Crenella washingtonensis, WEAVER, 1916

Hickman, Carole S., 2023, Paleogene marine bivalves of the deep-water Keasey Formation in Oregon, Part II: The pteriomorphs, PaleoBios 40 (5), pp. 1-51 : 8-9

publication ID

https://doi.org/ 10.5070/P940561331

publication LSID

lsid:zoobank.org:pub:1756B24A-813B-423F-896F-91B21FF58A79

DOI

https://doi.org/10.5281/zenodo.10913499

persistent identifier

https://treatment.plazi.org/id/C23987DD-FFF1-2936-FC18-FE84EFC3BE39

treatment provided by

Felipe

scientific name

Crenella washingtonensis
status

 

CRENELLA WASHINGTONENSIS WEAVER , 1916

FIGS. 3D, F View Figure 3 ; 4B View Figure 4

Crenella washingtonensis Weaver (1916) . p. 37; pl. 3, fig. 40.

Crenella washingtonensis Weaver, Weaver (1943) . p. 116; pl. 25, fig. 4

Crenella porterensis Weaver, Tegland (1933) . p. 112; pl. 6, fig. 2.

Crenella washingtonensis Weaver, Durham (1944) . p. 140, unfigured hypotype UCMP 35164.

Discussion — Crenella washingtonensis was described from the Lincoln Creek Formation after description of Crenella porterensis porterensis and from a different type locality in the Lincoln Creek. It is distinguished by its smaller shell, ovate outline, and inconspicuous sculpture. It is recognized here from a single, distinctly ovate specimen from a locality in the upper part of the middle member of the Keasey Formation. The shell is a left valve with the exterior surface imbedded in matrix ( Fig. 3F View Figure 3 ). The shell is considerably thinner and more fragile than that of C. porterensis . Portions of the opalescent interior layer remain intact, and thin exterior layer is sufficiently translucent that exceedingly fine radial sculpture is visible with a microscope under oblique lighting. The hinge plate is missing and probably was not well developed. The ovate shape may be primarily a correlate of smaller size, although the thin fragile shell and fine ornamentation serve to differentiate it from its more elongate, robust-shelled congener.

The stratigraphic range of this rarer species is unclear. It appears to extend into younger Oligocene strata. Close examination of Tegland’s (1933) hypotype of C. porterensis from the Oligocene type locality of Blakeley Formation at Restoration Point, Washington reveals an ovate shape and finer radial sculpture ( Fig. 3D View Figure 3 ). It is here re-assigned to C. washingtonensis . In addition to finer and more numerous radial ribs, the Tegland specimen also shows numerous insertions of new ribs by intercalation ( Fig. 3B View Figure 3 ).

Figured Keasey hypotype — UCMP 110727 (in matrix), approximate length 7.4 mm, approximate height 5.4 mm, Loc. UCMP IP7984.

UCMP

University of California Museum of Paleontology

Kingdom

Animalia

Phylum

Mollusca

Class

Bivalvia

Order

Mytilida

Family

Mytilidae

Genus

Crenella

Loc

Crenella washingtonensis

Hickman, Carole S. 2023
2023
Loc

Crenella washingtonensis

Weaver, Durham 1944
1944
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