Sunday, January 30, 2022

[Herpetology • 2021] Gephyromantis pedronoi • Target-enriched DNA Sequencing Clarifies the Identity of Name-bearing Types of the Gephyromantis plicifer complex (Anura: Mantellidae) and reveals A New Species of Mantellid Frog from Madagascar


Gephyromantis (Duboimantis) pedronoi 
Vences, Köhler, Andreone, Craul, Crottini, du Preez, Preick, Rancilhac, Rödel, Scherz, Streicher, Hofreiter & Glaw, 2021

 Spixiana. 44(2); 175-202. 

Mantellid frogs of the Madagascar-endemic Gephyromantis plicifer complex consist of three nominal species (G. luteus, G. plicifer and G. sculpturatus) as well as several genetically divergent lineages (candidate species), but uncertainties surround the identity of the name-bearing types of all three established nomina. We applied laboratory techniques to isolate archival DNA from the three old, liquidpreserved, name-bearing type specimens and conducted target-enriched DNA sequencing of a fragment of the mitochondrial 16S rRNA gene as basis for the revision of their taxonomy. Along with 16S sequences of 161 fresh samples, sequences of a fragment of the nuclear-encoded Rag-1 gene for 97 of these samples, a multi-gene data set of selected samples, and a comprehensive analysis of available advertisement call recordings, the new data suggest a novel taxonomic hypothesis: (1) The name G. plicifer applies to a highland clade of populations from the southern Central East, previously referred to as Gephyromantis sp. Ca21, with G. sculpturatus as a junior synonym. (2) The name G. luteus applies to a widespread clade distributed along most of Madagascar’s eastern rainforest band, and more specifically, is assigned to a subclade occurring mostly in coastal regions of the northern Central East and North East. (3) Large-sized specimens from Ranomafana (southern Central East) and Andohahela (South East) previously considered to belong to G. plicifer in fact represent a hitherto undescribed species, which we here formally name as Gephyromantis pedronoi sp. nov. The three species are distinguished by very high genetic distances (over 8 % in the 16S gene), an absence of haplotype sharing in Rag-1, as well as morphological and bioacoustic characteristics. Moreover, several infraspecific clades with 16S divergences > 4 % may represent distinct species, especially within the widespread G. luteus, but cannot be unambiguously delimited by available data. We suggest dedicated sampling at contact zones and more extensive bioacoustic study of genotyped call vouchers to clarify their taxonomic status.


 Three adult males of Gephyromantis pedronoi sp. nov. (clade C) from Ranomafana in life, in dorsolateral and ventral views.
 a-d. photographed in 1996; e-f. photographed in 2003.
The individuals cannot be reliably assigned to preserved voucher specimens, but a-d might correspond to ZFMK 62305-62306.

Gephyromantis pedronoi sp. nov.

Identity. This species has previously been assigned to Gephyromantis plicifer in various publications (e.g., Vences & Glaw 2001, Vences et al. 2006, Glaw & Vences 2007), based on the analysis of Vences & Glaw (2001) who relied on morphological similarities with the lectotype of Rana plicifera Boulenger, 1882 (distinct and large femoral glands of type 2), but also already remarked the smaller body size of the plicifer lectotype. It corresponds to the genetic clade C and is here recognised as distinct at the species level from G. plicifer (clade B).


Diagnosis. A species of Gephyromantis assigned to the G. luteus complex in the subgenus Duboimantis on the basis of presence of intercalary elements between ultimate and penultimate phalanges of fingers and toes present (assessed by external examination), absence of nuptial pads, a single patch of well-delimited femoral glands of type 2 in males (no rudiments in females), paired blackish subgular vocal sacs in males, fairly smooth skin, moderately large body size, outer metatarsalia separated by webbing, presence of inner and outer dorsolateral ridges, and molecular phylogenetic affinities. Within the G. luteus complex, the species can be identified by a unique combination of the following characters: moderately large body size (adult males >43 mm and often up to 44-46 mm, vs. up to 43 mm but often <40 mm in G. luteus and G. plicifer), distinct and relatively large femoral glands in males (vs. small, often indistinct to unrecognisable externally in G. luteus), and emission of advertisement calls in irregular series at low call repetition rate of <100 calls per minute (vs. fast, regular series of at least 140 calls per minute in G. luteus and G. plicifer), and distinct downward frequency modulation (vs. upward frequency modulation in G. luteus and G. plicifer). 


Etymology. The name is a patronym dedicated to Miguel Pedrono in recognition of his substantial contributions to our understanding of the biology of Madagascar’s tortoises, in particular the Angonoka, Astrochelys yniphora, and his immense efforts in tortoise conservation (e.g. Pedrono 2008, Pedrono & Clausen 2018). 

Distribution. The species is reliably known from DNA barcoded specimens from Ranomafana National Park at elevations of about 950 m a. s.l., and Andohahela National Park, from a site between Isaka and Eminiminy at around 600 m a. s.l. Additional specimens probably belonging to this species from the Anosy Chain (Ambana-Soavala, Camp IV, Camp V) reported above under additional material would originate from a rather wide elevational range, based on the elevational information of campsites reported by Rakotoarison et al. (2017b), i. e., from almost sea level (Ambana) over 550 m (Camp 4) to 1050 m a. s.l. (Camp V).


Miguel Vences, Jörn Köhler, Franco Andreone, Ann-Kristin Craul, Angelica Crottini, Louis du Preez, Michaela Preick, Lois Rancilhac, Mark-Oliver Rödel, Mark D. Scherz, Jeffrey W. Streicher, Michael Hofreiter and Frank Glaw. 2021. Target-enriched DNA Sequencing Clarifies the Identity of Name-bearing Types of the Gephyromantis plicifer complex and reveals A New Species of Mantellid Frog from Madagascar (Amphibia, Anura). Spixiana. 44(2); 175-202.
 https://pfeil-verlag.de/wp-content/uploads/2021/12/SPX_44-2_11_VE.pdf