Research Article |
Corresponding author: Mark D. Scherz ( mark.scherz@gmail.com ) Academic editor: Alexander Haas
© 2019 Mark D. Scherz, Jörn Köhler, Miguel Vences, Frank Glaw.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Scherz MD, Köhler J, Vences M, Glaw F (2019) A new yellow-toed Platypelis species (Anura, Microhylidae, Cophylinae) from the Maroantsetra region, northeastern Madagascar. Evolutionary Systematics 3(1): 75-83. https://doi.org/10.3897/evolsyst..33417
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We describe a new species of arboreal narrow-mouthed frog, genus Platypelis, from Ambodivoangy near Maroantsetra in northeastern Madagascar. The new species, Platypelis ando sp. nov., is characterised by small body size (under 19 mm), a generally rather slender body, yellowish finger and toe tips, and a dark brown dorsal chevron. Its advertisement call is a single, moderately long, high-pitched whistle repeated at regular intervals. It is the sister species of P. ravus from Marojejy National Park, but differs from that species by considerable pairwise genetic distances (7.9%) in a fragment of the mitochondrial 16S rRNA gene, and also in bioacoustic and morphological features, especially the absence of yellow on the posterior abdomen. It is also surprisingly similar in external appearance to Cophyla occultans and C. maharipeo, to which it is not, however, closely related; these species are most easily discerned based on their calls. Platypelis ando sp. nov. joins the ranks of several species recently described from Ambodivoangy with close affiliations to species in the nearby Marojejy National Park, that are still divergent at species level. The species qualifies as Critically Endangered according to the IUCN Red List criteria, in line with other species recently assessed from this area, but we urge that more research be conducted in the nearby forests to extend the range of this and other species known only from Ambodivoangy.
Amphibia, bioacoustics, systematics, taxonomy, morphology, molecular genetics
Platypelis Boulenger, 1882 is a genus of arboreal microhylid frogs endemic to Madagascar. They are characterised by expanded terminal discs on the toes and especially the fingers, with T- or Y-shaped terminal phalanges (
A considerable amount of the diversity of Platypelis is currently undescribed:
In this paper, we describe a new Platypelis species from Ambodivoangy in northeastern Madagascar, known for other recent discoveries of new anuran species (
Frog specimens were collected at night by opportunistic searching, using torches and head lamps. Specimens were euthanized by immersion in a solution of chlorobutanol, fixed in 95% ethanol, and preserved in 70% ethanol. Locality information was recorded with GPS receivers (WGS 84 datum). Specimens were deposited in the collection of the Zoologische Staatssammlung München (ZSM) and of the University of Antananarivo, Zoologie et Biodiversité Animale, Madagascar (UADBA), but only ZSM specimens were available for this study. FGZC refers to F. Glaw field numbers, ZFMK is the Zoologisches Forschungsmuseum A. Koenig, Bonn, Germany.
Measurements were taken with a digital calliper to the nearest 0.1 mm by MV. Abbreviations are as follows: SVL, snout-vent length; HW, head width; HL, head length, measured as the diagonal from the rictus to the anterior-most point of the head; TD, horizontal tympanum diameter; ED, horizontal eye diameter; END, eye-nostril distance (anterior corner of eye to centre of nostril); NSD, nostril-snout tip distance (centre of nostril); NND, nostril-nostril distance (from the centres of the nostrils); FORL, forelimb length, measured from the axilla to the tip of the longest (third) finger with the forelimb extended; HAL, hand length, measured from the base of the hand to the tip of the third finger; HIL, hindlimb length, measured from the cloaca to the tip of the longest (fourth) toe with the foot extended laterally outward from the body; FOTL, foot and tarsus length, measured from the tibiotarsal articulation to the tip of the longest toe; FOL, foot length, measured from the tarsal-metatarsal articulation to the tip of the longest toe; TIBL, tibia length, from the tibiotarsal articulation to the knee.
Vocalizations were recorded in the field using a Tascam DR-07 digital recorder with built-in microphone and saved as uncompressed files at a sampling rate of 44.1 kHz. Recordings were re-sampled at 44.1 kHz and 32-bit resolution and computer-analysed using ADOBE AUDITION 1.5. Frequency information was obtained through Fast Fourier Transformation (FFT; width 1024 points). Spectrograms were obtained at Hanning window function with 256 bands resolution. Temporal measurements are given as mean ± standard deviation with range in parentheses. Terminology in call descriptions follows
Tissue samples (tongue or leg muscle) were taken from the euthanized animals before fixation, and preserved in 99% ethanol. We extracted genomic DNA using a standard salt extraction protocol (
Sequences were combined with those from previous studies, and alignment performed using the Clustal algorithm in MEGA7 (
This paper is published in a journal published digitally and in print. The ISSN is 2535–0730. It conforms to the requirements of the amended International Code of Zoological Nomenclature, and the names are therefore valid from the date of electronic publication. The new name it contains is registered in ZooBank (the LSID of the publication is http://zoobank.org/87CCD4C8-9F21-471C-85DD-2AECD896FC1D). The journal Evolutionary Systematics is archived in the CLOCKSS and Zenodo repositories.
