New frog species ‘Ingerana aizawl’ discovered on Mizoram University Campus

Researchers have discovered a new species of stream-dwelling frog, Ingerana aizawl, in Mizoram, marking a significant addition to the region’s amphibian diversity.

The species was discovered during nighttime surveys conducted along the Hratdawng Stream on the Mizoram University campus on April 18, 2024. Researchers had long identified populations of the genus Ingerana in Mizoram as Ingerana borealis, but the absence of molecular data had left their taxonomic identity uncertain.

A joint research team led by Dr Hmar Tlawmte Lalremsanga, along with Manmath Bharali, Malsawm Dawngliana, Mara Duasa Hlychho, Malsawmtluanga and other researchers, carried out visual encounter surveys along forested streams across the university campus, which covers around 978.2 acres.

A male holotype of the new species was collected from Hratdawng Stream at an elevation of approximately 823 metres above sea level. Subsequent laboratory analysis of mitochondrial 16S rRNA gene fragments confirmed that the Mizoram population represents a distinct evolutionary lineage.

According to the research findings, Ingerana aizawl shows a genetic distance of 4.8–6.6 per cent from its sister species, I. occidens, and 15.3–17.6 per cent from I. borealis.

The frog is small and stout, with adult males measuring between 22 and 25.5 mm and females between 24.4 and 26 mm in snout-vent length. It is characterised by prominently wrinkled dorsal skin, a distinct circular tympanum with an elevated central protrusion and a strongly developed supratympanic fold.

Researchers recorded the species along forested stream banks, with individuals observed between 6 pm and 7 pm. Its advertisement call consists of a regular series of 12 notes lasting approximately 1.42 seconds, with a dominant frequency of around 3,359 Hz.

The species inhabits trickling and fast-flowing streams at elevations ranging from 94 to 823 metres above sea level, where it has been observed perching on wet rocks or sheltering beneath leaf litter and in rock crevices. It is active mainly during the monsoon season from April to August, with breeding reported between May and July.

Researchers have also highlighted conservation concerns surrounding the newly described species. Mizoram populations were previously included under I. borealis, which is assessed as Least Concern. With Ingerana aizawl now recognised as a separate species, the researchers have called for a standalone IUCN Red List assessment to determine its conservation status and help protect its habitat on and around university lands.