''Brookula decussata'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

, a marine

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

unassigned in the

superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...

Seguenzioidea Seguenzioidea is a superfamily of minute to medium-sized sea snails, marine gastropod mollusks in the clade Vetigastropoda.Gofas, S. (2010). Seguenzioidea. In: Bouchet, P.; Gofas, S.; Rosenberg, G. (2010) World Marine Mollusca database. Accessed ...

. This species is considered sometimes a synonym of '' Brookula pfefferi'' Powell, A.W.B., 1951, but B. decussata is somewhat smaller and a has a more definite

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

with fewer spirals and more axials. Discovery Reports, Antarctic and subantarctic mollusca; v. 26 1954, p. 104
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Description

The maximum recorded size of the shell is 2.5 mm.

Distribution

This marine species occurs off the

South Orkney Islands The South Orkney Islands are a group of islands in the Southern Ocean, about north-east of the tip of the Antarctic Peninsula Antarctic Peninsula The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martín in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctic ...

References

* Powell, A. W. B. 1951. ''Antarctic and Subantarctic Mollusca: Pelecypoda and Gastropoda''. Discovery Reports 26: 47–196, pls. 5–10 * Dell, R. K. 1990. ''Antarctic Mollusca, with special reference to the fauna of the Ross Sea''. Royal Society of New Zealand Bulletin 27: iv + 311 pp * Numanami, H. and T. Okutani. 1991. ''A new species of the genus Brookula collected by the icebreaker Shirase from Breid Bay, Antarctica (Gastropoda: Cyclostrematidae).'' Venus 50: 37–42. * Numanami, H. 1996. ''Taxonomic study on Antarctic gastropods collected by Japanese Antarctic research expeditions.'' Memoirs of National Institute of Polar Research (E)39: + 244 pp. * Engl W. (2012) ''Shells of Antarctica''. Hackenheim: Conchbooks. 402 pp. decussata Gastropods described in 1903 {{Seguenzioidea-stub