Variability of the pennatae diatom Gomphonema ventricosum Gregory from far eastern lakes

Abstract

The present study examined by light microscope the morphological variations of 625 specimens of Gomphonema ventricosum Gregory collected from Lake Hövsgöl (Mongolia), Lake Baikal (Russia) and Lake Kurilskoye (Kamchatka, Russia). We classified the specimens into five types with respect to valve outline; (1) type A (type form of Gomphonema ventricosum), (2) type B (Lake Baikal type), (3) type C (Lake Karluk type), (4) type D (Gomphoneis septa type) and (5) type E (G. ventricosum f. curta type). Based on the relative frequencies of these five types, specimens from Lake Baikal were shown to be different from those of the other two lakes. Specimens from Lake Baikal are remarkably smaller both in length and breadth; specimens from the other two lakes are longer than those from Lake Baikal, though specimens from Lake Kurilskoye are wider than those from Lake Hövsgöl. Thus, clear differences in morphological features are recognized between the specimens from these three lakes.