The species of the genus Craticula are widely distributed in Europe, mostly occurring in brackish, saline to heavily polluted waters. Some of the species are considered as being most tolerant to pollution. Recently, detailed observations of this genus in Macedonia have been performed. During this study, 15 taxa have been recorded. One of the species (Craticula simplex) was observed with three different morphotypes, which can be distinguished by the valve size and shape. Craticula cuspidata and C. ambigua were the most frequently recorded species in various habitats, while species C. halophila, C. germainii and C. fumantii were observed only on a single locality. The highest diversity of Craticula was observed in temporary ponds on halomorphic soils and mineral springs in Eastern Macedonia.

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Adult caddisflies were collected during 2018 and 2019 from Kožuf and Baba mountains, located in the southern end of the Republic of North Macedonia. A total of 36 species were recorded, of which 22 and 8 were recorded for the first time for Kožuf and Baba mountains, respectively. Limnephilus flavicornis (Fabricius, 1787) is reported for the first time from the country from Kožuf Mountain. In addition, new localities of several rare and endemic caddisfly species were found. The results of this study highlight Kožuf and Baba mountains as refugium for caddisfly species of conservation importance.

Lowland intermittent ponds, although biologically important, are poorly studied water habitats. During the analyses of the material taken from lowland pond in Pelagonia Valley, and Vitachevo, Republic of North Macedonia, the diatom Sellaphora pelagonica sp. nov. was recorded and described based on light and scanning electron microscopy. The species is characterized by a strictly linear valve outline with parallel to slightly concave margins and broadly rounded ends, 15.0–40.0 µm long and 5.0–7.0 µm wide. These features, together with raphe structure and areolar shape are compared with several similar taxa currently ascribed to Sellaphora.

Background and aims – An increased interest in the diatom flora from subaerial habitats in the Republic of North Macedonia has revealed the presence of a large number of interesting and often unknown, species. During a recent biodiversity survey, seven Muelleria species were recorded, several of which could not be identified based on the available literature. Methods – Using both Light Microscopy and Scanning Electron Microscopy techniques, the morphology of several Muelleria species has been analysed. The morphology of all taxa is described, illustrated and compared with other possible similar Muelleria taxa, known worldwide. Key results – Four already documented Muelleria species, M. gibbula, M. islandica, M. terrestris and M. undulata (= Navicula gibbula f. undulata) were identified, while two distinct species are described as new. These new species belong to the M. gibbula complex, and can be differentiated by valve size, stria density, shape of the proximal raphe ends and the shape of external areola foramina. The identity of one taxon remains uncertain due to a low number of observed specimens in the samples. As their ultrastructure is almost entirely unknown, they are briefly discussed. Conclusions – The diversity of Muelleria in Europe and the North Hemisphere is most likely underestimated and some of the previous records of M. gibbula belong to other species. Observations of diatoms from “extreme” habitats such as intermittent ponds, wet mosses and soils can reveal the existence of interesting and new species.