Expanding the cacao group: three new species of Theobroma sect. Herrania (Malvaceae: Byttnerioideae) from the Western Amazon Basin

Abstract

During the preparation of a taxonomic revision of Theobroma sensu lato (Malvaceae, Byttnerioideae), three new species of T. sect. Herrania were found: Theobroma globosum, T. nervosum and T. schultesii, which are described herein. Theobroma globosum and T. nervosum belong to T. sect. Herrania subsect. Subcymbicalyx, with species mostly found in the Amazon Basin, characterised, among other features, by petal ligules at least ten times longer than the petal claws. Theobroma schultesii is from T. sect. Herrania subsect. Herrania, with species with petal ligules less than ten times longer than the claw and is mainly found in the southern parts of the Caribbean Sea, the Pacific Ocean, western Colombia, and northern Ecuador. Theobroma globosum is diagnosed by the combination of spherical fruits with smaller leaflets and midrib proportions when compared to other species from the same region. Theobroma nervosum is identified by its toothed, obovate leaflets with secondary veins protruding beyond the leaflet margins, forming elongated projections across the entire leaflet. Theobroma schultesii exhibits a unique set of features in T. sect. Herrania subsect. Herrania, having both petiolulate leaflets and a cupuliform calyx.