Mark D. Scherz

Reconciling molecular phylogeny, morphological divergence and classification of Madagascan narrow-mouthed frogs (Amphibia: Microhylidae)

A recent study clarified several aspects of microhylid phylogeny by combining DNA sequences from Sanger sequencing and anchored phylogenomics, although numerous aspects of tree topology proved highly susceptible to data partition and chosen model. Although the phylogenetic results of the study were in conflict with previous publications, the authors made several changes to the taxonomy of Madagascars cophyline microhylids. We re-analyzed part of their data together with our own molecular and morphological data. Based on a supermatrix of 11 loci, we propose a new phylogeny of the Cophylinae, and discuss it in the context of a newly generated osteological dataset. We found several sample misidentifications, partially explaining their deviant results, and propose to resurrect the genera Platypelis and Stumpffia from the synonymy of Cophyla and Rhombophryne, respectively. We provide support for the previous genus-level taxonomy of this subfamily, and erect a new genus, Anilany gen. nov., in order to eliminate paraphyly of Stumpffia and to account for the osteological differences observed among these groups. Deep nodes in our phylogeny remain poorly supported, and future works will certainly refine our classification, but we are confident that these will not produce large-scale rearrangements.

Widespread bone-based fluorescence in chameleons

Fluorescence is widespread in marine organisms but uncommon in terrestrial tetrapods. We here show that many chameleon species have bony tubercles protruding from the skull that are visible through their scales, and fluoresce under UV light. Tubercles arising from bones of the skull displace all dermal layers other than a thin, transparent layer of epidermis, creating a ‘window’ onto the bone. In the genus Calumma, the number of these tubercles is sexually dimorphic in most species, suggesting a signalling role, and also strongly reflects species groups, indicating systematic value of these features. Co-option of the known fluorescent properties of bone has never before been shown, yet it is widespread in the chameleons of Madagascar and some African chameleon genera, particularly in those genera living in forested, humid habitats known to have a higher relative component of ambient UV light. The fluorescence emits with a maximum at around 430 nm in blue colour which contrasts well to the green and brown background reflectance of forest habitats. This discovery opens new avenues in the study of signalling among chameleons and sexual selection factors driving ornamentation.

A review of the taxonomy and osteology of the Rhombophryne serratopalpebrosa species group (Anura: Microhylidae) from Madagascar, with comments on the value of volume rendering of micro-CT data to taxonomists

Over the last three years, three new species of saw-browed diamond frogs (Rhombophryne serratopalpebrosa species group)-a clade of cophyline microhylid frogs native to northern and eastern Madagascar-have been described. We here review the taxonomy of these frogs based on a new multi-gene phylogeny of the group, which confirms its monophyly but is insufficiently resolved to clarify most intra-group relationships. We confirm Rhombophryne guentherpetersi (Guibé, 1974) to be a member of this group, and we re-describe it based on its type series and newly collected material; the species is characterised by small superciliary spines (overlooked in its original description), as well as large tibial glands and an unusually laterally compressed pectoral girdle. We go on to describe two new species of this group from northern Madagascar: both R. diadema sp. nov. from the Sorata Massif and R. regalis sp. nov. from several sites in the northeast of the island possess three superciliary spines, but they are characterised by several subtle morphological and osteological differences. The new species are separated from all known congeners by an uncorrected pairwise distance of at least 5.1% in a ca. 550 bp fragment of the 16S rRNA gene. In order to highlight the significance of the skeleton in the taxonomy of this group, we provide a detailed description of its generalized osteology based on volume-rendered micro-CT scans of all described members, revisiting already-described skeletons of some species, and describing the skeletons of R. guentherpetersi, R. coronata, and the new taxa for the first time. Use of volume rendering, instead of surface rendering of micro-CT data, resulted in some discrepancies due to the properties of each method. We discuss these inconsistencies and their bearing on the relative value of surface and volume rendering in the taxonomists toolkit. We argue that, while surface models are more practical for the reader, volumes are generally a more objective representation of the data. Thus, taxonomic description work should be based on volume rendering when possible, with surface models presented as an aid to the reader.

