Redescription of Tintinnopsis everta Kofoid and Campbell 1929 (Alveolata, Ciliophora, Tintinnina) Based on Taxonomic and Genetic Analyses—Discovery of a New Complex Ciliary Pattern

Abstract

The about 1,000 species of tintinnid ciliates are identified and classified almost exclusively based on their lorica features, although the shortcomings of this structure are well‐known, e.g. causing uncertain species limitations and nonmonophyletic taxa. Hence, the present redescription of Tintinnopsis everta Kofoid and Campbell, 1929 considers not only the lorica characteristics, but focuses on cell and genetic features. The species is redescribed from the North Atlantic and adjacent sea areas, namely the east coast of the USA, using live observation, protargol‐stained material, scanning electron microscopy, and genetic analyses. The main stages of cell division are described, and the species’ phylogenetic relationships are inferred from morphological data and the small subunit ribosomal RNA gene sequence. The estimates of its biogeographical distribution and autecology are based on a literature survey. The species is characterised by a complex somatic ciliary pattern with a unique position of the posterior kinety and a conspicuously large distance between the somatic ciliary fields and the collar membranelles. The phylogenetic relationships of Tintinnopsis everta vary in the molecular trees depending on the algorithms used and are, therefore, regarded as unresolved. Nevertheless, the new kind of complex somatic ciliary pattern distinctly contributes to a better understanding of the tintinnid biodiversity and evolution and provides features for a future split of the nonmonophyletic genus Tintinnopsis.

Three redescriptions in Tintinnopsis (Protista：Ciliophora: Tintinnina) from coastal waters of China, with cytology and phylogenetic analyses based on ribosomal RNA genes

“…Based on ITS1-5.8S-ITS2, a sequence previously obtained for this species in Qingdao, China (KU715813; [48]) groups with our sequence, and both are 96.2% similar. Tintinnopsis kiaochowensis forms a fully-supported clade with T. everta (MG461220; [33]) based on SSU rDNA, and both sequences are 99.0% similar. The newly sequenced population of T. uruguayensis forms a fully-supported clade with the North-Atlantic population of the same species, based on both SSU rDNA and LSU rDNA (JN831838 and JN831923; [25]); the two populations are 100% identical in both markers.…”

“…Thus, we applied common criteria to verify that eld-isolated specimens were not confounded with other species (e.g. as done by Gruber et al [33]): the three species were distinguished by careful evaluation of their morphological features and lorica size in vivo, and the absence of potentially confounding, cooccurring species was con rmed with further analyses of loricae and protargol-stained cells. For each species, a single specimen was isolated at 400× magni cation, washed ve times with 0.22-μm ltered sample water, and used for DNA extraction with the DNeasy Blood & Tissue kit (Qiagen).…”

“…Thus, the current lorica-based taxonomy does not allow estimating tintinnine diversity accurately, and it does not provide a natural classi cation. Accordingly, several studies have incorporated more informative characters, namely, cytological and/ or molecular data, in tintinnine systematics (e.g., [27] [28] [29] [30] [31] [32] [33][34] [35] [36]). Still, cell characters and DNA sequences are only known for about 3% and 10% of the described tintinnine morphospecies, respectively (e.g., [22] [37]), and considerable efforts are needed to increase the availability of these types of information.…”

Morphological redescriptions and neotypification of two poorly known tintinnine ciliates (Alveolata, Ciliophora, Tintinnina), with a phylogenetic investigation based on SSU rRNA gene sequences

“…Furthermore, recent researches have revealed that a combination of both molecular and classic morphological data is indispensable for studying the diversity, taxonomy, phylogeny and biogeography of tintinnines [21][22][23][24][25][26][27][28]. Unfortunately, SSU rRNA gene sequences and cytological data, including details of the ciliature, are available for only 10 and 5 % of nominal morphospecies, respectively [18,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. Jörgensen, 1924 are characterized by having a broadly obovate bowl with densely agglomerated particles and a cylindrical, hyaline collar that may be either spiraled or annular.…”

Three redescriptions in Tintinnopsis (Protista: Ciliophora: Tintinnina) from coastal waters of China, with cytology and phylogenetic analyses based on ribosomal RNA genes

“…Thus, the current lorica-based taxonomy does not allow estimating tintinnine diversity accurately, and it does not provide a natural classi cation. Accordingly, several studies have incorporated more informative characters, namely, cytological and/ or molecular data, in tintinnine systematics (e.g., [27] [28] [29] [30] [31] [32] [33] [34] [35] [36]). Still, cell characters and DNA sequences are only known for about 3% and 10% of the described tintinnine morphospecies, respectively (e.g., [22] [37]), and considerable efforts are needed to increase the availability of these types of information.…”