Bitis - African Vipers
Bitis rhinoceros
Atheris broadleyi - African Bush Vipers
Lawson (1999) described a new species of Atheris, A. broadleyi, from southeastern Cameroon and western Central African Republic. The new species is very similar to A. squamigera and A. anisolepis, with which it was confused in the past, but differs in aspects of colour pattern and scalation. The complex patterns of variation in the squamigera-anisolepis-broadleyi group of Atheris suggest that a more comprehensive revision of this complex is required. Photos can be viewed at The World of Atheris
Bitis - African Vipers
Bitis rhinoceros
Lenk et al. (1999) used molecular data
(immunological distances and mitochondrial DNA sequences) to estimate the
phylogenetic relationships among species of Bitis. They identified
four principal monophyletic groups, which they classify as subgenera of
the genus Bitis: (i) subgenus Bitis contains the single species
B.
arietans; (ii) subgenus Macrocerastes contains B. gabonica,
B. nasicornis, and probably B. parviocula; (iii) subgenus Calechidna
contains the smaller species of Bitis from southern Africa; (iv)
subgenus Keniabitis contains only Bitis worthingtoni, from
Kenya.
Subgenera are of limited importance for
nomenclatural purposes: all the species can continue to be referred to
simply as Bitis spp., without concern for subgeneric classification.
However, the definition of subgenera within a genus often precedes a full
split into several genera. Consequently, those interested in these snakes
or their venoms would be well advised to familiarise themselves with these
new subgenera.
In addition to the broader study of the
subgenera of Bitis, Lenk et al. (1999) also noted a considerable
degree of differentiation between the two conventionally recognised subspecies
of Bitis gabonica: B. g. gabonica and B. g. rhinoceros
are
as differentiated from each other as each is from B. nasicornis.
In consequence, Lenk et al. (1999) consider the western form of the Gaboon
viper to be a separate species, Bitis rhinoceros. The apparently
ancient divergence between B. gabonica and B. rhinoceros
suggests that comparisons of venom composition and antivenom effectiveness
between the two species may be required.
Bitis cornuta-inornata complex
- South African Dwarf Adders
Branch (1999) reviewed the Bitis cornuta-inornata complex of small viperids from southern Africa. Four species are recognised: B. cornuta from the Atlantic coastal regions of South Africa and southwestern Namibia; B. rubida is found in hilly inland regions of the Western Cape Province; B. armata is found in the coastal lowlands of the southwestern corner of the Western Cape; B. inornata is restricted to the Sneeuberg region of the Eastern Cape; and B. albanica is restricted to coastal areas in the Eastern Cape, between Port Elisabeth and Grahamstown. These species are usually assumed to be relatively innocuous, but Branch (1999) points out the need for caution, and for further research into venom composition and activity in these snakes.
Cerastes - Horned vipers
Cerastes cerastes
Werner et al. (1999) analysed the population systematics of Cerastes cerastes and C. gasperettii from the Arabian Peninsula and the 'Arava Valley. Populations of C. cerastes from the southwestern Arabian Peninsula (where they are partially sympatric with C. gasperettii) are described as a new subspecies, C. cerastes hoofieni. The population of C. gasperettii from the 'Arava Valley is described as a new subspecies, C. gasperettii mendelssohni. It is endemic to the 'Arava Valley, and may be threatened due to habitat destruction for agriculture. Analyses of venoms of the genus Cerastes should take these new findings into account.
Vipera - Eurasian vipers
Nilson et al. (1999) reviewed the systematic
status of the Vipera xanthina group. On the basis of the evidence
suggesting that this group constitutes a distinct lineage within Vipera,
the authors described a new subgenus, Montivipera, for this group.
The included taxa are xanthina, bornmuelleri, bulgardaghica, albizona,
wagneri, raddei, albicornuta, latifii and kurdistanica. The
status of some of these forms is controversial (Schätti et al., 1991;
Nilson and Andrén, 1992).
As in the case of Bitis, the description
of a new subgenus has no direct nomenclatural implications, but may presage
a more formal split of the genus Vipera.