Podocnemis lewyana Duméril 1852 – Magdalena River Turtle

Abstract

Podocnemis lewyana, the Magdalena River turtle (Family Podocnemididae), is a medium to large-sized river turtle confined to the Sinú, San Jorge, Cauca, and Magdalena river drain- ages in Colombia, making it a biogeographic anomaly, being the only South American podocnemid turtle to occur northwest of the Andes Mountains instead of inhabiting the Orinoco, Essequibo, or Amazon drainages. The species is currently classified as Endangered on the IUCN Red List due to the combined effects of habitat modification and the heavy exploitation of adults and eggs for con- sumption as well as some exploitation of hatchlings for the illegal pet trade. Recent analysis suggests it should be uplisted to Critically Endangered. Information on the species’ natural history has been fragmentary, but recent field and laboratory studies have generated more detailed information on P. lewyana systematics, ecology, distribution, trends in abundances, and levels of genetic diversity within and among populations. Podocnemis lewyana is primarily herbivorous as adults and nests in the dry season, preferentially but not exclusively on sandy beaches. Nests suffer heavy human and natural predation and also experience infestations by invertebrates and fungi. Sex ratios in the field covary with nest temperatures, and laboratory studies have confirmed the existence of temperature- dependent sex determination in this species and a high pivotal temperature (33.4°C). These studies have also demonstrated incubation temperature and maternal effects on hatchling size, mass, and growth rates. In most regions, P. lewyana population densities are low, with low levels of genetic diversity and no evidence of phylogeographic differences among sites. Existing legislation meant to protect the species is largely unenforced. However, recent attempts to support community-based conservation initiatives and educational activities make it more likely that well-founded manage- ment projects may be possible in the near future. DISTRIBUTION. – Colombia. Restricted to the Sinú, San Jorge, Cauca, and Magdalena river drain- ages in northwestern Colombia. SYNONYMY. – Podocnemis lewyana Duméril 1852. SUBSPECIES. – None recognized. Genetic analyses demonstrate no significant phylogeography. STATUS. – IUCN 2008 Red List: Endangered (EN A1bd) (assessed 1996, needs updating); CITES: Appendix II; Colombian Red Book: Endangered.