Taxonomy of epilithic diatoms and teratological forms under the presence of metals in surface sediment

Abstract

Epilithic diatom species in eight sampling sites of the Cascavel River, Southern Brazil, were taxonomically analyzed. The studied streams are located in a predominantly urban micro-watershed, with distroferric red latosol (rich in Fe and Al), being characterized by distinct metals, predominantly acidic pH, and high conductivity. Overall, 221 diatom species were identified at infrageneric level. Pinnularia was the most representative genus in number of species (28 spp.), followed by Eunotia (25 spp.), Gomphonema (17 spp.), Nitzschia (14 spp.), and Navicula (11 spp.). This is the first record of Fragilaria spectra, Fragilaria tenera var. nanana and Humidophila arcuatoides for the state of Paraná, and the first record of Pinnularia laucensis in Brazil. We found teratological valves in 34 taxa, containing modified outline, changes in the striae pattern, and doubled central area. The genus Eunotia showed the highest number of altered taxa (8 spp.). Mixed teratologies (deformed valve outline + unusual striae pattern) were found only in Ulnaria ulna, Encyonema neomesianum, and Gomphonema graciledictum. The metals and environmental variables in the Cascavel River micro-watershed likely contributed to the diatom teratologies. Our work contributes to the taxonomic knowledge of epilithic diatoms in the region, as well as extending the record of teratological taxa in the literature.