Light and scanning electron microscopical observations are made on two non-raphid pennate species from Lake Baikal, Russia. Based on their morphologies, they are assigned to the genus Ulnaria. Molecular data from rbcL sequences were also gener...

Two new Geissleria species from Siberian mountain lakes Baikal and Frolikha are described based on molecular and morphological data. The two new species are Geissleria baicalosimilis Kulikovskiy, Gusev, Andreeva & Annenkova sp. nov. and G. frolikhiensis Kulikovskiy, Gusev, Andreeva & Annenkova sp. nov. According to partial 18S rDNA and rbcL gene fragment analyses, Geissleria does not belong to the large catch-all genus Navicula as it was previously thought. Morphological features such as slit like areolae without hymenes, presence of one isolated pore near the central nodule and presence of props in areolae and an annulus structure support this conclusion. Plastid morphology of Geissleria species is typical for the Cymbellales, with one large chloroplast divided into two plates lying one against each valve, connected by a broad column. All of our data show that Geissleria is most closely to the genus Placoneis, with which they share naviculoid symmetry. Given these results, Geissleria should be included in the order Cymbellales.

This paper focuses on the flora of scale-bearing chrysophytes from eight provinces located in the central part of Vietnam. Khanh Hoa, Phu Yen, Binh Dinh, Thua Thien Hue, Quang Tri, and Quang Binh provinces are located in the coastal area of Vietnam. Lam Dong and Dak Lak provinces represent mountain territories with an elevation of 500–2000 metres above sea level. In total, 212 water bodies of different origins were studied. Samples were obtained from swamp areas, lakes, rivers, reservoirs, ponds, and small temporary water bodies. In total, 76 taxa were identified by electron microscopic observations of samples. A total of 54 taxa were found in the mountainous provinces, while 73 were found in the coastal provinces. Of these, 51 species are common for both areas. The most diverse was the genus Mallomonas with 66 species, varieties, and forms; followed by Synura with 7 taxa; Chrysosphaerella with 2; and Spiniferomonas with 1. Seven taxa of the genus Mallomonas were not identified to the lower rank. All these unidentified specimens may potentially represent new species for science. Ten taxa are reported for the first time in Vietnam.