Rattus vandeuseni Taylor and Calaby 1982

Rattus vandeuseni Taylor and Calaby 1982, in: Taylor et al., Bull. Am. Mus . Nat. Hist., Vol. 173: 211.

Type Locality: Papua New Guinea, Maneau Range, N slope Mt Dayman, Middle Camp, 1540 m.

Vernacular Names: Van Deusen's New Guinea Mountain Rat.

Distribution: Recorded only from the Mt Dayman region at the E end of the Owen Stanley Range in Papua New Guinea, 1500-1540 m (Musser and Carleton, 1993; Musser and Lunde, ms).

Conservation: IUCN – Endangered as Stenomys vandeuseni .

Discussion: Rattus leucopus species group. Cole et al. (1997) reported one example from an E ridge of Mt Dayman (identified by comparing it with two specimens from the type series) and noted that Flannery had indicated to them that most R. vandeuseni (in AM) from that area were from 1300 m. Flannery (1995 a) also reported specimens from the Agaun Valley at 300 m (according to Cole et al., 1997), but it is unclear if these are from 300 m (in which case they should be reexamined to determine if they are really the lowland R. verecundus) or the specimens from 1300 m. We can only vouch that the type series, which we studied, represents a montane species morphologically distinguishable from the lower altitudinal R. verecundus .

Taylor and Calaby described vandeuseni as a subspecies of R. verecundus (Taylor et al., 1982), but its distinctive morphology and habitat indicate otherwise, as the describers even suggested, and as Flannery (1990 b:245) speculated. Rattus verecundus occurs on Mt Dayman in rain forest at 700 m and is replaced at 1540 m in montane oak forest by R. vandeuseni, a relationship that is similar to the distributions of Leptomys elegans (rain forest) and Leptomys sp. (oak forest) on Mt Dayman (Musser and Lunde, ms).