Parvamussium intuscostatum

(Yokoyama, 1920)




Original name   Pecten intuscostatus Yokoyama, 1920
Autoreference   Yokoyama, 1920: 156, pl. 13, figs 9, 10.
Reference   Yokoyama, M., 1920. Fossils from the Miura Peninsula and its immediate north. - Journal of the College of Science, Imperial University, Tokyo 39(6): 1-198, pls 1-20.
Type data

  Holotype (rv) Geological Institute, Faculty of Science, Tokyo University (GT). Type locality: Japan, Kanagawa, Miura City, Kami-Miyata, 35*11'10"N, 139*39'34"E, Pleistocene.


  Shell up to ca. 10 mm high, fragile, opaque, weakly inflated, subcircular, somewhat higher than wide, inequivalve, nearly equilateral, anterior auricles larger than posterior, unequal in shape, many internal riblets (17-20) commence in late growth stage, umbonal angle ca. 90 degrees, translucent, colourless.

  Left valve with ca. 20 irregularly spaced, vesicular-like radial riblets and intercalated secondary riblets. Auricles with commarginal lamellae and a few lamellar-like radials.

  Right valve with numerous regularly spaced, delicate commarginal lirae. Byssal notch moderately deep, byssal fasciole very narrow, ctenolium lacking.



Pliocene-Recent. Japan (TL-fossil)

Habitat  Living bathyally on soft bottom assemblages.