Nephopteris out of the clouds: Molecular evidence places the enigmatic N. maxonii (Pteridaceae) within the Jamesonia clade

Abstract

The monospecific fern genus Nephopteris is restricted to four paramos in Colombia. Until now, its phylogenetic relationships have not been clarified, although morphological traits suggest that it belongs to the taenitidoid clade of the subfamily Pteridoideae in the Pteridaceae. We isolated four chloroplast (atpA, chlL, rbcL, and rps4) loci of N. maxonii and performed maximum parsimony and maximum likelihood phylogenetic analyses, including a preliminary analysis based on rbcL of 424 accessions of leptosporangiate ferns. Then, we carried out separate and combined reconstructions for all four loci, focusing the sampling in the subfamily Pteridoideae (Pteridaceae). Our results show that Nephopteris belongs to the taenitidoid clade of the subfamily Pteridoideae and is nested in Jamesonia. Thus, the new combination Jamesonia maxonii is provided. Its dimorphic sterile and fertile leaves appear to be unique within the taenitidoids. Given that this species shares the same microhabitat with other Jamesonia species, it is unlikely that leaf shape evolution within the entire clade is a result of adaptive processes to paramo conditions.