Mulinia exalbida Gray 1837

Mulinia exalbida Gray, 1837 (Figures 11���12) Mulinia exalbida Gray, 1837: 376, Hanley, 1843: 35; Adams & Adams, 1856: 380; Conrad, 1868: 31; Weinkauff, 1884: 100, pl. 34, fig. 1���2. Mactra exalbida Gray. Reeve, 1854: pl. 15, fig. 78. Mulinia bicolor Bernard, 1983: 40 (non Gray). Mactra cibaria Philippi, 1893: 9, pl. 2, fig. 4. Mactra calbucana Philippi, 1893: 9, pl. 2, fig. 5. Diagnosis. Shell oval, inequilateral; hinge plate anteriorly oriented; posterior end low, inflated, with a more defined angle; irregular growth lines protruded from external surface; pallial sinus circular, short and high. Description. Shell oval, subcircular, inequilateral, strong, maximum length up to 73 mm; with irregular growth lines very well defined, protruded from external surface; periostracum thin, yellowish, commonly absent in the umbonal area; umbos prosogyrous, located approximately at midpoint of shell length, not in contact. Posterior dorsal margin rounded, convex behind umbos, descending gently to posterior end and merging into the ventral rounded margin with a much defined angle (Fig. 11 A���B). Lunule and escutcheon not delimited by any ornamentation. Internally white; adductor muscle scars circular, conspicuous, similar in size and shape. Pallial sinus short, Ushaped, rounded and high (Fig. 11 D). Hinge formula as typical for Mactridae, right valve lateral teeth short and very close to cardinals; anterior ventral lateral teeth with subnodular morphology not observed in more elongated dorsal lateral teeth. Cardinal teeth unfused, on anterior side of ventrally well-developed chondrophore; two posterior lateral teeth similar in size and shape (Fig. 12 A). Left valve lateral teeth short but deep; cardinal teeth fused, Vshaped, flanked by accessory lamellae (Fig. 12 B). Shell ultrastructure (Fig. 12 C���D) coinciding with that of previous species analyzed (Taylor et al., 1973). Type material. [M. exalbida] NHM 1837.12.1.3688, holotype and one paratype (figs. 11 A���D); [M. cibaria] MNHN (unnumbered), holotype from Magellanic Strait (figs. 11 E���G); [M. calbucana] MNHNC (unnumbered) holotype from Calbuco, Chile (figs. 11 H���L). Type locality. ���South America ��� only mentioned in the original description. Other material examined. Chile. South America (NHM 1962.1087, 2 valves); de los Reyes Island, Concepci��n (NHM, coll. by M. Orellana in 1976, 8 valves.); Calbuco (MNHNC, 1 valve); Puerto Yates (MLP 9386, coll. by Beaufils in 1898, 1 valve); Estero de los Elefantes (NHM (unnumbered, Raleigh Int. Expedition, Chile 98); 52 �� 21��S, 73 �� 33��W (AMNH 137036); Magellanic Strait (MNHNC, 1 valve without periostracum). Distribution. Concepci��n, Chile, to Magellanic strait. Remarks. Mulinia exalbida has been neglected in the 20 th century South American literature (Carcelles, 1950; Carcelles & Williamson, 1951) probably because of its indefinite original type locality. However, Mulinia exalbida is a valid species that inhabits the Magellanic Province with Mactra cibaria (Fig. 11 E���G) and M. calbucana (Fig. 11 H���L) as its synonyms. The morphology of the type material of both taxa (MNHNC) coincides with Mulinia exalbida.
Published as part of Signorelli, Javier H. & Pastorino, Guido, 2011, Revision of the Magellanic Mactridae Lamarck, 1809 (Bivalvia: Heterodonta), pp. 47-67 in Zootaxa 2757 on pages 58-60, DOI: 10.5281/zenodo.201077
{"references":["Gray, J. E. (1837) A synoptical catalogue of the species of certain tribes of genera of shells contained in the collection of the British Museum. The Magazine of Natural History, n. s. 1, 370 - 376.","Conrad, T. A. (1868) Catalogue of the family Mactridae. American Journal of Conchology, 3, appendix, 31 - 47.","Weinkauff, H. C. (1884) Die Gattung Mactra. In: Kuster, H. C. & Weinkauff, H. C. (1841, 1842, 1880, 1881, 1882, 1884) Systematisches Conchylien Cabinet von Martini und Chemnitz. Bauer and Raspe, Nuremberg, 11 (2), pp. 93 - 124.","Reeve, L. (1854) Monograph of the genus Mactra. In Reeve, L. (1843.1873) Conchologia Iconica; or, Illustrations of the shells of Molluscous Animals. London, 8, 21 pls.","Bernard, F. R. (1983) Catalogue of the living Bivalvia of the eastern Pacific Ocean: Bering Strait to Cape Horn. Canadian Special Publication of Fisheries and Aquatic Sciences, 61, 1 - 102.","Philippi, R. A. (1893) Las especies chilenas del genero Mactra. Anales del Museo Nacional de Chile, Zoologia, 1 - 15.","Taylor, J. (1973) The structural evolution of bivalve shell. Paleontology, 16, 519 - 534.","Carcelles, A. (1950) Catalogo de los moluscos marinos de Patagonia. Anales del Museo Nahuel Huapi, 2 extra nueva serie, 8, 41 - 100.","Carcelles, A. & Williamson, S. (1951) Catalogo de los moluscos marinos de la provincia Magallanica. Revista del Instituto Nacional de Investigacion de las Ciencias Naturales, 2 Ciencias Zoologicas, 225 - 383."]}