Multigene‐based phylogeny of Urostylida (Ciliophora, Hypotrichia), with establishment of a novel family

摘要

> The Urostylida is a major taxon of hypotrichs with many unresolved evolutionary relationships. Due to incomplete or inaccurate character states and a paucity of morphogenetic data, the phylogeny of several taxa within urostylids is unresolved. Molecular phylogeny studies based on single gene ( SSU rDNA ) data may lead to conflict between morphological classification and SSU rDNA tree. In this work, 20 new sequences ( SSU rDNA , ITS 1‐5.8S‐ ITS 2 and LSU rDNA ) of five genera of urostylids are provided to further investigate the phylogenetic relationships of this group. The main findings are as follows: (i) the establishment of Hemicycliostylidae, a novel family presently including Hemicycliostyla and Australothrix , is supported by both single gene and concatenated phylogenies; (ii) all molecular data support the exclusion of Eschaneustyla from the family Epiclintidae; (iii) Australothrix , Bergeriella and Thigmokeronopsis are distinctly separated in all gene trees although they share the character that each posterior streak generates the ventral row together with the midventral pair; (iv) compared with closely related genera in all trees, that is Metaurostylopsis and Apourostylopsis , Neourostylopsis is characterized by having more than three frontal cirri arranged in distinct or indistinct corona rather than the length of the midventral complex; (v) Hemicycliostyla and Pseudourostyla , two morphologically