ROMANOV, Roman E., Vyacheslav Yu. NIKULIN, Regina S.W. YEO, Boon-Chuan HO, & Andrey A. GONTCHAROV 2020 (Apr. 6) Nitella singaporensis (Charophyceae, Charales): new species and implications for the taxonomy of the genus Nitella Phytotaxa 438(2): 80-94, 38 figs., 1 table