Taxonomic and cytogenetic studies in Opuntia ser. Armatae (Cactaceae)

LAS PEÑAS M. L.; OAKLEY L.; MORENO N; BERNARDELLO G.

BOTANY

NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS

Lugar: Otawa; Año: 2017 vol. 95 p. 101 - 120

1916-2790

Opuntia series Armatae is evaluated considering morphological (vegetative, floral and carpological) and cytogenetical (diploid number, presence of heterochromatin and physical localization of ribosomal genes) features to cast light on their systematics and evolution. Three complexes were here defined: O. elata, O. megapotamica, and O. monacantha according to fruit, stigma, and seed aryl traits. The main systematic conclusions include: 1. O. stenarthra, O. assumptionis, O. cognata and O. subsphaerocarpa are synonyms; 2. O. elata is a variable species with three varieties: var. elata, var. cardiosperma and var. obovata; 3. O. rioplatense is a synomym of O. elata var. obovata; 4. O. megapotamica is a polymorphic species with two varieties (a newly described and a new combination). All species had small similar-sized symmetrical chromosomes and resulted tetraploid (2n=44), except a population of O. arechavaletae and O. monacantha (2n=22). All showed one pair with CMA+/DAPI? NOR associated bands. 18-5.8-26S rDNA loci seem to be coincident with CMA+/DAPI-/NORs blocks and allowed the identification of homeologous pairs between species. The number of 5S signals detected was indicative of the ploidy level of the species. Cytogenetic and morphological features allowed to differentiate the complexes, species and varieties of Opuntia ser. Armatae.