# The First Report of Rhino DNA in Thailand: A Possible Extinct Indian Javan Subspecies, Rhinoceros sondaicus inermis

## TL;DR

This study identifies ancient rhino remains in Thailand as belonging to the extinct Indian Javan rhino subspecies, suggesting a broader historical range for this critically endangered species.

## Contribution

The first genetic analysis of rhino remains from Thailand, revealing possible evidence of the extinct Indian Javan rhino subspecies.

## Key findings

- Ancient Thai rhino DNA was identified as belonging to the Javan rhino but distinct from known subspecies.
- The Thai rhino DNA showed genetic differences similar to those between white rhino subspecies.
- The findings suggest the Indian Javan rhino may have lived in Thailand 100 years ago.

## Abstract

The Javan rhino is a critically endangered species where its wild population, approximately 50 individual rhinos, survive only in Java, Indonesia. In the past, there were three Javan rhino subspecies: the Indonesian Javan rhino, the Vietnamese Javan rhino, and the Indian Javan rhino, of which only the first subspecies still exists. The last Vietnamese Javan rhino was killed in 2010, while the Indian Javan rhino became extinct in the early nineteenth century. The Vietnamese Javan and the Indonesian Javan rhinos had been reported to exist in Thailand. In this study, two rhino remains, dated to approximately 100 years before present and found in Prachuap Kirikhan, the west of Thailand, had their species identified based on a partial DNA sequence. The results of genetic analyses demonstrated that the Thai rhino remains belonged to Javan rhinos. However, they had dramatic genetic distinctions from both the Indonesian and the Vietnamese Javan subspecies and possibly belonged to the Indian Javan rhino. The findings suggest that the Indian Javan existed in Thailand at least 100 years ago and that this Javan rhino subspecies had a broader habitat than previously believed. Our new DNA sequences can be used for conservation and evolutionary studies of this rhino species.

The Javan rhino is a critically endangered species that has become extinct in several Asian countries, including Thailand. There are three Javan rhino subspecies: Rhinoceros sondaicus sondaicus, R. s. annamiticus, and R. s. inermis, and the first two subspecies existed in Thailand decades ago. However, no genetic study on Thai rhinos has been reported. In this study, we amplified a partial D-loop region of two ancient rhino specimens dated to approximately 100 years before present, from southwest Thailand. Then, we constructed phylogenetic trees and a haplotype network based on the D-loop sequences of the Thai rhinos and 39 Javan, Sumatran, and Indian rhinos from the GenBank database. The ancient Thai rhino DNA belonged to Javan rhinos and was clearly separated from R. s. annamiticus and R. s. sondaicus. The nucleotide differences among the ancient Thai, R. s. annamiticus, and R. s. sondaicus rhino DNA were 5.14–8.30%, similar to those between two white rhino subspecies. Moreover, species delimitation analyses confirmed that the ancient Thai rhinos should belong to another Javan rhino subspecies, possibly the extinct Indian Javan rhino. This is the first report of rhino DNA from Thailand and possibly the Indian Javan rhino DNA, which could be used for evolutionary studies.