Study on the morpho-anatomy of Lepisorus species through light microscopy and scanning electron microscopy and its systematic implications

The genus Lepisorus is often associated with complex lineages in Polypodiaceae, which leads to difficulty in understanding taxonomic relationships among the species. The taxa is mostly epiphytic with some distinct features like rhizomes covered with clathrate scales, simple fronds, sori in a single row, intermixed with peltate paraphyses. In this study, we precisely focus on the Lepisorus species and seek a broader understanding of the taxonomic relationships that prevail in this genus. The morpho-anatomical traits of rhizomes, stipe, lamina, and sporangia were explored in nine species with the aid of light microscopy and scanning electron microscopy techniques for gathering the qualitative and quantitative data sets. These character traits were resolved into groups based on degree of similarity and principal component analysis to comprehend the covariance among the variables. The data were then employed to prepare an artificial dichotomous key and hierarchical cluster analysis was established that revealed five related clades with eight members whereas one member emerged as outgroup. The results correspond with other recent phylogenetic studies of the concerned genus hence confirming immense reliability and thrust of light microscopy, scanning electron microscopy, and morphology-based studies that are being less utilized in fern taxonomy.