragonitic layer that extends well outside the pallial line on the disk and comprises the hinge structure. This layer, generally white, is bordered along the open margins of the shell by more darkly coloured foliated calcite. Carter (1990: 388) described aragonitic structures in more detail, including the presence in some taxa of an innermost layer of columnar prismatic aragonite covering part of the region inside the pallial line. The extensive inner crossed-lamellar aragonite is plesiomorphic in that it is shared with members of all of the earlier branching clades of the Pectinoidea and with most pre-Cenozoic Pectinidae. The pectiniform early growth stage of Spondylus s.s. (Fig. 11) is very small, generally no more than approximately 2 mm in height, and lacks any trace of a calcitic columnar prismatic outer layer. Instead, its surface is marked by a fairly coarse irregular antimarginal microsculpture that continues into later ontogeny. Its shape is Chlamys-like, with the right anterior auricle having a deep byssal notch and a distinctly demarcated byssal fasciole but lacking a ctenolium. The posterior auricles of this stage tend to be shorter than the anterior auricles and have posterior margins that meet the hinge at a slightly obtuse angle. The pectiniform stage is terminated by the frilling of the shell margins in association with cementation to the substrate, the first frill commonly extending around the disk margin and into the byssal notch. Although in most spondylids the auricles continue to be recognizable throughout ontogeny, the byssal notch of the right valve and the byssal sinus of the left valve are permanently lost at the end of the pectiniform stage.» WALLER, T. R. 2006. Phylogeny of families in the Pectinoidea (Mollusca: Bivalvia): importance of the fossil record. Zoological Journal of the Linnean Society, 148: 313-342, figs. 1-12. [p. 332]
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«Family Spondylidae Gray, 1826
Cemented Pectinacea lacking simple, prismatic calcite; crossed-lamellar aragonite prominent, extending well outside pallial line nearly to distal margins and covering hinge plate, which bears prominent dysodont teeth. Byssal notch generally present in early growth stages and lacking a ctenolium. Mantle curtains without guard tentacles.
Remarks. Corallospondylus gussoni (Costa 1829) of the eastern Atlantic and Mediterranean lacks the pectiniform early growth stage. Yonge (1973) interpreted the lateral fibrous portions of the spondylid resilium to be the anterior and posterior outer (lamellar) ligaments which have migrated inward and become transverse (left and right) rather than anterior and posterior as in Pecten. The boundary between the anterior and posterior segments of 'outer ' ligament on each side of the resilium is indicated in Yonge’s fig. 11b by a groove. This interpretation requires calcification of ‘outer’ ligament and decalcification of ‘inner’ ligament, which seem unlikely events considering that a more parsimonious interpretation is possible. The early ontogeny of the spondylid ligament is precisely like that of pectinids, with the central, lamellar portion of the resilium being continuous with the anterior and posterior outer ligaments, which continue throughout ontogeny along the straight hinge. The lateral fibrous pads originate as in the Pectinidae. The grooves, which arise late in ontogeny and in many cases become multiple, appear to be nothing more than crenulations ol the resilium possibly resulting from confinement to a narrow space.» WALLER, T. R. 1978. Morphology, morphoclines and a new classification of the Pteriomorphia (Mollusca: Bivalvia). Philosophical Transactions of the Royal Society of London [Series B], 284: 345-365, figs. 1, 2, tabs. 1,2. [p. 354]
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