Lasaea undulata A. A. Gould, 1861

Lasaea undulata A. A. Gould, 1861 View in CoL View at ENA

Native status

Attached to the byssus of the septifer and the roots of seaweeds between tidal marks.

Distribution

Yellow Bay (Shandong Province) of China, Japan.

Notes

Lasaea consists of small pelecypod species, the largest of which attains a size of about 8 mm in length; adult specimens of the smaller species are about 2 mm long. In general, these shells are quadrangular in outline; they are equivalved, but inequilateral, the anterior end being the longer ( Keen 1938). Most, if not all, species of Lasaea are nestlers, finding shelter in dead barnacle tests and amongst the holdfasts of seaweeds. It is cosmopolitan, but only L. undulata is found in China.

Diagnosis

Shell small (2.7 ± 0.15 mm in length, 1.9 ± 0.11 mm in height), elongate-ovate, thin, fragile (Fig. 19 View Figure 19 ). Surface purplish-red, ornamented with concentric growth striae. Umbo prominent, situated slightly behind the mid-point of the dorsal margin. Break located near posterior margin. Hinge plate very strong, with one cardinal socket, with one anterior lateral cardinal tooth and two posterior lateral cardinal teeth of different sizes in right valve.