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| Mantidactylus (Ochthomantis) ambony Scherz, Rasolonjatovo, Köhler, Rancilhac, Rakotoarison, Raselimanana, Ohler, Preick, Hofreiter, Glaw & Vences, 2020 Mantidactylus (Ochthomantis) ambreensis Mocquard, 1895 |
Abstract
Taxonomic progress is often hindered by intrinsic factors, such as morphologically cryptic species that require a broad suite of methods to distinguish, and extrinsic factors, such as uncertainties in the allocation of scientific names to species. These uncertainties can be due to a wide variety of factors, including old and poorly preserved type specimens (which contain only heavily degraded DNA or have lost important diagnostic characters), inappropriately chosen type specimens (e.g. juveniles without diagnostic characters) or poorly documented type specimens (with unprecise, incorrect, or missing locality data). Thanks to modern sequencing technologies it is now possible to overcome many such extrinsic factors by sequencing DNA from name-bearing type specimens of uncertain assignment and assigning these to known genetic lineages. Here, we apply this approach to frogs of the Mantidactylus ambreensis complex, which was recently shown to consist of two genetic lineages supported by concordant differentiation in mitochondrial and nuclear genes. These lineages co-occur on the Montagne dʼAmbre Massif in northern Madagascar but appear to have diverged in allopatry. We use a recently published bait set based on three mitochondrial markers from all known Malagasy frog lineages to capture DNA sequences from the 127-year-old holotype of Mantidactylus ambreensis Mocquard, 1895. With the obtained sequences we are able to assign the name M. ambreensis to the lowland lineage, which is rather widespread in the rainforests of northern Madagascar, leaving the microendemic high-elevation lineage on Montagne d’Ambre in north Madagascar in need of description. We describe this species as Mantidactylus ambony sp. nov., differing from M. ambreensis in call parameters and a smaller body size. Thus, using target enrichment to obtain DNA sequence data from this old specimen, we were able to resolve the extrinsic (nomenclatural) hindrances to taxonomic resolution of this complex. We discuss the broad-scale versatility of this ‘barcode fishing’ approach, which can draw on the enormous success of global DNA barcoding initiatives to quickly and efficiently assign type specimens to lineages.
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| Preserved holotypes of Mantidactylus (Ochthomantis) ambony sp. nov. (adult female, ZSM 2078/2007) and Mantidactylus ambreensis (adult female, MNHN 1893.241) in dorsal and ventral views. |
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| Individuals of Mantidactylus(Ochthomantis) ambony sp. nov. from Montagne dʼAmbre in life, in dorsolateral (left) and ventral (right) views. (A,B) female holotype (ZSM 2078/2007); (C,D) adult male paratype (ZFMK 57417, call voucher). |
Mantidactylus (Ochthomantis) ambony sp. nov
Natural history: As for M. ambreensis, this species is rheophilous and mostly terrestrial by day, sitting on the ground, on rocks, wood, lichen, or hiding under rocks, always in close proximity to streams. The species is semi-arboreal by night, often found on elevated spots above the water level (once recorded at up to 2 m height), and sitting on substrates like leaves, rocks, dead wood, and plant stems. Its soft calls are emitted sporadically, and often from rather concealed positions.
Etymology: The species epithet ‘ambony’ (pronounced am-BOO-nee) is a Malagasy word meaning ‘above’, in reference to this species’ distribution at higher elevation compared to that of M. ambreensis. It is used as an invariable noun in apposition.
Distribution and conservation status: Mantidactylus ambony sp. nov. is apparently microendemic to mid- to high-elevation areas of Montagne d’Ambre (recorded elevational range 940–1375 m a. s. l.[Rasolonjatovo, et al. 2020]). In the absence of current or immediate future threats to habitat integrity we suggest an IUCN conservation status of Near Threatened for this species despite its small extent of occurrence, as we have recently proposed for syntopic Stumpffia species[Rakotoarison, et al., 2017].
Mark D. Scherz, Safidy M. Rasolonjatovo, Jörn Köhler, Loïs Rancilhac, Andolalao Rakotoarison, Achille P. Raselimanana, Annemarie Ohler, Michaela Preick, Michael Hofreiter, Frank Glaw and Miguel Vences. 2020. ‘Barcode Fishing’ for Archival DNA from Historical Type Material Overcomes Taxonomic Hurdles, Enabling the Description of A New Frog Species. Scientific Reports. 10: 19109. DOI: 10.1038/s41598-020-75431-9
