Corbicula is a genus of freshwater and brackish water clams, aquatic bivalve mollusks in the family Cyrenidae, the basket clams.Gofas, S. (2015). Cyrenidae Gray, 1847. In: MolluscaBase (2015). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=238370 on 2015-08-26 The genus name is the Neo-Latin diminutive of Latin corbis, a basket, referring to the shape and ribs of the shell.
The genus Corbicula includes numerous extant and fossil species; the status of several of them is unclear (species inquirenda).MolluscaBase eds. (2022). Corbicula Megerle von Mühlfeld, 1811. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=238371 on 2022-05-29 The best known is Corbicula fluminea, originally native to freshwater systems in East Asia, now an invasive species in many areas of the world.
Unusually, some members reproduce via androgenesis, wherein all genes are inherited from the male, one of the very few animals to do so.
In many Asian countries, these clams are used as ingredients for soup. In South Korea, there is popular soup made of these species of clams (usually Corbicula japonica, Corbicula fluminea, Corbicula leana) known as 재첩국 (jaechup-guk).
Androgenesis Androgenesis occurs rarely in the tree of life, with only a few occurrences documented and multiple mechanisms through which it is achieved. In Corbicula, androgenesis occurs through the ejection of maternal chromosomes from the egg following fertilization by sperm. Fertilization in androgenetic and sexual lineages of Corbicula occurs while the developing egg is arrested at metaphase 1 of meiosis. In sexual species of Corbicula, the axis of the meiotic spindle orienting the duplicated maternal chromosomes is perpendicular to the plasma membrane of the zygote. However, androgenetic lineages of Corbicula have an axis parallel to the membrane. As a result of this unusual orientation, the two maternal polar bodies formed during anaphase 1 are extruded from the zygote, leading to the complete elimination of all maternal chromosomes. Androgenetic Corbicula lineages also have unreduced sperm; therefore, these lineages retain the same ploidy level after maternal chromosome extrusion. Since only maternal chromosomes are eliminated from the zygote, the zygote inherits only the paternal genome. Sperm of sexually reproducing Corbicula are uniflagellate, which is considered the ancestral trait, while androgenetic Corbicula lineages interestingly possess biflagellate sperm.
While androgenesis would likely lead to species extinction in dioecious species, all androgenetic lineages of Corbicula are hermaphroditic, meaning individuals can produce both sperm and egg, and these individuals can self-fertilize to create effectively clonal offspring. Androgenetic lineages of Corbicula are capable of cross-breeding with sexual and other androgenetic lineages in a phenomenon known as “egg parasitism”. This leads to several interesting consequences for determining androgenetic Corbicula phylogeny. The first is a “cytonuclear mismatch” whereby the mitochondrial DNA shows congruence with the parasitized lineage but the genomic DNA is congruent with the selfish androgenetic lineage whose sperm fertilized the egg. Further complicating phylogenetic studies is the rare occurrence of partial or complete nuclear capture, when the maternal DNA is not eliminated from the zygote. Nuclear capture can result in genome recombination or polyploidy. Partial genome capture has been documented when native and androgenetic or multiple androgenetic lineages are sympatric. Egg parasitism has been offered as one explanation for the persistence of androgenetic lineages through increasing allele heterozygosity.
Taxonomy Despite extensive phylogenetic study of the genus, appropriate categorization of invasive populations has remained a challenge. Lack of clarity in their phylogeny may be due to being hermaphroditic androgens, though no single species of Corbicula has been described as fully androgenetic. Rather, 4-5 specific androgenetic lineages are described in the scientific literature. Form A, B, and D are found within the North America; Form C is in South America; and another form(s) has described in Europe. Cross-breeding between androgenetic and native Corbicula lineages have made it difficult to create a clear taxonomy of the genus, and it is still unclear whether androgenesis arose independently multiple times or originated from a smaller number of lineages that then cross-bred with sexual Corbicula species. A comprehensive molecular phylogenetic study based on the largest DNA sequence dataset assembled for the genus revealed that Corbicula comprises two subgenus-level clades: Corbicula s.s. and Sphaerocorbicula Bolotov, Bespalaya & Aksenova, 2026. The analysis identified at least 27 well-supported species-level clusters. Two new species were described from Myanmar: C. bilini and C. lemroae. Additionally, Sphaerium avanum Theobald, 1874 was transferred to Cyrenidae as Corbicula (Sphaerocorbicula) avana comb. nov., and five nominal species were synonymised.
Invasiveness Corbicula clams are remarkably proficient invasive species, with native ranges spanning from Australia to Africa, but can now be found in most other continents. In North America, Corbicula may have initially invaded as a human food source, though the origin of invasion in other continents has not been determined. However, genotyping may aid in tracking the number of introductions occurring in non-native habitats.
Part of what contributes to its invasive success is its androgenetic reproductive strategy, wherein a single individual may be capable of creating an entire population, but beyond androgenesis, Corbicula owe their invasive potential to anthropogenic factors and their life history strategies. Corbicula have high reproductive capacities, which may be in part due to their ability to self-fertilize, and the high dispersal potential of their larvae. Corbicula are also phenotypically plastic, which may allow them to outcompete native mussels, and their occurrence at high densities may drive native mussel glochidia mortality. Their high competitive ability is of concern, in part due to the already endangered status of many of the world's mussel species.
Though Corbicula are proficient competitors, they have a small number of lineages, and have worldwide low genetic diversity, which is attributed to their reproductive capabilities. While this generally does not contribute to their success, phenotypic plasticity may buffer them from the effects of low genetic diversity, though it is suggested that population bottlenecks may have occurred during their invasions. Despite the potential for population bottlenecks, there is a need for better control methods, as active spread has occurred. While some eradication methods work, such as deposition of dry ice pellets, the use of a heat torch, and temperature shock, preventative measures are of utmost importance as invasives are often difficult to detect prior to establishment.
