Taxonomy: Dendrolagus taxonomy and systematics in the Papuan region has not yet been fully resolved, they have undergone an extensive radiation and diverged into at least twelve distinct species (Groves, 2005; Helgen, 2007b), even though a comprehensive molecular analysis of the genus is yet to be conducted. The taxonomy of the Dendrolagus goodfellowi complex has long been confused, partly due to the lack of museum material. This species was originally described as a subspecies of Goodfellow's Tree-kangaroo D. goodfellowi (Flannery, 1993a) and it was continued being treated as such by Flannery et al. (1996) who conducted the most extensive revision of Dendrolagus taxa based primarily on morphological data, and classified the Goodfellow's taxa as three subspecies: Goodfellow's Tree-kangaroo (D. g. goodfellowi), Timboyok (D. g. buergersi) and Golden-mantled (D. g. pulcherrimus).
This taxonomic treatment has since been followed (Aplin et al. 1999; Martin, 2005). But it differs diagnostically (colour patten, in its slightly smaller size, and it its wide premolars) from D. goodfellowi and it was subsequently elevated as an distinct allopatric species by Groves (2005). However, it is morphologically extremely close to D. goodfellowi with its appropriate rank deserving further study (Helgen, 2007b). Preliminary research by McGreevy et al. (2011) showed that the genetic distance between D. g. pulcherrimus and D. g. buergersi was similar to the genetic distance between D. matschiei and D. spadix. This provide the first genetic evidence supporting the reclassification of D. g. pulcherrimus as a distinct species as suggested by Groves (2005).
Characteristics and identification:
Distribution: Endemic to the Papuan region this species is believed to have become extirpated from 99% of its historic range (much of it within living memory). It is now restricted to the North Coastal Range, where its known to survive in the extreme eastern end of the Torricelli Mtns (in the vicinity of Nunsi, Sibilanga and Weigin on Mt. Sapau), situated in Sandaun (West Sepik) Province, PNG. It also occurs in the nearby Foja Mts, situated just to the north of the Mamberamo River Basin, Indonesia (Diamond, 1985; Flannery, 1993a, 1995b, 1996; Groves, 2005; Helgen, 2007b; Leary et al. in litt 2008).
It was not found on Mt. Menawa in the Bewani Mts, despite extensive fieldwork by Timothy Flannery throughout the North Coastal Range in 1985-1990. It has already been extirpated from the western Torricelli Mts, at least as far east as the Mount Sulen area. Furthermore, it is unknown in the Cyclops Mts and the Sentani area and is likely to have become extinct in these extensive areas in prehistoric and historic times (Flannery, 1993a).