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Nuculidae Gray, 1824

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Shell aragonitic, with prismatic outer, lenticular nacreous middle, and nacreous inner layers. Outline triangular to ovate, inequilateral, equivalve. Umbones opisthogyrate, posterior. Sculpture absent or of various combinations of radial and concentric riblets or striae. Periostracum thick, polished in many, dull in others, yellow to dark brown. Lunule strong to weak or absent; escutcheon wide, frequently long. Hinge plate strong, with anterior and posterior series of V-shaped teeth separated by deep resilifer. Adductor muscle scars subequal. Pallial line simple but obscure. Mantle lobes free. Hypobranchial gland present. Gills small to medium sized. Labial palps large; palp probóscides developed. Foot large, with planar sole and byssal groove, but adult not byssiferous. Alimentary canal with type 1 stomach, strongly chitinized, with two ducts leading to the digestive diverticula; style sac and mid-gut conjoined; intestine long, convoluted, on right side of stomach, passing through ventricle of heart.
The family comprises at least four living genera containing approximately 160 species distributed in all oceans. They have small, inflated shells and lack siphons. There is an anterior to posterior water current. Species are shallow infauna on friable substrata where they are deposit feeders. The large active foot, with wide planar sole, is well suited for active movement through the substratum. Known from the Silurian.
Source: Coan, E. et al., 2000. Bivalve Seashells of Western North America. Marine bivalve mollusks from Arctic Alaska to Baja California.
The nuculid shell is usually small (including the smallest recorded living bivalves [Moore, 1977], but also to 50 mm), obliquely oval to trigonal or wedge-shaped, solid, with the pos¬terior end truncate and the anterior one longer and rounded. It is EQUIVALVE, inflated, not gaping, INEQUILATERAL (umbones posterior), with OPISTHOGYRATE UMBONES. Shell microstructure is ARAGONITIC and three-layered, with a composite PRISMATIC outer layer, a lenticular NACREOUS or HOMOGENOUS middle layer, and a sheet-nacreous inner layer; TUBULES are apparently absent. Exteriorly nuculids are covered by thick, polished, yellow to green to dark brown, adherent PERIOSTRACUM. Sculpture is usually smooth, or in some species sculptured by various combinations of radial and commarginal striae. Both LUNULE and ESCUTCHEON are usually present but variable in strength and sculpture. [The anterior prolongation of the shell and opisthogyrate umbones of nuculids apparently once caused reverse definition of these two structures; the heart-shaped escutcheon lying below the curved beaks at the shorter end of the shell resembles the more typical lunule of a heterodont (e.g., Veneridae) and has occasionally been called a "pseudo-lunule" (Schenck, 1934). This is likely the source of the statement by some authors, "true lunule not present."] Interiorly the shell is NACREOUS. The PALLIAL LINE is ENTIRE and obscure. The inner shell margins are usually denticulate, or smooth in some species. The HINGE PLATE is strong and TAXODONT, with an anterior and a posterior series of chevron-shaped teeth separated by a deep, narrow, subumbonal RESILIFER inclined obliquely anteriorly and inwardly projecting. The LIGAMENT is SIMPLE, with an internal portion (RESILIUM).
Mikkelsen, P.M. & Bieler, R. 2003, Seashells of Southern Florida. Living Marine Mollusks of the Florida Keys and Adjacent Regions: Bivalves.

Zařazené taxony

Počet záznamů: 11

rod Acila H. & A. Adams, 1858 - oříškovka
rod Austronucula Powell, 1939
rod Brevinucula Thiele, 1934
rod Condylonucula D. R. Moore, 1977
rod Ennucula Iredale, 1931
rod Linucula Marwick, 1931
rod Neonucula T. C. Lan & Y. C. Lee, 2001
rod Nucula Lamarck, 1799 - oříškovka
rod Pronucula Hedley, 1902
rod Sinonucula Xu, 1985
rod Varinucula Maxwell, 1988

Odkazy a literatura
EN Australian Faunal Directory [895e497f-60b4-4694-946c-d5493b2b4526]

ABRS (2009-2019): Australian Faunal Directory [], Australian Biological Resources Study, Canberra [jako Nuculidae J. Gray, 1824]
Datum citace: 22. červenec 2015
CZ Pfleger V. (1999): České názvy živočichů III. Měkkýši (Mollusca), Národní muzeum, (zoologické odd.), Praha, 108 pp. [jako Nuculidae]
Datum citace: 11. listopad 2013
EN Carter J. et al (2011): A Synoptical Classification of the Bivalvia (Mollusca), Paleontological Contributions 4 [jako Nuculidae J. Gray, 1824]
Datum citace: 6. duben 2014

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