Species Extant species within the genus Corbicula include:
Corbicula africana (Krauss, 1848) Corbicula angulifera E. von Martens, 1897 Corbicula anomioides (Bogan & Bouchet, 1998) Corbicula astartina (E. von Martens, 1860) Corbicula aurea Nesemann & G. Sharma, 2007 Corbicula australis (Deshayes, 1830) Corbicula baudoni Morlet, 1886 Corbicula bitruncata E. von Martens, 1908 Corbicula blandiana Prime, 1864 Corbicula bocourti (Morelet, 1865) Corbicula cashmiriensis Deshayes, 1855 Corbicula castanea (Morelet, 1865) Corbicula consularis Prime, 1870 Corbicula cyreniformis Prime, 1860 Corbicula dautzenbergi Prashad, 1928 Corbicula elatior E. von Martens, 1905 Corbicula elongata Clessin, 1878 Corbicula erosa Prime, 1861 Corbicula ferghanensis Kursalova & Starobogatov, 1971 Corbicula fluminalis (O. F. Müller, 1774) Corbicula fluminea (O. F. Müller, 1774) – Asian clam Corbicula formosana Dall, 1903 Corbicula gabonensis Preston, 1909 Corbicula gustaviana E. von Martens, 1900 Corbicula iravadica Blanford, 1880 Corbicula japonica Prime, 1864 Corbicula javanica (Mousson, 1849) Corbicula lamarckiana Prime, 1864 Corbicula largillierti (Philippi, 1844) Corbicula larnaudieri Prime, 1862 Corbicula leana (Prime, 1864) Corbicula leviuscula Prime, 1864 Corbicula loehensis Kruimel, 1913 Corbicula lutea Morelet, 1862 Corbicula lydigiana Prime, 1861 Corbicula madagascariensis Smith, 1882 Corbicula mahalonensis Kruimel, 1913 Corbicula malaccensis Deshayes, 1855 Corbicula manilensis (Philippi, 1844) Corbicula maroubra (Iredale, 1943) Corbicula masapensis Kruimel, 1913 Corbicula matannensis Sarasin & Sarasin, 1898 Corbicula messageri Bavay & Dautzenberg, 1901 Corbicula moltkiana Prime, 1878 Corbicula moreletiana Prime, 1867 Corbicula mortoni M. Huber, 2015 Corbicula nitens (Philippi, 1844) Corbicula noetlingi E. von Martens, 1899 Corbicula ovalina Deshayes, 1855 Corbicula poppei Thach & F. Huber, 2021 Corbicula possoensis Sarasin & Sarasin, 1898 Corbicula pulchella (Mousson, 1849) Corbicula pullata (Philippi, 1850) Corbicula rectipatula B.-Y. Huang, 1981 Corbicula regia Clessin, 1879 Corbicula rivalis (Philippi, 1850) Corbicula sandai Reinchardt, 1878 Corbicula senegalensis Clessin, 1877 Corbicula siamensis Prashad, 1928 Corbicula similis (W. Wood, 1828) Corbicula solida Clessin, 1887 Corbicula solidula Prime, 1861 Corbicula straminea Reinhardt, 1877 Corbicula striatella Deshayes, 1855 Corbicula subnitens Clessin, 1887 Corbicula subplanata E. von Martens, 1897 Corbicula tenuis Clessin, 1887 Corbicula tibetensis Prashad, 1929 Corbicula tobae E. von Martens, 1900 Corbicula towutensis Kruimel, 1913 Corbicula tsadiana E. von Martens, 1903 Corbicula virescens Brandt, 1974
References
Bogan, A., Bouchet, P. (1998). Cementation in the freshwater bivalve family Corbiculidae (Mollusca: Bivalvia): a new genus and species from Lake Poso, Indonesia. Hydrobiologia, 389: 131–139 Suzuki, K.; Oyama, K. (1943). Überblick über die Corbiculiden Ostasiens (Materialien zur Monographic der Ostasiatischen Corbiculiden 1). Venus. 12(3-4): 138–149. Ota, Y. [Ohta, Y.]. (1970). A review of some Cretaceous corbiculids in North America. Transactions and Proceedings of the Palaeontological Society of Japan, new series. 79: 291–315.
Further reading Alexei V. Korniushin, Matthias Glaubrecht (2003) Novel reproductive modes in freshwater clams: brooding and larval morphology in Southeast Asian taxa of Corbicula (Mollusca, Bivalvia, Corbiculidae) Acta Zoologica 84 (4), 293–315. https://doi.org/10.1046/j.1463-6395.2003.00150.x (Redescription) Coan, E. V.; Valentich-Scott, P. (2012). Bivalve seashells of tropical West America. Marine bivalve mollusks from Baja California to northern Peru. 2 vols, 1258 pp.
External links
von Mühlfeld J.C. (1811). Entwurf eines neuen Systems der Schaltiergehäuse. Magazin für die neuesten Entdecklungen in der gesammten Naturkunde von der Gesellschaft Naturforschaft Freunde zu Berlin. 5(1): 38-72, plate 3 Dall, W. H. (1903). Review of the classification of the Cyrenacea. Proceedings of the Biological Society of Washington. 16: 5-8. Lindholm W.A. (1933). Eine verschollene Muschel aus Zentralasien. Archiv für Molluskenkunde. 65: 264–268 Sandberger, C.L.F. (1870-1875). Die Land- und Süßwasser-Conchylien der Vorwelt. C. W. Kreidel, Wiesbaden.