Pseudopythina rugifera (Carpenter, 1864)

Common name(s): Mud shrimp clam, Wrinkled montaculid, Rough wrinkled lepton

Synonyms:  Orobitella rugifera, Neaeromyra rugifera clam
Phylum Mollusca
 Class Bivalvia
  Subclass Heterodonta
   Order Veneroida
    Family Montacutidae
Pseudopythina rugifera on the abdomen of the mud shrimp Upogebia pugettensis.  Shell length 18 mm.
(Photo by: Dave Cowles, July 2005)
Description:  This small bivalve with a white shell is a frequent symbiont on the mud shrimp Upogebia pugettensis and the ventral surface of Aphrodita polychaetes.  The shell has a hinge plate with teeth but no chondrophore, 2 adductor muscle scars of almost equal size, no pallial sinus, umbones are near the middle, no radial ribs but with small concentric growth lines.  The ventral margin of the shell is nearly straight or slightly concave.  Thickness is more than 1/3 the length.  Up to about 2 cm long.

How to Distinguish from Similar Species: This is the only clam found attached by byssal threads to the abdomen of Upogebia. Pseudopythina compressa has a serrated dorsal margin of its right valve, and a thickness about 1/3 the length; plus does not have an indented ventral margin (and is not on Upogebia).

Geographical Range:  Kodiak, Alaska to Punta Rompiente, Baja California.

Depth Range: Intertidal to 5m

Habitat: Symbiont on the abdomen of Upogebia pugettensis and on Aphrodita polychaetes.

Biology/Natural History: Males in this species are dwarves and can be found in the mantle cavity of the larger female.

Smith et al. (2008) found in a small sample that parasitism by this clam did not seem to cause weight loss in Upogebia pugettensis.

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Dichotomous Keys:
  Kozloff 1987, 1996

General References:
  Harbo, 1999
  Morris et al., 1980
  Ricketts et al., 1985

Scientific Articles:

Smith, Andrew E., John W. Chapman, and Brett R. Dumbauld, 2008.  Population structure and energetics of the bopyrid isopod parasite Orthione griffinis in mud shrimp Upogebia pugettensis.  Journal of Crustacean Biology 28(2): 228-233

Web Sites:
University of Michigan Museum of Zoology:  Discusses dwarf males

General Notes and Observations:  Locations, abundances, unusual behaviors:

Authors and Editors of Page:
Dave Cowles (2005):  Created original page