A new species of the genus Adlafia (Anomoeoneidaceae, Bacillariophyta) from Moscow Region (Russia) and North Macedonia

Adlafia is a relatively small diatom genus in terms of number of species and consisting of small-celled species with delicate morphology that is barely visible under the light microscope. Only a few morphological characteristics recognizable under a light microscope can be used to identify species. This could lead to a broader species concept and misidentifications of species. Recent observations of the diatom flora of Russia and North Macedonia reveal the existence of a new Adlafia species. This study describes it based on light and scanning electron microscopy observations. The new species resembles Adlafia minuscula, but its valves are narrowly lanceolate, more slender and have a smaller width. The species is probably widely distributed in Europe, but was overlooked in earlier studies.