Repeated divergence of amphibians and reptiles across an elevational gradient in northern Madagascar.

How environmental factors shape patterns of biotic diversity in tropical ecosystems is an active field of research, but studies examining the possibility of ecological speciation in terrestrial tropical ecosystems are scarce. We use the isolated rainforest herpetofauna on the Montagne d'Ambre (Amber Mountain) massif in northern Madagascar as a model to explore elevational divergence at the level of populations and communities. Based on intensive sampling and DNA barcoding of amphibians and reptiles along a transect ranging from ca. 470-1470 m above sea level (a.s.l.), we assessed a main peak in species richness at an elevation of ca. 1000 m a.s.l. with 41 species. The proportion of local endemics was highest (about 1/3) at elevations >1100 m a.s.l. Two species of chameleons (Brookesia tuberculata, Calumma linotum) and two species of frogs (Mantidactylus bellyi, M. ambony) studied in depth by newly developed microsatellite markers showed genetic divergence up the slope of the mountain, some quite strong, others very weak, but in each case with genetic breaks between 1100 and 1270 m a.s.l. Genetic clusters were found in transect sections significantly differing in bioclimate and herpetological community composition. A decrease in body size was detected in several species with increasing elevation. The studied rainforest amphibians and reptiles show concordant population genetic differentiation across elevation along with morphological and niche differentiation. Whether this parapatric or microallopatric differentiation will suffice for the completion of speciation is, however, unclear, and available phylogeographic evidence rather suggests that a complex interplay between ecological and allopatric divergence processes is involved in generating the extraordinary species diversity of Madagascar's biota. Our study reveals concordant patterns of diversification among main elevational bands, but suggests that these adaptational processes are only part of the complex of processes leading to species formation, among which geographical isolation is probably also important.

Sympatric lineages in the Mantidactylus ambreensis complex of Malagasy frogs originated allopatrically rather than by in-situ speciation.

Madagascar's biota is characterized by a high degree of microendemism at different taxonomic levels, but how colonization and in-situ speciation contribute to the assembly of local species communities has rarely been studied on this island. Here we analyze the phylogenetic relationships of riparian frogs of the Mantidactylus ambreensis species complex, which is distributed in the north of Madagascar and was originally described from Montagne d'Ambre, an isolated mountain of volcanic origin, currently protected within Montagne d'Ambre National Park (MANP). Data from mitochondrial DNA, and phylogenomic data from FrogCap, a sequence capture method, independently confirm that this species complex is monophyletic within the subgenus Ochthomantis, and identify two main clades within it. These two clades are separated by 5.6-6.8% pairwise distance in the mitochondrial 16S rRNA gene and co-occur in MANP, with one distributed at high elevations (940-1375 m a.s.l.) and the other at lower elevations (535-1010 m a.s.l.), but show almost no haplotype sharing in the nuclear RAG1 gene. This occurrence in syntopy without admixture confirms them as independent evolutionary lineages that merit recognition as separate species, and we here refer to them as high-elevation (HE) and low-elevation (LE) lineage; they will warrant taxonomic assessment to confidently assign the name ambreensis to one or the other. Populations of the M. ambreensis complex from elsewhere in northern Madagascar all belong to the LE lineage, although they do occur over a larger elevational range than in Montagne d'Ambre (285-1040 m a.s.l.). Within LE there are several phylogroups (LE1-LE4) of moderately deep divergence (1.5-2.8% in 16S), but phylogroup LE4 that occurs in MANP has a deeply nested phylogenetic position, as recovered separately by mitochondrial and sequence capture datasets. This suggests that HE and LE did not diverge by a local fission of lower and upper populations, but instead arose through a more complex biogeographic scenario. The branching pattern of phylogroups LE1-LE4 shows a clear south-to-north phylogeographic pattern. We derive from these results a testable hypothesis of vicariant speciation that restricted the HE lineage to MANP and the LE candidate species to a climatic refugium further south, with subsequent northwards range expansion and secondary colonization of MANP by LE. These results provide an example for complex assembly of local microendemic amphibian faunas on Madagascar.

Description of the lucky Cophyla (Microhylidae, Cophylinae), a new arboreal frog from Marojejy National Park in north-eastern Madagascar.

We describe a new species of arboreal microhylid frog from northern Madagascar. The new species is assigned to the genus Cophyla based on molecular phylogeny and morphological similarities to other species of this genus. Molecular phylogenetic analysis resolved Cophyla fortuna sp. nov. as closely related to C. noromalalae. However, the two species were reciprocally monophyletic both in a tree reconstructed from a combination of mitochondrial genes, and in a tree based on the nuclear RAG-1 gene. The new species, previously identified as candidate species Cophyla sp. Ca4, occurs in lowland bamboo forests around the Marojejy Massif in northeastern Madagascar. It differs from the allopatric C. noromalalae, so far only known from the Montagne d'Ambre Massif in northern Madagascar, by slightly smaller body size and shorter duration and higher spectral frequency of advertisement calls. Several additional genetically divergent mitochondrial lineages of Cophyla, related to the C. fortuna/noromalalae complex and to C. phyllodactyla, occur in intervening areas between Montagne d'Ambre and Marojejy, and their status requires further study.

Finaritra! A splendid new leaf-tailed gecko (Uroplatus) species from Marojejy National Park in north-eastern Madagascar.

The Marojejy Massif in northern Madagascar is a constant source of herpetological surprises. Herein we describe a new species of leaf-mimicking leaf-tailed gecko, Uroplatus finaritra sp. nov., based on morphological and molecular phylogenetic evidence. This new species inhabits the rainforests of Marojejy National Park at low elevations and is morphologically similar to Uroplatus phantasticus, but differs by having a larger body size, relatively shorter tail, and dark-red pigmentation of the oral mucosa. Molecular data reveals a distance of 14.0-14.7% in the 16S rRNA gene to U. phantasticus, and haplotype sharing in the c-mos nuclear gene only with species of much shorter tails (i.e., with U. kelirambo and two undescribed candidate species). Similar to other members of the leaf-mimicking Uroplatus species in northern Madagascar, Uroplatus finaritra sp. nov. likely has a small geographic distribution, and is currently known only from the lowland rainforests of Marojejy. We discuss the value of the buccal mucosa colouration and tail dimensions of Uroplatus as taxonomic characters, and the potential drivers of their evolution. In order to reduce the risk of international trade under incorrect species names we suggest that exported CITES species should be obligatorily accompanied by information about their precide geographic origin within Madagascar.

Yet another small brown frog from high altitude on the Marojejy Massif, northeastern Madagascar (Anura: Mantellidae).

Madagascar hosts a high diversity of small brown frogs. In this paper, we add another one by describing Gephyromantis (Duboimantis) tohatra sp. nov. The new species is a small brown mantellid frog discovered on a recent expedition to Marojejy National Park in northeastern Madagascar. It is characterised, among other things, by its small size (snout-vent length ~33 mm), an orange to yellowish belly, two dorsolateral ridges, and a distinctive call composed of 7-10 pulsed notes. The new species occurs sympatrically with other members of the subgenus Duboimantis at high altitude (~1700 m above sea level), including its sister species G. schilfi from which it radically differs by advertisement call and by a substantial genetic divergence of 4.3% uncorrected pairwise distance in the mitochondrial 16S rRNA gene. It thus joins the diverse assemblage of Gephyromantis species known from high altitudes on the mountain massifs of northern Madagascar.