Research Article |
Corresponding author: Mark D. Scherz ( mark.scherz@gmail.com ) Academic editor: Johannes Penner
© 2018 Mark D. Scherz, Oliver Hawlitschek, Jary H. Razafindraibe, Steven Megson, Fanomezana Mihaja Ratsoavina, Andolalao Rakotoarison, Molly C. Bletz, Frank Glaw, Miguel Vences.
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Citation:
Scherz MD, Hawlitschek O, Razafindraibe JH, Megson S, Ratsoavina FM, Rakotoarison A, Bletz MC, Glaw1 F, Vences M (2018) A distinctive new frog species (Anura, Mantellidae) supports the biogeographic linkage of two montane rainforest massifs in northern Madagascar. Zoosystematics and Evolution 94(2): 247-261. https://doi.org/10.3897/zse.94.21037
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We describe a new species of the genus Gephyromantis, subgenus Gephyromantis Vatomantis (Mantellidae, Mantellinae), from moderately high elevation (1164–1394 m a.s.l.) on the Marojejy, Sorata, and Andravory Massifs in northern Madagascar. The new species, Gephyromantis (Vatomantis) lomorinasp. n. is highly distinct from all other species, and was immediately recognisable as an undescribed taxon upon its discovery. It is characterised by a granular, mottled black and green skin, reddish eyes, paired subgular vocal sacs of partly white colour, bulbous femoral glands present only in males and consisting of three large granules, white ventral spotting, and a unique, amplitude-modulated advertisement call consisting of a series of 24–29 rapid, quiet notes at a dominant frequency of 5124–5512 Hz. Genetically the species is also strongly distinct from its congeners, with uncorrected pairwise distances ≥10 % in a fragment of the mitochondrial 16S rRNA gene to all other nominal Gephyromantis species. A molecular phylogeny based on 16S sequences places it in a clade with species of the subgenera Laurentomantis and Vatomantis, and we assign it to the latter subgenus based on its morphological resemblance to members of Vatomantis. We discuss the biogeography of reptiles and amphibians across the massifs of northern Madagascar, the evidence for a strong link between Marojejy and Sorata, and the role of elevation in determining community sharing across this landscape.
Bioacoustics, Biogeography, Marojejy, Montane Endemism, Sorata, Taxonomy
In recent decades, the number of frog species that have been discovered in Madagascar, while steadily increasing (
At present, 44 species of Gephyromantis are recognized and assigned to six subgenera (Asperomantis, Duboimantis, Gephyromantis, Laurentomantis, Phylacomantis, and Vatomantis) based on molecular and morphological criteria (
Specimens were collected at night using head torches along montane streams, euthanized using MS222 anaesthesia and subsequent overdose, fixed in 96 % ethanol, and deposited in 75 % ethanol for long-term storage. Tissue samples were stored in 96 % ethanol. Field numbers refer to the zoological collections of Miguel Vences (ZCMV), Frank Glaw (FGZC), and Steven Megson (SM). Specimens were deposited in the amphibian collections of the Mention Zoologie et Biodiversité Animale, Université d’Antananarivo (
Morphological measurements were taken to the nearest 0.1 mm using a digital calliper. Measurement schemes followed generally previous work on the genus (e.g.
DNA was extracted from tissue samples using a Qiagen DNeasy blood & tissue kit (Qiagen, Hilden, Germany), or standard salt extraction protocols. For two samples from Sorata and one sample from Marojejy (ZCMV 15269), we amplified a fragment of the mitochondrial 16S rRNA gene (hereafter 16S) in 25 µl polymerase chain reactions with the primers 16Sra-L and 16Sb-H (
For an exploratory analysis, we aligned the new sequences with 16S sequences used by
We aligned sequences in MEGA 7 (
Recordings from Marojejy were made on a Marantz PMD661 MKII with a Sennheiser ME66/K6 supercardioid microphone, at a bandwidth of 44.1 kHz. Recordings from Sorata were made on an Edirol R-09 with its internal microphone. Call analysis was conducted in Cooledit 2.0 (Syntrillium Corp.). To obtain frequency information, the recording was transformed with Fast Fourier Transformation (FFT; width 1024 points). Spectrograms were created with a Hanning window of 512 or 256 bands. Measurements are given as mean ± one standard deviation, with range in parentheses. Terminology follows the recently-published recommendations of
The electronic version of this article in Portable Document Format (PDF) will represent a published work according to the International Commission on Zoological Nomenclature (ICZN), and hence the new names contained in the electronic version are effectively published under that Code from the electronic edition alone. This published work and the nomenclatural act it contains have been registered in ZooBank, the online registration system for the ICZN. The ZooBank LSIDs (Life Science Identifiers) can be resolved and the associated information viewed through any standard web browser by appending the LSID to the prefix http://zoobank.org/. The LSID for this publication is urn:lsid:zoobank.org:pub:8A83DE58-A2EE-494F-A03C-820DC836CDDF. The online version of this work will be archived and made available from the following digital repositories: CLOCKSS and Zenodo.
