Polyphyly of the traditional family Flabellinidae affects a major group of Nudibranchia: aeolidacean taxonomic reassessment with descriptions of several new families, genera, and species (Mollusca, Gastropoda).

The Flabellinidae, a heterogeneous assembly of supposedly plesiomorphic to very derived sea slug groups, have not yet been addressed by integrative studies. Here novel material of rarely seen Arctic taxa as well as North Atlantic, North and South Pacific, and tropical Indo-West Pacific flabellinid species is investigated morpho-anatomically and with multi-locus markers (partial COI, 16S rDNA, 28S rDNA and H3) which were generated and analysed in a comprehensive aeolid taxon sampling. It was found that the current family Flabellinidae is polyphyletic and its phylogeny and taxonomic patterns cannot be understood without considering members from all the Aeolidacean families and, based on a robust phylogenetic hypothesis, morpho-anatomical evolution of aeolids is more complex than suspected in earlier works and requires reclassification of the taxon. Morphological diversity of Flabellinidae is corroborated by molecular divergence rates and supports establishing three new families (Apataidae fam. n., Flabellinopsidae fam. n., Samlidae fam. n.), 16 new genera, 13 new species, and two new subspecies among the former Flabellinidae. Two families, namely Coryphellidae and Paracoryphellidae, are restored and traditional Flabellinidae is considerably restricted. The distinctness of the recently described family Unidentiidae is confirmed by both morphological and molecular data. Several species complexes among all ex-"Flabellinidae" lineages are recognised using both morphological and molecular data. The present study shows that Facelinidae and Aeolidiidae, together with traditional "Tergipedidae", deeply divide traditional "Flabellinidae." Diagnoses for all aeolidacean families are therefore provided and additionally two new non-flabellinid families (Abronicidae fam. n. and Murmaniidae fam. n.) within traditional tergipedids are established to accommodate molecular and morphological disparity. To address relationships and disparity, we propose a new family system for aeolids. Here the aeolidacean species are classified into at least 102 genera and 24 families. Operational rules for integration of morphological and molecular data for taxonomy are suggested.

Corrigenda: Polyphyly of the traditional family Flabellinidae affects a major group of Nudibranchia: aeolidacean taxonomic reassessment with descriptions of several new families, genera, and species (Mollusca, Gastropoda). https://doi.org/10.3897/zookeys.717.21885.

[This corrects the article DOI: 10.3897/zookeys.717.21885.].

Mitogenome polymorphism in a single branch sample revealed by SOLiD deep sequencing of the Lophelia pertusa coral genome.

We present an initial genomic analysis of the non-symbiotic scleractinian coral Lophelia pertusa, the dominant cold-water reef-building coral species in the North Atlantic Ocean. A significant fraction of the deep sequencing reads was of mitochondrial and microbial origins. SOLiD deep sequencing reads from fragment library experiments of total DNA and PCR amplified mitogenome generated about 21,000 times and 136,000 times coverage, respectively, of the 16,150 bp mitogenome. Five polymorphic sites that include two non-synonymous sites in the NADH dehydrogenase subunit 5 genes were detected in both experiments. This observation is surprising since anthozoans in general exhibit very low mtDNA sequence variation at intraspecific level compared to nuclear sequences. More than fifty bacterial species associated with the coral isolate were also sequence detected, representing at least ten complete genomes. Most reads, however, were predicted to originate from the Lophelia nuclear genome.

Mitogenome rearrangement in the cold-water scleractinian coral Lophelia pertusa (Cnidaria, Anthozoa) involves a long-term evolving group I intron.

Group I introns are genetic insertion elements that invade host genomes in a wide range of organisms. In metazoans, however, group I introns are extremely rare, so far only identified within mitogenomes of hexacorals and some sponges. We sequenced the complete mitogenome of the cold-water scleractinian coral Lophelia pertusa, the dominating deep sea reef-building coral species in the North Atlantic Ocean. The mitogenome (16,150 bp) has the same gene content but organized in a unique gene order compared to that of other known scleractinian corals. A complex group I intron (6460 bp) inserted in the ND5 gene (position 717) was found to host seven essential mitochondrial protein genes and one ribosomal RNA gene. Phylogenetic analysis supports a vertical inheritance pattern of the ND5-717 intron among hexacoral mitogenomes with no examples of intron loss. Structural assessments of the Lophelia intron revealed an unusual organization that lacks the universally conserved ωG at the 3' end, as well as a highly compact RNA core structure with overlapping ribozyme and protein coding capacities. Based on phylogenetic and structural analyses we reconstructed the evolutionary history of ND5-717, from its ancestral protist origin, through intron loss in some early metazoan lineages, and into a compulsory feature with functional implications in hexacorals.