Two new diatoms of the genus Gomphosinica from Chumba Yumco, Xizang, China

This paper describes two new species of the genus Gomphosinica from Chumba Yumco, in the south of Kangma County, Xizang. The detailed morphological descriptions of the two new species, named Gomphosinica kangmaensis sp. nov. and G. chongbayongcuoensis sp. nov., are presented; the descriptions are based on light and scanning electron microscopy. The two species have the morphological characteristics that are typical for the genus Gomphosinica, including the striae composed of 2–3 rows of areolae, a prominent stigma with a round external opening and internal opening with a siliceous hooded structure comprised of many small, round openings, as well as the presence of septa and pseudosepta at the apices. G. kangmaensis sp. nov. and G. chongbayongcuoensis sp. nov. have morphological characteristics that mostly resemble those of G. selincuoensis W. Zhang, Q.M. You & Kociolek and G. lacustris Kociolek, You & Wang, respectively, but they differ from these species in details of the size, shape of valve and central area, the density of striae, the pattern of areolae, the position of apical pore-fields, and the deflection of raphe ends.