New snake species discovered in Mizoram forests

A team of researchers from Mizoram University, in collaboration with the biodiversity conservation group Help Earth, has discovered a new species of rain snake belonging to the genus Smithophis in the lush tropical montane forests of Mizoram.

 The study, published in the latest issue of Taprobanica: The Journal of Asian Biodiversity, describes the new species as Smithophis leptofasciatus sp. nov.—commonly referred to as the narrow-banded rain snake.

The discovery is based on detailed morphological and molecular analyses of two collected specimens, along with observations of several live individuals. The new species is distinguished by its narrow, incomplete creamish-white or yellowish-lime transverse bands on a shiny black body—features that set it apart from its close relatives.

“This species not only adds to the growing diversity within Smithophis, but also redefines the distribution of previously known species,” said Dr. Jayaditya Purkayastha, one of the corresponding authors. 

“Our study confirms that what was previously identified as Smithophis bicolor from Mizoram is, in fact, a genetically and morphologically distinct species.”

Smithophis leptofasciatus was found inhabiting humid, shaded microhabitats near small streams in montane forests between 900 and 1,200 meters above sea level. Its semi-aquatic, nocturnal lifestyle was revealed through field observations during the monsoon. A gravid female observed in captivity laid six eggs, providing rare reproductive data for this elusive group.

The authors have also proposed a Mizo common name for the species—"Ruahrul"—reflecting its local significance. The species name leptofasciatus is derived from Greek and Latin, meaning "narrow-banded," referencing its distinctive dorsal markings.

This marks the third species of Smithophis to be described from Mizoram after S. atemporalis and S. mizoramensis, further reinforcing the state’s importance as a biodiversity hotspot. 

“Mizoram clearly plays a central role in the evolution and diversification of this genus,” noted Dr. H.T. Lalremsanga, co-author and head of the Developmental Biology & Herpetology Lab at Mizoram University.

The study recommends additional surveys and habitat assessments, as the narrow range and forest dependency of S. leptofasciatus suggest it may be vulnerable to habitat degradation.