Morphology and Molecular Phylogeny of Two New Ciliates, Holostichides heterotypicus n. sp. and Holosticha muuiensis n. sp. (Ciliophora: Urostylida)

Abstract

Two new urostylid species, Holostichides heterotypicus n. sp. and Holosticha muuiensis n. sp., were discovered in South Korea. Morphological and phylogenetic analyses were carried out to confirm that these species are new to science. Holostichides heterotypicus is mainly characterized by the following combination of features: 110-205 μm long in vivo; 5-10 frontoterminal cirri; 6-8 midventral pairs with 2-3 midventral cirral rows; cortical granules present; four bipolar dorsal kineties; and 6-9 caudal cirri. Ontogenetic features of H. heterotypicus are similar to those of H. typicus. Phylogenetic analyses revealed that H. heterotypicus was distantly separated from bakuellid genera Apobakuella, Bakuella, Metaurostylopsis, and Neobakuella. This result is supported by the following features: transverse cirri (present in the other four bakuellids vs. absent in Holostichides) and caudal cirri (absent in the other four bakuellids vs. present in Holostichides). Holosticha muuiensis n. sp. is mainly distinguished from its congeners by the following combination of features: 100-185 long in vivo; shortened undulating membrane; cortical granules lacking; contractile vacuole absent; 51-66 adoral zone of membranelles; 42-60 macronuclear nodules; and five bipolar dorsal kineties. In the phylogenetic tree, Holosticha muuiensis n. sp. clustered with a Holosticha group (containing Holosticha diademata, Holosticha foissneri, and Holosticha heterofoissneri).

Morphogenesis and Molecular Phylogeny of the Soil Ciliate Holostichides chardezi (Ciliophora, Hypotrichia, Bakuellidae), with Redefinition of Holostichides Foissner, 1987 and Establishment of a New Genus Anteholostichides

“…The following morphogenetic features of the present population are similar to that of H. heterotypicus and H. typicus : (1) a frontoterminal row and midventral row(s) are formed; (2) both marginal rows and dorsal kineties anlagen develop within the parental rows; (3) macronuclear nodules fuse to a single mass; (4) caudal cirri are formed at the ends of dorsal kineties 1–4 (Kim et al. ; Song and Wilbert ). Some minor differences also exist between them, and are as follows: (1) only one midventral row is generated in H. chardezi while more than one midventral row is generated in H. typicus and H. heterotypicus ; (2) only one caudal cirrus is generated at the end of each dorsal kinety while more than one caudal cirri are formed in H. heterotypicus and H. typicus .…”

“…To date, ontogenetic data of Holostichides are reported for three species: H. typicus , H. heterotypicus and H. chardezi (Kim et al. ; Kumar et al. ; Song and Wilbert ).…”

“…Holostichides chardezi Foissner, (type species); H. dumonti Foissner, ; H. heterotypicus Kim et al., ; and H. typicus (Song and Wilbert, ) Eigner, 1994…”

“…Established by Foissner () and assigned to the family Bakuellidae, Holostichides can be separated from other urostyloids by having the following features: three distinct frontal cirri, midventral rows present, transverse and pretransverse cirri lacking, one left and one right marginal row, caudal cirri present and four to six dorsal kineties. To date, five species have been reported: H. chardezi Foissner, (type species); H. dumonti Foissner, ; H. heterotypicus Kim et al., ; H. terrae Jung et al., ; and H. typicus (Song and Wilbert, ) Eigner, 1994. However, morphogenetic data is available for H. chardezi (partly known), H. heterotypicus and H. typicus, and gene sequences of small subunit rDNA (SSU rDNA) are available for only H. heterotypicus and H. terrae (Jung et al.…”

“…Established by Foissner (1987) and assigned to the family Bakuellidae, Holostichides can be separated from other urostyloids by having the following features: three distinct frontal cirri, midventral rows present, transverse and pretransverse cirri lacking, one left and one right marginal row, caudal cirri present and four to six dorsal kineties. To date, five species have been reported: H. chardezi Foissner, 1987 (type species); H. dumonti Foissner, 2000; H. heterotypicus Kim et al, 2017;H. terrae Jung et al, 2018;andH.…”