Abstract
Species belonging to the genus Kobayasiella Lange-Bertalot may occur over a narrow range of environmental conditions. The genus may be common in diatom communities of acidic, oligotrophic and dystrophic habitats. In this study observations on valve ultrastructure and descriptions of four Kobayasiella species from pristine and altitudinal environments of Carajas National Forest, Brasil is presented. These taxa include Kobayasiella grandis (Metzeltin & Lange-Bertalot) Lange-Bertalot and three new species—Kobayasiella brasiliana Kociolek & Burliga, sp. nov., Kobayasiella carajasiana Burliga & Kociolek, sp. nov., and Kobayasiella xikriniana, Burliga & Kociolek, sp. nov. The first SEM observations of K. grandis are presented along with LM and SEM observations on the three new species, and compared with previously described taxa. The genus may have more species that are endemic to specific regions than cosmopolitan species.