A New Caribbean Species of Helosis (Balanophoraceae) with a Revised Key to the Genus

A new species, Helosis antillensis (Scybalioideae: Helosieae), is described, illustrated, and annotated. A key of the known species of Helosis is presented. The new species is the third recognized within the genus and the second Helosis species in the Neotropics. It is also the second Balanophoraceae endemic to the islands of the Caribbean Sea. The new species, related to H. cayennensis, is distinguished by runners with remarkable verrucous surface projections, an inflorescence stalk up to 4.5 cm long, volva that are medially to apically inserted, peltate bracts with distinctly apiculate apices, staminate flowers with free filaments, and pistillate flowers with bifid and deltoid perianth segments (0.3-0.4 mm long).