Content uploaded by Angelica Crottini
Author content
All content in this area was uploaded by Angelica Crottini
Content may be subject to copyright.
A preview of the PDF is not available
The amphibians of Isalo Massif, southern-central Madagascar: High frog diversity in an apparently hostile dry habitat
Abstract and Figures
We provide a list of the amphibians from the Isalo Massif, southern-central Madagascar with data on their ecology and acoustics. Although this area is constituted by a xeric sandstone massif crossed by canyons and extended savannah-like grasslands, the number of discovered frog species turned out to be high (21). This is the highest number of amphibian species ever found at a western locality of Madagascar. The number of species known to be endemic from this area is at least five (Mantella expectata, Gephyromantis azzurrae, G. corvus, Mantidactylus noralottae ,a nd Scaphiophryne gottlebei), with some other taxa (Boophis occidentalis, B. cf. periegetes, Mantidactylus sp. aff. ulcerosus), that are possibly Isalo-endemic too. This high endemicity level indicates the refuge effect played by the massif during repeated climatic changes, and the specialisation of these species to the peculiar canyon-habitat. Two sympatric species of Gephyromantis (G. azzurrae and G. corvus) evolved independently, likely for adaptation to two different aspects of the canyons (narrow or open). Part of the massif is currently managed as a national park, which is the most visited protected area of Madagascar. The remaining part of the massif is still unprotected and is threatened by the repeated fires and by the ongoing exploitation for sapphire mining. Two species, Mantella expectata and Scaphiophryne gottlebei, are captured for pet-trade, and considerations are provided regarding their conservation status.
Figures - uploaded by Angelica Crottini
Author content
All figure content in this area was uploaded by Angelica Crottini
Content may be subject to copyright.
... this is in line with most other Madagascar-endemic vertebrate radiations whose species richness is strongly influenced by the colonization-or not-of these rainforests (Crottini et al. 2012). A number of species also occur in the more arid west and South-west of the island (Blommers-Schlösser 1979;Blommers-Schlösser & Blanc 1993;, the majority of which live in small relict humid forests such as in the canyons of the Isalo limestone massif (Mercurio et al. 2008;Cocca et al. 2018) or the tsingy de Bemaraha limestone karst (Bora et al. 2010). however, several species have adapted specifically to arid environments, such as Scaphiophryne brevis, S. calcarata, S. obscura, Dyscophus insularis, or Laliostoma labrosum, all of which are rather robust species that evade desiccation during dry episodes by burrowing into the ground (Blommers-Schlösser & Blanc 1991;Pabijan et al. 2015;Scherz et al. 2021). ...
... In Isalo this species is commonly found on the ground of gallery forests (e.g., Andriamanero, Sakamalio), along temporary rivers and in Pandanus swamps in the open savannah (e.g., Ilakaka, zahavola). tadpoles develop in temporary ponds and individuals of this species have been observed in egg-guarding behaviour both in Ankarafantsika (Fig. 4C) and Isalo (Mercurio et al. (2008). In the Sahamalaza Peninsula, this species seems to be abundant and it is found along streams and ponds in intact forested areas as well as in paddy fields in cleared areas. ...
... aff. wittei byMercurio et al. (2008), Blommersia sp. (aff. ...
