Allogramma formosa (Jeffreys, 1881)Pandoroidea : Lyonsiidae
To size: To 15mm. Shell Structure: Thin, fragile. Equivalve: Equivalve. Equilateral: Inequilateral, beaks slightly in front of midline. Tumidity: Moderate. Outline: Subrectangular; anterior rounded, posterior truncate, ventral margin gently curved, dorsal margins long sloping gently. Contour: Umbos prominent; posterior area set off by a radial carina running from the beaks to the posterior ventral junction.
Sculpture: Anterior area with few oblique weak ridges, anterior and median areas with dense, radial rows of minute spines, these larger on dorsal anterior area; posterior area with radial riblets bearing spines, these becoming larger on dorsal area and projecting above the margin. Margin: Inner margin smooth. Ligament: Small, set on a shallow internal lithodesma below the beaks. Hinge: Lacking teeth. Pallial Musculature: Obscure. Periostracum: Obscure. Colour: White.
Distribution & Ecology
Mostly from lower slope and abyssal depths, widely distributed in the North Atlantic including Rockall Trough and Porcupine Bight.
Bathyal (500 - 2000m)
Abyssal Rise (2000 - 4000m)
Juveniles & Similar Species
Small shells are more trapezoidal in outline, the anterior distinctly narrower than posterior.
Key Features & Similar Species
Listed are literature citing Allogramma formosa (Jeffreys, 1881). Reference containing the species Type Description is highlighted.
Jeffreys J.G. 1881. On the Mollusca procured during the ‘Lightning’ and ‘Porcupine’ Expeditions, 1868-70. (Part III). Proceedings of the Zoological Society of London. 1881: 693-724.
Olabarria C. 2005. Patterns of bathymetric zonation of bivalves in the Porcupine Sea Bight and adjacent abyssal plain, NE Atlantic. Deep-Sea Research I. 52: 15-31.
- Conchological Society
of Great Britain & Ireland
Provides resources for understanding, identifying, recording, and conserving molluscs
Check List of European Marine Mollusca
The Marine Life Information Network for Britain and Ireland (MarLIN) provides information for marine environmental management, protection and education. It is a centre of excellence in spatially based and time-series marine biological information and supports good stewardship in the marine environment.
- NBN Gateway
National Biodiversity Network's Gateway. Use it to explore UK biodiversity data, as contributed by participating data providers.
- Malacological Society
- Unitas Malacologica
- Census of Marine Life
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.