Phylogeny of the species of the genus Celtis (Cannabaceae) of southern South America: morphological and molecular evidence

CHAMORRO, DÉBORA; MOGNI, VIRGINIA Y.; ZAMENGO, HENRIQUE BORGES; OAKLEY, LUIS; ORTIZ, JUAN P.A.; PRADO, DARIÉN E.

Sao Paulo

Congreso; II First Virtual Meeting of Systematics, Biogeography & Evolution-SBE; 2021

SBEmeeting

The genus Celtis (Cannabaceae) comprises around 70 temperate to tropical woody species, commonly known as hackberries. In southern South America it is represented by around ten taxa (all belonging to the subgenus Mertensia Planch.) restricted to the Domain of Neotropical Seasonally Dry Forests, and the subtropical Chaco and Espinal biogeographical regions. The latter species present signicant inter- and intraspecic morphological variability and similarity that has generated widespread taxonomic confusions. This work aim was to study the phylogeny of some species of the genus Celtis, with morphological characters and DNA sequences combined, as well as the main morphological features to improve taxonomic circumscriptions. Twenty-nine specimens representing seven taxa of Celtis and five outgroup accessions were included. Twenty vegetative and reproductive morphological characters were selected based on previous works. The nuclear FA16180b marker was amplified and sequenced. The sequences were aligned using Mega 6.06, through ClustalW v1.8. The data were analyzed under the parsimony optimality criterion using the program TNT. This group of Celtis species resulted as monophyletic, although there is no clear resolution between these taxa. Nevertheless, six species of southern South America Celtis are recognized. As regards C. pallida (with its two varieties), a polytomy of specimens was observed; however, it differentiates clearly from the rest of the species. Meanwhile, C. tala, C. chichape and C. clausseniana do not form a clade but are visibly separated from the rest of the species. A definedclade formed by C. serratissima and C. spinosissima differentiates from the rest. The characters that have the greater correspondence with the formed groups were: growth habit, type of spines, type of styles, type of foliar margin, indument of the foliar veins and pyrene ornamentation. Except for the hygrophilous C. chichape, the other five species are confined to well-defined biogeographical regions, thus coinciding with its distribution in the phylogenetic tree.