Frogs of the Blommersia wittei complex are widespread in western and northern Madagascar, and are one of two clades of the family Mantellidae that have colonized the Comoran island of Mayotte. Based on a comprehensive set of DNA
sequences of the mitochondrial 16S rRNA gene and the nuclear-encoded RAG1 and SACS genes, integrated with morphological and bioacoustic data, we here analyze the genetic differentiation of populations of this complex across Madagascar. We confirm that a candidate species named B. sp. Ca5 in previous studies represents a genetically welldefined evolutionary lineage distributed over much of western Madagascar, which we describe herein as Blommeria bara sp. nov. based on its molecular and bioacoustic differentiation. Blommersia wittei occurs across northern Madagascar but its type locality Ambanja, at the lower Sambirano river, is very close to the range of another, newly discovered microendemic lineage that was only found at two sites along the upper Sambirano river (here named as candidate species B. sp. Ca12). The B. wittei complex thus provides an example of a clade of closely related Malagasy frogs that contains species widespread over hundreds of kilometers, as well as extreme microendemics. For a full resolution of this species
complex, more data need to be collected on the geographical contact among these two lineages, on the morphology and bioacoustics of B. sp. Ca12, and on the north-eastern populations of B. wittei at Sambava, which are weakly differentiated in mitochondrial genes but differ in bioacoustics and possibly in the extent of foot webbing.
... femoralis, Boophis cf. goudoti and B. luteus (Raxworthy and Nussbaum, 1997), as well as a number of locally endemic species (Mercurio et al., 2008). It is understood that the isolation of these humid gallery forests within an otherwise dry savannah habitat has favored the differentiation of new endemic species (Mercurio and Andreone, 2007). ...
... Habitats within the boundaries of the park are mostly protected from anthropogenic pressure ( Swierkosz, 2007;Crottini et al., 2008). However, anthropogenic pressure is degrading habitats outside of the park and within unguarded portions along its boundary. ...
... Hunting and the illegal collection of animals for the pet trade is a concern (Crottini et al., 2008). Cattle grazing and the burning of grasslands threaten lowland areas, whilst illegal wood exploitation in the canyons threaten the gallery forests ( Swierkosz, 2007;Mercurio et al., 2008). ...
One of the most threatened ecosystems on a global scale is the tropical dry and gallery forest in Madagascar. These forests are one of the world's most important biodiversity hotspots, imperiled because of accelerated rates of deforestation that menace remaining patches of dry forest, only a few small areas formally under protection endure. The dry/gallery forests along the central highlands and towards the northwestern part of the country have been neglected by conservation projects for decades. However, these areas are linked with important rivers and lakes that sustain high levels of biodiversity and densities of Critically Endangered species while providing crucial support for surrounding communities. A detailed description and specifications of gallery forests and freshwater will highlight the importance of the sites, in terms of biodiversity and livelihoods, the threats they face, and the proposed conservation and research actions.
... This is mostly due, among other reasons, to the difficult access to many key areas, including protected areas, hampering a regular monitoring of the local wildlife. These are, for example, Isalo, Montagne d'Ambre, Ranomafana, and Andasibe (i.e., Raxworthy & Nussbaum, 1994;Andreone et al., 2001;Penny et al., 2017;Mercurio et al., 2008;Cocca et al., 2018), all of which are also well-known touristic destinations (Gardner et al., 2018;Goodman et al., 2018). Other sites, like the ones visited by Andreone et al., (2000) and are instead very seldom visited and never surveyed repeatedly. ...
... Parc National de l'Isalo. In this area of south-western Madagascar our survey enabled the identification of 24 species, of which nine were considered candidate species at the time of the first surveys(Mercurio et al., 2008;Cocca et al., 2018). The possibility to collect specimens over several repeated expeditions gave Cocca et al.(2018) the chance to identify two new species with respect to Mercurio et al. (2008), Mantidactylus riparius and Scaphiophryne obscura, and characterise Mantella sp. ...
