Diversity and evolution in the zoanthid genus Palythoa (Cnidaria: Hexacorallia) based on nuclear ITS-rDNA
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- Reimer, J.D., Takishita, K., Ono, S. et al. Coral Reefs (2007) 26: 399. doi:10.1007/s00338-007-0210-5
Previous phylogenetic studies based on mitochondrial DNA markers have suggested that the zoanthid genus Palythoa may consist of both Palythoa species (Palythoa tuberculosa) and species formerly assigned to the genus Protopalythoa (Palythoa mutuki, Palythoa heliodiscus). In the present study various Palythoa spp. samples collected primarily from southern Japan with additional samples from the Indo-Pacific and Caribbean Sea were examined. The nuclear internal transcribed spacer of ribosomal DNA (ITS-rDNA) was sequenced and aligned for phylogenetic analyses to further investigate the relationship between P. tuberculosa, P. mutuki, and P. heliodiscus. ITS-rDNA analyses showed species groups forming monophylies with similar topology but with much higher resolution than seen for mitochondrial phylogenetic analyses. The results also confirmed the very close relationship of P. tuberculosa and P. mutuki. Some specimens appeared to be a potentially undescribed Palythoa species (designated Palythoa sp. sakurajimensis). Additionally, ITS-rDNA sequences of P. mutuki and P. tuberculosa showed additive polymorphic site, demonstrating for the first time a potential history of reticulate evolution in Palythoa.