New records and morphological recognition of Metaxya C. Presl (Metaxyaceae) species in the Brazilian Amazon

ABSTRACT

The record of new occurrences of species is of paramount importance for the study of neotropical biodiversity, needing to be allied to a set of well-defined morphological characters. Hence, with a focus on Amazonian biodiversity, the object of our study is the genus Metaxya (Metaxyaceae). Metaxya C. Presl. has a wide distribution in Tropical America and in Brazil are recorded four of the six recognized species in the genus: M. lanosa A. R. Sm. & Tuomisto, M. rostrata (Kunth) C.Presl, M. scalaris Tuomisto & G.G.Cárdenas and M. parkeri (Hook. & Grev.) J. Sm. Thus, our aim was to revisit and look for diagnostic morphological traits for each species, adding one more point of view of species recognition, therefore, contribute to the understanding of the geographic distribution of this group. To achieve these aims, around 1,450 Metaxya samples deposited in the herbaria of national and foreign institutions were analyzed. This work presents brief morphological descriptions of species occurring in the Brazilian Amazon, comments on the morphological differences between species and their phylogenetic relationships. Additionally, we provide an identification key, new occurrences of M. rostrata for the States of Rondônia and Roraima, also M. scalaris for the Antilles and the first citation of M. parkeri for the Cerrado biome. Finally, we indicate here an isolectotype of M. parkeri in the collection of the Kew Botanical Garden (K).

Keyword:
fern; geographical distribution; identification key; neotropics