Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Tunicata
Classis: Larvacea
Familia: Kowalevskiidae
Genus: Kowalevskia
Kowalevskia is a genus of larvacean tunicates, the only one in the family Kowalevskiidae.[1]
Species
Kowalevskia oceanica Lohmann, 1899
Kowalevskia tenuis Fol, 1872
Description
Kowalevskia is a small larvacean. In the adult, the body measures around 1 mm long, while the tail is 8 mm long, appearing stretched and tapered at its ends.[2][3]
Unlike other Appendicularia species, Kowalevskia doesn't have a heart. Instead, the circulatory system is powered by the beating tail.[2]
Kowalevskia also lacks an endostyle, being replaced by a ciliated groove without glandular cells.[4][5]
The spiracles also differ from other families, being shaped as long, narrow slits.[4]
House
Uniquely among larvaceans, Kowalevskia's house is ellipsoidal or toroidal in shape, 1 to 2 cm in diameter. It has a single opening, acting both as inlet and outlet.[3]
Distribution
Both species of Kowalevskia have a wide distribution. K. tenuis can be found in the East Atlantic and West Pacific, as well as in the Mediterranean and Black Seas. Meanwhile, K. oceanica is found in the Mediterranean and North-East Atlantic, as well as in the Red Sea and West Indian Ocean. [3]
Phylogeny
The monotypic Kowalevskiidae is believed to be the sister taxon to Fritillariidae, with both sharing specialized characteristics and forming a clade to the exclusion of Oikopleuridae.[4]
References
"Kowalevskia". www.gbif.org. Retrieved 13 May 2023.
"Kowalevskia tenuis – Appendiculaire ellipsoïdal" (in French).
"Appendiculaire ellipsoïdal" (in French).
Brena, Carlo; Cima, Francesca; Burighel, Paolo (31 July 2003). "Alimentary tract of Kowalevskiidae (Appendicularia, Tunicata) and evolutionary implications". Journal of Morphology. 258 (2): 225–238. doi:10.1002/jmor.10145. PMID 14518015. S2CID 22635979.
"Appendicularia" (PDF). Australian Government – Department of Climate Change, Energy, the Environment and Water. Retrieved 2023-04-10.
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