Description of three new predator species of Litostomatea (Alveolata: Ciliophora), including sequencing and annotation of their mitochondrial genomes

Three new species of haptorian ciliates, Lacrymaria venatrix sp. nov., Phialina famelica sp. nov., and Chaenea vermicularis sp. nov., recovered from water bodies in Tuscany, Italy, are described according to the standards of Next Generation Taxonomy, which include morphology, ultrastructure, phylogeny, analysis of the associated microbial consortium, and mitochondrial genome sequencing and annotation. Lacrymaria venatrix sp. nov. is characterized by a spindle-shaped trunk, a highly contractile neck that equals the trunk in length when fully extended, and a nuclear apparatus consisting of two macronuclear nodules and a single micronucleus. Phialina famelica sp. nov. has a blunter spindle-shaped trunk, with a shallow oral bulge and an elongated macronucleus. Chaenea vermicularis sp. nov. differs from its congeners by modest contractility combined with greater ability to elongate, mucocysts organized into multiple rows forming stripes, and the presence of several hundred macronuclear nodules. The 18S ribosomal DNA-based phylogenetic analysis supports previous observations of the paraphyly of the genera Lacrymaria and Phialina, which require a comprehensive systematic revision. The genus Chaenea does not appear to be challenged in a similar manner; however, its position within Haptoria remains unclear, and Chaenea vermicularis sp. nov. appears rather divergent from its congeners.