''Cucullaea labiata'' 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 ...

of saltwater clam or ark shell, a

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

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 ...

in the family

Cucullaeidae The false ark shells (''Cucullaea'') are a small genus of Marine (ocean), marine bivalve molluscs related to the ark clams. The genus is the only member of the Family (biology), family Cucullaeidae. Species The World Register of Marine Species l ...

.Huber M. (2010) Compendium of bivalves. A full-color guide to 3,300 of the world’s marine bivalves. A status on Bivalvia after 250 years of research. Hackenheim: ConchBooks. 901 pp., 1.

Description

The shell of ''Cucullea labiata'' is inequilateral and inequivalve, and is thin but not brittle. It grows to about in length though is a more usual size. The left valve is a little larger than the right and the shape is roughly triangular with a long, rounded margin. The umbo is prominent and slightly nearer the posterior end of the shell. It is on the summit of a triangular cardinal area which has fine sculptured ribs. The rest of the valve has further fine ribs but also concentric sculpturing giving it a reticulated pattern. The black ligament is exterior and the hinge is long and straight. It bears a row of teeth that diverge outwards and a few long teeth at the ends that are nearly horizontal. The exterior of the shell is purplish-brown and the inside white, shaded with reddish-brown posteriorly. The pallial line is faint and there is no pallial sinus. The two adductor scars are asymmetrical. The

periostracum The periostracum ( ) is a thin, organic coating (or "skin") that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods and ...

is yellowish, velvety and conspicuous and covers the outer surface of the valves.Laternulidae: Lantern clams
The living marine resources of the Western Central Pacific. p158. Retrieved 2012-02-14.

Distribution and habitat

''Cucullea labiata'' is found in the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

, from northern

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

and

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. It is found buried in sandy or muddy substrates.

References

Cucullaeidae Molluscs described in 1786 {{bivalve-stub