A new Nitzschia Hassall species (Bacillariaceae, Bacillariophyta) from saline ponds in Serbia

In the present study, a new species, Nitzschia haloserbica Vidaković, Ector, C.E.Wetzel & Krizmanić, sp. nov., is described from alkaline saline ponds and channels from Vojvodina Province (Serbia). In 2019 the new species was found in four saline ponds: Bela Bara, Čoka Kopovo, Velika Rusanda and Slatina. The same species was recorded four years ago in saline lakes in Hungary, but the authors listed it as Nitzschia sp. 2. The sigmoid valve outline of the new Nitzschia Hassall species is similar to N. austriaca Hust. but differs in striae density and fibulae distribution. In N. haloserbica sp. nov. the transapical striae are so dense that they are not visible in light microscopy. Both species have fibulae that are quite regularly distributed along the raphe canal, but in N. austriaca the central two fibulae are more widely spaced, reflecting the presence of central raphe endings, which are absent in N. haloserbica sp. nov. At the type locality (Bela Bara) both species were found with relative abundances of 94.93 % for N. haloserbica sp. nov. and 1.21 % for N. austriaca (of the 400 valves counting per slide). The valve morphology, ultrastructure and autecology of the new species are discussed and compared with morphologically similar taxa.