Sawia R.E.Romanov, 2025

Sawia R.E.Romanov View in CoL , gen. nov.

Type: Sawia boldii (Sawa) R.E.Romanov , comb. nov., infra

Registration (of name): http://phycobank.org/105334

Registration (of type): http://phycobank.org/105333

Diagnosis: Sawia has acute end-cells of branchlets, terminal antheridia situated at tops of rays of furcate, i.e. non-monopodial, branchlets, although antheridia are formed mostly at bases of branchlet whorls. In contrast, Sphaerochara has no terminal antheridia; they are situated at nodes of monopodial branchlets and at bases of branchlet whorls. In comparison, Tolypella has blunt, rounded end-cells of branchlets and bipartite basal plates of oospores. Terminal placement of antheridia, the presence of non-monopodial branchlets, phylogenetic affinity, and, probably, the absence of gyrogonites allow delineation of Sawia and Sphaerochara . Acute end-cells, undivided basal plates of oospores, and phylogenetic affinity allow delineation of Sawia and Tolypella .

Etymology: The feminine genus noun honours Takashi Sawa (1929–2013), a Japanese charophytologist who described two species of this genus, critically describing and illustrating a key genus trait, terminal antheridia ( Sawa, 1973).