An approach to the phylogeny of Chloraeinae (Orchidaceae)

CHEMISQUY, M. A.; MORRONE, O.

San Javier, Tucumán, Argentina

Jornada; XXVII Meeting of the Willi Hennig Society y VIII Reunión Argentina de Cladística y Biogeografía; 2008

Willi Hennig Society

The systematic position and the relationships among some South American terrestrial orchids, Bipinnula, Chloraea, Gavilea and Geoblasta is unclear. The four genera have been grouped in the subtribe Chloraeinae by several authors; also, Chloraeinae has been placed under the tribes Diurideae, Geoblasteae, Spirantheae and Cranichideae. Besides, some authors raised the subtribe Chloraeinae to the tribe level. Previous phylogenetic studies of the group have only included a few species of Chloraea and Gavilea (only one or two species) while Bipinnula and Geoblasta have not been included in a phylogeny before. Therefore, the monophyly of Chloraeinae should be tested, and the monophyly of Bipinnula, Chloraea, Geoblasta and Gavilea needs to be explored. For the molecular phylogenetic analysis three chloroplast markers where used: matK+trnK, atpB-rbcL spacer and rpoC1. The taxonomic sampling includes six species of Gavilea, 11 species of Chloraea, the only species of Geoblasta and several species from tribes Diurideae, Spirantheae and Cranichideae as outgroups. Bipinnula was not included due to the lack of fresh material. Sequences were aligned using the program Dialign and then the alignment was edited manually, as conservative as possible. The three matrices were analyzed separately and combined using the program TNT version 1.1. All characters were equally weighted, gaps were scored as missing data and parsimony uninformative characters were deactivated. Heuristic searches were performed using 1000 series of RAS and TBR, saving 10 trees per replicate. After that, a new search with TBR, using the shortest trees saved on memory, was performed to obtain all the most parsimonious trees, and with them calculate the strict consensus tree. Branch support was assessed using 10000 parsimony jackknife replicates, calculating the absolute jackknife values and the frequency differences. Preliminary results show that Chloraea, Gavilea and Geoblasta are in a clade with high support where Geoblasta and Gavilea are nested inside Chloraea. Consequently, for the taxa here sampled, the subtribe is monophyletic, Chloraea is paraphyletic while Gavilea turned out to be monophyletic with high values of support. As sister group of the Chloraeinae are the Cranichideae species, but a more exhaustive taxonomic sampling is needed to solve the taxonomic placement of the subtribe Chloraeinae.