Descriptive skeletal anatomy of Blommersia transmarina (Amphibia: Anura: Mantellidae) from the Comoro Islands

Abstract

Mantellid frogs present an extensive adaptive radiation endemic to Madagascar and Comoros, being the subfamily Mantellinae the most morphologically and ecologically diverse. The Mantellinae present key innovative evolutionary traits linked to their unique reproductive behavior, including the presence of femoral glands and a derived vomeronasal organ. In addition, previous studies pointed to size differentiation in playing an important role in species’ dispersal capacities and shaping of their geographic ranges. Despite the high phenotypic variation observed in this clade, to date an exhaustive morphological analysis of their anatomy has still not been performed, much less in relation to internal structures. Here, we present a comprehensive skeletal description of a mantellid species, Blommersia transmarina, from the island of Mayotte in the Indian Ocean, which has potentially undergone a process of moderate gigantism compared to other Blommersia species. We describe its intraspecific skeletal variation utilizing non-destructive volume renderings from μCT-scans, and characterize the presence of sexual dimorphism and size covariation in skeletal structures. Notably, we found numerous signs of hyperossification, a novel structure for mantellids: the clavicular process, and the presence of several appendicular sesamoids. Our findings suggest that skeletal phenotypic variation in this genus may be linked to biomechanical function for reproduction and locomotion.

The phylogeny of the Casque‐headed Treefrogs (Hylidae: Hylinae: Lophyohylini)

“…Lynch, 1971, 1995, 1996; Sánchez‐Nivicela et al, 2019), Dicroglossidae ( Nannophrys and apparently at least two species of Limnonectes ; Clarke, 1983; Lambertz et al, 2014: fig. 5c, 5d), Discoglossidae ( Latonia ; Sanchiz, 1998; Biton et al, 2016), Hemiphractidae ( Fritziana , Hemiphractus , Stefania , and most species of Gastrotheca ; Trueb, 2015), Mantellidae (at least Blommersia transmarina ; Santos‐Santos et al, 2020); Megophryidae (at least Megophrys carinensis , M. feae , M. montana , and M. nasuta ; Zweifel, 1956; A. Ohler, pers. comm.…”

Hidden in plain sight: a new frog species of the genus Blommersia from the oceanic island of Mayotte, Comoros archipelago

“…Blommersia wittei shows intermediate measurements between the two in most characters, being a typical small Blommersia species. B. transmarina has undergone a process of increase in body size, which can be considered towards a moderate gigantism compared to other Blommersia, being the largest Blommersia species known so far (Glaw et al 2019;Santos-Santos et al 2020). The overall aspect of B. transmarina more closely resembles other Mantellinae genera from Madagascar than a typical Blommersia, being bigger, more robust, and darker in coloration with proportionally longer and more robust legs.…”

“…In this context, the known species present on Mayotte offer an exciting opportunity to study the morphological and life history evolution of species that have evolved in isolation without the presence of other congeners for the last 5 or 6 million years. Blommersia transmarina evolved into a bigger body size than any other Blommersia from Madagascar, likely having undergone a process of moderate gigantism compared to the rest of Blommersia species (Santos-Santos et al 2020). During fieldwork on the Comoran island of Mayotte to collect specimens of this Blommersia species, we discovered a second undescribed species of much smaller body size that occurs in syntopy.…”

Descripción Morfométrica de la Anatomía Externa e Interna del Ambystoma mexicanum

“…Las imágenes mostradas en este estudio fueron capturadas utilizando una cámara digital Canon ® T6i réflex. Por otra parte, se realizaron estudios radiográficos de los ejemplares en proyecciones laterolateral izquierda derecha y ventro-dorsal utilizando un equipo de rayos X MSL modelo MSLVX17 (MSL ®, China); las imágenes fueron digitalizadas y analizadas para su estudio con el programa dicomPACS®DX-R (Santos-Santos et al, 2019). Los valores morfométricos de órganos internos provenientes de los distintos sistemas se realizaron mediante una incisión longitudinal desde la sínfisis mandibular hasta el pubis.…”