Chlamys (Swiftopecten) leohertleini MacNeil, 1970
MACNEIL,
F. S. 1970. New Pliocene Chlamys (Swiftopecten) and Beringius from
Alasca Peninsula. The Nautilus, 84 (2): 69-74, figs. 1-5. [p. 70, figs. 1-3]
Chlamys (Swiftopecten) leohertleini MacNeil, n. sp.
figs. 1-3 «Description: Shell of medium size, moderately inflated, slightly higher than long. Apical angle moderately broad and nearly symmetrical, possibly broader in young juveniles. Ears moderately large; anterior ear broad, byssal sinus narrow and of moderate depth; posterior ear with a nearly vertical posterior margin. Dorsal margins subequal in length, posterior margin straight, ante¡ior margin very weakly concave. Juvenile sculpture discordant and irregular, right valve with about 8 primary fascicles, each consisting of from 3 to 7 secondary riblets of unequal size and spacing, left valve with primary lirations corresponding to interfascicular areas of right valve and broad irregularly lirate interspaces corresponding to fascicles of right valve. Adult sculpture consisting on the right valve of irregular and poorly defined plications resulting from the fusion of the secondary riblets at the first growth varix; left valve with more sharply rounded and weakly nodose plications, some of the secondary lirations of the juvenile stage developing unevenly as secondary and tertiary plications. Growth varices stronger and more widely spaced on young stages, about 3 on medium sized individuals, about 6 on large specimens. Ears sculptured with moderately strong ribs and interspaces of about equal width. Byssal fasciole with growth lines only.
Discussion: The only fossil reported previously from Alaska that bears any resemblance to this species is a fragment (MacNeil, 1967, pl. 8, fig. 9) from the middle part of the section (supposedly Pliocene) of Tugidak Island and referred, with other fragments, to Chlamys ("Chlamys") aff. C. ("C.") trinitiensis MacNeil. Chlamys (Swiftopecten) leohertleini has a wider apical angle and more irregular sculpture than either C. (S.) cosibensis (Yokoyama) or the most closely related California species, C. (S.) nutteri (Arnold). Furthermore, there is more discordance between the juvenile and adult sculpture of C. (S.) leohertleini than in any other known species of the subgenus. Dimensions: The holotype (U.S. Nat. Mus. Cat. no. 646461) measures: height, 69.5 mm., length, 64.5 mm. The smaller figured left valve (U.S. Nat. Mus. Cat. no. 646462) measures: height, 61 mm., length, 53.5 mm. The largest specimen collected, a right valve with 6 growth varices, measures: height, 94 mm., length, 89 mm.» FRANCIS STEARNS MACNEIL, 1970
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F. S. MacNeil, 1970, figures 1-5.
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