During the investigations of the diatom flora of Lake Qinghai, China (see Liu et al. 2020 for details), specimens of an undescribed species of Pinnularia Ehrenberg (1843: 45) were encountered, which are hereby illustrated and described.

Three sympatric Entomoneis species, found at the same specific locality in Lake Qinghai, China, are studied by using light and scanning electron microscope. Two species are proposed as new to science and named as E. sinensis sp. nov. and E. qinghainensis sp. nov. The third species is identified as E. paludosa (W. Smith) Reimer. Entomoneis sinensis has a linear-lanceolate valve outline and Ƨ-shaped keel, bears two distinct 8-shaped loops formed by the valvocopula pars media in each cell and each of its stria is composed of either a long hymen strip or a long hymen strip plus one separated areola close to the raphe. Its hymen strip belongs to Type Two, which is a siliceous membrane strip perforated by two rows of linear pores next to transapical costae and two rows of rounded pores between these two rows of linear pores. Entomoneis qinghainensis has large cells, very high keel and evident hymen strip regions like a U-shaped neck pillow at the middle of valve face. Its hymen strip belongs to Type One, which is a siliceous membrane strip perforated by irregularly distributed round pores. Entomoneis paludosa also has the hymen strip regions that are worm-like and close to the raphe canal. Its hymen strip is same as that of E. qinghainensis. The two kinds of the outside areola occlusions in Entomoneis are compared, summarised and discussed.

N/A

During our investigations on the freshwater diatoms from Qinghai Province, China, four sympatric Surirella taxa belonging to the group Pinnatae were analysed. Based on morphological observations derived from light and scanning electron microscopy, three of these four taxa were identified as: S. minuta, S. lacrimula, and S. brebissonii var. kuetzingii. The fourth taxon is described as Surirella liubingii sp. nov., a new species with a unique combination of characteristics. These include the distribution pattern of its costa-stria bundles (CSBs) alternating with its over-fibula costae (OFCs), which is formed by the distinctly elevated CSBs on the valve face, mostly composed of three costae, and OFCs with a remarkedly lower position. Other characteristics include the presence of robust fibulae extending to the valve midline, the presence of only one portula between two adjacent fibulae, and a “pseudoseptum” extending internally from the valve margin. From the observations on these four Surirella taxa, we described and discussed two types of fibula (one in which the fibula nearly reaches the valve midline and one with short fibula) and two types of portula morphology (one with only one portula between two adjacent fibulae and the other with 2–4 portulae between two adjacent fibulae).

Lake Qinghai is an ancient brackish water lake in which several endemic diatom species have been discovered. In this study, a species of Diatoma is observed under light and scanning electron microscopy and described as new, Diatoma sinensissp. nov. The living cells of D. sinensis always lie in girdle view due to the cell depth being much larger than valve width (3.3–8.8 vs. 2.0–3.0 μm). The valves of D. sinensis are characterized by their narrow, linear-lanceolate outline, with capitate to subcapitate apices, the presence of two rimoportulae, one at each apex, embedded in the last rib or located among striae and a 4:2 configuration of girdle bands in normal vegetative cells, with four bands assigned to the epivalve and two to the hypovalve. The new taxon is compared with similar species from the genera Diatoma and Distrionella.