The phylogenetic tree obtained under the ML optimality criterion (Fig.
Maximum Likelihood phylogenetic tree of Platypelis and Cophyla, based on a fragment of the mitochondrial 16S rRNA gene (total alignment length 633 bp, of which 301 bp available for the new taxon). Numbers at nodes are support values in percent from a bootstrap analysis (500 pseudoreplicates). Madecassophryne cf. truebae was used as the outgroup. Cophyla sp. ‘fortuna’ (formerly C. sp. Ca04) is under description by
Genetic divergences of the Ambodivoangy lineage to other Platypelis and Cophyla were high; in the 251 bp available for all species studied here for the fragment of the 5’ end of the 16S rRNA mitochondrial gene studied here, it had an uncorrected pairwise distance (p-distance) of 7.2% to P. ravus, of 11.2% to P. milloti, and 10.8–25.2% to all other Platypelis and Cophyla species. The lowest divergence of the Ambodivoangy lineage (7.2% to P. ravus) was at similar levels as between pairs of other well-established and morphologically highly distinct species of Platypelis, such as between P. alticola and P. olgae (6.0%), P. alticola and P. tsaratananaensis (4.4%), or Platypelis sp. aff. tetra and P. pollicaris (8.8%). Given its strong genetic distinction and presence of morphological and/or bioacoustic differences from related and similar-looking species, we describe the form from Ambodivoangy as a new species.
ZSM 293/2010 (FGZC 4285), adult male, collected on 3 April 2010 in Ambodivoangy (15.2899S, 49.6203E, ca. 100 m a.s.l.), Analanjirofo Region, northeastern Madagascar, by P.-S. Gehring, F. Glaw, J. Köhler, M. Pabijan, and F. M. Ratsoavina.
ZSM 291/2010 (FGZC 4200), adult male, and ZSM 292/2010 (FGZC 4226), probably a male, collected on 31 March 2010 from the same locality as the holotype by the same collectors.
The new species is assigned to the genus Platypelis based on molecular phylogenetic relationships (Fig.
The new species is distinguished from Platypelis cowanii, P. mavomavo, P. grandis, P. tsaratananaensis, P. pollicaris, P. alticola, P. olgae, P. tuberifera, P. barbouri and P. milloti by considerably smaller size (16.9–18.7 vs >25 mm). Among Platypelis species of similar size, it can be distinguished from P. tetra by its smaller dorsal tubercles, absence of large white spots on the dorsum (vs presence), and presence of a brown chevron-shaped marking on the dorsum (vs absence); and from P. karenae by its brown colouration and dorsal patterning (vs yellow colouration and lack of dorsal patterning), short supratympanic dark brown marking (vs extended along the flank), and less pointed snout. Morphologically and genetically, P. ando sp. nov. most closely resembles P. ravus. It differs from that species in the lack of yellowish colour on its venter (vs present), yellowish to orangish dorsal finger and toe tip colouration (vs brownish), and by a chevron-shaped brown marking on dorsum (vs W-shaped).
From all members of the externally similar Cophyla, except C. occultans and C. sp. ‘fortuna’ (
From all members of the genus Anodonthyla, the species can be distinguished by the absence of a distinct finger-like prepollex in males.
The new species differs bioacoustically from other Platypelis species with known advertisement calls as follows: from P. barbouri, P. karenae, P. milloti, P. pollicaris, P. tsaratananaensis, and P. tuberifera by significantly longer call duration (= note duration; single note calls); and in addition from P. barbouri, P. milloti, P. pollicaris, P. ravus, P. tsaratananaensis, and P. tuberifera by significantly higher dominant frequency (see bioacoustics section below).
Adult male in a good state of preservation, tongue taken as tissue sample. Snout-vent length 18.7 mm; for other measurements, see Table
Measurement data on Platypelis ando sp. nov. All measurements in mm. For abbreviations, see the material and methods. HT = holotype, PT = paratype.
Voucher | Field no | Sex | SVL | HW | HL | TD | ED | END | NSD | NND | FORL | HAL | HIL | FOTL | FOL | TIBL |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
ZSM 293/2010 (HT) | FGZC 4285 | M | 18.7 | 5.4 | 5.2 | NA | 2.1 | 1.5 | 1.2 | 1.9 | 10.0 | 4.4 | 23.1 | 10.0 | 6.0 | 7.1 |
ZSM 291/2010 (PT) | FGZC 4200 | M | 16.9 | 5.1 | 5.3 | NA | 2.2 | 1.6 | 1.1 | 1.7 | 9.3 | 4.4 | 22.8 | 9.1 | 9.1 | 7.0 |
ZSM 292/2010 (PT) | FGZC 4226 | M? | 17.9 | 5.1 | 5.0 | NA | 2.1 | 1.3 | 1.2 | 1.9 | 10.2 | 4.4 | 22.5 | 10.6 | 7.0 | 7.3 |
In life, the holotype was olive brown in dorsal colouration with a slightly green-tinged cream saddle marking on its middle, demarcated posteriorly with a dark brown broken border, and anteriorly bordering a dark brown chevron over the suprascapular region that extended to the middle of the eyes, where it stopped abruptly behind an olive-green bar between the eyes (Fig.