Based on 16S sequences, the newly collected specimens represent an undescribed and hitherto unknown species of Gephyromantis that is highly distinct from all others (≥10 % p-distance). Exploratory phylogenetic analyses including all species of Gephyromantis clearly suggested their relationships with the subgenera Laurentomantis and Vatomantis, which also is strongly supported by morphological affinities, in particular by the greenish dorsal colour, granular skin, riparian habits, and paired subgular vocal sacs of partly white colour in males (see Diagnosis below for more details). A phylogenetic analysis of 16S sequences (total alignment length 532 bp) for all described species of Laurentomantis and Vatomantis as well as G. klemmeri, which was related to these subgenera in the multi-gene analysis of
Preliminary phylogenetic tree of Gephyromantis (Vatomantis) lomorina sp. n., based on Maximum Likelihood analysis of a 532 bp fragment of the mitochondrial 16S rRNA gene. Numbers at nodes indicate bootstrap values in percent (500 replicates, above) and posterior probabilities from a Bayesian Inference analysis (20 million generations, below), shown only if >50 % (bootstrap) or >90 % (posterior probabilities). Each specimen/species is followed by the corresponding GenBank accession number used in the alignment. Schematic drawings of femoral glands of all species in the subgenera Laurentomantis and Vatomantis as well as of G. klemmeri are shown to the right of the phylogeny, and coloured according to the subgenus to which they are assigned.
Phenotypically the new specimens bear resemblance to both Laurentomantis and Vatomantis. Their advertisement call is more similar to Laurentomantis, but their morphological resemblance to Vatomantis is greater (see the diagnosis below). We here tentatively assign them to Vatomantis due to their morphological affinities and preliminary phylogenetic relationships. Given their very high genetic divergence to all other Gephyromantis, isolated phylogenetic position (not placed as close sister group to any other species), and morphological and bioacoustic differences, there is no doubt that these specimens belong to a new species, which we describe below.
Photographs of Gephyromantis (Vatomantis) lomorina sp. n. and its habitat in Sorata. (a,d)
A species assigned to the genus Gephyromantis on the basis of its granular skin, moderately enlarged finger tips, small femoral glands consisting of a small number of large granules and present in males only (thus of type 2 as defined by
Within the genus Gephyromantis, G. lomorina sp. n. can be distinguished from all subgenera except Laurentomantis and Vatomantis on the basis of the combination of femoral glands composed of few large granules (vs. composed of many, small granules; note that G. klemmeri is here treated separately from all other subgenera, below, due to its unclear assignment), SVL < 26 mm (vs. > 27 mm in all other subgenera except Gephyromantis), absence of a white stripe along the upper lip (vs. general presence in subgenus Gephyromantis), and absence of distinctly enlarged supraocular spines (vs. presence in Asperomantis and some Duboimantis). It may be distinguished from all members of the subgenus Laurentomantis (G. ventrimaculatus (Angel), G. malagasius (Methuen & Hewitt), G. striatus (Vences, Glaw, Andreone, Jesu & Schimmenti), G. horridus (Boettger), and G. ranjomavo Glaw & Vences) by paired subgular vocal sacs (vs. single), absence of outer metatarsal tubercles (vs. presence), and at least partly greenish dorsal skin (vs. mostly yellowish to brown to reddish), and from several of these by the absence of tibial glands in males (vs. typical presence). Within the subgenus Vatomantis, G. lomorina sp. n. may be distinguished from all species by its more granular dorsal skin (vs. granular but not rough) and venter spotted with white (vs. generally without whitish spotting except on the chin and over the sternum); from G. rivicola (Vences, Glaw & Andreone) and G. webbi (Grandison) by its reddish iris colouration (vs. copper and greenish, respectively); from G. silvanus (Vences, Glaw & Andreone) by its smaller size (SVL 20.5–25.5 mm vs. 31 mm) and partly whitish vocal sacs (vs. yellowish); from G. webbi by femoral glands composed of few large granules (vs. composed of many, small granules) and large inner metatarsal tubercle (vs. small). Gephyromantis lomorina sp. n. may be distinguished from G. klemmeri by its roughly granular dorsal skin (vs. smooth to shagreened), greenish skin colour (vs. brownish), reddish iris (vs. gold), and strongly protruding inner metatarsal tubercle (vs. small and not protruding).
