A skeletochronological estimate of age and growth in a large riparian frog from Madagascar (Anura, Mantellidae, Mantidactylus)

Fabio M Guarino,Jasmin E Randrianirina,Marcello Mezzasalma,Franco Andreone,Angelica Crottini

doi:10.3897/herpetozoa.32.e35576

Fabio M Guarino, Jasmin E Randrianirina + Show 3 more

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https://doi.org/10.3897/herpetozoa.32.e35576

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Journal: Herpetozoa	Publication Date: May 13, 2019
Citations: 5	License type: CC BY 4.0

Affiliation: Tsimbazaza Zoo, University of Porto

Abstract

We characterized the body size (as snout-vent length), age, sexual size dimorphism, and growth rate in a population of one of the larger riparian frog from Madagascar (Mantidactylusgrandidieri) from a rainforest patch close to Vevembe, SE Madagascar. We identified a significant female-biased sexual size dimorphism. Age was estimated using phalangeal skeletochronology and was significantly higher in females than in males. Modal age class turned out to be 4 years in both sexes but a large percentage of adult females (75%) fell in the 5–6 years-old classes, while no male exceeded 4 years. We here report M.grandidieri as a medium-long-lived anuran species. Von Bertalanffy’s model showed similar growth trajectories between the sexes although the growth coefficient in females (k = 0.335) was slightly but not significantly higher than in males (k = 0.329).

Highlights

Madagascar is renowned for being one of the most important spots in the world for amphibian diversity (Vieites et al 2009; Perl et al 2014; Brown et al 2016) and a model region to study biological evolution and spatial ecology at different taxonomic levels (Mezzasalma et al 2016; 2017a, b)
The observed maximal longevity of M. grandidieri turned out to be 4 years in males and 6 years in females. This result poses this species in an intermediate position among the Malagasy anurans studied so far, being older than the smallsize species, such as those belonging to the genus Mantella and of Scaphiophryne gottlebei, but having a shorter observed life span than other species of aproximatively equal body size, such as the tomato frogs (Dyscophus antongilii and D. guineti) whose males reach 6–7 years and females 11 years (Tessa et al 2007)
The females mostly exceed the males in body size, with 90% of anurans and 61% of urodeles showing a female-biased dimorphism (Shine 1979; Reinhard et al 2015)

Summary

Introduction

Madagascar is renowned for being one of the most important spots in the world for amphibian diversity (Vieites et al 2009; Perl et al 2014; Brown et al 2016) and a model region to study biological evolution and spatial ecology at different taxonomic levels (Mezzasalma et al 2016; 2017a, b). More than 350 endemic species are known from there (AmphibiaWeb 2018), and another 200 candidate species still need to be thoroughly assessed and possibly described (Glaw and Vences 2007; Vieites et al 2009; Perl et al 2014), making this large island one of the priority places for amphibian conservation (Andreone et al 2005; 2008; Andreone and Randriamahazo 2008a). Guarino et al.: Age and growth in Mantidactylus grandidieri by skeletochronology ern and northeastern rainforest belt (Brown et al 2016; Andreone et al 2018), comparatively many species occur in the most arid areas of the west and south of the island (Andreone et al 2013; Cocca et al 2018)

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