Geographical and altitudinal distribution ofBrachycephalus(Anura: Brachycephalidae) endemic to the Brazilian Atlantic Rainforest

Abstract

Mountains of the Brazilian Atlantic Forest can act as islands of cold and wet climate, leading to the isolation and speciation of species with low dispersal capacity, such as the toadlet species of the genus Brachycephalus. This genus is composed primarily by diurnal species, with miniaturized body sizes (<2.5 cm), inhabiting microhabitats in the leaf litter of montane forests. Still, little is known about the geographical distribution, altitudinal range, and ecological limits of most Brachycephalus species. In this study, we review the available data on the geographical and altitudinal distribution of Brachycephalus based on occurrence records compiled from literature and museums, both for the genus as a whole and separately for the three recently proposed groups of species (ephippium, didactylus, and pernix). The final ensemble dataset comprised 333 records, 120 localities, 28 described species, and six undescribed ones. Species were recorded in six relief units, the richest of which being the Serra do Mar, with 30 species. When the Serra do Mar is subdivided into three subunits, Northern, Central and Southern Serra do Mar, the number of species increase from north to the south, with records of six, nine, and 16 species, respectively. We were able to estimate the extent of occurrence of nearly half of the described species, and the resulting estimates indicate that many of them show remarkably small ranges, some of which less than 50 ha. Brachycephalus species are present from sea level to roughly 1,900 m a.s.l., with the highest richness being found between 751 and 1,000 m a.s.l. (21 spp.). The species with the broadest altitudinal range were B. didactylus (1,075 m) and Brachycephalus sp. 1 (1,035 m), both in the didactylus group, and B. ephippium (1,050 m), of the ephippium group. The broadest altitudinal amplitude for species of the pernix group was recorded for B. brunneus (535 m). The lowest altitudinal records for the pernix group were at 845 m a.s.l. in the state of Paraná and at 455 m a.s.l. in the state of Santa Catarina. The altitudinal occurrence in the pernixspecies group seems to decrease southward. Syntopy between species is also reviewed.

A new species ofBrachycephalus(Anura: Brachycephalidae) from Santa Catarina, southern Brazil

“…Given the dense sampling of other potential locations with climatic and vegetation conditions similar to the type locality (Fig. 7), it likely that B. albolineatus has a microendemic distribution, as found in other species of the pernix group (Bornschein et al, 2016). For instance, we searched for the new species on a mountain named Pedra Branca just 4.8 km from the type locality (26°32′52″S, 49°05′11″W) on the border of the municipalities of Jaraguá do Sul and Massaranduba, Santa Catarina, on 6 March 2016.…”

“…Bornschein et al (2016) and Firkowski et al (2016) postulated that altitudinal migration and population isolation during the climatic variation that occurred during the Quaternary could explain the richness and the relatively widespread distribution of montane Brachycephalus throughout the Atlantic Forest. In particular, during cold and dry periods, montane forests would have migrated into lower altitudes and allowed ancestral lineages to be widespread, whereas hot and wet periods led montane forests to shift upwards to mountain tops, isolating populations and leading to speciation (Bornschein et al, 2016; Firkowski et al, 2016).…”

“…Brachycephalus Fitzinger, 1826 is a remarkable genus of miniaturized frogs endemic to the Brazilian Atlantic Forest (Pie et al, 2013; Bornschein et al, 2016). Brachycephalus species often display an extraordinarily high level of endemism, with one or a few adjacent mountaintops representing the entire known geographical ranges of many species (e.g., Ribeiro et al, 2015; Bornschein et al, 2016).…”

“…Brachycephalus species often display an extraordinarily high level of endemism, with one or a few adjacent mountaintops representing the entire known geographical ranges of many species (e.g., Ribeiro et al, 2015; Bornschein et al, 2016). Such extreme endemism is probably due to their particular cold/humid environmental requirements found in high-elevation regions, as in the case of cloud forests (see Pie et al, 2013; Bornschein et al, 2016). Firkowski et al (2016) recently studied the process of diversification of montane Brachycephalus species using a combination of species delimitation methods and molecular divergence dating.…”

“…In the present study, we describe a new species of the pernix species group from northeastern state of Santa Catarina, southern Brazil. This discovery is part of a continuing effort to investigate montane anurans of southern Brazil (see Bornschein et al, 2015; Bornschein et al, 2016; Pie & Ribeiro, 2015; Ribeiro et al, 2015; Firkowski et al, 2016). …”