Freshwater Mastogloia (Bacillariophyceae) taxa from Macedonia, with a description of the epizoic M. sterijovskii sp. nov.

Abstract

Mastogloia is one of the few species-rich diatom genera the majority of whose taxa inhabit the marine environment with only a small number of taxa in freshwater habitats. An ongoing revision of the Macedonian diatom flora, mainly over the last decade, has revealed many previously misidentified taxa. Currently, seven freshwater Mastogloia taxa have been recorded from Macedonia: M. elliptica (C. Agardh) Cleve, M. dansei (Thwaites) W. Smith, M. grevillei W. Smith, M. lacustris (Grunow) Grunow, M. ohridana Cvetkoska & Levkov, M. albertii nom. nov. and M. sterijovskii sp. nov. The main morphological features have been analysed with light and scanning electron microscopy. These taxa inhabit a variety of freshwater habitats, including oligotrophic rivers, eutrophic ponds, mine lakes, thermo-mineral springs, with one species from fossil sediments of ancient Lake Ohrid. Mastogloia albertii nom. nov., which we also lectotypify, is a new name for M. smithii var. amphicephala Grunow, since the latter is clearly distinct from the lectotype of M. smithii Thwaites. In addition, one of the observed taxa does not fit within any previously described Mastogloia taxa and is hereby described as a new species, M. sterijovskii. Mastogloia sterijovskii was found as epizoic on the dorsal carapace of the European pond turtle, Emys orbicularis Linnaeus, from the Mladost reservoir near Veles, central Macedonia. This species resembles M. albertii in valve outline, but can be distinguished by the shape of the valve apices and its size.