title: Ultrastructural and molecular characterization of diversity among small araphid diatoms all lacking rimoportulae. I. Five new genera, eight new species.
abstract: Pennate diatoms are important contributors to primary production in freshwater and marine habitats. But the extent of their diversity, ecology, and evolution is still largely unknown. This is particularly evident among the clades of pennate diatoms without raphe slits, whose diversity is likely underestimated due to their small size and features that can be difficult to discern under light microscopy. In this study, we described five new araphid genera with eight new species based on morphological observations (light and electron microscopy) and molecular data (nuclear-encoded small subunit ribosomal RNA and chloroplast-encoded rbcL and psbC): Serratifera varisterna, Hendeyella rhombica, H. dimeregrammopsis, H. lineata, Psammotaenia lanceolata, Castoridens striata, C. hyalina, and Cratericulifera shandongensis. We also transferred Dimeregramma dubium to Hendeyella dubia. Phylogenetic analysis of the molecular data revealed that all the newly established taxa fell into a monophyletic group, with Fragilariforma virescens located at the base. The group was composed by two subclades: one comprising Castoridens, Cratericulifera, and Plagiostriata, and the larger including also the rest of the new genera plus some of the smallest known diatoms, such as Nanofrustulum, Opephora, Pseudostaurosira, Staurosirella, and Staurosira with a high level of support. This study enhances the general knowledge on the phylogeny and biodiversity of a group of small araphid diatoms that have been generally poorly described both by electron microscopy and DNA sequence data.
authors.affiliation: Palaeoceanology Unit, Faculty of Geosciences, Natural Sciences Research and Educational Center, University of Szczecin, Mickiewicza 16a, PL-70-383, Szczecin, Poland.
authors.forename: Chun L
authors.initials: CL
authors.lastname: Li
authors.affiliation: Department of Integrative Biology, University of Texas at Austin, 205 W. 24th St. MS C0930, Austin, Texas, 78712, USA.
authors.forename: Matt P
authors.initials: MP
authors.lastname: Ashworth
authors.affiliation: Palaeoceanology Unit, Faculty of Geosciences, Natural Sciences Research and Educational Center, University of Szczecin, Mickiewicza 16a, PL-70-383, Szczecin, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Witkowski
authors.affiliation: Division of Natural Sciences, University of Guam, Mangilao, Guam, 96923, USA.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Lobban
authors.affiliation: Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507, Warsaw, Poland.
authors.forename: Izabela
authors.initials: I
authors.lastname: Zgłobicka
authors.affiliation: Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507, Warsaw, Poland.
authors.forename: Krzysztof J
authors.initials: KJ
authors.lastname: Kurzydłowski
authors.affiliation: Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 17 Chunhui Rd, 264003, Yantai, China.
authors.forename: Song
authors.initials: S
authors.lastname: Qin
mesh_terms: D020418:Algal Proteins / Q000235:genetics; D044822:Biodiversity; D004275:DNA, Ribosomal / Q000235:genetics; D017377:Diatoms / Q000145:classification / Q000166:cytology / Q000235:genetics* / Q000648:ultrastructure*; D008854:Microscopy, Electron; D010802:Phylogeny; D048030:RNA, Algal / Q000235:genetics
chemical_list: D020418:Algal Proteins; D004275:DNA, Ribosomal; D048030:RNA, Algal
keywords: Araphid diatoms; Fragilariaceae; SSU rRNA; biodiversity; phylogeny; psbC; rbcL; small-celled diatoms