Molecular study of the rare genus Neoabbottiella (Rhodophyta) reveals its assignment to the Halymeniaceae is incorrect

The rare red algal genus Neoabbottiella from the Russian Pacific coast was taxonomically re-examined. Currently, Neoabbottiella is assigned to the Halymeniales; however, some features of the reproductive anatomy cast doubt on the correctness of assigning the genus to Halymeniaceae sensu lato. We investigated the phylogenetic affinities of Neoabbottiella using four DNA markers (nuclear LSU and SSU rDNA, rbcL and COI-5P). Neoabbottiella failed to group with any families of the Halymeniales, but it was nested in a highly supported clade containing representatives of the genus Schmitzia (Calosiphoniaceae incertae sedis). Reproductive anatomy and post-fertilization development also separate Neoabbottiella from the Halymeniaceae. The main characteristics distinguishing Neoabbottiella from the Halymeniales include the intercalary position of the auxiliary cell, the contact of the connecting filament with the auxiliary cell via the lateral process, the origin of the initial gonimoblast cell from the connecting filament at a distance from the auxiliary cell and a lack of a pericarp of branched ampullar filaments. These traits bring Neoabbottiella close to its genetic sister genus Schmitzia, making the classification of Neoabbottiella at the family and order levels difficult. The eventual taxonomic classification of Neoabbottiella awaits the input of data of other species of Schmitzia as well as Calosiphonia, the type genus of the Calosiphoniaceae; thus, Neoabbottiella should be provisionally excluded from the Halymeniales and considered as incertae sedis in the Rhodymeniophycidae. Further, the results of the present study showed that Neoabbottiella is monotypic; Neoabbottiella decipiens should be recognized as a synonym of the generitype Neoabbottiella araneosa.

Automated summary

This study re-examined the taxonomic classification of the rare red algal genus Neoabbottiella from the Russian Pacific coast. The results showed that Neoabbottiella is not closely related to other families of the Halymeniales, but is more similar to the genus Schmitzia. Additionally, the reproductive anatomy and post-fertilization development of Neoabbottiella differ from those of the Halymeniaceae. Therefore, the classification of Neoabbottiella at the family and order levels is challenging and requires further data.