Axinodon ellipticus Verrill & Bush 1898

• Main Author: Oliver, P. Graham
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2012
• Subjects: Biodiversity; Taxonomy; Animalia; Mollusca; Bivalvia; Veneroida; Thyasiridae; Axinodon; Axinodon ellipticus; North Atlantic
• Online Access: https://doi.org/10.5281/zenodo.3858690; http://treatment.plazi.org/id/546087F47C5CFFE6871327E8FEF3FE4B

Axinodon ellipticus Verrill & Bush, 1898 Axinodon ellipticus Verrill & Bush, 1898: 796, pl. XC figs 5, 6; pl. XCII, fig. 1. Axinodon symmetros – Aartsen 1996: 30, fig. 5. Material examined Holotype 1 shell, North Atlantic, off New Jersey, United States Fish Commission Albatross , stn 2096, 39˚22'20"N 70˚52'20"W, 1451 fathoms (2864 m), United States National Museum- USNM35175. Redescription of holotype (Fig. 1) Shell small, length 3.5 mm, height 3.3 mm. Thin, fragile. Equivalve. Inequilateral, beaks behind the midline. Umbos prominent, beaks prosogyrate. Outline obliquely subcircular, distinctly expanded anteriorly; anterior dorsal margin short, as a poorly defined lunule; posterior dorsal margin indistinct sloping into broadly rounded posterior, anterior broadly rounded more so than posterior, ventral margin broadly rounded no distinct junctions with lateral margins. Sculpture of dense, fine commarginal ridges most obvious on margins. Prodissoconch II distinct, 754 µm across, with weak commarginal lines (Fig. 1H). Hinge plate narrow, ligament deeply sunken on a groove running from under the beaks posteriorly for about one-third of the posterior dorsal slope. Right valve lacking any projecting teeth, hinge plate slightly and irregularly thickened below lunule. Left valve with a short, weak. marginal flange beneath the lunule; a very weak protuberance is visible below the beak. Adductor scars oval, roughly of equal size; pallial line entire. Interior with feeble radial striae. Differential diagnosis At the generic level Chavan (1969) lists Kelliola Dall, 1899 as congeneric with Axinodon and assigns them to the Galeommatoidea in the family Montacutidae. This is despite Verrill & Bush (1898) describing Axinodon as edentulous and Dall (1899) describing Kelliola with teeth. The hinge of A. ellipticus has been examined carefully to ascertain if it is edentulous as stated by Aartsen (1996) or if a cardinal peg was present but has been broken off. The SEM images presented here (Fig. 1A) show no indication of ...