1.1. Pontederia meyeri (A.G.Schulz) M.Pell. & C.N.Horn comb. nov.

Eichhornia meyeri A.G.Schulz, Darwiniana 6: 56. 1942. Lectotype (designated here). ARGENTINA. Chaco, Cote Lai, 25 June 1939, fl., fr., T. Meyer 2640 (SI barcode SI000621!; isolectotypes: GH barcode GH00057534!, LIL barcode LIL000196!).

Distribution.

Restricted to Argentina, Paraguay and Brazil (states of Ceará, Mato Grosso and Mato Grosso do Sul).

Nomenclatural notes.

Schulz (1942), when describing his new E. meyeri, cites two specimens from the same collection, one housed at SI and another at GH. Furthermore, a third specimen, housed at LIL was found by us. After carefully analysing the syntypes, we noticed that the specimen at SI perfectly matches the original illustration. Furthermore, it is widely known that Schulz worked at the Instituto de Botánica Darwinion, thus, making the specimen at SI the obvious choice of a lectotype.

Taxonomical notes.

Current databases (eMonocot 2010; The Plant List 2013; Govaerts 2018; Tropicos.org 2018) have treated E. meyeri (≡ P. meyeri) as a synonym of E. paniculata (≡ P. paniculata). Nonetheless, as indicated in our identification key and by Horn (1998), both species are distinct, being easily differentiated in the field and herbaria. Thus, E. meyeri is here re-established and transferred to Pontederia s.l.