The call of G. lomorina sp. n. may be distinguished from all Vatomantis and Laurentomantis species in having notes that are clearly pulsed (vs. unpulsed notes in all species except G. ventrimaculatus); Gephyromantis ventrimaculatus has a higher number of pulses per note notes than G. lomorina sp. n. (ca. 6 pulses per note vs. 2–4 in G. lomorina sp. n.). The call of G. lomorina sp. n. is somewhat similar to that of G. klemmeri, especially in having pulsed notes, but the call duration is much longer (1681–1827 ms vs. 626–982 ms), the call has a more distinct amplitude decay (vs. complex amplitude modulation, see
A specimen in a good state of preservation, a piece of tissue taken from the left thigh. SVL 23.3 mm; for other body measurements see Table
Morphological data on specimens of Gephyromantis lomorina sp. n. Abbreviations: m = male, f = female, sa = subadult; for measurement abbreviations, see the Materials and methods. The holotype is bolded. Additive measurements (FARL, FORL, and HIL) are not explicitly shown but can be deduced from these data.
Catalogue (field number) | Sex | SVL | HW | HL | TD | ED | END | NSD | NND | UAL | LAL | HAL | THIL | TIBL | TARL | FOL | FGL | FGW |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
m | 23.3 | 7.2 | 8.5 | 2.1 | 4.0 | 2.2 | 1.4 | 2.2 | 6.0 | 7.3 | 8.2 | 13.4 | 13.9 | 7.4 | 12.1 | 2.8 | 2.0 |
|
m | 22.2 | 6.6 | 8.2 | 1.9 | 3.4 | 2.1 | 1.5 | 2.2 | 4.8 | 6.0 | 8.0 | 12.2 | 12.8 | 7.0 | 10.6 | 2.2 | 1.8 |
|
m | 23.0 | 7.3 | 9.1 | 1.9 | 3.0 | 1.9 | 1.5 | 2.1 | 5.1 | 6.8 | 8.2 | 11.5 | 13.3 | 7.0 | 11.8 | 2.2 | 1.5 |
|
f | 25.5 | 7.7 | 9.1 | 2.0 | 4.1 | 2.4 | 1.4 | 2.1 | 5.2 | 7.7 | 8.4 | 13.6 | 14.8 | 6.7 | 12.6 | n/a | n/a |
|
m | 22.1 | 6.5 | 8.0 | 2.7 | 3.4 | 1.5 | 1.4 | 1.9 | 4.9 | 6.1 | 7.2 | 10.8 | 12.3 | 6.4 | 11.0 | 2.6 | 1.6 |
|
f | 24.6 | 7.6 | 9.0 | 2.0 | 3.8 | 2.2 | 1.4 | 2.1 | 6.4 | 6.4 | 8.3 | 12.1 | 13.5 | 7.3 | 12.4 | n/a | n/a |
|
sa | 20.2 | 5.7 | 7.8 | 1.6 | 3.1 | 1.9 | 1.6 | 1.9 | 4.8 | 5.9 | 7.6 | 11.1 | 12.0 | 6.6 | 9.5 | n/a | n/a |
|
f | 24.6 | 8.0 | 8.7 | 2.1 | 3.5 | 2.4 | 1.3 | 2.2 | 5.7 | 6.1 | 8.6 | 12.4 | 14.7 | 7.3 | 12.0 | n/a | n/a |
|
f | 23.2 | 6.8 | 8.5 | 2.0 | 3.6 | 2.0 | 1.4 | 2.0 | 5.6 | 6.9 | 8.1 | 12.6 | 14.9 | 7.6 | 11.6 | n/a | n/a |
|
f | 22.0 | 7.0 | 8.1 | 2.1 | 3.5 | 2.3 | 1.5 | 2.0 | 5.0 | 6.0 | 7.5 | 10.4 | 12.4 | 7.0 | 11.6 | n/a | n/a |
|
m | 23.3 | 8.0 | 8.3 | 2.3 | 3.3 | 2.6 | 1.5 | 1.9 | 5.8 | 6.7 | 8.8 | 11.1 | 13.2 | 6.7 | 12.6 | 3.0 | 2.1 |
|
m | 22.8 | 7.1 | 8.0 | 2.2 | 3.0 | 2.8 | 1.5 | 2.1 | 6.0 | 6.9 | 8.1 | 11.9 | 13.1 | 6.7 | 13.2 | 2.9 | 2.1 |
|
