Species in the genus Turritopsis (Cnidaria, Hydrozoa): a molecular evaluation

Mitochondrial ribosomal gene sequences were used to investigate the status of several populations of hydromedusae belonging to the genus Turritopsis (family Oceaniidae). Several nominal species have been described for this genus, but most of them had been synonymized and attributed to one cosmopolit...

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Bibliographic Details
Published in:Journal of zoological systematics and evolutionary research 2007-02, Vol.45 (1), p.11-19
Main Authors: Miglietta, M. P., Piraino, S., Kubota, S., Schuchert, P.
Format: Article
Language:English
Subjects:
Hydrozoa
phylogeny
species introduction
systematics
Turritopsis
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Summary:Mitochondrial ribosomal gene sequences were used to investigate the status of several populations of hydromedusae belonging to the genus Turritopsis (family Oceaniidae). Several nominal species have been described for this genus, but most of them had been synonymized and attributed to one cosmopolitan species, Turritopsis nutricula. A recent revision based on morphological and reproductive characters, however, has shown that many different populations can be distinguished and that several of the nominal Turritopsis species are likely valid biological species. Our investigation using molecular sequence data of 16S mitochondrial gene confirms these results. The Mediterranean Turritopsis must be attributed to Turritopsis dohrnii and the Turritopsis of New Zealand must be referred to Turritopsis rubra. The situation of the Japanese Turritopsis is more complex, though all sampled populations are clearly distinct from T. nutricula, a species likely confined to the Western Atlantic. The Japanese Turritopsis fall into three widely separated lineages. One of them, corresponding likely to Turritopsis pacifica, is closely related to T. rubra. A second clade, which potentially represents an as yet undescribed species, produces smaller medusae than T. pacifica and is morphologically distinguishable from it. Finally, a third group was distinguished by a single haplotype sequence that is identical with a Mediterranean sample of T. dohrnii. It is postulated that the last group of Japanese Turritopsis is likely a recent introduction, most probably by human activity. A survey of all known and potentially valid Turritopsis species is given in table format to facilitate identifications and future revisory work. Sommario Sequenze del gene mitocondriale 16S sono state utilizzate per studiare lo stato tassonomico di idroidi appartenenti al genere Turritopsis (Famiglia Oceaniidae). In letteratura, tra le numerose specie nominali di TurritoSPSis descritte, molte di queste sono state successivamente messe in sinonimia e attribuite ad un'unica specie cosmopolita, Turritopsis nutricula. Una recente revisione, basata su dati morfologici e caratteri riproduttivi, ha comunque mostrato che diverse popolazioni di Turritopsis possono essere distinte in numerose specie nominali e probabilmente rappresentano valide specie biologiche. Il presente studio conferma questa recente interpretazione, mediante lo studio di sequenze molecolari del gene 16S. La popolazione mediterranea di Turritopsisè
ISSN:0947-5745
1439-0469
DOI:10.1111/j.1439-0469.2006.00379.x