Vouchering, integrative taxonomy and natural history collections: a case study with the amphibians of Madagascar SUMMARY Natural history collections have played an important role in the origin of natural history museums. Over the time these institutions have become places where "voucher specimens" and other kinds of natural history objects were preferably deposited. In this paper we further highlight the importance to consider collecting biological specimens as a useful / needed action for the expansion and diffusion of scientific collections, as well as for advancing sciences and, indirectly, conservation. We also report on a recent trend of underestimating the need of voucher specimens and provide evidences that the collection of a selected number of individuals as voucher specimens is necessary to contribute to such a goal and duty of cataloguing the world biodiversity and promote its conservation. Voucher specimens play the crucial function-among the others-to confirm the presence of a species at a locality at a given time, document the original ecological and biological diversity before change, can enable long-term studies and comparisons (i.e., using for example morphological or molecular tools) and can serve as a basis for ecological studies. Specifically, we used the amphibians of Madagascar as a case-study to highlight the need to continuing the collection activities, showing that their collection has been crucial to the cataloguing of Malagasy biodiversity and thus moving towards their conservation. The use of ancillary data alone (including photographs, videos, acoustic recordings, and genetic analysis carried out on tissue samples), frequently considered in alternative to vouchering, although useful, remains insufficient.
... A few rivers are permanent, whereas many others are seasonal. Temperatures vary greatly between monthly means: 17 • C in June and 25 • C in February [18]. The northernmost part of the massif is currently managed as a national park by MNP (Madagascar National Park) and is one of the largest protected areas of Madagascar, with 815 km 2 of extension [19]. ...
... A few rivers are permanent, whereas many others are seasonal. Temperatures vary greatly between monthly means: 17 °C in June and 25 °C in February [18]. ...
Understanding the spatial ecology of species has important implications for conservation, as it helps identify suitable habitats and minimum requirements for biodiversity monitoring and management. The spiny-tailed lizard Oplurus cyclurus is a widespread endemic iguanid occurring in dry areas of southern and western Madagascar. While the species is known to be mostly arboreal, populations of the Isalo sandstone massif suggest local adaptation to a less forested savannah and a more exposed habitat. We radio-tracked 19 spiny-tailed lizards to investigate the species’ rock-dwelling behaviour and spatial ecology at Isalo National Park. Tracked individuals showed high site and burrow fidelity, and a basking behaviour mostly tied to the accessibility of their burrow, the time of day, and their life stage. Activity peaked during the sunniest hours, while juveniles were more active than adults with unfavourable weather conditions. Despite high burrow fidelity, lizards used shelters non-exclusively, regularly changing (approx. once a week) with neighbouring burrows (average distance between burrows = 13.6 m). However, there was no obvious relation between lizards’ body and/or tail size and the width and depth of selected burrows. Dynamic Brownian Bridge Movement Models estimated frequented areas over 247.8 m2 (95% isopleth), where territorial overlap is common. Our results challenge the notion that burrow-site fidelity is the sole driving factor behind space utilization in the studied population. We argue that the apparently unusual saxicolous habits imposed by habitat features (the absence of trees) may lead to local behavioural adjustments influencing antipredatory and foraging strategies, as well as intraspecific interactions.
... Heterixalus luteostriatus has a wide and discontinuous distribution across north-western and western Madagascar, including the Isalo Massif. This species can commonly be found in swamps and rice fields Mercurio et al. 2008) and the record reported here constitutes an extension of the known species distributional range by ca. 180 km to the east from the Isalo Massif (Glaw and Vences 2007). ...
... This species is discontinuously reported from multiple localities in western Madagascar between the Isalo Massif, at the south, and Bemaraha, at the north. Within Isalo National Park, this species can be observed around both temporary and permanent water bodies, generally outside of the canyons (Glaw and Vences 2007; Mercurio et al. 2008). ...
Madagascar has historically suffered from high fragmentation of forested habitats, often leading to biodiversity loss. Neverthless, forest fragments still retain high levels of biological diversity. The Haute Matsiatra Region (south-eastern Madagascar) hosts the renowned Andringitra National Park and several surrounding isolated forest fragments embedded in a matrix of human-dominated landscape. During a herpetological survey conducted in the Region, we visited a total of 25 sites. We applied a molecular taxonomic approach to identify the collected material and generate new reference sequences to improve the molecular identification of Malagasy herpetofauna. We identified a total of 28 amphibian and 38 squamate taxa and provided a systematic account for each one of them. Nine of the identified taxa are candidate species, amongst which one was newly identified. We extended the known distributional range of 21 taxa (nine amphibians and 12 squamates). Although the largest forest fragments hold a higher number of species, we also detected a relatively high herpetological diversity in small patches. Our results highlight the importance of investigating small forest fragments to contribute to a better understanding of the patterns of diversity and distribution of the amphibians and reptiles of Madagascar.