m | 24.6 | 8.0 | 9.7 | 2.2 | 3.3 | 2.8 | 1.6 | 2.3 | 7.0 | 7.5 | 9.3 | 13.1 | 14.5 | 6.6 | 13.4 | 3.4 | 2.5 |
|
m | 23.9 | 8.1 | 9.1 | 2.2 | 3.4 | 2.6 | 1.6 | 2.2 | 6.4 | 7.0 | 9.5 | 12.1 | 14.2 | 6.5 | 13.6 | 2.5 | 2.1 |
|
f | 24.1 | 7.7 | 9.2 | 2.2 | 2.8 | 2.8 | 1.4 | 2.2 | 5.5 | 6.6 | 9.3 | 12.5 | 14.0 | 6.5 | 13.8 | n/a | n/a |
|
f | 25.2 | 7.9 | 9.4 | 2.1 | 2.6 | 3.0 | 2.0 | 2.4 | 7.1 | 6.4 | 8.9 | 13.6 | 14.2 | 7.2 | 13.6 | n/a | n/a |
Colouration in life (Fig.
After six months in preservative, the colouration of the holotype has faded to become more uniformly brownish, and areas that were greenish in life have become cream. White areas of the venter are still immaculately white.
All paratypes resemble the holotype in gross morphology; see Table
Call recordings were made in Marojejy from the holotype
Spectrogram (above) and waveform (below) of a call of the holotype of Gephyromantis (Vatomantis) lomorina sp. n.,
Similar calls were recorded in Sorata from
The new species is known from three localities in northeastern Madagascar: (1) Marojejy National Park (type locality), (2) Sorata massif, and (3) Andravory massif (Fig.
Distribution of Gephyromantis (Vatomantis) lomorina sp. n. in northern Madagascar. Areas with diagonal lines are official protected areas. The dotted outline indicates the proposed area with the scope of the WWF protection plan for this part of Madagascar (
Specimens were collected near mountain streams in pristine montane riparian rainforest (Fig.
There are no other, earlier names currently available (e.g., junior synonyms) that are assignable to the subgenera Vatomantis or Laurentomantis and that could apply to the new species.
The specific epithet is the Malagasy word lomorina, meaning ‘covered in moss’, in reference to the green, mossy appearance of the species in life. It is used as an invariable noun in apposition to the genus name.
The species occurs in two regions with very different conservation situations: the highly protected forests of Marojejy National Park, and the unprotected, isolated, and highly threatened forests of Sorata and Andravory.
By contrast in Marojejy, forest extends down to roughly 200 m a.s.l., is highly protected, and the high elevation forest where this species occurs does not seem to be facing any immediate threats. Although the tourist load to Marojejy is relatively high, and the area upslope from the collection locality of the holotype and several paratypes is somewhat polluted with refuse from the nearby tourist camp, the species was abundant around this stream during our survey there in 2016, and presumably inhabits other streams around the same elevation across the massif.
