Monday, March 7, 2016

[Herpetology • 2016] Raorchestes honnametti • Integrative Taxonomic Approach for Describing a New Cryptic Species of Bush Frog (Raorchestes: Anura: Rhacophoridae) from the Western Ghats, India

Raorchestes honnametti 
Gururaja, Priti, Roshmi & Aravind, 2016


A new cryptic species of bush frog Raorchestes honnametti sp. nov. is described from the south-eastern part of the Western Ghats, India. This newly described species belongs to the Charius clade and is morphologically similar to other clade members—R. charius and R. griet. Therefore, an integrative taxonomic approach based on molecular and bioacoustic analysis along with morphology was used to delimit the new species. Raorchestes honnametti sp. nov., is currently known only from Biligiri Rangaswamy Temple Tiger Reserve, a part of Biligiri Rangaswamy horst mountain range (a mountain formed due movement of two faults) formed during the Late Quaternary period (1.8–2.58 Ma). Discovery of cryptic species from a highly speciose and well-studied genus Raorchestes hints at the possible existence of several more cryptic species in this genus. We discuss the possible reasons for crypsis and emphasize the need for continued systematic surveys of amphibians across the Western Ghats.

Raorchestes honnametti sp. nov. Gururaja, Priti, Roshmi and Aravind

Suggested common name: Honnametti Bush Frog.

Holotype: BNHS 5941, an adult male collected by authors from Strobilanthus shrubs at 0.48m above ground at Honnametti, on 13th October 2012 at 20:20 h from Biligiri Rangaswamy hills (11.8987° N, 77.1741° E, 1659 m amsl).

Paratypes: BNHS 5942, BNHS 5943, BNHS 5945 and BNHS 5946, male individuals collected by authors in Honnametti, collection date and place same as holotype. BNHS 5944, a male collected by authors on 14th October 2012 at 19:45 h Dodda Sampige (11.9473° N and 77.1836° E, 1142 m amsl).

Fig 4. Holotype (BNHS 5941) of Raorchestes honnametti sp. nov.
a-— Live specimen; — ventral view; — dorsal view; — ventral view of hind limb; — ventral view of forelimb; — lateral profile of head; — Schematic view of webbing in hind limb.

Diagnosis: Raorchestes honnametti belongs to the genus Raorchestes as they are relatively small sized frogs (15–45 mm), active in night, vomerine teeth absent, transparent/translucent vocal sac while calling and direct development without free swimming tadpoles. It is a small sized adult (male: 21.7–24.8 mm, n = 6); snout longer than the horizontal diameter of eye; groin uniform light brown with 3–4 yellow blotches; both anterior and posterior part of thigh uniform light brown with small round to oval shaped yellow blotches and relatively short hind limbs ShL/SVL ratio <0.5. It belongs to the Charius clade and morphologically similar to R. charius and R. griet.

Etymology: Named after the locality of holotype – Honnametti. Honnametti is treated as an invariable noun in apposition to the generic name.

Fig 1. Biligiri Rangaswamy Temple Tiger Reserve and sampling sites of Raorchestes honnametti sp. nov. (blue circles).

Natural history: Raorchestes honnametti sp. nov. is known only from Biligiri Rangaswamy hills and is one of the very common frogs in that landscape. It is found in shola forests, evergreen forests, semi-evergreen forests and around human habitations. Individuals were found calling in an open area within Ageratina adenophora (Asteraceae) and Strobilanthus bushes. Some individuals were also found on tree saplings in the understory. Individuals call at a perched height between 0.48–1.00 m from ground. Call starts at around 6 pm and goes till early morning. During monsoon (June to September), individuals call almost throughout the day except on days with heavy rains or dry days. Other anuran species like Pseudophilautus sp., Hylarana sp., Fejervarya sp., Duttaphrynus melanostictus, Microhyla sholigari, M. ornata, M. rubra and Euphlyctis cyanophlyctis co-occur with R. honnametti in Biligiri Rangaswamy hills.

There are no immediate threats from human activities to this newly described species as Biligiri Rangaswamy hills is a tiger reserve and enjoys high level of protection. However, in the last one decade, a significant area of the Reserve has been taken over by highly invasive species like Lantana camara (Verbenaceae) and Ageratina adenophora (Asteraceae). On subsequent visits, we have seen several calling males of R. honnametti on Lantana and Ageratina bushes, indicating that this species might have adapted to the presence of these invasive species. However, a systematic research needs to be undertaken to assess the impact of invasive species on R. honnametti.

H. Priti , Rekha Sarma Roshmi, Badrinath Ramya, H. S. Sudhira, G. Ravikanth, Neelavara Anantharam Aravind, Kotambylu Vasudeva Gururaja. 2016. Integrative Taxonomic Approach for Describing a New Cryptic Species of Bush Frog (Raorchestes: Anura: Rhacophoridae) from the Western Ghats, India. PLoS ONE. DOI: 10.1371/journal.pone.0149382