Cyclocardia Conrad 1867
Creators
Description
Genus Cyclocardia Conrad, 1867
Type species. Cardita borealis Conrad, 1831 (pl. 8, fig. 1) (subsequent designation by Stolickza, 1871). Pleistocene–Recent, Northwest Atlantic Ocean.
Diagnosis. Carditid with thick shell, subcircular outline and convex dorsal margin. Umbo rounded. Right anterior tooth small, middle tooth very curved, broad and thick. Left anterior tooth large and posterior tooth strong and very curved. External sculpture of 15 to 27 entire and smooth radial ribs, that are low and covered by small subcircular or subrectangular nodes. Periostracum coarse and hirsute in living species.
Included species. Cyclocardia is an Eocene to Recent cosmopolitan genus that includes more than a hundred species (Maxwell 1969; Coan 1977; Stilwell & Zinsmeister 1992; Kafanov et al. 2001; Huber 2010; Güller & Zelaya 2013).
Remarks. Conrad (1867) highlighted that this genus was characterized by a thick shell with a coarse periostracum, generally smooth radial ribs and strongly inclined posteriorly hinge teeth. Subsequently, Stewart (1930) indicated that Cyclocardia has grooved hinge teeth, but that character is not found in all species.
According to Heaslip (1968), Cyclocardia has some convergent characters with planicostate carditids, such as the development of a thick shell with low and smooth radial ribs, and pointed out that the sculpture of juvenile specimens is similar to alticostate carditids, inferring that Cyclocardia could have originated within this group.
The most ancient records of Cyclocardia are represented by the Eocene C. mesembria Stilwell & Zinsmeister, 1992 (Marambio Island, La Meseta Formation, Antarctica), C. steinekei Clark & Dunham, 1946 (El Carmen District, unnamed formation, Colombia), C. otatsumei Uozomi, 1955 (Hokkaido, Wakkanabe Formation, Japan), C. ezoensis (Takeda, 1953) and C. hamiltonensis (Clark, 1932) (Kamchatka, Aluginskaya Formation, Russia) and by C. caumontiensis (Cossmann & Pisarro, 1904) (Paris Basin, France).
Cyclocardia is represented by four Patagonian species (C. cannada, C. dalek n. sp., C. nortensis and C. compressa) and is the most diverse carditid genus in the region. According to the large amount of intraspecific variability on this genus, Huber (2010) proposed the existence of at least three subgenera within Cyclocardia. As already discussed by Maxwell (1969), New Zealand representatives may belong to a different lineage or genus (see ‘ C. ’ nortensis below).
Notes
Files
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Linked records
Additional details
Identifiers
Biodiversity
- Family
- Carditidae
- Genus
- Cyclocardia
- Kingdom
- Animalia
- Order
- Carditoida
- Phylum
- Mollusca
- Scientific name authorship
- Conrad
- Taxon rank
- genus
- Taxonomic concept label
- Cyclocardia Conrad, 1867 sec. Pérez & Río, 2017
References
- Conrad, T. A. (1867) Description of a new genus of Astartidae. American Journal of Conchology, 3, 191.
- Conrad, T. A. (1831) Descriptions of fifteen new species of Recent and three of fossil, chiefly from the Coast of the United States. Journal of the Academy of Natural Science of Philadelphia, 6, 256 - 268.
- Stolickza, F. (1871) Paleontologica Indica: Cretaceous Fauna of Southern India. Memoirs of the Geological Survey of India, 3, 1 - 538.
- Maxwell, P. (1969) Middle Tertiary Mollusca from North Otago and South Canterbury, New Zealand. Transactions of the Royal Society of New Zealand, Geology, 6 (13), 155 - 185.
- Coan, E. V. (1977) Preliminary Review of the Northwest American Carditidae. The Veliger, 19 (4), 375 - 386.
- Stilwell, J. & Zinsmeister, W. (1992) Molluscan Systematics and Biostratigraphy. Lower Tertiary La Meseta Formation, Seymour Island, Antarctic Peninsula. Antarctic Research Series, 55, 1 - 192. https: // doi. org / 10.1029 / ar 055
- Kafanov, A. I., Ogasawara, K. & Marincovich Jr., L. (2001) Checklist and bibliography of the Cenozoic marine Bivalvia (Mollusca) of Northeastern Asia (Russian Far East), 1968 - 1999. Bulletin of the Mizunami Fossil Museum, 28, 1 - 138.
- 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. ConchBooks, Hackenheim, 901 pp.
- Guller, M. & Zelaya, D. G. (2013) The families Carditidae and Condylocardiidae in the Magellan and Peru-Chile provinces (Bivalvia: Carditoidea). Zootaxa, 3682 (2), 201 - 239. https: // doi. org / 10.11646 / zootaxa. 3682.2.1
- Stewart, R. B. (1930) Gabb's California Cretaceous and Tertiary type Lamellibranchs. Special Publication of the Academy of Natural Sciences of Philadelphia, 3, 1 - 314.
- Heaslip, W. G. (1968) Cenozoic evolution of the alticostate venericards in Gulf and East Coastal North America. Palaeontographica Americana, 6 (39), 55 - 135.
- Clark, B. L. & Dunham, J. W. (1946) Eocene faunas from the department of Bolivar, Colombia. Geological Society of America Memoirs, 16, 1 - 116. https: // doi. org / 10.1130 / mem 16
- Uozomi, S. (1955) On some molluscan fossils from the Palaeogene Wakkanabe Formation in Hokkaido. Transactions and Proceedings of the Palaeontological Society of Japan New Series, 19, 73 - 80. https: // doi. org / 10.5575 / geosoc. 56.157
- Takeda, H. (1953) The Poronai Formation (Oligocene Tertiary) of Hokkaido and South Sakhalin and its fossil fauna. Geological Section, the Hokkaido Association of Coal Mining Technologists, Sapporo. Studies on Coal Geology, 3, 1 - 103. https: // doi. org / 10.5575 / geosoc. 75.387
- Clark, B. L. (1932) Fauna of the Poul and Yakataga formations (upper Oligocene) of southern Alaska. Bulletin of Geological Society of America, 43, 798 - 846. https: // doi. org / 10.1130 / gsab- 43 - 797
- Cossmann, M. & Pissarro, G. (1904) Iconographia complete des coquilles fossiles de l " Eocene des environs de Paris. Pelecypodes. Tome 1 er. Unkown Publisher, Paris, 490 pp.