Huge but moderately long-lived: age structure in Leptodactylus fallax, a critically endangered frog from Montserrat, West Indies.

We applied skeletochronological methodology to assess the age and growth in one of the largest living anurans, the mountain chicken, Leptodactylus fallax. We compared bone cross-sections obtained from wild animals, found dead in 2009 after the chytrid outbreak occurred in Montserrat, and captive individuals part of the breeding program at Jersey Zoo. Lines of arrested growth (LAGs) were visible in both groups. Individuals reared in captivity reached an older age than their wild counterparts. Additionally, at the same age, captive males were larger than captive females and wild females were much larger than captive females. A literature screening of age and snout-vent length (SVL) for 46 species (including L. fallax) ascribed to seven families (Bufonidae, Dicroglossidae, Leptodactylidae, Mantellidae, Microhylidae, Ranidae, and Rhacophoridae) showed that the largest species were also the most long-lived. Nevertheless, the position of L. fallax was an outlier (reaching a maximum documented SVL of 280 mm and a maximum longevity of 9 years) in respect to the other species considered. Its body size was larger than expected, indicating a case of gigantism most probably associated with adaptation to an insular environment.