KEY TO SPECIES OF HYMENASPLENIUM PERRIEI AND ITS CONFUSING SPECIES

1a. 1–2(–3) basal basiscopic veins lacking..............................................................................................................................................2

b. 3–4(–8) basal basiscopic veins lacking..............................................................................................................................................4

2a. Pinnae spreading or deflexed, obtuse ............................................................................................................................ H. apogamum

b. Pinnae ascending, subacute-acute......................................................................................................................................................3

3a. Pinnae falcate; sori supramedial-marginal .................................................................................................... H. murakami-hatanakae

b. Pinnae trapeziform to narrowly triangular-falcate; sori medial...................................................................................... H. hondoense

4a. Phyllopodia less than 10 mm; pinna marginal teeth irregular, retuse................................................................................... H. perriei

b. Phyllopodia more than 10 mm; pinna marginal teeth regular, entire or rarely (semi)retuse..............................................................5

5a. Rhizome scales sparse; sori medial to supramedial (Vietnam) ........................................................................... “ H. phamhoanghoi ”

b. Rhizome scales dense; sori inframedial (S Africa, Indian Ocean islands, Malaysia) ................................................... H. unilaterale