What is in a name? Diatom classification should reflect systematic relationships.

Abstract

Large numbers of diatom taxa are currently being described each year and molecular data sets are providing phylogenetic evidence that challenges the traditional systematic arrangement of diatoms, but is such information being integrated into the classification? The traditional diatom classification originated as an aid to identification rather than as an arrangement expressing perceived relationships, and characters for identification continue to bias taxonomic descriptions. Reference to types for nomenclatural purposes has resulted in overly narrow taxon descriptions; i.e. types have been considered representative specimens (typical) of taxa, whereas they may not lie at the centre of the range of variation of a taxon. This paper discusses how taxonomic concepts are subject to change in the light of new data and that such changes should be reflected in the systematic arrangement. It presents some thoughts on character choice and the need to make appropriate comparisons before new taxa are erected. The importance of the suprageneric classification is also discussed.