Morphology ⁸

The overall shape is elongate ovate. The posterior margin is subtruncated, and slightly pointed at its confluence with the ventral margin. The anterior and ventral margins are rounded. The anterior and posterior dorsal margins are both nearly straight. The valves are equal in size and shape (equivalve), and there is no gape when they are closed. Sculpture consists of growth lines only. The lunule is defined by a fine, shallow groove and extends 1/2 of the anterior dorsal margin. The commissural margin is raised at the center of the lunule and projects above the flank. The umbo is anterior, and the beaks also point slightly to the anterior. The escutcheon is not well defined.

The exterior is white or tan with brown and purple tent marks, comarginal and/or radial stripes. There may also be blotches of coloration. The brown coloration is typically darker along two prominent radial stripes. The umbo is generally white or tan. The interior is white, and there may be purple coloration in the central area of the interior.

The ligament is external, extends 1/3 of the posterior dorsal margin and is supported by nymphal ridges. On the left valve, there are three cardinal teeth (2a, 2b, 4b), none of which are bifid. The anterior (2a) and central (2b) teeth are joined dorsally, forming an inverted "v" shape. The posterior tooth (4b) is fused with the nymph. There is also one anterior lateral tooth (A2) on the left valve. On the right valve, there are three cardinal teeth: the anterior (3a) and central (1) teeth are not bifid, and the posterior tooth (3b) is bifid. There are two anterior lateral teeth (A1, A3) and a weak ridge running parallel to the posterior dorsal margin. The anterior and posterior adductor muscle scars are similar in area, but the anterior is more elongate in shape. The pallial sinus is deep and extends to the middle of the nymph in length; the deepest part of the pallial sinus forms an acute angle.

Sources and Credits

1. (c) Marlo F. Krisberg, some rights reserved (CC BY-NC), https://calphotos.berkeley.edu/imgs/512x768/0000_0000/1211/1370.jpeg
2. (c) Jose Nunez, some rights reserved (CC BY-NC-ND), uploaded by Jose Nunez
3. (c) Marlo F. Krisberg, some rights reserved (CC BY-NC), https://calphotos.berkeley.edu/imgs/512x768/0000_0000/1111/1152.jpeg
4. (c) Marlo F. Krisberg, some rights reserved (CC BY-NC), https://calphotos.berkeley.edu/imgs/512x768/0000_0000/1111/1154.jpeg
5. (c) Marlo F. Krisberg, some rights reserved (CC BY-NC), https://calphotos.berkeley.edu/imgs/512x768/0000_0000/1111/1156.jpeg
6. (c) Marlo F. Krisberg, some rights reserved (CC BY-NC), https://calphotos.berkeley.edu/imgs/512x768/0000_0000/1111/1157.jpeg
7. (c) Victor W Fazio III, some rights reserved (CC BY-NC), uploaded by Victor W Fazio III
8. Adapted by matbio from a work by (c) Anderson, Katherine L., some rights reserved (CC BY-NC), http://eol.org/data_objects/17784752

More Info

• iNat taxon page
• Animal Diversity Web
• Biodiversity Heritage Library
• BOLD Systems BIN search
• Global Biodiversity Information Facility (GBIF)
• SeaLifeBase
• World Register of Marine Species

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