In the summer of 2022, the diatom and macroinvertebrate communities in a small river system near the town of Morogoro (Tanzania) have been sampled and analysed. On 10 localities, diatom samples were collected from submerged stones, sediments and, when present, aquatic plants. On each locality the macroinvertebrate population was samples using a hand net.
The results of the diatom analysis showed that a rather diverse diatom flora was encountered in the different samples. Based on the ecological preferences of the composing flora, the river can be characterized as a rather polluted river, as shown by the large number of Nitzschia, Tryblionella and Navicula taxa, all typical for higher electrolyte contents and eutrophic conditions. The analysis of the macroinvertebrates and the resulting water quality calculation indicates a similar trend, although not every locality seemed equally affected.
During the analysis, an unknown Planothidium taxon has been observed that could not be identified using the currently available literature. Based on detailed light and scanning electron microscopy observations and a comparison with other Planothidium taxa worldwide, resulted in the description of the taxon as a new species: P. africanum Van de Vijver et al. The new species shows some resemblance to P. incuratum, P. rostratum and P. biporomum, and was found in some alkaline streams with a higher electrolyte content and β- to α-mesosaprobic conditions, pointing
to a high degree of pollution (Van de Vijver et al. 2023).

References
Van de Vijver B., Gogne B., Hoogsteyns G., Van de Velde L., Vlaminck L., Kabota S.A., Teunen L. & Wetzel C.E. (2023). Planothidium africanum sp. nov., a new freshwater diatom (Bacillariophyta) species from Tanzania. Phytotaxa 585 (4): 281–286.