Cymbella maggiana Krammer (Figs. 35-43)

References. Krammer, 2002, p. 62, pl. 45, figs. 6-13; Le Cohu and Azémar, 2011, p. 139, figs. 31-39; Bahls, 2016a in Diatoms of North America.

Description. Valves moderately dorsiventral, semi-lanceolate in outline, dorsal margin moderately arched, ventral margin straight or weakly tumid in the central portion. Valves 50-57 μm long, 11-13 μm wide. Raphe slightly lateral, becoming reverse-lateral near the proximal ends. Striae, 7-9 in 10 μm in the middle, areolae on a stria slitlike, 19-21 in 10 μm. Isolated stigmata 2-3 in the middle of the ventral side.

Diagnoses. Cymbella maggiana can be differentiated from C. vulgata Krammer and C. pervarians Krammer within the same group based on its coarse areolae, presence of multiple stigmata in the central area, and bluntly rounded ends of the valve (Krammer, 2002). This species exhibits distinct dissimilarities when compared with C. diversa Krammer, as it does not possess the cymbiform outline.

Occurrence. In South Korea, this species was obtained from the Ian Stream located in Sangju. Morphological characteristics of the specimens collected at the local site closely corresponded with those described by Krammer (2002) and Le Cohu and Azémar (2011). The species occurred frequently in the Ian Stream, Sangju, and in various other sections of the upper stream. However, it was found very rarely in each sample.

Cymbella maggiana was initially documented in the Maggia River, which is situated in a mountainous area of Switzerland (Krammer, 2002). It has also been reported from a lake abundant in organic matter in the Pyrenees region of France (Le Cohu and Azémar, 2011), as well as in a mountainous area of Northwest Montana, USA (Bahls, 2016a).