The mitochondrial genomes of Crispatotrochus rubescens and Crispatotrochus rugosus (Hexacorallia; Scleractinia): new insights on the phylogeny of the family Caryophylliidae.

Background: Caryophylliidae is one of the most diverse scleractinian families, however it was recovered as polyphyletic in multiple molecular studies. Recently, the mitochondrial gene order was proposed as a character for a taxonomic revision of the family. Here we describe the first mitogenome of the caryophylliid genus Crispatotrochus, whose phylogenetic position remains uncertain. Methods and results: The complete mitochondrial genomes of Crispatotrochus rubescens and Crispatotrochus rugosus were sequenced, assembled, and annotated. The two mitogenomes are identical and circular, have a length of 16,536 bp, a GC content of 35.9%, and contain 13 protein-coding genes, 2 ribosomal RNAs and 2 transfer RNAs. Both species have a transposition of a three gene block - cob, nad2, and nad6 - similarly to a group of caryophylliid genera that were recovered as monophyletic, including the type genus (Caryophyllia) of the family. The phylogenetic analyses recovered Crispatotrochus within the clade that presents the gene rearrangement and specifically as sister taxa of the genus Caryophyllia, a result consistent with previous studies and the similar gross morphology of the two genera. Conclusions: We determined the mitochondrial genomes of the genus Crispatotrochus to investigate their relations within Scleractinia. Results from this study provide insights on the phylogenetic position of the genus and corroborate that the mitochondrial gene order could be used as taxonomic character for the family Caryophylliidae. [ABSTRACT FROM AUTHOR]