Nombre científico: Lachesis melanocephala
Familia: Viperidae Family
Nombre común: black-head bushmaster
The body is robust, with a large head moderately differentiated from the neck. Its dorsal base color is yellow or light pink to orange-brown; the back of the head is all black, the bottom is white to light yellow, the tail also ends in a nail or pointed spine. The average length of the adults ranges between 1,90 and 2 m, and males are longer than females.
Terrestrial and active at twilight and night, but very little is known of its biology. Its eating habits are mostly unknown, but the information available points to small mammals (rodents and marsupials) as possible preys. Its reproduction is oviparous, and its reproductive cycle in natural conditions is unknown.
Endemic to Costa Rica, although it may also be found on the west area of Panama. Its specific habitat is primary forests, or forests with little alterations. In Costa Rica it is found only in tropical and subtropical rainforests of the south and southwest Pacific, from sea level to 1600 m of altitude. An uncommon species, the accelerated destruction of the primary forest in its limited environment of distribution has significantly decreased its population. This species has disappeared from different areas where it was considered common; however, there are some fragmented but relatively stable populations in certain sectors of the south and southwest pacific.