Surirella nyassae O. Muller, S-malombae O. Muller and S-chepurnovii Cocquyt & R. Jahn sp nov (Bacillariophyta) typification and variability of three closely related East African diatoms

摘要

Three Surirella taxa described by O.Muller from material collected at the beginning of the 20(th) century in Lakes Malawi and Malombe were re-evaluated, and lectotypes are assigned from the original material. One infraspecific taxon, S. nyassae var. sagitta, was synonymized with the nominate variety of S. nyassae and one forma, S. malombae f. acuta, was synonymized with S. malombae. As S. malombae is very rare in the original material from Lake Malombe, an epitype was also assigned from material collected at the end of the 19(th) century in Lake Victoria. Light and scanning electron microscopic information is given for these two taxa; their distribution in Africa and their habitat preference is summarized from the literature. A third, closely related taxon which was regularly observed in Lake Tanganyika is here described as Surirella chepurnovii sp. nov.