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| Pseudoboa neuweiidi, Trinidad, JCM |
There are six species of snakes
in the genus Pseudoboa, all occur in
South America, with one species, Pseudoboa
neuweiidi, extending its range into the Lesser Antilles (Trinidad, Tobago,
Grenada) and possibly into Panama. Pseudoboa coronata (the type
species of the genus) and P. neuwiedii occur throughout the Amazon
basin. Pseudoboa haasi and P. serrana are endemic to the
southeastern and southern regions of the Atlantic rainforest respectively. Pseudoboa
nigra occurs throughout the Caatinga, Cerrado, and Chaco biomes in Bolivia, Paraguay,
and possibly Argentina. And, the most recently described species, Pseudoboa martinsi (Zaher et al. 2008), is from the
Brazilian Amazon basin in the states of Pará, Amazonas, Roraima, and Rondônia.
Recent molecular (Vidal et al. 2010) work places these snakes in the family
Dipisididae, subfamily Xenodontinae, tribe Pseudoboini. The tribe also includes
the genera Boiruna, Clelia, Drepanoides,
Mussurana, Phimophis Oxyrhopus, Siphlophis,
and Hydrodynastes. All of these
are rear-fanged, venomous, and tend to feed on squamates and most of them show
interesting ontogenetic color changes with the smaller individuals being more
brightly colored or having more contrasting patterns, presumably the coloration
and pattern are aposematic. Hydrodynastes
may be the exception to most of these generalizations. Additionally many of
these snakes have a nape marking that is collar-like that may last into
adulthood.
Recently, Orofino et al (2010) have
reported on the natural history of Pseudoboa nigra using 147 museum
specimens. That had been collected in Brazil’s Cerrado mostly from the states
Sao Paulo and Mato Grosso. Females were found to be larger than males, the
presence of eggs and neonates throughout the year suggests year round
reproduction, and they suggest nigra has smaller clutches than other
species in the genus. They found it feeds mostly on lizards, Ameiva were
the most commonly found food. While the authors suggest that nigra is
found in open habitats and other members of the genus are found in more
forested environments, my experience with neuwiedii suggests it occurs
in a variety of habitats including savanna, coastal, and semi-urbanized habitats
that are open (Murphy 1997). While P. nigra may be uniform black in
color, it can also have white, irregular blotches that could be considered aposematic
coloration. Robert Mertens (1956) considered Pseudoboa a model for more
palatable mimics in his proposed mimicry complex hypothesis that eventually
became known as Mertens mimicry. To be sure the venom of Pseudoboa neuwiedii
is quite toxic, being reported to kill cats, as well as conspecifics (Murphy,
1997). The fact that so many of these snakes are red or orange with a dark
collar may mean they are all part of a mimicry complex that use the pattern to
remind predators that the head is the business end of the snake. And, because the
aposematic coloration is most often found in small individuals and usually not large adults, the warning
message may be directed at smaller predators not capable of dealing with a
larger snake.
Literature
Mertens R. 1956. Das Problem der Mimikry bei Korallenschlangen. Zool. Jahrb. Syst. 84:541–575.
Morato, S. A. A., J. C. de Moura-Leite, A. L. C. Prudenete
and R. S. Bernils. 1995. A new species of Pseudoboa
Schneider, 1801 from southeastern Brazil (Serpentes: Colubridae: Xenodontinae:
Pseudoboini). Biociências 3
(2):253-264.
Murphy, J. C. 1997. Amphibians and Reptiles of Trinidad and Tobago. Malabar: Krieger
Publishing.
Orofino, R. de P., L. Pizzatto,
and O, A. V. Marques. 2010. Reproductive biology and food habits of Pseudoboa
nigra (Serpentes Dipsididae) from the Brazilian Cerrado. Phylomedusa
9:53-61.
Vidal, N.,
M. Dewynte,r and D. J. Gower. 2010. Dissecting
the major American snake radiation: A molecular phylogeny of the Dipsadidae
Bonaparte (Serpentes, Caenophidia). Comptes Rendus Biologies, 333:48-55
Zaher, H.; Oliveira, M.E. & Franco, F.L. 2008. A
new, brightly colored species of Pseudoboa
Schneider, 1801 from the Amazon Basin (Serpentes, Xenodontinae). Zootaxa 1674: 27-37
Labels: distribution, ecology, mimicry, pseudoboa
