Species Account

Isognomon bicolor (Adams, 1845)

Pterioidea : Isognomonidae

Tebble name: n/a
Smith & Heppell name: n/a

To size: To 35 mm. Shell Structure: Robust valves, flaky, fragile at ventral margin. Equivalve: Slightly inequivalve. Equilateral: Inequilateral. Tumidity: Compressed. Outline: Irregular oblique ov.

Sculpture: Smooth or with flaky commarginal lamellae. Margin: Irregular but smooth margin. Ligament: Multiple set in grooves along straight dorsal margin. Hinge: Hinge edentulous. Pallial Musculature: One large adductor large muscle. Colour: White with purple tinge, may be brown to purple brown. Internal nacreous.

Distribution & Ecology

From Florida to Brazil.

4 specimens attached to plastic spool, Chesil Beach, Dorset.

Depth Range
Continental Shelf (to 200m)

Additional Information & Related Species

Related Species

Pterioidea : Isognomonidae


Listed are literature citing Isognomon bicolor (Adams, 1845). Reference containing the species Type Description is highlighted.

Adams C.B. 1845. Specierum novarum conchyliorum, in Jamaica repertorum, synopsis.. Proceedings of the Boston Society of Natural History. 2: 1-17.
Breves, A., Scarabino F. & Leoni V. 2014. First records of the non-native bivalve Isognomon bicolor (CB Adams, 1845) rafting to the Uruguayan coast. http://dx.doi.org/10.15560/10.3.684. Checklist of the Journal of Biodiveristy data. 10(3): 684-6.
Britton, J.C. 1975. The shallow water marine mollusks of the Swan Islands, Honduras. Bulletin of the American Malacological Union. 1975: 33-40.
Domaneschi O. & Mantovani Martins C. 2002. Isognomon bicolor (CB Adams) Bivalvia: Isognomonidae): first record to the Brazilian littoral, redescription of the species and comments on the occurrence and distribution of Isognomon in the Brazilian Coast. http://dx.doi.org/10.1590/S0101-81752002000200017. Revista Brasileira de Zoologia. 19(2):
Holmes A.M., Oliver P.G., Trewhella S, Hill R. & Quigley D.T.G. 2015. Trans-Atlantic rafting of inshore mollusca on macro-litter. American molluscs on British and Irish shores, new records. Journal of Conchology. 42 (1): 41-49.


  • Conchological Society of Great Britain & Ireland
    Provides resources for understanding, identifying, recording, and conserving molluscs
    Check List of European Marine Mollusca
  • MarLIN
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  • NBN Gateway
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  • BivAToL
  • MarBEF
  • Malacological Society
  • Unitas Malacologica
  • Census of Marine Life
  • MarBEF
    MarBEF, a network of excellence funded by the European Union and consisting of 94 European marine institutes, is a platform to integrate and disseminate knowledge and expertise on marine biodiversity, with links to researchers, industry, stakeholders and the general public.

Record last modified: 03/03/2022