A new Pisonia (Nyctaginaceae) from Jamaica, with an updated list of species in the genus and a key to the West Indian taxa

Marcos A. Caraballo-Ortiz, Botany Department, National Museum of Natural History, Smithsonian Institution

Keron C. St. E. Campbell, Botany Department, Natural History Museum of Jamaica, Institute of Jamaica

Sashalee J. Cross, Botany Department, Natural History Museum of Jamaica, Institute of Jamaica

The genus Pisonia L. (Caryophyllales: Nyctaginaceae) is widely distributed in tropical regions around the globe, although its diversity certainly lies within the American continent (Stevens 2001 onwards). Recent studies have reexamined the circumscription of the genus and transferred a number of species to other genera within tribe Pisonieae (Rossetto et al. 2019; Cha-gas and Costa-Lima 2020; Rossetto and Caraballo-Ortiz 2020). As a result, the number of currently accepted species in Pisonia has been estimated to be around 25 (The Plant List 2013 onwards; Ulloa Ulloa et al. 2018 onwards).In the West Indies, the genus is represented by approximately 15 species, most of them endemic to the region (Acevedo-Rodríguez and Strong 2012). During current studies on the diversity of Pisonia, Caraballo-Ortiz found collections from Jamaica that did not match any of the previously published congeners. After morphological comparisons with all known species for the West Indies, we concluded that this taxon represents an undescribed species.

This finding concords with the view of George R. Proctor, who labeled a series of specimens from the Institute of Jamaica Herbarium as “Pisonia jamaicensisProctor” during the early 2000’s, although he did not provide a description and effectuate its publication. In this work, we decided to adopt Proctor’s proposed name and formally describe the species as P.jamaicensis Proc-tor ex Caraballo, K.Campbell, & S.Cross.Pisonia jamaicensis is a tree restricted to wooded summits and upper cliffs of limestone hills in cen-tral and western Jamaica. We complement the species’ description with an illustration, pictures, a distribution map, and notes on its biology. We also discuss how to separate this species from the other congener in Jamai-ca, and present a preliminary conservation assessment following the IUCN criteria. A table summarizing the currently accepted Pisonia worldwide with their general distributions is also included, along with a dichotomous key to separate the taxareported for the West Indies.

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