... Grasslands are home to a diversity of plants and animals, including those in Isalo massif. A diversity of ants, amphibians, reptiles and birds are found there (although not all are well documented), as well as restricted endemic species (e.g., Monotes madagascariensis trees, Mantella expectata frogs) (Mercurio et al. 2008, MNP 2017. Bond et al. (2008) hypothesized that the presence of endemic plants and animals in Madagascar's grasslands is consistent with a pre-human history. ...
Grasses are one of the best documented plant families worldwide in terms of taxonomy, but they are still poorly known in Madagascar. Our understanding of their diversity remains incomplete since grasses and grasslands are assumed by many tobe weeds and degraded wastelands. This project aimed to list thegrasses in Isalo National Park (NP) in order to understand theirdiversity and endemicity, as well as the history of Isalo’s grasslands. Examination of herbarium specimens and new field inventories allowed us to confirm 589 records of grass occurrences in ourstudy area. They were assigned to 112 species, of which 38 species are new records for Isalo NP. The Isalo grass flora includes seven of the eleven Poaceae subfamilies present in Madagascar and is particularly rich in Panicoideae, which make up 65% of the species. Nearly 22% of the grass species of Isalo are endemic to Madagascar, of which three species and one variety are restricted to Isalo massif, including two unusual ground cover species Tristachya humbertii A.Camus and Tristachya [Isalus isalensis]. Open grasslands harbour the highest diversity of grass species, followed closely by riparian forests. The history of the management of Isalo NP by the Bara people, as well as the endemism and the native origin of its grasses and other species are consistent with an ancient origin of Isalo’s ecosystems. We urge that the conservation of Isalo’s grassy ecosystems, as well as that of the plants and animals that inhabit them be prioritized.Les graminées sont parmi les familles de plantes les mieux documentées au niveau mondial en termes de taxonomie, mais sont encore mal connues à Madagascar. Notre compréhension de leur diversité reste incomplète, vu que les graminées et les savanes sont considérées par beaucoup comme des mauvaises herbes et des friches dégradées. Ce projet visait à établir une liste des graminées connues du Parc National (PN) de l’Isalo, afin de comprendre leur diversité et leur endémicité, ainsi que l’histoire des écosystèmes herbeux de l’Isalo. L’examen des spécimens d'herbiers et les nouveaux inventaires sur terrains nous ont permis de générer 589 occurrences de graminées de notre site d’étude. Elles ont été attribuées à 112 espèces de Poaceae, dont 38 sont de nouvelles collectes pour le massif de l’Isalo. La flore herbacée du massif de l'Isalo comprend sept des onze sous-familles de Poaceae présentes à Madagascar et est particulièrement riche en Panicoideae qui représentent 65% des espèces. Près de 22% des espèces de graminées de l’Isalo sont endémiques de Madagascar, dont trois espèces et une variété sont restreintes à Isalo, y compris les deux espèces de plantes couvre-sols inhabituelles Tristachya humbertii A.Camus et Tristachya [Isalus isalensis]. Les prairies ouvertes abritent la plus grande diversité d'espèces de graminées, suivies de près par les forêts ripicoles. L’histoire de la gestion du PN de l’Isalo par les habitants de la région du groupe Bara, ainsi que l’endémisme et l’origine autochtone de ses graminées et autres espèces sont cohérents avec une origine ancienne des écosystèmes de l’Isalo. Nous préconisons instamment que la conservation de ces prairies et savanes de l'Isalo, ainsi que les plantes et les animaux qui les habitent soit priorisée.
