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Issue: Vol. 782 No. 3: 30 Oct. 2026
Type: Article
Published: 2026-10-30
DOI: 10.11646/phytotaxa.782.3.3
Page range: 239-253
Abstract views: 17
PDF downloaded: 5

Epitypification of Mesotaenium endlicherianum and the description of two new Mesotaenium species

Department of Biology; Technical University Darmstadt; Schnittspahnstraße 3; D-64287 Darmstadt; Germany
Auf dem Buechel 54; D-53925; Kall; Germany
Department of Applied Bioinformatics; Institute for Microbiology and Genetics; Georg-August-University Göttingen; Julia-Lermontowa-Weg 3; D-37077 Göttingen; Germany
Department of Biology; Technical University Darmstadt; Schnittspahnstraße 3; D-64287 Darmstadt; Germany
Algae Zygnematophyceae Serritaeniales Mesotaenium endlicherianum Integrative Taxonomy

Abstract

Since the emergence of molecular phylogenetics, several genera within the Zygnematophyceae have been shown to be polyphyletic. Polyphyly is particularly apparent among taxa with a plain morphology such as the genus Mesotaenium Nägeli. Currently, this genus name is applied to zygnematophyte species of several distinct evolutionary lineages, which require a taxonomic revision. For this, the type species, M. endlicherianum Nägeli, needs to be clearly assigned to one of these lineages. We studied three closely related Mesotaenium-like strains of lineage Meso-2 with an integrative approach combining morphology, cell cycle characterisation, and molecular phylogenetics based on the rbcL gene. Our results reveal clear genetic and morphological differences among the strains, supporting their recognition as three distinct species. To establish a stable taxonomic framework, we epitypify M. endlicherianum based on strain SAG 12.97 and thus formally assign the genus Mesotaenium to lineage Meso-2. Additionally, we describe two new species for this clade and establish the common cellular details of the latter. The defined phylogenetic placement of Mesotaenium established in this work now paves the way for additional taxonomic revisions of provisionally described lineages.

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How to Cite

Busch, A., Berg, K.-H.L.V., Darienko, T. & Hess, S. (2026) Epitypification of Mesotaenium endlicherianum and the description of two new Mesotaenium species. Phytotaxa 782 (3): 239–253. https://doi.org/10.11646/phytotaxa.782.3.3