ABSTRACT Aim Cyclophorus Montfort, 1810 is a widespread genus of operculate land snails distributed across South and Southeast Asia, with its westernmost limit in the Western Ghats of India. Despite its broad distribution, the evolutionary origin of the genus and the biogeographic history of Indian taxa remain unresolved due to the absence of molecular data from India. Here, we test whether the Indian Cyclophorus fauna represents an ‘Into India’ dispersal scenario and investigate its diversification history. Location South and Southeast Asia. Time Period Miocene to present. Major Taxa Studied Cyclophorus Montfort, 1810 (Caenogastropoda: Cyclophoridae). Methods We generated new molecular data for 25 Cyclophorus specimens from across India, representing 18 lineages and combined these with existing global datasets. Two mitochondrial (COI, 16S) and one nuclear (28S) markers were analysed using maximum likelihood and Bayesian phylogenetic methods. Divergence times were estimated in BEAST using fossil calibration. Historical biogeography was inferred using BioGeoBEARS and stochastic mapping and diversification dynamics were assessed using lineage‐through‐time plots and an episodic birth–death model implemented in RevBayes. Results Our analyses indicate a mainland Southeast Asian origin centred on South Indochina, followed by multiple dispersal events that shaped the present‐day distribution of the genus. Cyclophorus was recovered as a monophyletic genus comprising six major clades. Indian taxa were polyphyletic, distributed across three distinct clades nested within a predominantly Southeast Asian radiation. Divergence dating and ancestral range reconstructions supported a mainland Southeast Asian (South Indochina–Sundaland) origin and possible overseas dispersal into island archipelagos such as the Philippines, Taiwan and Japan. A dispersal into the Himalayan region and subsequent colonisation of Peninsular India during mid‐miocene is inferred. Additional back‐dispersal into Indochina and later long‐distance dispersal into island systems were inferred. Diversification rates increased markedly during the late Miocene (~7 Mya), with low extinction through time. Main Conclusions The Indian Cyclophorus fauna was assembled through multiple dispersal events from Southeast Asia, supporting an ‘Into India’ scenario. Although colonisation occurred early, diversification within India was delayed until the late Miocene, likely driven by regional climatic and environmental reorganisation.
Das et al. (Fri,) studied this question.