RESUMO
We compiled a checklist with all known endemic plants occurring in the Sierras of Córdoba and San Luis, an isolated mountainous range located in central Argentina. In order to obtain a better understanding of the evolutionary history, relationships and age of the regional flora, we gathered basic information on the biogeographical and floristic affinities of the endemics, and documented the inclusion of each taxon in molecular phylogenies. We listed 89 taxa (including 69 species and 20 infraspecific taxa) belonging to 53 genera and 29 families. The endemics are not distributed evenly, being more abundant in the lower than in the middle and upper vegetation belts. Thirty-two genera (60.3%) have been included in phylogenetic analyses, but only ten (18.8%) included local endemic taxa. A total of 28 endemic taxa of the Sierras CSL have a clear relationship with a widespread species of the same genus, or with one found close to the area. Available phylogenies for some taxa show divergence times between 7.0 - 1.8 Ma; all endemic taxa are most probably neoendemics sensu Stebbins and Major. Our analysis was specifically aimed at a particular geographic area, but the approach of analyzing phylogenetic patterns together with floristic or biogeographical relationships of the endemic taxa of an area, delimited by clear geomorphological features, could reveal evolutionary trends shaping the area.
ResumenSe presenta una lista comentada de todas las especies endémicas conocidas de las Sierras de Córdoba y San Luis, una región montañosa aislada del centro de Argentina. A fin de obtener una mejor comprensión de la historia evolutiva, relaciones y edad de la flora regional, recopilamos información básica sobre afinidades florísiticas y biogeográficas de las endémicas, y relevamos su inclusión en estudios filogenéticos moleculares. El listado incluye 89 taxones (69 species y 20 taxones infraespecíficos), pertenecientes a 53 géneros y 29 familias. La distribución altitudinal de los endemismos no es uniforme, ya que el piso de vegetación inferior tiene más taxones endémicos que los pisos intermedio y superior. Treinta y dos géneros (60.3%) han sido incluidos en algún análisis filogenético, pero sólo 10 de ellos (18.8%) incluyeron taxones locales. Un total de 28 taxones endémicos de las Sierras CSL tienen una clara relación con una especie de amplia distribución del mismo género, o con una de distribución cercana al área. Las filogenias disponibles para algunos taxones muestran tiempos de divergencia entre 7.0 1.8 Ma; todos los endemismos del área son probablemente neoendemismos sensu Stebbins y Major. Aunque nuestro análisis estaba dirigido específicamente a un área geográfica particular, el enfoque de analizar patrones filogenéticos junto con relaciones florísticas y biogeográficas de los endemismos de un área delimitada por características geomorfológicas, podría revelar las tendencias evolutivas que modelaron el área.
RESUMO
PREMISE OF THE STUDY: The South American genus Gymnocalycium (Cactoideae-Trichocereae) demonstrates how the sole use of morphological data in Cactaceae results in conflicts in assessing phylogeny, constructing a taxonomic system, and analyzing trends in the evolution of the genus. METHODS: Molecular phylogenetic analysis was performed using parsimony and Bayesian methods on a 6195-bp data matrix of plastid DNA sequences (atpI-atpH, petL-psbE, trnK-matK, trnT-trnL-trnF) of 78 samples, including 52 species and infraspecific taxa representing all the subgenera of Gymnocalycium. We assessed morphological character evolution using likelihood methods to optimize characters on a Bayesian tree and to reconstruct possible ancestral states. KEY RESULTS: The results of the phylogenetic study confirm the monophyly of the genus, while supporting overall the available infrageneric classification based on seed morphology. Analysis showed the subgenera Microsemineum and Macrosemineum to be polyphyletic and paraphyletic. Analysis of morphological characters showed a tendency toward reduction of stem size, reduction in quantity and hardiness of spines, increment of seed size, development of napiform roots, and change from juicy and colorful fruits to dry and green fruits. CONCLUSIONS: Gymnocalycium saglionis is the only species of Microsemineum and a new name is required to identify the clade including the remaining species of Microsemineum; we propose the name Scabrosemineum in agreement with seed morphology. Identifying morphological trends and environmental features allows for a better understanding of the events that might have influenced the diversification of the genus.