Off the scale: a new species of fish-scale gecko (Squamata: Gekkonidae: Geckolepis) with exceptionally large scales

The gecko genus Geckolepis, endemic to Madagascar and the Comoro archipelago, is taxonomically challenging. One reason is its members ability to autotomize a large portion of their scales when grasped or touched, most likely to escape predation. Based on an integrative taxonomic approach including external morphology, morphometrics, genetics, pholidosis, and osteology, we here describe the first new species from this genus in 75 years: Geckolepis megalepis sp. nov. from the limestone karst of Ankarana in northern Madagascar. The new species has the largest known body scales of any gecko (both relatively and absolutely), which come off with exceptional ease. We provide a detailed description of the skeleton of the genus Geckolepis based on micro-Computed Tomography (micro-CT) analysis of the new species, the holotype of G. maculata, the recently resurrected G. humbloti, and a specimen belonging to an operational taxonomic unit (OTU) recently suggested to represent G. maculata. Geckolepis is characterized by highly mineralized, imbricated scales, paired frontals, and unfused subolfactory processes of the frontals, among other features. We identify diagnostic characters in the osteology of these geckos that help define our new species and show that the OTU assigned to G. maculata is probably not conspecific with it, leaving the taxonomic identity of this species unclear. We discuss possible reasons for the extremely enlarged scales of G. megalepis in the context of an anti-predator defence mechanism, and the future of Geckolepis taxonomy.

Two New Microhylid Frogs of the Genus Rhombophryne with Superciliary Spines from the Tsaratanana Massif in Northern Madagascar

Abstract:  The Rhombophryne serratopalpebrosa (Guibé 1975) species complex consists of numerous cryptic narrow-mouthed frogs (Microhylidae) mostly restricted to northern Madagascar. We here provide an updated phylogeny of the genus Rhombophryne, and formally define the R. serratopalpebrosa group, characterized by the possession of small, fleshy superciliary spines. We describe two new species belonging to this group from the Tsaratanana Massif in northern Madagascar: Rhombophryne ornata sp. nov. and R. tany sp. nov. Both of the new species have fewer superciliary spines above each eye than any other member of the group (2 vs. 3–4). Rhombophryne ornata sp. nov. is unusual in having fairly elaborate dorsal markings, and is unique in having reddish thighs. In contrast, R. tany sp. nov. is a truly cryptic species characterized by a combination of characters unique within the R. serratopalpebrosa group. Micro-CT scans revealed differences between the skeletons of these species and other members of the group: the pubis is unossified in both species, and R. ornata sp. nov. lacks ossification in the epiphyses of its limb bones and in many of its small bones. We give a full osteological description of these frog species to facilitate ongoing research concerning this group. Genetic data suggest that these two syntopic species might be sister to each other, but they show a substantial genetic divergence of 3.9% and 8.4% uncorrected pairwise distance in the mitochondrial 16S rRNA and cytochrome oxidase subunit I genes, respectively. As these species have a limited extent of occurrence, and are known only from a single location in a forest that is declining in quality, we propose they be listed as Vulnerable B1ab(iii) on the International Union for Conservation of Nature Red List.

Resurrection of the Comoran fish scale gecko Geckolepis humbloti Vaillant, 1887 reveals a disjunct distribution caused by natural overseas dispersal

Fish scale geckos (Geckolepis) are taxonomically poorly resolved, mainly because of the difficulty of applying standard morphological characters to diagnose taxa. Three species, Geckolepis maculata, G. polylepis, and G. typica, are currently recognized from Madagascar and the Comoro Islands. Molecular studies suggested a number of operational taxonomical units within the G. maculata complex, but none of these has been formally described. The Comoran population was described as Geckolepis humbloti Vaillant 1887 but later synonymized. Prior to our study, no genetic data and little other information were available for this taxon. We revised the status of G. humbloti using molecular genetics, external morphology, and osteological characters retrieved from 3D skeletal models created using micro-computed tomography (micro-CT). Our results demonstrate that G. humbloti represents a genetic lineage strongly distinct from all other Geckolepis species. It is furthermore distinguished by a combination of external morphological characters and probably by osteology. We therefore resurrect G. humbloti Vaillant, 1887 from synonymy with G. maculata. Remarkably, this lineage is not restricted to the Comoros: A specimen from Tsingy de Bemaraha in western Madagascar falls as a closely related sister lineage to all Comoran Geckolepis in our molecular phylogenetic analysis and is osteologically almost identical with a specimen from the type locality Grand Comoro. We therefore include it in G. humbloti. The phylogenetic topology and the intraspecific genetic divergences suggest that the Comoros were colonized naturally from western Madagascar by overseas dispersal. G. humbloti is not considered as threatened, but its presence is indicative of natural or near-natural habitats.

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.