Accommodating this spread of risk is a challenge for the IUCN Red List status. However, G. (V.) lomorina sp. n. is not the first species to have almost exactly this distribution. Rhombophryne vaventy Scherz, Ruthensteiner, Vences & Glaw was recently recovered from Sorata (
Gephyromantis (Vatomantis) lomorina sp. n. is a distinctive species, mostly due to its granular, greenish skin, which is rougher than in all other members of the subgenus Vatomantis, but not as rugose as in many species of the subgenus Laurentomantis. Indeed, it is in several aspects intermediate between these subgenera, having a call that sounds similar to both (
Gephyromantis (Vatomantis) rivicola, G. (V.) silvanus, G. (V.) lomorina sp. n., and most Laurentomantis species share a unique femoral gland morphology with glands being composed of a small number of large, round granules (each granule representing a single gland within the femoral macrogland;
The apparently highly divergent G. (V.) lomorina sp. n. sheds some light on questions regarding the relationships of G. klemmeri. Formerly, G. klemmeri was considered a member of the subgenus Gephyromantis, but
Gephyromantis (Vatomantis) lomorina sp. n. also sheds light on the biogeography of northern Madagascar, providing yet more evidence for a strong link between Sorata and Marojejy. The environmental conditions of these two regions are similar (
We predict that similarities between faunal compositions of the mountainous massifs of northern Madagascar are limited by elevational connectivity. For instance, there is continued connectivity between regions of elevation up to 1400 m from Sorata to Marojejy and indeed roughly to the Manongarivo massif as well. There is no connectivity above this elevation however; areas of over 1400 m across the different massifs are separated by lower elevations, leading to island-like isolation of peak areas. Therefore, we predict that species occurring above 1400 m will show a greater degree of microendemism, and those below this elevation will have a greater probability of occurring more widely; the higher a species’ centre of elevational distribution is located, the greater its chance of being microendemic. No absolute threshold of turnover is expected, because major climate fluctuations in the past will likely have blurred elevational boundaries over time.
So far, evidence appears to support this hypothesis; as already stated, several species from around 1300 m are shared between Marojejy and Sorata (and Andravory, though at present only limited and generally unpublished data are available from this forest), and some species known from higher elevations are so far thought to be microendemic to either region, e.g. Rhombophryne longicrus (
As always, we are grateful to the Malagasy authorities of the Ministry of Environments and Forests for providing us with permits. Field research was conducted under permit No 215/16/MEEF/SG/DGF/DSAP/SCB.Re (dated 5 September 2016) and N° 265/12/MEF/SG/DGF/DCB.SAP/SCB (dated 18 October 2012). Specimens were exported under permits N° 010N-EA01/MG17 (dated 4 January 2017) and N° 163N-EA12/MG12 (dated 17 December 2012). This work was carried out in collaboration with the Mention Zoologie et Biodiversité Animale, Universite d’Antananarivo, to whom we are also grateful for the loan of the paratype series. We are also grateful to R. Walker, W.-Y. Crawley, T. H. Rafeliarisoa, and the Andravory team for their help in Andravory, and A. Razafimanantsoa and T. Rajoafiarison for their help in Marojejy and Sorata. AR and MCB were supported by fellowships of the Deutscher Akademischer Austauschdienst. MV and MDS were supported by grants of the Deutsche Forschungsgemeinschaft (VE247/13-1 and 15-1). The fieldwork of OH, FG, AR, and FR was supported by the Mohamed bin Zayed Species Conservation Fund (project 11253064). The publication of this article in Zoosystematics and Evolution was made possible by the Museum für Naturkunde Berlin.
Advertisement call of Gephyromantis lomorina sp. n.
Data type: WAV File (.wav)
Explanation note: Call recording of Gephyromantis (Vatomantis) lomorina sp. n.
Advertisement call of Gephyromantis lomorina sp. n.
Data type: WAV File (.wav)
Explanation note: Call recording of Gephyromantis (Vatomantis) lomorina sp. n.