Antrophyum species are characterized by their short creeping rhizomes, short and fleshy stipes, laminas that are fleshy, pendulous, simple, entire and gradually widen from the base and the sori that spread along the veins in broken lines and are usually sunk in grooves (Holttum 1954; Chin 1977; Piggott 1988; Smith et al. 2006).
The species name of Antrophyum parvulum derived from the Latin ‘parvus’ that means small, so it is not surprising that it is the smallest among the four species of Antrophyum in Peninsular Malaysia. In Peninsular Malaysia, this fern is commonly found on rocks in limestone areas but it was once collected as an epiphyte and twice from Penang Hill where there is no limestone. It mostly occurs on limestone rocks in the north but has also been recorded from the limestone throughout Peninsular Malaysia. Adapted to its habitat on limestone, it can withstand long drought periods (Holttum 1954; Piggott 1988).
Our field observations on Gunung Baling, Kedah, in 2010, noted that the population there grows directly on the limestone rocks in partially shaded area. Most fronds were fresh with only some wilted. Two populations were found on limestone hills nearby Gunung Senyum, Pahang, in 2011. The first population occurred as a very small population that grew among mosses on the limestone rocks at the base of the hill in a quite shady area. All the fronds were fresh and healthy. However, the other population was found on the top of the hill and grew directly on the limestone rock in a quite exposed and hot area. Its fronds were all wilted (Kiew et al. 2011).
Antrophyum parvulum is characterised by scales to 5 mm long with hair-like tips; fronds up to 15 cm long and 2 cm wide, usually not distinctly stalked; small obovate laminas with a rounded apex, large laminas gradually widening from the base to a point about a third to a quarter from the shortly pointed apex, with narrow scales beneath; the midrib is not distinguished and veins form long narrow areoles; the sori are sunk in quite deep grooves, which usually are long but little anastomosing, and the paraphyses club-shaped.
