A new ecalcarate species of Impatiens (Balsaminaceae) from the lowland wet zone of Sri Lanka

Impatiens yakandawalarum Gopallawa, Hapuarachchi & Jayathissa, sp. nov., a new ecalcarate species from the lowland wet zone of Sri Lanka, is described and illustrated based on morphological evidence. The species was discovered on a wet rocky slope at Manna Kathi Ella, Kitulgala, Kegalle District, and represents the first Sri Lankan Impatiens characterized by a consistently ecalcarate lower sepal across the examined population and material. It is distinguished by a completely ecalcarate navicular lower sepal, a fleshy, globose to subglobose subterranean storage organ, and glabrous leaves. The flowers superficially resemble those of Impatiens thwaitesii Hook.f. ex Grey-Wilson, while the habit shows similarities to Impatiens janthina Thwaites. A description, illustrations, comparisons, and a preliminary conservation assessment are provided.