Maxomys Sody 1936

Maxomys Sody 1936, Natuurk. Tijdschr. Ned.-Ind., 96: 55.

Type Species: Mus bartelsii Jentink 1910

Species and subspecies: 17 species:

Species Maxomys alticola (Thomas 1888)

Species Maxomys baeodon (Thomas 1894)

Species Maxomys bartelsii (Jentink 1910)

Species Maxomys dollmani Ellerman 1941

Species Maxomys hellwaldii (Jentink 1878)

Species Maxomys hylomyoides (Robinson and Kloss 1916)

Species Maxomys inas (Bonhote 1906)

Species Maxomys inflatus (Robinson and Kloss 1916)

Species Maxomys moi (Robinson and Kloss 1922)

Species Maxomys musschenbroekii (Jentink 1878)

Species Maxomys ochraceiventer (Thomas 1894)

Species Maxomys pagensis (Miller 1903)

Species Maxomys panglima (Robinson 1921)

Species Maxomys rajah (Thomas 1894)

Species Maxomys surifer (Miller 1900)

Species Maxomys wattsi Musser 1991

Species Maxomys whiteheadi (Thomas 1894)

Discussion: Maxomys Division. Definition and contents of Maxomys provided by Musser et al. (1979), who discussed historical allocations of species to groups of Rattus and summarized chromosomal information. The exclusion of Maxomys from Rattus also supported by allozymic data (Chan et al., 1979), albumin immunology (Watts and Baverstock, 1994 b), and DNA/DNA hybridization studies (Ruedas and Kirsch, 1997). Morphological analyses indicated that Maxomys shares all its dental derived molar traits with Berylmys, Mus, and Niviventer, and some of its external features with Mus (Musser and Newcomb, 1983) . Estimate of relationships based on karyotypic data placed Maxomys close to Niviventer and Lenothrix and far from Rattus (Gadi and Sharma, 1983) . Spermatozoal morphology of Malayan Maxomys and one Sulawesian species is similar to Chiropodomys and Hapalomys, a configuration also like that seen in Mus and Apodemus (Breed and Musser, 1991; Breed and Yong, 1986). Sperm conformation in the other species of Sulawesian Maxomys were unlike the Malayan species and resembled that of the Sulawesian endemic Margaretamys (Breed and Musser, 1991) . In their study of DNA/DNA hybridization, Ruedas and Kirsch (1997) sampled five of the 19 species of Maxomys, all Sundaic ( M. ochraceiventer, M. whiteheadi, M. rajah, M. bartelsii, and M. surifer); they formed a monophyletic clade relative to other Indomalayan genera sampled ( Rattus, Sundamys, Niviventer, and Leopoldamys); whether all other species of Maxomys, especially those endemics on Sulawesi, are also members of this clade remains to be determined. Albumin immunology indicates Maxomys to be "a separate lineage within South-east Asian murines not particularly close to any other" (Watts and Baverstock, 1994 b), and analysis of DNA sequence of LINE-1 elements places Maxomys in a clade separate from that containing Leopoldamys and Niviventer (members of our Dacnomys Division), and another formed by Rattus, Berlymys, Sundamys, and Bandicota, genera in our Rattus Division (Verneau et al., 1997, 1998). We isolate Maxomys in its own division, which highlights current estimates of its phylogenetic position within the evolutionary diversity of extant Indomalayan murines.

Closest relative of Maxomys may be the extinct Ratchaburimys ruchae, described from jaw fragments and isolated molars recovered from late Pliocene and early Pleistocene cave sediments in S Thailand north of the Isthmus of Kra (10E30' N) (Chaimanee, 1998). Aside from late Pliocene and Pleistocene examples of Thai M. surifer (see that account), the only other fossils determined as Maxomys come from early Pleistocene beds in E Java (Van der Meulen and Musser, 1999). There is an undescribed species of Maxomys from Mindoro Isl in the Philippines (see accounts of Anonymomys mindorensis and Apomys gracilirostris), one from C Laos (specimens examined by Musser), and two from C Sulawesi (Musser, ms).