Pseudoboa

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

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