A new species is described and a new combination is established in genus Argentina Hill (Rosaceae) in New Guinea. Argentina wanimboi Danet, sp. nov. is close to Argentina linilaciniata (P.Royen) Soják but is distinct by having leaves that are conduplicate, stiff and chartaceous, leaflets that are less segmented, and by having pauciflorous inflorescences and bifid epicalyx segments. Synonymy of Potentilla novoguineensis Merr. & L.M.Perry with Argentina parvula (Stapf) Soják is countered. To support the recognition of Argentina novoguineensis (Merr. & L.M.Perry) Danet, comb. nov., some morphological characters are highlighted as the indeterminate growth of floriferous axis, the creeping habit, narrowly obovate shape of the leaves, more serrate leaflets and more stamens.
Rosaceae, New Guinea, Indonesia, Papua, new species, new combination.