... The most recent edition of this guide was published in Malagasy and distributed throughout the island to institutions and organizations involved in conservation and the management of natural resources (Glaw & Vences 2007a, b). In addition to these major works, numerous herpetological research teams recently have carried out many field missions throughout Madagascar (e. g., Andreone 1994;Andreone & Randriamahazo 1997;Raxworthy & Nussbaum 1996a,b;Raxworthy et al. 1998;Nussbaum et al. 1999;Vences et al. 2002;Mercurio et al. 2008;Bora et al. 2010;Gehring et al. 2010;Crottini et al. 2011b;Rosa et al. 2012;Cocca et al. 2018Cocca et al. , 2020. These expeditions resulted in a nearly continuative description of new species and identification of others (Perl et al. 2014), leading to a more thorough understanding of the taxonomy and the distribution of the amphibians of Madagascar Brown et al. 2016). ...
Oviparous species that reproduce in unpredictably variable environments risk depositing their eggs in situations that may become unsuitable for offspring survival at any time. This uncertainty often leads to selection for iteroparity as a form of bet‐hedging to spread offspring development spatially and temporally, thereby improving the odds of some cohorts experiencing optimal conditions. Paradoxically, an iteroparous mode appears to be the exception for a small number of amphibians that exploit temporary aquatic systems. In this study, we provide evidence of this paradox in an Australian anuran, the sandpaper frog, Lechriodus fletcheri , which breeds almost exclusively in small, highly ephemeral pools that often dry before the completion of tadpole development. A capture‐mark‐recapture study was conducted on a population over three consecutive breeding seasons, to determine how often adults returned to breeding sites within and between years and the extent of iteroparity. We found practically no adult returns between seasons, even though recapture events often occurred within season, suggesting that this species is virtually semelparous. A similar life history is apparent in other amphibians, suggesting that some species are able to persist in unpredictable environments by likely taking advantage of other forms of bet‐hedging in the absence of iteroparity. For L. fletcheri , we suggest that an extended breeding season may lend itself to the process of cohort splitting at a population level, resulting in the future reproductive activity of offspring from each generation being spread across multiple seasons. Our study shows how an iteroparous life history is not the only way to deal with environmental uncertainty.
The eyes of frogs and toads (Anura) are among their most fascinating features. Although several pupil shapes have been described, the diversity, evolution, and functional role of the pupil in anurans have received little attention. Studying photographs of more than 3200 species, we surveyed pupil diversity, described their morphological variation, tested correlation with adult habits and diel activity, and discussed major evolutionary patterns considering iris anatomy and visual ecology. Our results indicated that the pupil in anurans is a highly plastic structure, with seven main pupil shapes that evolved at least 116 times during the history of the group. We found no significant correlation between pupil shape, adult habits, and diel activity, with the exception of the circular pupil and aquatic habits. The vertical pupil arose at least in the most recent common ancestor of batrachians, and this morphology is present in most early-diverging anuran clades. Subsequently, a horizontal pupil, a very uncommon shape in vertebrates, evolved in most neobatrachian frogs. This shape evolved into most other known pupil shapes, but it persisted in a large number of species with diverse life histories, habits and diel activity patterns, demonstrating a remarkable functional and ecological versatility.
The genus Gephyromantis belongs to the species-rich family Mantellidae and is currently divided in six subgenera. Among these is the subgenus Phylacomantis, which currently includes four described species: Gephyromantis pseudoasper , G. corvus , G. azzurrae , and G. atsingy . The latter three species are distributed in western Madagascar, and two of them ( G. azzurrae and G. corvus ) occur in the Isalo Massif. Based on the analysis of molecular data (a fragment of the 16S rRNA gene), morphological inspection of museum specimens, and photographic comparisons, G. azzurrae is synonymised with G. corvus and the second Phylacomantis lineage of Isalo is described as G. kintana sp. nov. This medium-sized frog species (adult snout-vent length 35–44 mm) is assigned to this subgenus according to genetic and morphological similarities to the other known species of Phylacomantis . Gephyromantis kintana sp. nov. is known only from the Isalo Massif, while new records for G. corvus extend its range to ca. 200 km off its currently known distribution. These two taxa seem to occur in syntopy in at least one locality in Isalo, and the easiest way to distinguish them is the inspection of the ventral colouration, dark in G. corvus and dirty white in G. kintana .