Platypelis specimens in life. (a–b) Holotype (ZSM 293/2010) of Platypelis ando sp. nov. in (a) dorsolateral and (b) ventral view; (c–d) paratype of P. ando sp. nov. (ZSM 292/2010) in (c) lateral and (d) ventral view; (e–f) holotype (ZSM 349/2005) of P. ravus in (e) dorsolateral and (f) ventral view.
After almost nine years in preservative, the specimen has faded considerably, resulting in the loss of distinction in its pattern (Fig.
For variation in measurements, see Table
The advertisement call recorded on the night of the 3rd of April 2010 in Ambodivoangy (estimated air temperature ca. 25 °C) from the holotype, ZSM 293/2010, consists of a single moderately long, high-pitched tonal whistle, repeated at regular intervals (Fig.
Audiospectrogram (Hanning window function at 256 FFT width; high-pass filtered at 3750 Hz) and oscillograms of the advertisement call of Platypelis ando sp. nov. (holotype, ZSM 293/2010) recorded on 3 April 2010 at Ambodivoangy, northern Madagascar. Lower oscillogram shows a 10 second section of a regular call series.
Call comparison: The advertisement call of the sister species P. ravus (see
Compared to the call of P. ando sp. nov., the advertisement calls of other Platypelis species differ significantly. The call of P. tuberifera is shorter (280 ms) and has a lower dominant frequency of 2300–3000 Hz (
As is typical for Platypelis species, calling activity was only heard after dusk. ZSM 291/2010 was found calling 1.8 m above the ground. Nothing further is known about the habits of this species, but based on the reproductive ecology of congeners, it is likely to reproduce in phytotelms and have endotrophic nidicolous tadpoles.
Only two available synonyms of any Cophyla or Platypelis refer to small-sized species that could possibly refer to our new species. Cophyla tuberculata Ahl, 1929 ‘1928’ is currently a synonym of P. grandis. The two syntypes are juveniles according to
We dedicate this species to our friend and colleague, Dr. Andolalao Rakotoarison, in recognition of her valuable contributions to the systematics and taxonomy of the Malagasy microhylid fauna. The name is to be treated as an invariable noun in the nominative singular.
The new species is reliably known only from the type locality Ambodivoangy, but the species is likely to be more widespread in low altitude forest of the adjacent Makira Natural Park.
The new species, Platypelis ando, is genetically, bioacoustically, morphologically, and chromatically distinct from all other members of the genus Platypelis and Cophyla, being a small frog with yellow fingers and toes but without yellow on its hindlimbs. It is one of the smallest members of this group, with a maximum size under 20 mm, although currently P. karenae remains the smallest member of the genus, with a SVL ranging from 16.1–18.3 mm (
Platypelis ando occurs at low elevation, ca. 100 m a.s.l., in the rainforest of Ambodivoangy. Its sister species, P. ravus, is from considerably higher elevation (ca. 1350 m a.s.l.) on Marojejy. A similar biogeographic pattern has not yet been reported for any other Platypelis or Cophyla, but is known for another cophyline genus, Stumpffia: three species, S. fusca Rakotoarison et al., 2017, S. pardus Rakotoarison et al., 2017, and S. contumelia Rakotoarison et al., 2017 from Ambodivoangy are also sister to species from Marojejy (S. achillei Rakotoarison et al., 2017, S. diutissima Rakotoarison et al., 2017, and S. tridactyla Guibé, 1975, respectively), and most notably, S. contumelia and S. tridactyla differ in elevation to the same degree as P. ando and P. ravus, namely ca. 1200 m in elevation (
The low-elevation forest of Ambodivoangy is under pressure from anthropogenic habitat destruction, and the current knowledge of P. ando from this single location makes it potentially highly threatened, although the type locality is very close to the border of the Makira reserve, where P. ando is likely to occur as well. Despite our considerable uncertainty regarding the full distribution of the species, we follow the rationale applied by
We are thankful to Philip-Sebastian Gehring, Maciej Pabijan and Fanomezana M. Ratsoavina for help and assistance in the field, and to Meike Kondermann for help with laboratory work. Work in Madagascar was carried out within a collaboration of the authors’ institutions and the Département de Biologie Animale of the Université d’Antananarivo (UADBA). We are grateful to the Malagasy authorities for research and collection permits. This research was supported by grants of the Volkswagen Foundation to MV and FG, and of the Deutsche Forschungsgemeinschaft to MV (grant number VE247/2-1). We thank SD Biju and S Nielsen for helpful reviews of this manuscript.