The genus Arrhyton is endemic to Cuba, with eight currently known species. A new species, Arrhyton albicollum sp. nov., is described from the karst areas of Gibara, Holguín Province. The new species is closely related to A. redimitum, another eastern species, according to morphology and molecular phylogeny. It differs from all other species of the genus by having a conspicuous, white nuchal band, a contrasting black pattern on the head, a gray-colored body with faint stripes, and a high number of ventral and subcaudal scales. Additional comments on other species include new locality records and information on morphology and relationships.

Animal-plant interactions are ubiquitous and critical for tropical ecosystem functioning. Neotropical rodents perform key ecosystem functions such as seed dispersal and predation, however few information is available regarding their ecological interactions. Here, we reported the interaction between the Sumichrast’s Vesper Rat, Nyctomys sumichrasti, and the plant Jacaratia spinosa in the Central Caribbean of Costa Rica. Rodents were observed feeding on the flesh and seeds of the plants. Natural history observations such as this are critical to the knowledge on the feeding links of poorly known Neotropical rodents.