The Black-headed Bushmaster, Lachesis melanocephala (Viperidae: Crotalinae), is an endemic pit viper from south-eastern Costa Rica. Despite its importance with regard to medicine and conservation, the ecology and distribution of this species are still poorly known, mainly because it was only recently recognized as a full species and records are scarce across its range. Known only from the Pacific slopes of the Talamanca mountain range, L. melanocephala is considered uncommon, restricted to undisturbed habitats, and likely threatened with extinction.
Here we summarize its distribution, in terms of the Extent of Occurrence (EOO) and Species Distribution Model (SDM), and present a new locality record for the Las Tablas Protected Zone, at an elevation of 1,873 m, in a mixed premontane and montane oak forest habitat with steep slopes. The new record is located 14 km from the Panama border, so it is very likely that the species is also found in that country.
Our results indicate that L. melanocephala has a very small geographic range, between 3,432 and 10,507 km2, depending on the method of assessment. It is found mostly in undisturbed habitats, including tropical, premontane and montane humid, very humid, and pluvial forests. Due to its restricted geographic range and habitat specificity, the severe and continued loss of lowland and mid-elevation forests throughout its range pose serious threats to the persistence of the Black-headed Bushmaster.
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