Comments on Mertens et al. (2022): the taxonomic identity of Micracanthodinium setiferum (Lohmann) Deflandre (Dinophyceae incertae sedis) remains elusive, and its epitypification is not achieved

Abstract Micracanthodinium setiferum is a very distinctive but poorly known dinophyte with characteristically delicate, unbranched, filiform and pointed setae. A recent study by Mertens et al. (2022, Palynology 46: 1934908) aims to clarify the taxonomy of the species and to introduce two new formae acknowledging the presence or absence of setae in environmentally collected cells. We assert that the epitype choice of illustrations by these authors is inappropriate, but also not achieved following the rules of the International Code of Nomenclature for algae, fungi, and plants (ICN). Additionally, the two new formae are not described in accordance with the rules of the ICN. A more suitable epitype may therefore be chosen, once corresponding physical material from the type locality off Sicily is at hand. The taxonomic identity of M. setiferum meanwhile remains elusive.