Cardiomya pavascotti, Carole & Hickman & Ca, 2014

Carole, Hickman, S. & Ca, 2014, Paleogene marine bivalves of the deep-water Keasey Formation in Oregon, part IV: The anomalodesmatans, PaleoBios 31 (3), pp. 1-21 : 16

Cardiomya pavascotti n. sp.

Figs. 6A–B

Diagnosis— Shell strongly inequilateral, with exceptionally long, narrow and straight posterior rostrum with numerous very fine co-marginal striae; disc ovate-elongate, strongly inflated and with coarse radial ribs where exterior shell is preserved; five posterior ribs stronger than anterior ribs; anterior margin broadly rounded; ventral margin scalloped by ribs extending beyond rib interspaces.

Description —Shell poorly preserved, but interior of left valve ( Fig.6B) preserving circular anterior muscle scar and impressions of three strongest posterior radial ribs on disc; hinge plate insufficiently preserved to describe hinge teeth.

Discussion —This striking species is represented by a part and counterpart of the left valve of a single specimen from the lower member of the Keasey Formation.Shell adhering to the rostrum on the external mold ( Fig.6A) appears to be smooth, but numerous fine growth lines are distinctly preserved in the matrix ( Fig.6B). Interspaces between the strongest radial ribs are two times the width of the ribs. This lower Keasey species is readily distinguished from Cardiomya anticepsella n. sp. from the upper portion of the middle member by the narrower and more elongate posterior rostrum.

Etymology —Named in honor of Paul Valentich-Scott in recognition of his contributions to knowledge of the Holocene anomalodesmatan fauna of the Eastern Pacific.

Holotype — UCMP 110678 , length 7.7 mm, height (approximate) 2.9 mm.

Keasey Formation type locality —LowerMember, Loc. UCMP 7983 (= USGS 25026 ) .