Morphology and 18S rDNA phylogeny of Hemicycliostyla sphagni (Ciliophora, Hypotricha) from Brazil with redefinition of the genus Hemicycliostyla

Abstract

Morphology of the urostylid ciliate Hemicycliostyla sphagni Stokes, 1886, the type of Hemicycliostyla Stokes, 1886, is investigated based on live and protargol-impregnated specimens from a Brazilian population. The absence of transverse cirri, which has been considered the main diagnostic feature of Hemicycliostyla, separating it from Pseudourostyla Borror, 1972, was found to vary within the studied population, with 50 % of the specimens exhibiting inconspicuous and/or rudimentary transverse cirri. A redefinition of Hemicycliostyla was possible based on combined features of interphase and divisional morphogenesis: Retroextendia Berger, 2006, with bi- or multicoronal frontal cirral pattern; fronto-terminal cirri present; multiple left and right marginal cirral rows that replicate independently via within-row development, each parental row producing one primordium per divider; caudal cirri lacking; and presence/absence of transverse cirri may be intrapopulationally variable. Phylogenetic analyses of the 18S rDNA marker unambiguously placed H. sphagni as sister group of Pseudourostyla franzi Foissner, 1987, which is herein transferred to Hemicycliostyla as Hemicycliostyla franzi comb. nov.

Description and Phylogeny of Tetrakeronopsis silvanetoi gen. nov., sp. nov. (Hypotricha, Pseudokeronopsidae), a New Benthic Marine Ciliate from Brazil

“…The phylogenetic trees obtained in the present study are generally in agreement with the literature concerning the internal kinships of the core urostyloids [20], [23], [24], [44], including their families and the paraphyly of pseudourostylids, which is recurrent in the literature [22], [23], [40]. In addition, the spreading of Anteholosticha spp.…”

“…Specimens were then isolated for DNA extraction and amplification of the 18S marker following Paiva et al [21]. The obtained sequence was added to a data matrix containing 54 other sequences representing the “core urostyloids” [22]–[24], which is the largest monophylum of urostyloids recovered in molecular phylogenies, but also the group in which pseudokeronopsids are included, e.g. [20]–[24], [26].…”

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

“…The molecular phylogeny of Australothrix and Hemicycliostyla indicates that these two genera represent a family-level clade even though they have many different features (e.g., three frontal cirri vs. many ranged in a bicorona; one left marginal row vs. more; midventral complex composed of rows and pairs vs. only pairs; frontoterminal cirri absent vs. present; transverse cirri lacking vs. present; caudal cirri present vs. lacking). A novel family Hemicycliostylidae was proposed, which was supported by both morphological and morphogenetic data as these two genera can be distinguished from other urostylids by the process of replicating multiple left and/or right marginal cirral rows via independent primordia in each row, and by having more than three dorsal kineties (Jung et al, 2012;Li, Lyu, Warren et al 2017;Lu, Gao, Shao, Hu, & Warren, 2014;Paiva et al, 2012). Another characteristic of this group worthy of note is the mode of development of the oral apparatus: the old adoral zone of membranelles is retained in the proter with the exception of the posterior part which is renewed in situ; this is unique within the urostylids.…”

“…The absence of transverse cirri is considered the main diagnostic feature separating Hemicycliostyla from Pseudourostyla (Berger, 2006). Paiva, Borges, Silva-Neto, and Harada (2012) transferred Pseudourostyla franzi to the genus Hemicycliostyla based on the feature that H. franzi derive its marginal rows from individual anlagen within each parental row, which is totally different from the formation pattern in Pseudourostyla (Berger, 2006;Kumar, Kamra, & Sapra, 2010). Hemicycliostyla resembles Pseudourostyla in having a bicorona, a midventral complex likely composed of cirral pairs only, and more than one marginal row on each side, suggesting it should belong to the same family that is Pseudourostylidae (Chen, Hu, Kusuoka, & Li, 2010;Huang et al, 2014;Li, Lyu, Warren et al, 2017;Paiva & Silva-Neto, 2006;Shao, Lv, Jin, & Warren, 2014).…”

An Integrative Investigation of Parabistichella variabilis (Protista, Ciliophora, Hypotrichia) Including Its General Morphology, Ultrastructure, Ontogenesis, and Molecular Phylogeny

“…This group includes numerous taxa with uncertain systematic positions, mainly as a result of insufficient descriptions of their morphology and the lack of ontogenic and molecular data (Berger , , , ; Paiva et al. ; Park et al. ; Schmidt et al.…”