Phylogeography of Red Spiny Rats Maxomys surifer (Miller, 1900) (Mammalia: Rodentia: Muridae) based on Cytochrome b in peninsular Thailand

Spiny rats (Genus Maxomys) are an endemic rodent species in Southeast Asia belonging to the family Murinae. There are currently 18 species recognized in the genus Maxomys, with a general distribution extending from mainland Southeast Asia eastward over the Sunda Shelf to some nearby islands. The phylogeography of M. surifer (Miller, 1900) in Thailand, particularly in peninsular Thailand, is presented in this study. A phylogenetic tree and haplotype networks were reconstructed to comprehend the geographic variation in the study area. Analyses included 898 base pairs of mitochondrial cytochrome b sequence data for 92 individuals of M. surifer, comprising 59 newly obtained sequences and 33 sequences from GenBank. The phylogenetic tree with the maximum likelihood inference revealed five highly divergent lineages within M. surifer. Three lineages (Clades I - III) were found in peninsular Thailand: Clade I includes specimens from a small area in the southern part of the peninsula; Clade II consists of specimens from both the mainland of peninsular Thailand and nearby islands in the Andaman Sea, including those from the type locality; Clade III comprises specimens from the central to northern parts of peninsular Thailand, extending toward the Kra Isthmus. Clades IV and V involved specimens from the Indochinese subregion. The results extend a view proposed in previous studies that M. surifer comprises several highly differentiated and well-supported phylogenetic lineages, possibly belonging to several distinct species. This study, for the first time, clearly showed five distinct clades found in Thailand with geographic overlap between Clades I and II, Clades II and III, and Clades IV and V. As well, the island populations in the Andaman Sea were included in Clade II, and also showed genetic difference between the distant islands (Adang and Rawi islands) and the island closer to the peninsular Thailand (Tarutao island). We propose that Peninsular Thailand acted as a center of isolation and diversification for three clades (Clades I, II, and III), and that subsequent dispersal events shaped their current complex and mosaic distribution with overlapping ranges in the Peninsular Thailand.