Rising from the ashes: resurrection of the Malagasy chameleons Furcifer monoceras and F. voeltzkowi (Squamata: Chamaeleonidae), based on micro-CT scans and external morphology

The taxonomy of the Malagasy chameleon Furcifer rhinoceratus (Gray, 1845) is poorly resolved. The aim of this study is to clarify the taxonomic status of Chamaeleon voeltzkowi Boettger, 1893 and Chamaeleon monoceras Boettger, 1913 both only known from single or very few specimens mostly collected more than 100 years ago and currently considered as synonyms of Furcifer rhinoceratus. Using osteological data from micro-X-ray computed tomography (micro-CT) combined with traditional morphological characters and morphometrics we resurrect both taxa from the synonymy of F. rhinoceratus as F. voeltzkowi and F. monoceras, respectively. Compared to F. rhinoceratus, F. monoceras is smaller, has a relatively shorter tail, a longer and thinner rostral appendage, a poorly developed gular crest and no ventral crest, whereas F. voeltzkowi has a smaller rostral appendage, higher casque and the dorsal crest is continuous with the tail crest. Compared to the broad rostral appendage formed by the anterior protuberance of the premaxillary process of the maxilla, which has serrated edges in F. rhinoceratus, F. monoceras presents a long rostral appendage with a smooth dorsal edge that progressively narrows, and the nasal aperture is extended along the elongated appendage; F. voeltzkowi presents a smaller but curved rostral appendage with a crenate edge. The prefrontal and postorbitofrontal approach one another forming a large, laterally closed supraorbital fontanelle in F. rhinoceratus while in F. monoceras they do not approach, leaving a laterally open fontanelle, and in F. voeltzkowi the fontanelle is diminutive. Furcifer voeltzkowi also differs from the similar F. labordi by a smaller size of the rostral appendage, less bulging casque and body pholidosis. The former exhibits a conspicuous white lateral band comprising heterogeneous scalation. Furcifer labordi, on the other hand, has a homogeneous scalation with a remarkable reticulate pattern. Osteologically, the shape of the prefrontal and the connection of the postorbitofrontal with the parietal also differ greatly between the two. Using micro-CT scans we detected key differences that would be otherwise impossible to determine. We also provide a brief morphological and osteological description of the species and strongly recommend efforts to rediscover these two poorly known taxa in order to enable additional studies and to assess their conservation status.

Stumbling upon a New Frog Species of Guibemantis (Anura: Mantellidae) on Top of the Marojejy Massif in Northern Madagascar

We describe a new frog species of the genus Guibemantis, subgenus Pandanusicola, from Marojejy National Park in northeastern Madagascar. Guibemantis milingilingy, the new species, exhibits high genetic divergence from all other described species of Guibemantis based on DNA sequences of a fragment of the mitochondrial 16S rRNA gene. This new species inhabits Pandanus plants like the majority of other members of this subgenus, but is found at much higher elevations (2026 m a.s.l.). It differs from its closest relative, G. punctatus, by the lack of speckled or spotted dorsal patterns and by the presence of a distinctly dark tympanum. As a high-elevation species, it is likely to be a species sensitive to climate change, similar to other montane endemics in Madagascar.

Two new species of leaf-tailed geckos ( Uroplatus ) from the Tsaratanana mountain massif in northern Madagascar

The Tsaratanana Massif is the highest mountain massif of Madagascar and is characterized by a high species-level endemism of its biota. Here we describe two new small-sized species of leaf-tailed geckos of the Uroplatus ebenaui group from this region. Named in a preliminary way as confirmed candidate species Uroplatus ebenaui [Ca1] and [Ca2] in previous studies, we here provide detailed data on their molecular and morphological differentiation and describe them as Uroplatus fotsivava sp. nov. and Uroplatus kelirambo sp. nov. Their closest relatives are U. fiera and U. finiavana, respectively, as revealed by a phylogeny based on DNA sequences of four mitochondrial genes. However, integration of various lines of evidence confirms that the new species are independent evolutionary lineages, differing from other Uroplatus by high mitochondrial divergences, lack of haplotype sharing in the nuclear CMOS gene, and shape and relative size of the tail. While U. fotsivava is known from multiple sites at elevations between 1100-1538 m above sea level, U. kelirambo was found only at high elevations between 2000-2200 m a.s.l.; it therefore is the only known forest-dwelling nocturnal gecko reaching such high elevations in Madagascar, and might be narrowly endemic to montane forests of the Tsaratanana Massif.