Berg Adder (Bitis atropos)
Previous names
- Coluber atropos – Linnaeus 1758
- Vipera montana – Smith 1826
- Echidna ocellata – Tschudi 1845
- Echidna atropos — DUMÉRIL & BIBRON 1854
- Bitis atropos —
- Bitis atropos unicolor – FitzSimons 1959
Holotype – The specimen collected by Carlos Linnaeus has been lost and the locality was listed as “America” in error. It is very likely to have been collected from the mountains surrounding the Cape Colony, now Cape Town, South Africa.
In 1956, Vivian FitzSimons described the red coloured Bitis atropos from the Mpumalanga escarpment (the old Transvaal) as a subspecies, Bitis atropos unicolor due to its plain reddish-brown colouring. He lists the type locality as a farm 30 kilometres (around 20 miles) north of the town Belfast, Mpumalanga province, South Africa.
Etymology – Atropos comes from Greek mythology, the goddess Atropos, one of three sisters who controlled fate and destiny. Atropos controlled death and was portrayed with scissors in her hand, with which she cut the life threads of mortals – an appropriate name for a venomous snake.
Species history
One of the first dwarf Bitis described by Carolus Linnaeus in 1758 from the Cape region of South Africa. In 1959 Fitzsimons named the Mpumalanga Berg Adders as Bitis atropos unicolor due to their brick-red or brownish colour and lack of patterning. The name Bitis unicolor has long since been used in the hobby but is not formally accepted. Genetic work suggests there are four major populations of Berg Adder and that these may indeed represent cryptic species.
No further specimens have been found from the type locality of Bitis atropos unicolor or west of the Badfontein Valley since the 1970s.
Description
A unique looking Dwarf Adder and partly distinct per population.
Natural habits
The Western Cape population occurs from sea level up into the Cape Fold mountains. It is fond of basking on baths and open areas of thick fynbos. Unlike the Mpumalanga population, the Cape population is hardly found under rocks and appears to take refuge under thick fynbos plants. Much of the Cape Fold Mountains receive annual snowfall and the adders probably take refuge underground during this time. Along the coast from Gordons Bay to Hermanus and again in the Tsitsikamma region, Plettenbergbay, St Francis Bay and Jeffreys Bay this species can be found down at sea level, usually associated with rocky outcrops and thick coastal vegetation. Historically they occurred at Port Elizabeth and Kenton-on-sea at sea level, but these areas have produced no records since the 1930s. They also appear absent from Grahamstown, possibly due to previous forestry operations in the 1980s that altered the mountainous grassland habitat.
The Drakensberg population is a high-altitude group, occurring from western Lesotho, around the south-eastern edge to northern Drakensberg with a few scattered records from the lower areas of the Natal Midlands. It is a grassland group, sheltering under grass tussocks and the occasional rock. They are often found basking on hiking paths in summer. In winter much of the region has frequent snow fall and the adders probably go underground or under large rocks.
The Mpumalanga and Limpopo population are also a high-altitude grassland population often found under rocks. They are frequently found basking on paths in the morning and late afternoons. Much of this area has intense mist and rainfall and the adders seem to become active in the heavy mist, probably hunting the active and calling Rain Frogs (Breviceps sp.).
The Zimbabwean Eastern Highlands population occurs into Mozambique in rocky grasslands. It is a moist region with high rainfall. There are a number of other snake species that have a disjunct population occurring in Mpumalanga/Limpopo and then again in the Zimbabwean Highlands, being absent from the hot Limpopo Valley. For example, the Rinkhals (Hemachatus nyangensis), Cross-marked Grass Snake (Psammophis crucifer) and Bibron’s Blind Snake (Afrotyphlops bibronii) all share the disjunct population like the Berg Adder.
Venom – each of the four populations have varied venom, with the Cape population having the strongest venom. The venom is predominantly neurotoxic, which is unlike the cytotoxic venom from that of other Adders. Berg Adder venom causes neurological symptoms that attack the facial muscles. Symptoms include swelling, nausea, drooping eyelids (Ptosis), excessive salivation, dilated pupils, temporary blindness and lack of taste and smell. These symptoms usually only last a day or two, but dilated pupils have been experienced for more than six months in severe bites. No confirmed human deaths have been recorded from this species, but bites are best treated in a hospital environment by a medical professional.
