Asia-Tropical: Borneo present (Sarawak present); Malaya (Peninsular Malaysia present), Perak present
Malesia: Malay Peninsula (Perak), Borneo (Sarawak) (one collection from each).
The type was collected by Haniff on a journey to Gunung Korbu in 1909. The collector's label was not preserved. Ridley assigned numbers in his own series to all Haniff's specimens and wrote the locality cited for 14142, indicating a source near the summit of the mountain. The evidence that the type was not from a high altitude is as follows. The second collection, reported by Holttum in 1986, was from 'slope of bat guano in cave mouth' in a limestone area in Gunung Mulu National Park, Sarawak. There is also a specimen from a low altitude in Perak, consisting of basal pinnae and the pair next above them; these are about intermediate between P. australis and the type of P. acutissima. The lobes of basal pinnae are little different from those of P. acutissima; one of the pair has one almost free basal lobe; hairs at the bases of costae are like those of P. australis; the upper pinnae of the frond have not been preserved. More information is needed.