Spathelia L. as currently circumscribed is endemic to the western portion of the West Indies, and contains nine species, one endemic to the Bahamas, three endemic to Jamaica and five endemic to Cuba. The discovery of a new species in Belize brings the total number of species in Spathelia to ten and expands its known distribution beyond the West Indies. Spathelia belizensis sp. nov. is herein described, illustrated and contrasted to its most morphologically similar congener. A key to the species of Spathelia is provided.

El género Spathelia es en la actualidad circunscrito como endémico de la porción occidental de las Antillas con un total de nueve especies, una endémica de las Bahamas, tres endémicas de Jamaica y cinco endémicas de Cuba. El descubrimiento de una nueva especie en Belice amplía el número total de especies a diez y expande la distribución del género más allá de las Antillas. En este artículo Spathelia belizensis es descrita e ilustrada y se compara con el congénere morfológicamente más similar. También, se proporciona una clave para las especies de Spathelia.

Belize, Golden Stream Corridor Preserve, identification key, Spathelieae

The genus Spathelia L. (tribe Spathelieae, Rutaceae) is characterized by palm-like trees with unbranched, slender trunks, and a distal crown of spirally arranged, compound leaves. The trees are reported as monocarpic, i.e., producing a distal massive inflorescence after six to eight years and dying right after fruiting. As currently circumscribed, Spathelia is considered endemic to the western portion of the West Indies and closely related to Dictyoloma and Sohnreyia, two monospecific South American genera (Appelhans et al. 2011, Pirani and Groppo 2015).

While carrying out ecological surveys in the Golden Stream Corridor Preserve in Belize, the junior author discovered a population of trees that refers to an undescribed species of Spathelia. This discovery documents for the first time the occurrence of Spathelia s.s. outside the West Indies, i.e., the northern, eastern tip of Central America. Previous reports of Spathelia (i.e., S. rhoifolia DC.) from Mexico are referred to the anacardiaceous genus Pseudosmodingium.

The study of this novel collection from Belize reveals a new species which seems to be closely related to S. brittonii P. Wilson due to morphological similarities. The new species, Spathelia belizensis is herein described, illustrated and contrasted to S. brittonii its putative closely related species. A key to the species of Spathelia is presented to facilitate the identification of the species.

The description of the new species is based on a single collection, field notes and photographs obtained by the junior author. The study is based on a morphological comparative study of the species of Spathelia as recognized by Beurton (2008) and indicates that the Belizean collection is an undescribed species in the genus. A key to the species is based on various floristic treatments of the Antilles (Marie-Victorin 1948, Adams 1972, Correll and Correll 1982, Beurton 2008) and the examination of specimens when necessary. The type specimens are composed of two sheets, one bearing leaf material and the other bearing portions of the fruiting inflorescence. The holotype is deposited in US herbarium, and the isotypes were distributed to K and NY herbaria (acronyms follow Index Herbariorum; http://sweetgum.nybg.org/science/ih/).

Spathelia belizensis and S. brittonii seem closely related as they share similar heights, large leaves, and indument of stellate and simple hairs. Nevertheless, Spathelia belizensis differs from the latter by having leaves with 75–91 leaflets (vs. 42–65), crenate leaflets (vs. crenate-dentate), unequal sepals (vs. equal), petals 6 and white (vs. 5 and bright red to pink), and fruits with ovate outline and obtuse apex (vs. obovate and marginate at apex).

The type specimens of Spathelia belizensis contained only 6-merous flowers, a feature that departs from other species of Spathelia as they are known to have only 5-merous flowers. Because this collection only had few flowers, it is premature to regard the presence of 6-merous flowers as a distinctive character of the new species. Future collections may show it also to have 5-merous flowers.

We thank Judith Knight and Mark T. Strong for proofreading the manuscript and Alice Tangerini for the accurate illustration of the new species. The authors are also indebted to Paul Kessler for his valuable comments upon reviewing the manuscript. Logistical and financial support of fieldwork were provided to S. Brewer and G. Stott by the Ya’axche Conservation Trust (Belize) and by the Global Trees Campaign (a joint initiative between Fauna & Flora International and Botanic Gardens Conservation International dedicated to saving the world’s threatened tree species).