Endemic Asian Chytrid Strain Infection in Threatened and Endemic Anurans of the Northern Western Ghats, India

Abstract

The Western Ghats of India harbors a rich diversity of amphibians with more than 77% species endemic to this region. At least 42% of the endemic species are threatened due to several anthropogenic stressors. However, information on amphibian diseases and their impacts on amphibian populations in this region are scarce. We report the occurrence of Batrachochytridium dendrobatidis (Bd), an epidermal aquatic fungal pathogen that causes chytridiomycosis in amphibians, from the Western Ghats. In the current study we detected the occurrence of a native Asian Bd strain from three endemic and threatened species of anurans, Bombay Night Frog Nyctibatrachus humayuni, Leith's Leaping Frog Indirana leithii and Bombay Bubble Nest Frog Raorchestes bombayensis, for the first time from the northern Western Ghats of India based on diagnostic nested PCR, quantitative PCR, DNA sequencing and histopathology. While, the Bd infected I. leithii and R. bombayensis did not show any external symptoms, N. humayuni showed lesions on the skin, browning of skin and sloughing. Sequencing of Bd 5.8S ribosomal RNA gene, and the ITS1 and ITS2 regions, revealed that the current Bd strain is related to a haplotype endemic to Asia. Our findings confirm the presence of Bd in northern Western Ghats and the affected amphibians may or may not show detectable clinical symptoms. We suggest that the significance of diseases as potential threat to amphibian populations of the Western Ghats needs to be highlighted from the conservation point of view.

Overview of chytrid emergence and impacts on amphibians

“…Bd is widely distributed throughout Asia [67] and has been present in the region since at least 1911 [68], but no reports exist of disease-driven mortality or population declines [67]. Many distinct genotypes are being described from the regions, including Japan [69], Korea [70] and India [71] as well as Bsal [58]. The growing diversity of chytrid pathogens of amphibians from Asia suggests a likely site of origin for these pathogens.…”

Raorchestes ghatei, a new species of shrub frog (Anura: Rhacophoridae) from the Western Ghats of Maharashtra, India

“…nov. need verification. Based on the examination of vouchers, we suggest that the records of R. bombayensis from Tamhini (Dahanukar & Padhye 2005) and Taleghar (Dahanukar et al 2013), should be considered as R. ghatei sp. nov. tuberohumerus from Thoseghar by Padhye & Ghate (2012) should also be asigned to R. ghatei sp.…”

“…Pande et al (2013) have discussed threat of wind farms to avifauna wherein they discuss the windmill erection activity to be a measured threat to general diversity as well. Recently, Dahanukar et al (2013) reported the presence of chytrid fungal infection in morphologically identified R. bombayensis from Taleghar, which should be attributed to the R. ghatei sp. nov. based on the current study.…”

Sighting of Red-breasted Parakeet Psittacula alexandri (Linnaeus, 1758) (Psittaciformes: Psittaculidae) from Vellayani, Thiruvananthapuram, Kerala, India

“…Western Ghats is known as an amphibian hot spot. For the first time in 2011 "killer fungus" Batrachochytrium dendrobatidis which causes Chytridiomycosis in amphibians was reported from Western Ghats (Nair et al 2011), further its widespread occurrence in Western Ghats was reported in 2013 and 2015 (Dahanukar et al 2013;Molur et al 2015). Amphibian trade and introductions are prominent hypotheses for the spread of B. dendrobatidis in many parts of the world (Fisher & Garner 2007).…”