A natural hybrid of Sindora (Fabaceae, Detarioideae) from Singapore

Abstract

Sindora × changiensis L.M.Choo, Loo, W.F.Ang & K.Er is a new hybrid from the subfamily Detarioideae in Fabaceae. This is the first reported instance of natural hybridisation in Sindora. Based on population genetics analyses using ddRAD and morphological observations, this taxon represents a fertile hybrid between Sindora coriacea and Sindora echinocalyx. This new hybrid is so far only known to occur naturally from Changi at the north-eastern coast of Singapore. It has pods that are sparsely spiny. This is intermediate between the smooth, non-spiny pods of S. coriacea, and the densely spiny pods of S. echinocalyx. The calyx is smooth and unarmed, resembling S. coriacea. Last but not least, the ovary is entirely pubescent, different from S. coriacea and S. echinocalyx. The ovary of S. coriacea has a glabrous patch in the middle, while that of S. echinocalyx has minute spines protruding from the dense pubescence. A taxonomic description and an updated key to the Sindora of Singapore and Peninsular Malaysia are also provided.