Multi-gene phylogeny of the subclass Astomatia (Protista: Ciliophora) refreshed with two rare astome ciliates from the digestive tube of endogeic earthworms

Autor: Peter Vďačný, Tomáš Obert
Rok vydání: 2021
Předmět:
Zdroj: Organisms Diversity & Evolution. 21:59-77
ISSN: 1618-1077
1439-6092
DOI: 10.1007/s13127-020-00469-6
Popis: Astome ciliates are a diverse group of obligate endosymbionts, living in the alimentary tract of invertebrates and vertebrates. In the digestive tube of two endogeic lumbricid earthworms, we discovered Metaradiophrya speculorum sp. n. and re-discovered Maupasella mucronata after almost half a century. Their systematic positions were determined using the 18S rRNA gene, ITS1-5.8S-ITS2 region, and the barcoding D1/D2 domains of the 28S rRNA gene. According to the present phylogenetic analyses, astomes isolated from the alimentary tract of endogeic earthworms form a diverse paraphyletic assemblage, whose crown radiation contains species isolated from anecic and epigeic earthworms. The genus Metaradiophrya was depicted as monophyletic in multi-gene analyses and its taxa clustered according to the ecological groups of their host earthworms. The traditional classifications of the genus Metaradiophrya within the family Radiophryidae, which is characterized by a Λ-shaped attachment organelle, was however questioned. Genetic data suggested Metaradiophrya to be closely related to Anoplophrya, which does not possess any holdfast organelles and belongs to the family Anoplophryidae. The genus Maupasella was traditionally classified in the nominotypical family Maupasellidae, which is defined by the presence of a short, apical attachment spine. Interestingly, genetic data suggested that Maupasella represents an “orphan” lineage within the endogeic cluster, with some affinity to Subanoplophrya, which lacks holdfast organelles. Since there is only little correlation between the morphology-based and molecular classifications of astomes, the reconciliation of both frameworks will require accounting for adaptive radiation and host-driven diversification—two phenomena that have very likely shaped the evolution of astomes.
Databáze: OpenAIRE
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