Asia-Tropical:, New Guinea ‒ present; Sulawesi (Sulawesi ‒ present) Pacific Islands: present
Malesia: Sulawesi, New Guinea; Pacific Islands
1 Selliguea plantaginea is the most widely spread New Guinean/Pacific representative of the complex of mainly allopatric species around S. feei, to which also belong S. elmeri (Philippines), S. caudiformis (East Malesia) and S. feeoides (Pacific). Within this complex, the species boundaries are rarely sharp. From S. feei, S. caudiformis and S. feeoides, the present species differs mainly in the absence of hydathodes. At the same time, S. plantaginea is the central species in a complex of mainly sympatric species, in which specific boundaries are occasionally even less clear: S. albicaula, S. archboldii, S. bellisquamata, S. costulata, S. cretifera, S. dekockii, S. ferrea (Oleandropsis ferrea), S. lauterbachii (used to be called ‘gibbsiae’), S. tafana (often identified as ‘squamisora’). 3. Throughout the mountain ranges of New Guinea two forms occur. One has fairly thick rhizomes, densely set with spreading, elongated, acute scales which are dark near the attachment and lighter coloured in the acumen; usually found at altitudes up to 2700 m. The other form has usually thinner rhizomes (1.5-3 mm), strongly glaucous, and sparsely set with deciduous, appressed, obtuse scales often with a darker, thickened, distinctly cucullate apex. It is almost exclusively restricted to heights of over 3000 m. Apart from the rhizomes, the two forms are indistinguishable in many locations, exhibiting the same variation in frond shape, size and soral disposition. Moreover, over a fairly wide altitudinal range (2400-3400 m), specimens are occasionally found which combine characters of the two forms, often on different parts of the same rhizome. 2. The species is very variable in the degree to which the sori are confluent.