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A new species Pinnularia lacustrigibba sp. nov. within the Pinnularia subgibba group (Bacillariophyceae) Aloisie Poulíčková, Jan Kollár , Petr Hašler, Petr Dvořák & David G. Mann Some traditional diatom species have long been considered ‘cosmopolitan’, i.e., they are ubiquitous in suitable habitats. However molecular methods have revealed that some of these diatoms are complexes consisting of a few or many species, whose identification by eye with LM is difficult or impossible. This is true of several groups within Pinnularia , including the P. subgibba group, in which molecular species delimitation based on cox1-5P and D1–D3 LSU rDNA markers revealed 15 species within a dataset of 58 unique genotypes, representing 105 strains of the group. One clade comprises reproductively compatible clones from Scottish lakes and its morphology does not correspond exactly to any of the known Pinnularia species; thus the description of a new species ‘ P. lacustrigi...

A polyphasic approach to the delimitation of diatom species: a case study for the genus Pinnularia (Bacillariophyta) 2019 Jan Kollár , Eveline Pinseel , Pieter Vanormelingen, Aloisie Poulíčková, Caroline Souffreau, Petr Dvořák & Wim Vyverman Diatoms are one of the most abundant and arguably the most species‐rich group of protists. Diatom species delimitation has often been based exclusively on the recognition of morphological discontinuities without investigation of other lines of evidence. Even though DNA sequences and reproductive experiments have revealed several examples of (pseudo)cryptic diversity, our understanding of diatom species boundaries and diversity remains limited. The cosmopolitan pennate raphid diatom genus Pinnularia represents one of the most taxon‐rich diatom genera. In this study, we focused on the delimitation of species in one of the major clades of the genus, the Pinnularia subgibba group, based on 105 strains from a worldwide orig...

PINSEEL, E. , VANORMELINGEN, P., HAMILTON, P.B., VYVERMAN, W., VAN DE VIJVER, B. & KOPALOVÁ K. 2017.  Molecular and morphological characterization of the Achnanthidium minutissimum complex (Bacillariophyta) in Petuniabukta (Spitsbergen, High Arctic) including the description of A. digitatum sp. nov.   European Journal of Phycology   Recent morphology-based investigations of freshwater Arctic diatoms suggest that many species remain to be discovered, reflecting a unique polar flora. During a survey of the freshwater diatom flora of northern Billefjorden, including the Petuniabukta fjord region (Spitsbergen), several morphodemes belonging to the Achnanthidium minutissimum species complex were recorded. Molecular phylogenies based on rbc L, 28S and 18S sequences, including single cells from Canada and strains from Marion Island (sub-Antarctica) and GenBank revealed the presence of 12 distinct A. minutissimum complex lineages, of which t...

  CARBALLEIRA, R., TROBAJO, R., LEIRA, M.,  BENITO, X ., SATO, S. & MANN D.G. 2017.   A combined morphological and molecular approach to Nitzschia varelae sp. nov., with discussion of symmetry in Bacillariaceae.   European Journal of Phycology .  A previously unknown member of the Bacillariaceae was discovered almost simultaneously in four different brackish coastal wetlands on the Atlantic and Mediterranean coasts of the Iberian Peninsula. It appears to tolerate a wide range of salinities but was never common in samples where it occurred. The frustules were consistently hantzschioid (i.e. with the raphe systems always on the same side of the frustule) and the valve outline was asymmetrical about the apical plane, two features that have until recently been considered characteristic of Hantzschia . Molecular phylogenies based on rbc L and LSU rDNA indicated, however, that the new species does not belong in Hantz...