Rufous-sided Honeyeater (Ptiloprora erythropleura) - HBW 13, p. 657

Taxonomy: Ptilotis erythropleura Salvadori, 1876, Arfak Mountains, north-west New Guinea.
Formerly considered conspecific with P. mayri, P. guisei and P. perstriata, but the four differ in size, plumage (crown colour, dorsal coloration, colour of wing-covert edgings, distinctness of ventral spotting, flank colour) and iris colour. Present species is sympatric (and with broad altitudinal overlap) with P. perstriata over distance of at least 400 km in W New Guinea. Birds from Wissel Lakes area (between Weyland Mts and Snow Mts) described as race incerta, but validity uncertain, and thought possibly a hybrid between race dammermani and P. perstriata (of nominate race); further study needed. In NW (Bomberai Peninsula), female specimen in Kumawa Mts like race dammermani in size and iris colour, but with pale yellowish wash below; birds almost certainly of this species seen commonly in Fakfak Mts also had somewhat yellowish underbody, and thought by later researchers to differ from nominate race in larger size, distinct streaking below and lack of rufous in plumage (also, tuft at side of breast yellowish, and at least some had pale iris); both populations provisionally included with present species, but study required in order to determine whether they represent one or two undescribed races, or even new species. Two subspecies currently recognized.