Neidiopsis baicalensis sp. nov. (Bacillariophyta) - the first recorded occurrence of the genus in Lake Baikal

A diatom from Lake Baikal examined using light and scanning electron microscopy, exhibits the internal valve morphology characteristic of the genus Neidiopsis. This includes two offset rows of transverse alveoli with a porous hymen and with paired linear foramina along alveolus margins arranged in two apical rows. Additional features consistent with the diagnosis include external longitudinal canals along the valve margins, striae composed of open uni- and biseriate areolae.

However, the broad lanceolate or elliptic-lanceolate valve shape, biseriate areolae on the surface of the longitudinal canals, a row of enlarged round areolae adjacent to and encircling the sternum, and straight raphe endings terminating in drop-shaped depressions are unique features of the species that make it distinctive from all currently known Neidiopsis species. We describe a new species, Neidiopsis baicalensis, the first representative of the genus observed in Lake Baikal.