Discovery: Brook Dwarf Mountain Frog (Alcalus fontinalis) found from Motijheel track

Researchers have discovered a new species of the genus Alcalus in the northeast Indian state of Arunachal Pradesh. The identification of the new species is based on molecular, morphological, and osteological characteristics.

The new species stands out from its congeners due to a unique combination of morphological features. These include a snout-vent length of 27–28 mm in males and 29.9–36.2 mm in females, a disc on fingers and toes with a horizontal/transverse groove on the dorsal surface, wrinkled dorsal skin, and a pair of faint dorsolateral stripes on the back.

In addition to these physical traits, the new species also exhibits a DNA sequence divergence of 7.6–25.4% in the mitochondrial gene fragment 12S–tVal–16S rRNA (1533 base pairs), further distinguishing it from its congeners.

Alcalus fontinalis: A Significant addition to Indian biodiversity

A team of researchers led by Abhijit Das came across this unique frog in the tiny pools of water. The frog appeared to be a mix of a bush frog and a water frog, something they had not seen before in India.

The frog was formally named Alcalus fontinalis, meaning “spring or fountain,” referencing the tiny streams or brooks where the frog was found in Arunachal Pradesh. This discovery marks a significant addition to the genus Alcalus, which was previously unknown from India.

The discovery of Alcalus fontinalis is a testament to the rich biodiversity of the region and underscores the importance of continued exploration and conservation efforts. The finding was published in the latest issue of the NHM-UK-based journal "Systematics and Biodiversity".

This discovery also indicates hidden diversity in the poorly sampled Myanmar region. The genus Alcalus is named in honour of Angel Alcala, a Filipino biologist who worked with Southeast Asian amphibians. The genus is known from Sunda Shelf and Palawan Island (the Philippines), Borneo, and the Malay Peninsula.

The researchers used multiple lines of evidence using morphological, osteological, and molecular analysis, revealing they are no ordinary frogs but members of a dwarf mountain frog of the genus Alcalus hitherto unknown from India.

Challenges and Future directions in explorative research

The researchers led by Abhijit Das comprised Bitupan Boruah, Surya Narayanan, Jason D Gerard and V Deepak. Abhijit Das, the leader of the research team, shared their journey through the peak herpetological season in Namdapha.

Dr. Abhijit Das, the lead author of the study, told Ground Report that it's a significant challenge to obtain a research grant for explorative research in today’s times. He thanked Nat Geo for funding their research and expressed his gratitude to the Forest Department of Arunachal Pradesh and the authorities of Namdapha Tiger Reserve (NTR) for their support. People consider NTR as one of the richest tiger reserves in India in terms of biodiversity."

He further added, "Fieldwork during the peak monsoon season, which coincides with the herpetological season, presents its own set of challenges. The swelling rivers and arduous night treks along torrential forest streams make accessibility difficult. However, special discoveries like that of Alcalus fontinalis demand sampling special habitats at the right time".

Das further added "the discovery of Alcalus fontinalis contributes significantly to our understanding of biodiversity in the Indo-Burma region. The finding reports a species new to science and a new genus from India."

"The study also underscores the importance of basic field-based research even within well-known Protected Areas (PAs) of India. This discovery will contribute towards understanding the biogeographic scenario in the eastern borderland of India and trigger further research on such interesting habitat specialist species" he further added.

Plans for further Exploration

Dr. Das confirmed that they have plans to continue their explorative research in Northeast India, especially in Arunachal Pradesh.

He states that PAs serve as the cornerstone of biodiversity conservation and argues that further exploration within PAs is necessary for climate-vulnerable groups, such as amphibians. This exploration also assists in determining the actual distribution of the lesser-known "Data deficient" fauna in the Indo-Burma Region.

Dr. Das further said "Using a rigorous science-based approach, they aim to prioritize conservation for endemic and range-restricted species. This type of preliminary research also sets the stage for more in-depth studies on ecology, biogeography, and behavior".

They encountered this unique frog in multiple locations, all characterized by tiny streams or brooks in evergreen forests, primarily in low to mid-elevation regions. This marks the second species of frog discovered from Namdapha Tiger Reserve this year.

The Brook’s dwarf mountain frog is a small species with a body size of almost 3 cm. Das emphasized that the discovery of a new frog from Namdapha Tiger Reserve underscores the need for biodiversity surveys, particularly in under-explored protected areas across the Indo-Burma biodiversity hotspot.

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