Institute of Ecological Science, South China Normal University, 510631 Guangzhou, China; Institute of Marine and Environmental Sciences, Natural Sciences Research and Educational Center, University of Szczecin, Mickiewicza 16a, PL-70-383 Szczecin, Poland.
UTEX Culture Collection of Algae, Department of Molecular Biosciences, University of Texas at Austin, 205 W. 24th St. MS A6700, Austin, TX 78712, USA.
Mol Phylogenet Evol. 2020 Jul;148:106808. doi: 10.1016/j.ympev.2020.106808. Epub 2020 Mar 31.
Although previous phylogenetic analyses suggested that the araphid diatom family Plagiogrammaceae is monophyletic, there is still not a clear understanding of relationships among the genera, and the taxonomy of several genera--Dimeregramma and Plagiogramma--remains questionable in light of paraphyly for both genera using molecular and morphological data. We have expanded the available DNA for molecular work for dozens of plagiogrammacean clones and analyzed 29 morphological characters from plagiogrammarian taxa and closely related genera, to increase understanding of the evolutionary history and systematics of the family and re-evaluate the current taxonomical classification of plagiogrammacean genera. The addition of more taxa and more data confirm the results from previous molecular phylogenies: most plagiogrammacean genera are monophyletic, except for Dimeregramma and Plagiogramma. Interestingly, the morphological analysis resolves only Talaroneis and Glyphodesmis as monophyletic. Given these results, we feel there is limited support for retaining Dimeregramma and Plagiogramma as distinct genera, and formally propose amending Plagiogramma and transferring six Dimeregramma species. As the Plagiogrammaceae is also one of the first-diverging clades of pennate diatoms, we also used these molecular data to estimate the age of the family, based on multiple calibration points derived from fossil taxa within or close to the Plagiogrammaceae. The results indicated that the Plagiogrammaceae evolved more than 114 million year ago and its diversification appears to correspond to a time of climate cooling. Additionally, we described a new monotypic genus (Coccinelloidea) with one new species C. gracilis, and five new species within established genera, e.g. Plagiogramma marginalis, Plagiogramma harenae, Plagiogramma porcipellis, Neofragilaria montgomeryii and Psammogramma anacarae.
尽管先前的系统发育分析表明无壳缝硅藻科是单系的，但对于该科属间的关系仍然没有清晰的认识，而且根据分子和形态数据，两个属（Dimeregramma 和 Plagiogramma）的并系现象表明它们的分类仍然值得商榷。我们已经扩展了可用于分子工作的数十个 plagiogrammacean 克隆的 DNA，并分析了来自 plagiogrammarian 分类群和密切相关属的 29 个形态特征，以增加对该科进化历史和系统发育的理解，并重新评估 plagiogrammacean 属的当前分类。更多分类群和更多数据的增加证实了先前分子系统发育研究的结果：除了 Dimeregramma 和 Plagiogramma 之外，大多数 plagiogrammacean 属都是单系的。有趣的是，形态分析仅将 Talaroneis 和 Glyphodesmis 解析为单系。鉴于这些结果，我们认为保留 Dimeregramma 和 Plagiogramma 作为不同的属的支持有限，并正式提议修改 Plagiogramma 并转移六个 Dimeregramma 种。由于 Plagiogrammaceae 也是有肋硅藻最早分化的分支之一，我们还使用这些分子数据根据化石分类群在 Plagiogrammaceae 内或附近的多个校准点来估计科的年龄。结果表明，Plagiogrammaceae 进化于 11400 万年前，其多样化似乎与气候变冷的时期相对应。此外，我们描述了一个新的单种属（Coccinelloidea），一个新种 C. gracilis，以及五个新种，包括 Plagiogramma marginalis、Plagiogramma harenae、Plagiogramma porcipellis、Neofragilaria montgomeryii 和 Psammogramma anacarae。
