Euvola insula (Dall & Ochsner, 1928)
DALL, W. H. & W. H. OCHSNER. 1928. Tertiary and Pleistocene Mollusca from the Galapagos Islands. Proceedings of the California Academy of Sciences, 17 (4): 89-139, pls. 2-7. [p. 119, pl. 2, figs. 19-20]
1928 Pecten insulus Dall & Ochsner, 1928
W. H. Dall & W. H. Ochsner, 1928, plate 2.
|
«Shell small, sharply sculptured, convex, with 16 flattish radial ribs separated by subequal interspaces; the ribs are depressed and rounded at the sides and the interspaces not channelled; submargins deeply impressed, concentrically striated, anterior ear with four or five rather strong radial ribs concentrically, prominently lamellose; concentric sculpture covering the whole disk of close-set rather thick, flattish threads not obsolete on top of the ribs and not tending to be sharp or lamellose; interior grooved in harmony with the ribbing; both valves (?) apparently similarly sculptured. Height. 17 mm.; width, 18 mm.; diameter about, 12 mm.
Holotype: No. 2946; paratype: No. 2947, Mus. Calif. Acad. Sci., collected by W. H. Ochsner and Joseph R. Slevin, November 17, 1905, from upper horizon (zone D), on east shore of Indefatigable Island, Galapagos Group. Probably Pliocene. This species recalls some of the Oligocene Antillean species, but its sculpture is characteristic. Both the specimens were filled with matrix and the posterior ears wanting.» WILLIAM HEALEY DALL & WASHINGTON HENRY OCHSNER, 1928
|
«Euvola insula, a fossil species described by Dall and Ochsner (1928) from the same locality that yielded E. slevini and which they claimed came from the same upper horizon, is represented only by two juvenile right valves. The holotype (Fig. 8.8) is missing most of its posterior auricle, and the paratype (Fig. 8.9) consists only of a fragment of the anteroventral portion of the right disk. The holotype, however, is complete enough to furnish a rib count of 16. Among the specimens of the extant Galápagos species, E. galapagensis, such a low rib count was found in only one juvenile right valve (USNM 753309a, west of James Bay, Isla San Salvador, depth 34 m; Fig. 8.10). The commarginal lamellae of both the holotype and paratype of E. insula bend over distally and rejoin the shell surface, a feature present also at a comparable growth stage of many specimens of E. galapagensis. Without more complete and more mature specimens of the fossil species, however, it is not yet possible to determine whether these two taxa are synonymous. If this is proven to be the case, the name E. insula (Dall and Ochsner, 1928) will have priority over the name E. galapagensis (Grau, 1959).»
WALLER, T. R. 2007. The evolutionary and geographic origins on the endemic Pectinidae (Mollusca: Bivalvia) of the Galápagos Islands. Journal of Paleontology, 81 (5): 929–950. [p. 941]
|
Euvola insula (Dall and Ochsner, 1928); T. R. Waller, 2007, Pectinidae of the Galápagos Islands, figures 8.8, 8.9.
|