Hadromys Thomas 1911

Hadromys Thomas 1911 View in CoL

Hadromys Thomas 1911 View in CoL , J. Bombay Nat. Hist. Soc., 20: 999.

Type Species: Mus humei Thomas 1886

Species and subspecies: 2 species:

Species Hadromys humei (Thomas 1886)

Species Hadromys yunnanensis Yang and Wang 1987

Discussion: Hadromys Division. Usually considered closely allied to Arvicanthis and its relatives, especially Golunda ( Misonne, 1969) , but a combination of primitive and derived cranial and dental traits divorces Hadromys from that group: best hypothesis now available on phylogenetic affinities would be to derive the species of Hadromys from some late Miocene Asian ancestor, possibly a species of Karnimata (= Progonomys , according to Mein et al., 1993), and to consider any resemblance to the Arvicanthis cluster a reflection of convergent evolution ( Musser, 1987 b). No fossils have been described that suggest phylogenetic links between Hadromys and either Asian Golunda or extinct Asian genera such as Saidomys , Parapelomys , and Dilatomys (see descriptions of those genera in Brandy, 1981; Gupta and Prasad, 2001; Jacobs, 1978; Ôen, 1983) that have been labeled "Asian arvicanthines" (e.g., Cheema et al., 2003)

Hadromys loujacobsi , known by fossil fragments from Late Pliocene and early Pleistocene sediments in Punjab region of N Pakistan, is a more derived (dentally) relative of living H. humei ( Cheema et al., 2003; Musser, 1987 b). Prohadromys varavudhi , described from isolated molars found in Thailand (late Pliocene to early Pleistocene) is dentally closely related to the species of Hadromys , but has less specialized molars reflected by their lower coronal heights and more arcuate cusp rows ( Chaimanee, 1998). Something with that kind of molar configuration could be a direct potential ancestor of Hadromys . An earlier dental fragment from middle Pliocene of Pakistan was identified as Hadromys sp. and is also less derived than H. loujacobsi ( Cheema et al., 1997) . Available data indicate that H. humei and its extant and extinct relatives once occurred over a wide area of the Indomalayan region and may have originated and evolved in what is now Indochina ( Chaimanee and Jaeger, 2000 b) .