Corresponding author: Mark D. Scherz (
Academic editor: Peter Bartsch
The Madagascar-endemic microhylid genus
The microhylid frog genus
Repeated swapping of ecological niches (i.e. transitions between gross ways of life, such as between terrestrial and arboreal lifestyles) has led to high ecological diversity in the
Here, we describe a new
Specimens were collected, euthanized, fixed in 90% ethanol and transferred to 70% ethanol for long-term storage. One specimen was deposited in the Université d’Antananarivo Département de Biologie Animale (UADBA), and the other in the Zoologische Staatssammlung München (ZSM).
In this work we refer to the species
Morphological measurements were taken with a digital calliper to 0.01 mm and rounded to the nearest 0.1 mm for presentation here. Fig.
Measurement scheme used to measure
Micro-CT scanning was carried out on a nanotom m (GE Measurement & Control, Wunstorf, Germany). The holotype of the new species, ZSM 1630/2012, was mounted on a polystyrene board inside a sealed polyethylene vessel, and secured in place using small wooden struts and additional polystyrene. A small volume of 80% ethanol was added to achieve air saturation, preventing desiccation of the specimen. The vessel was mounted on a polyvinylchloride tube, and placed inside the micro-CT scanner. Scanning was conducted at a voltage of 140 kV and a current of 80 mA, with a timing of 500 ms for 20 minutes (2440 projections). Scan data were assembled in phoenix DATOS|X 2 RECONSTRUCTION CT software (GE Measurement & Control, Wunstorf, Germany) and visualised in VG STUDIO MAX 2.2 (Volume Graphics GmbH, Heidelberg, Germany) and subsequently processed into a 3D surface render in AMIRA 5.4.5 (FEI Visualization Sciences Group, Burlington MA, USA). Skeletal description is based on both surface and volume renderings of micro-CT data, due to artefacts produced in surface rendering. Readers are advised that micro-CT scanning does not render poorly calcified structures, especially cartilage. Cartilages are therefore omitted from the osteological description below and the respective figures; additional specimens will need to be cleared and stained in order to assess cartilaginous characters of these frogs. We provide a PDF-embedded interactive 3D model of the skeleton of the holotype as Suppl. material
We extracted total genomic DNA from ethanol-preserved tissue samples using proteinase K digestion (final concentration 1 mg/mL) and a standard salt extraction protocol (
We calculated a phylogenetic tree from the 16S sequences by Bayesian inference (BI) with MRBAYES 3.2 (
The new species described below is phylogenetically nested in the genus
Majority-rule consensus tree derived from Bayesian inference analysis of the genus
ZSM 1630/2012 (FGZC 3653), an adult female with immature oocytes, collected in the montane forest of the Sorata Massif, north Madagascar (ca.
UADBA-A 60271 (FGZC 3651), an adult male with the same collection data as the holotype.
A microhylid assigned to the genus
Within the genus,
Osteologically, a micro-CT scanned specimen of
Adult female in an excellent state of preservation. A ventral incision was made in order to check the sex and access the stomach contents. The incision runs laterally and posteroventrally anterior to the pubis and up the middle of the venter.
Body gracile; dorsal and ventral skin smooth. Head wider than long (HW 122.5% of HL), snout rounded in dorsal view, squarish in lateral view; nostrils weakly protuberant, directed laterally, equidistant between eye and snout; canthus rostralis concave; loreal region concave; tympanum indistinct, oval, horizontally 47% of eye diameter; pupil round; supratympanic fold weak, almost absent; tongue unlobed, posteriorly free; vomerine teeth present in a straight row with a small medial gap (<1 mm; see Osteology below); choanae small, oval.
Arms slender and long; fingers without webbing, long, without distinct subarticular tubercles, relative lengths 1<2<4<3, second finger much shorter than fourth, without enlarged terminal discs; inner metacarpal tubercle present; nuptial pads absent. Legs exceptionally long and slender (HIL 185% of SVL), tibiotarsal articulation reaching the nostril when hindlimb is adpressed along body; toes long, unwebbed, with indistinct subarticular tubercles, relative toe lengths 1<2<5<3<4, third toe much longer than fifth; inner metatarsal tubercle present and indistinct.
Colouration of the holotype: (Fig.
After three years in 70% ethanol, all browns have faded to shades of grey. Dorsal areas that were lightest in shade are whitish, particularly between the eyes anterior to the dark inter-ocular bar. Ventrally, all areas that lack pigmentation and were pink in life are cream in preservation. Chin the same colour as the snout.
Osteology of the holotype: (Fig.
Osteology of the holotype of
Mandible slim, edentate. Mentomeckelian small, in narrow medial contact with counterpart (possibly artefactual), and in dorsolateral contact with dentary. Dentary long and thin with a sculpted outer face and smooth inner face, overlapping angulosplenial for much of its length. Angulosplenial broadening posteriorly, with a posterior dorsomedial crista; possessing a lateral channel running from the posterior into the sculpted outer edge of the dentary.
Posterolateral processes of hyoid shovel-like, a medial crista running along posteromedial process, the base of which is broad and flat with a rounded anteromedial edge and sharp anterolateral and posteromedial corners; parahyoid absent.
Humerus long, slim and straight; crista lateralis weak, crista ventralis short (~30% of humerus length), crista medialis absent. Radioulna broadening distally. Finger phalangeal formula 2-2-3-3. Terminal phalanges of fingers 2, 3, and 4 with distal knobs. Prepollex 31% of first finger.
