Discrepancy between conventional morphological systematics and nuclear phylogeny of tintinnids (Ciliophora: Choreotrichia)

Abstract

Tintinnid ciliates have been traditionally classified according to morphological and morphometric features of the lorica. To examine if the morphological characteristics of loricae reflect the phylogenetic relationships, we collected 23 tintinnid morphospecies (11 genera) and reconstructed phylogenetic trees based on 84 partial sequences of nuclear small subunit rRNA (SSrRNA) gene fragments of 44 morphospecies from a total of eight families (55 sequences from this study, and 29 sequences from the literature). We found that tintinnid ciliates could be classified into six clades consisting of five major clades. While one clade consisted of one family, each of the other five clades consisted of more than two families. Although two families were found only in one clade, the remaining six families were found in more than two clades. In addition, each of six morphospecies was found in more than two major clades, indicating that they are polyphyletic. Principal coordinate analysis showed that morphology of the lorica overlapped substantially between the clades. These results imply that most of the morphological and morphometric traits of marine tintinnid species do not reflect SSrRNA genetic distances even at family levels. It is necessary to identify new characteristics that reflect phylogenetic relationships robustly.

Symbioses of Ciliates (Ciliophora) and Diatoms (Bacillariophyceae): Taxonomy and Host–Symbiont Interactions

“…According to the available molecular data, E. fraknoi and E. lususundae are independent species ( Figure S3 in Supplementary Materials). Both species were described from the Mediterranean Sea, but molecular data of E. lususundae were only available from the Pacific Ocean [8,61,62]. Kazama et al [61] reported DNA sequences of E. lususundae that clustered with two species with agglutinated loricae (Leprotintinnus pellucidus and Tintinnopsis dadayi).…”

“…Both species were described from the Mediterranean Sea, but molecular data of E. lususundae were only available from the Pacific Ocean [8,61,62]. Kazama et al [61] reported DNA sequences of E. lususundae that clustered with two species with agglutinated loricae (Leprotintinnus pellucidus and Tintinnopsis dadayi). Xu et al [62] provided more sequences of E. lususundae from specimens with hyaline or agglutinated loricae.…”

Diversity Patterns of Protists Are Highly Affected by Methods Disentangling Biological Variants: A Case Study in Oligotrich (s.l.) Ciliates

“…Ecological habitat is classified as F = freshwater (≤0.5‰), L = low-brackish (0.5–18‰), H =high-brackish (18–30‰), and M = marine (30–40‰). References [ 66 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 ...…”