Background and aims

: Polystichum is represented in Argentina and Chile by 11 species, which originated within the Austral South American and the Andean lineages. The taxonomy of Polystichum is controversial because of its widespread hybridization and complex patterns of reticulation. The aims of the present study are: 1) to define morpho-anatomical characters that contribute to the differentiation of both lineages, 2) to improve the species delimitation.

M&M

: Morphological measurements and histological examinations under light microscope, were made of fronds and rhizomes of nine Polystichum species (seven belong to the Austral South American Clade and two to the Andean Clade). Furthermore, 13 quantitative characters of 77 Austral South American herbarium specimens were included in two multivariate statistical procedures.

Results

: The main characters we found that separate the South American Austral clade from the Andean species studied are: indusia, spinules of ultimate segments and edge of rhizomes and petioles scales. In the South American Austral clade, we found shape and division of lamina, basal pinnae length, the number of pinnae pairs per lamina and the number of them with sori, and some anatomical features, such as glandular hairs of indusia, circumendodermal band and petiole meristemeles number, are informative characters at the species level.

Conclusions

: For the first time, our study recovered anatomical and morphometric features that consistently can be used to separate the nine Polystichum species inhabit southern South America.