Ascetoaxinus ovoidea ( Dall, 1890 )
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publication ID |
https://doi.org/ 10.11646/zootaxa.3869.4.8 |
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publication LSID |
lsid:zoobank.org:pub:EE91053B-A15A-4A1F-866E-D23BA7F79D58 |
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DOI |
https://doi.org/10.5281/zenodo.4947374 |
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persistent identifier |
https://treatment.plazi.org/id/A462AF16-B978-4C11-CBBB-B11866961196 |
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treatment provided by |
Felipe |
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scientific name |
Ascetoaxinus ovoidea ( Dall, 1890 ) |
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Ascetoaxinus ovoidea ( Dall, 1890) View in CoL
Fig. 7 View FIGURE 7
Type material. Holotype, single specimen, 87 miles off Cape Fear , North Carolina, United States, 646m. Coll. United States Fish Commission. USNM 64226 View Materials .
Synonymy. Cryptodon ovoideus, Dall, 1890 ; Thyasira ovoidea ( Dall, 1890) .
Measurements.
Description. Shell ( Fig. 7 View FIGURE 7 ). 25mm in length. Brittle, chalky. Equivalve. Moderately tumid. Strongly inequilateral, prosogyrous beaks close to the anterior margin. Outline obliquely oval; anterior margin almost straight bounding a large excavated lunule; ventral margin long, almost straight; posterior margin broad, sulcate with a distinct posterior dorsal sinus and faint submarginal sulcus. Posterior sulcus sharply defined, relatively narrow; submarginal sulcus sharply defining a projecting escutcheon. Posterior ventral slope anterior of the posterior sulcus a little flattened, creating a weak secondary ridge. Hinge teeth lacking; ligament partially sunken, relatively short with length less than half that of escutcheon. Sculpture of well-defined growth lines; edge of lunule drawn out into two rounded projections. Muscle scars prominent; anterior adductor scar elongate, mostly separate from pallial line, and in parallel with ventral margin. Shell colour, creamy-white.
Remarks. Based on putative geographic distributions coupled with obvious biogeographic barriers, it is most unlikely that Ascetoaxinus quatsinoensis is conspecific with A. ovoidea . Panamic and Caribbean geminate taxa in the Arcoidea have been shown to be distinct species ( Marko and Moran, 2009) and this probably applies to most bivalves. Shell morphology differences are present; in A. quatsinoensis the scalloping of the lunule is more prominent as is the definition of the escutcheon.
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