The genera of Lauraceae in Madagascar with nomenclatural novelties in Cryptocarya Werff, Henk van der Candollea 2017 2017-07-20 72 2 323 328 64222 Thouars Thouars [824,1015,599,623] Magnoliopsida Lauraceae Potameia Plantae Laurales 4 327 Tracheophyta genus    Typus:  Potameia thouarsiiRoem. & Schult.   Diagnostic characters.– The combination of dimerous flowers (flowers with 4 tepals and 6 or fewer stamens) and alternate leaves.   Distribution.– Endemic to Madagascar(but see notes).   Number of species. – Estimated at 25 (all endemic)  Recent literature.– VAN DER WERFF (1991, 1996).   Notes. –  Potameiais closely related to  Beilschmiediaand differs from that genus by its dimerous flowers. Both genera have fruits seated on the pedicel with remnants of the tepals at the base, four in  Potameiaand six in  Beilschmiedia. One species of  Beilschmiedia(  B. pedicellatavan der Werff) may have dimerous flowers, but differs from  Potameiain its opposite leaves (all species of  Potameiahave alternate leaves). Most species of  Potameiahave flowers with six bilocular stamens. In a few species the adjacent locelli become fused so the stamens are unilocular. The number of stamens can also be reduced; the extreme is  P. micranthavan der Werff, a species with flowers with two stamens, each unilocular. Most herbarium specimens of  Potameiahave a light colored, grey bark. While such a bark color may also occur outside  Potameia, its presence strongly suggests  Potameia. Several Asian species, mostly from southern China, have been placed in  Potameiabut are now considered to belong to  SyndiclisHook.f.. The single Indian species placed in  Potameia,  P. tirunelvelica(Manickam, Murugan, Jothi & Sundaresan) M. Gangop., was originally placed in  Beilschmiedia; the description stated that it has opposite leaves and dimerous flowers. Because the combination of opposite leaves and dimerous flowers also occurs in a  Beilschmiediaand not in  Potameia, I consider the Indian species as a  Beilschmiediaand  Potameiaas a genus endemic to Madagascar.  Potameiais in need of taxonomic revision.