Sunday, December 5, 2021

[Herpetology • 2021] Gephyromantis marokoroko • A Fantastic New Species of Secretive Forest Frog (Anura: Mantellidae) discovered from Forest Fragments near Andasibe, Madagascar

Gephyromantis (Laurentomantismarokoroko 
Hutter, Andriampenomanana, Andrianasolo, Cobb, Razafindraibe, Abraham & Lambert, 2021

We describe a fantastic new species of forest frog (Mantellidae: Gephyromantis: subgenus: Laurentomantis) from moderately high elevations in the vicinity of Andasibe, Madagascar. This region has been surveyed extensively and has a remarkably high anuran diversity with many undocumented species still being discovered. Surprisingly, by exploring areas around Andasibe that lacked biodiversity surveys, we discovered a spectacular and clearly morphologically distinct species, previously unknown to science, Gephyromantis marokoroko sp. nov., documented for the first time in 2015. The new species is well characterised by a very rugose and granular dorsum, dark brown skin with bright red mottling, sparse light orange to white spots on the ventre, vibrant red eyes and femoral glands present only in males that consist of eight medium-sized granules. Bioacoustically, the new species has a quiet advertisement call that differs from related species by having a moderate call duration, 2–4 strongly pulsed notes and a slow note repetition rate. Furthermore, it has substantial differentiation in mitochondrial DNA, with pairwise distances of 7–9% to all other related species in sequences of the mitochondrial 16S rRNA marker. Additional evidence is given through a combined four mitochondrial markers and four nuclear exons concatenated species tree, strongly supporting G. striatus as the sister species of the new species in both analyses. The discovery of this new species highlights the need for continued inventory work in high elevation rainforests of Madagascar, even in relatively well-studied regions.

Key Words: Amphibia, Anura, Andasibe, Gephyromantis marokoroko, Mantadia, new species, taxonomy

Ex-situ dorsal-lateral, dorsal and ventral photographs of Gephyromantis marokoroko sp. nov. 
A. Male (holotype, KU 343230) and
B. Female (paratype, KU 343218) in life.

Ex-situ dorsal-lateral, dorsal and ventral photographs of
A. Male Gephyromantis marokoroko sp. nov. (holotype, KU 343230);
B. Gephyromantis striatus (Marojejy, ZCMV 15140; photographs by Mark D. Scherz); and
C. Gephyromantis ventrimaculatus (Ranomanfana, KU 340917).

 Gephyromantis marokoroko sp. nov.
Common English name: Rugose Forest Frog. 
Common Malagasy name: Ny sahon’ala marokoroko.

Diagnosis: Gephyromantis marokoroko (Fig. 2) is a member of the family Mantellidae, subfamily Mantellinae, as diagnosed by Glaw and Vences (2006). The new species can be diagnosed to the genus Gephyromantis morphologically through its granular dorsum, moderately enlarged fingertips, absence of foot webbing, bifid tongue and small femoral glands present only in males as a small number of large granules (type 2; Glaw et al. 2000). Within Gephyromantis, the new species can be diagnosed to the subgenus Laurentomantis through its irregular and rough granular dorsum, single subgular vocal sac in males, completely connected lateral metatarsalia, inner and outer metatarsal tubercle present and tympanum is the same size in male and female.

Distribution: Gephyromantis marokoroko is known from several sites in the forests in the vicinity of Andasibe, but has only been found at high elevation sites (~ 1000–1200 m a.s.l.; Fig. 1). The new species is known from the following localities: Vohidrazana Forest (18.976°S, 48.499°E), Tavalobe (19.005°S, 48.461°E), Vohimana (18.926°S, 48.489°E) and Andasibe-Mantadia National Park (Belakato: 18.821°S, 48.439°E).

Natural history: Gephyromantis marokoroko is apparently locally rare and, thus far, only found within undisturbed, primary forests at highland elevations (ca. 1000–1200 m). Individuals of the species were perched on the surfaces of vegetation less than 50 cm in height (Fig. 7). The species was infrequently encountered, always after moderate to heavy rain, with multiple individuals occasionally grouped in small clusters (~ 20 m2). The species’ call is very quiet and irregular and is barely audible to a human observer, even within three metres of a calling individual. Individuals of the new species were often found syntopically with another Laurentomantis, G. sp. Ca13, which is a candidate species identified in Vieites et al. (2009). Other syntopic Gephyromantis include G. eiselti, G. salegy, G. sp. aff. plicifer (not yet assessed for a candidate species number) and G. cornutus.

Etymology: The specific epithet marokoroko is a Malagasy word meaning “rugose” or “rugged”. The name was chosen to describe the rugose skin texture of this species. The name is to be treated as an invariable noun in apposition.

  In-situ photograph of Gephyromantis marokoroko sp. nov. (UADBA-CRH1629).

 Carl R. Hutter, Zo F. Andriampenomanana, Ginah Tsiorisoa Andrianasolo, Kerry A. Cobb, Jary H. Razafindraibe, Robin K. Abraham and Shea M. Lambert. 2021. A Fantastic New Species of Secretive Forest Frog discovered from Forest Fragments near Andasibe, Madagascar. Zoosystematics and Evolution. 97(2): 483-495. DOI:  10.3897/zse.97.73630