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•Phylogeny based on mt genomes places Diazonidae within Aplousobranchia.•The thorax regeneration of Rhopalea supports the aplousobranch nature of Diazonidae.•Our results support the ...loss of a colonial lifestyle in Rhopalea.•Mitochondrial phylogeny places Ciona as sister clade of Aplousobranchia.
The order Aplousobranchia (Chordata, Ascidiacea) contains approximately 1500 species distributed worldwide. Their phylogeny, however, remains unclear, with unresolved family relationships. While most Aplousobranchia are colonial, debates exist concerning the phylogenetic position of families such as the Diazonidae and Cionidae, which exhibit a solitary lifestyle and share morphological characteristics with both Aplousobranchia and Phlebobranchia orders. To clarify the phylogenetic position of the Diazonidae and Cionidae, we determined the complete mitochondrial sequence of the solitary diazonid Rhopalaea idoneta. The phylogenetic reconstruction based on the 13 mitochondrial protein coding genes strongly supports a positioning of Diazonidae well-nested within the Aplousobranchia rather than a positioning as a sister clade of the Aplousobranchia. In addition, we examined the regenerative ability of R. idoneta. Similar to colonial Aplousobranchia, R. idoneta was found to be able to completely regenerate its thorax. Ciona, also known to possess high regenerative abilities, is the Aplousobranchia sister clade rather than a member of the Phlebobranchia. Our results thus indicate that the colonial lifestyle was acquired in the Aplousobranchia, starting from a Ciona-like solitary ancestor and secondarily lost in Diazonidae representatives such as Rhopalaea. The solitary lifestyle of Rhopalaea is thus a derived characteristic rather than an ancestral trait.
The complete mitochondrial genome of the gilthead seabream Sparus aurata Linnaeus 1758, one of the world's most important mariculture species, was sequenced using next generation sequencing ...technology. The genome sequence is comprised of 16,652 bp exhibiting the canonical vertebrate mitochondria gene order. Regions of gene overlap, tRNA length, as well as start and stop codon were similar to those observed in other Sparidae. Phylogenetic reconstructions based on mitochondrial protein coding genes corroborate the view that Sparidae is paraphyletic and includes Centracanthidae.
The complete mitochondrial genome of the devil firefish Pterois miles (Bennett, 1828) was obtained using next generation sequencing approaches. The genome sequence was comprised of 16,497 bp ...exhibiting the standard vertebrate mitochondrial gene arrangement. Regions of gene overlap, tRNA lengths, as well as start and stop codons were similar to those observed in closely related families (i.e. Sebastidae, Peristediidae). Phylogenetic reconstructions support the polyphyly of Scorpaeniformes, and confirm the close relationship of Scorpaenidae and Sebastidae.