Pectoral girdle composed of paired coracoids, clavicles, scapulae, cleithra and suprascapulae. Sternal characters not visible in CT render. Coracoids in medial contact; medially dorsoventrally flattened, laterally rounded, posterior surface straight, anterior surface strongly concave. Clavicle thin and curved approximately parallel to the anterior edge of the coracoid, its lateral end broadened, posteriorly in contact with ventral edge of scapular pars acromialis. Scapula thick, hourglass shaped, its posterior edge less strongly curved than its anterior edge, medioventrally bifurcated; pars acromialis distally rounded, in contact with the lateral end of the clavicle, its anterior surface concave; pars glenoidalis curved ventrally, in contact with lateral face of coracoid, posterior face concave; dorsal edge of scapula approaching cleithrum. Cleithrum thin and long, not possessing any cristae, anteriorly thicker than posteriorly. Suprascapula with highest X-ray absorption ventrally and posteriorly suggesting possible ossification in these areas.
Toe phalangeal formula 2-2-3-4-3; terminal phalanges without distinct distal knobs. Leg bones long and thin. Femur without any crests. Tibiofibula slightly longer than femur. Tibiale and fibulare proximally and distally fused, articulating distally with metatarsals V and IV, tarsals 1–3, and the centrale. Prehallux present, short.
Ilium, ischium, and pubis forming ossified acetabulum, each composed of paired, medially fused elements. Iliac shafts oval in cross-section, dorsal-ventral diameter larger, possessing a weak dorsal tubercle posterior to shallow oblique groove. Iliosacral articulation type IIA sensu
Eight presacrals present; no vertebrae fused. Posterior articular processes round. Transverse processes of presacrals II–IV broader than those of V–VIII. Neural spines decreasing in size from presacral II to absent by V. Sacrum wide, with broad diapophyses articulating with the ilia; anterior edge of each diapophysis roughly perpendicular to body axis, posterior edge oblique. Urostyle long and thin, with a dorsal ridge along a third of its length, beginning at its anterior end; articulation with sacrum bicondylar.
Holotype (paratype in brackets), measurements in mm: SVL 28.0 (23.8), HW 9.9 (9.7), HL 8.0 (7.0), ED 3.3 (2.8), END 2.0 (2.0), NSD 1.9 (1.7), NND 3.0 (2.2), TDH 1.5 (1.3), TDV 1.8 (1.4), HAL 8.4 (7.0), UAL 5.7 (4.7), LAL 6.8 (5.7), FORL 20.9 (17.4), THIL 13.2 (11.7), THIW 3.9 (3.4), TIBL 14.6 (11.7), TIBW 2.97 (2.64) TARL 8.6 (7.3), FOL 14.8 (12.5), FOTL 23.4 (19.8), HIL 51.2 (43.2), IMCL 1.0 (0.9), IMTL 1.3 (1.0).
Only two specimens are known. The paratype is male, and smaller than the holotype (SVL 23.8 mm). It agrees in all aspects of its morphology with the holotype, but differs strongly in colouration (see Fig.
The species epithet is an invariable noun in apposition to the genus name, derived from the Latin words
This species has only been found at high altitude in the montane forests of the Sorata massif in north Madagascar. Its distinctiveness leads us to hypothesize that it has never been found elsewhere and misidentified, so it may be microendemic to this small area. Additional surveys are required in areas in and around Sorata to identify its full distribution.
Both specimens described here were captured in the early evening on the ground along a path through primary montane forest. The stomachs of both specimens contained remains of several small insects (mostly
The forests of Sorata are currently unprotected. All locally endemic species are threatened by uninhibited deforestation and forest degradation. The greatest pressure on forests is at their edges. High altitude species like
While this species is, at present, known from just two specimens collected on one expedition, the fact that it has not been collected by previous expeditions suggests it may be scarce, seasonal, or have a scattered distribution. Even if it were distributed throughout the forests of the Sorata massif, its distribution would still only constitute an area of ~250 km2 (as calculated in Google Earth® Pro 6.1.0.500, Google Inc., Mountain View, CA). Thus, because of its potentially limited range inside an unprotected forest, the on-going and intensifying threat of deforestation, potential threat by climate change, and potential scarcity or seasonality, it qualifies as Endangered B1ab(iii) under the IUCN Red List Criteria (2012).
Hindlimb length is significantly associated with habitat and mode of life in frogs (
Robust and at least partly burrowing frogs typify the genus
In addition to leg length, several other characters are also associated with more saltatorial locomotion.
The iliosacral articulation of
The discovery of such a distinctive new species highlights the incompleteness and patchiness of herpetological survey work in Madagascar. Whilst some forests, particularly accessible, protected ones, are receiving a lot of research attention (e.g. Betampona:
We would like to thank Theo Rajoafiarison, Fanomezana M. Ratsoavina and Angeluc Razafimanantsoa for their enormous help during the fieldwork, Hanta Razafindraibe for the loan of the paratype from the UADBA collection, and Jennifer Luedtke for her assistance with IUCN Red List status assessment. Field research was conducted under permit No. 265/12/MEF/SG/DGF/DCB.SAP/SCB (dated 18 Oct. 2012), exportation of specimens under permit No. 163N-EA12/MG12 (dated 17 Dec. 2012), (both issued by the Direction Générale des Forêts de Madagascar), and funded by the Mohamed bin Zayed Species Conservation Fund (project 11253064) and BIOPAT. We are grateful to the three anonymous reviewers who helped us to improve this manuscript.
PDF-embedded 3D Skeletal Model
Adobe PDF file
This file contains a PDF-embedded interactive 3D model of the skeleton of the holotype of