Rediscovery of the Poorly Known Angolan Adder, Bitis heraldica (Bocage, 1889) (Serpentes: Viperidae): New Records, Live Photographs, and First Case History of Envenomation

摘要

The Angolan Adder, Bitis heraldica (Bocage, 1889), endemic to the Angolan central plateau, is one of the most poorly known and rarely observed species of African snakes. The species was described by Bocage (1889) based on a single specimen collected by the Portuguese explorers Hermenegildo Capelo (1841-1917) and Roberto Ivens (1850-1898) on the banks of the river "Calae" [= Calai], a tributary of the Cunene River, Huila Province. Since its original description, the species has only been collected and reported a handful of times (Bocage 1895; Boulenger 1905; Monard 1937; Bogert 1940; Hellmich 1957; Mertens 1958) and no records for this species exist since 1953 (Hellmich 1957). The extant specimens in natural history collections are listed in Appendix I. Its known distribution is limited to the rocky slopes at high elevation in western regions of the Angolan central plateau, namely in the provinces of Kwanza Sul, Huambo, Bié, and northern Huila, being known from no more than eight different localities (Marques et al. 2018). The species has never been evaluated by the IUCN, and nothing is known regarding its biology, behavior, composition or toxicity of the venom, and no case histories of envenomation have been published (Spawls and Branch 1995). The species can be easily distinguished from other small species of the genus Bitis due to its heavily speckled venter, the presence of a "trident" on its forehead, and absence of supraocular ornamentation (Mertens 1958).