The tadpoles of the microhylid Scaphiophryne gottlebei and of the mantellid Mantella expectata from the Isalo Massif (south-central Madagascar) are described and compared with already known tadpoles belonging to the same genera. The tadpole of S. gottlebei is peculiar in having the oral apparatus with a horny beak surrounded by dermal papillae, and a spiracle in intermediate position, between ventral and lateral. Furthermore, it shows unique feeding habits and a peculiar associated behaviour. During the day it stays close to the bottom and often burrows half of the body into the sand with the tail obliquely upwards; in this position it ingests organic material from among the substrate particles. During night time the tadpole leaves the bottom and swims throughout the water column. Since this tadpole cannot be included in any of the currently known ecomorphological categories we create a new category for this species, the "psammonektonic" tadpole. Mantella expectata was often found in the same environments, although it appears to prefer more open habitats. In some cases, tadpoles of both species were found together, although M. expectata usually prefers small and temporary streams for reproduction. The mantella tadpoles were also found in quite open savannah areas. The tadpole morphology agrees in general with that of other mantellas, mainly of the M. betsileo group, and is of the generalized ranoid type.
A new species of treefrog of the Boophis luteus (Boulenger 1882) species group is described from the Tsingy de Bemaraha National Park, central-western Madagascar. It differs from all other members of the group mainly by colouration in life and advertisement call. A phylogenetic analysis based on comparison of a sequence fragment of the mitochondrial 16S rRNA gene clearly placed the new species as the sister taxon of B. luteus from eastern Madagascar. However, the pairwise total 16S sequence divergence between the species is high (5.7%). The presence of a pair of sibling species with an allopatric east-west distribution pattern is a unique case in the B. luteus group, with the new species being the only one in the group endemic in a seasonally arid environment.
The reptiles of Mt Nlonako, a mountain at the southeastern edge of the Cameroon mountain range ("Dorsale camerounaise"), were inventoried continually over a six year period from 1998 to 2004. This area encompasses 150 km2 of lowland, submontane and montane rainforest with an elevation up to 1,825 m. Accounts of 89 species are provided based on collected and photo-documented material. This inventory proved Mt Nlonako to be the most species rich single-locality area in reptilian fauna in Africa. With 63 snake species Mt Nlonako exhibits the greatest number of species in Africa and possibly worldwide. Analysis showed the reptilian species composition to be most similar within Cameroon with that of Korup National Park followed by the Dja Faunal Reserve in the south. Relative to the snake composition the Korup NP and the Dimonika region in Congo-Brazzaville show the highest resemblance. In an African context the reptile fauna of Mt Nlonako is characterized by species which occur in both West and Central Africa as opposed to the mountain's amphibian species which more closely resemble Central African fauna. The high species richness and endemicity is discussed from a paleoclimatic perspective. Conservation status and threats to the reptiles are noted.
We describe the adult and larval morphology, advertisement call, ecology, and life history of a new species of Marbled Toad from the dry deciduous forests of western Madagascar on the basis of eight specimens from Kirindy Forest C. F. P. F. in the central Menabe area. Scaphiophryne menabensis n. sp. is larger, but morphologically similar to S. marmorata from the eastern rainforests. However, DNA sequence anal- ysis of the mitochondrial 16S rRNA gene resulted in a clear differentiation from this species. The strongest mitochondrial affinities are with S. madagascariensis ,a morphologically highly divergent species occurring in montane savanna and forest areas on the high plateau of Madagascar.
