DOI: 10.5091/plecevo.119907

Authors: Bart Van de Vijver, Wolf-Henning Kusber, Ingrid Jüttner, Tanja M. Schuster, David M. Williams

Abstract: Background and aims – Small-celled araphid diatoms form an important part of the diatom flora in our rivers and lakes. Although several of these species are frequently reported, their correct taxonomic identity is often obscured due to a lack of good knowledge of the original (type) material. Material and methods – Several historical (nineteenth century) original samples were retrieved from different European and North American diatom collections. The samples have been analysed using light (LM) and scanning electron microscopy (SEM). Key results – Staurosirella crux comb. nov., based on Ehrenberg’s Navicula crux, proved to be the oldest valid name for Staurosirella harrisonii, the latter now being considered a younger synonym. A new European species, S. neorhomboides sp. nov., is described to replace the name S. rhomboides, now considered a younger synonym of S. leptostauron. The North American populations of S. rhomboides and S. martyi differ sufficiently from the type populations and are described as new species: S. moralesii sp. nov. and S. manoyloviana sp. nov. The new combination Staurosirella informis comb. nov. is proposed for a taxon described in 1856 from the French Pyrenees as Odontidium informe. Staurosirella leptostauron turns out to be insufficiently described and is now documented for further use. Conclusion – The analysis of the original (type) material corrected several taxonomic errors and better characterised the morphology of several commonly observed Staurosirella species.

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DOI: 10.5091/plecevo.84534

Authors: Ralitsa Zidarova, Plamen Ivanov, Elitsa Hineva, Nina Dzhembekova

Abstract: Background and aims – Despite a long research history, knowledge of Antarctic marine benthic diatoms is fragmentary. This study reports on marine benthic diatoms from South Bay, Livingston Island, focusing on diatoms living on hard substrata, and species distribution across different coastal habitats.Material and methods – Samples were collected from tidal pools (19), intertidal cobbles (9), artificial substrata installed at various depths (10), coastal rocks (2), and bottom sediments at depths > 20 m (2). Species identifications and community analyses were done using LM with additional information obtained using SEM. nMDS based on diatom abundance data was applied to display differences between the samples by habitat/substratum type and sampling month. The significance of the habitat/substratum type and sampling month on diatom communities was checked with PERMANOVA. Similarity/dissimilarity within and between sample groups and their contributing species were explored with SIMPER.Key results – In total, 133 diatom taxa were recorded, of which 110 are benthic. A large number of taxa could not be certainly identified. Taxonomic remarks and ecology and distribution data for some rarely reported species with convoluted taxonomic and nomenclatural histories are given. One new combination is proposed. Diatom communities were influenced by the habitat/substratum type, but not by seasonality. Significant differences existed between communities in tidal pools and those on cobbles, artificial substrata, and sediments, and between those on sediments and artificial substrata. Navicula aff. perminuta dominated on cobbles and often on artificial substrata. Species forming mucilage tubes, tree-like colonies, and chains of cells embedded in mucilage were restricted to tidal pools.Conclusion – Benthic diatom communities from South Bay are highly diverse and species show distinct distributions in the coastal habitats, but the scarce studies and often confusing nomenclature history of the taxa make their identification challenging, and potentially common species for the region remain unknown.

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