Iconographia Diatomologica, Volume 8: Taxonomy: Zur Revision der Gattung Gomphonema: Die Arten um G. affine/insigne, G. angustatum/micropus, G. acuminatum sowie Gomphonemoide Diatomeen aus dem Oberoligozän in Böhmen [A Revision of the Genus Gomphonema: The Species around G. affine / insigne, G. angustatum / micropus, G. acuminatum as well as Gomphonemoid Diatoms from the Upper Oligocene in Bohemia]

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Language: German with English abstract

This book presents a revision of four groups of Gomphonema or gomphonemoid taxa, amongst them many widespread, frequent or important species. An extensive iconography of nearly 1100 figures shows ranges of variation as well as morphological details of the diatoms discussed. Altogether 47 species, 1 subspecies, 3 varieties and 2 “morphotypes“ are treated. 21 species, 1 subspecies and 1 variety are described for the first time and depicted in numerous light microscopic (LM) and electron microscopic (SEM) figures. All the new taxa can be distinguished under a light microscope and with the exception of one fossil diatom they all were found outside the type-locality, too.

In the first section Gomphonema affine Kütz., G. insigne Greg. and similar species are treated. It is shown that G. insigne cannot be combined with G. affine. It is clearly a species of its own with a peculiar structure of the intemal opening of the stigma. G. affine has proved to be a widespread diatom in tropical and subtropical habitats. Reports of findings in other regions in the world should be treated with caution. However, there exist several independent taxa within the clusters of these diatoms which have been confused or unknown up to present. Eight of these are described as new and four similar taxa are discussed in detail.

The second part deals with Gomophonema angustatum (Kütz.) Rabenh. or rather with what has been classified as such. It is shown that the identity of G. angustatum has been completely unknown until recently and that very often G. micropus Kütz. has been classified as G. angustatum. Therefore a thorough revision of the species cluster of G. micropus and related taxa is given considerable space in this section. In all the 23 taxa described or discussed in this chapter are somewhat inhomogeneous. Partly they are very similar or related to each other, partly they differ to a larger extent but have been assigned to or combined with G. angustatum so far.

Gomphonema acuminatum Ehr., referred to in the third section, is commonly known as unmistakable. But even this taxon is shown to be a “catch-all species“ in which G. coronatum Ehr. and G. brebissonii Kütz. are the most striking. In addition three new diatoms are described.

The last chapter deals with the gomphonemoid diatoms in oligocene deposits in northem Bohemia and adjoining regions in Germany. This treatise comes to the conclusion that Gomphonema bohemicum Reichelt & Fricke is an extinct species with one subspecies. Furthermore a detailed description or discussion respectively is presented for other gomphonemoid diatoms in these deposits, including two new species and new combinations.

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