Laboratorio de Biología Molecular, Instituto Multidisciplinario de Biología Vegetal (IMBIV), Universidad Nacional de Córdoba, Av. Velez Sarsfield 1609, X5016GCA, Córdoba, Argentina.
Am J Bot. 2011 Nov;98(11):1841-54. doi: 10.3732/ajb.1100054. Epub 2011 Oct 19.
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.
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.
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.
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.
南美属 Gymnocalycium（仙人掌科-Trichocereae）展示了仅使用形态数据在仙人掌科中评估系统发育、构建分类系统以及分析属进化趋势会产生冲突。
使用简约法和贝叶斯方法对来自 78 个样本的叶绿体 DNA 序列（atpI-atpH、petL-psbE、trnK-matK、trnT-trnL-trnF）的 6195-bp 数据矩阵进行了分子系统发育分析，其中包括代表 Gymnocalycium 所有亚属的 52 个种和种下分类群。我们使用似然法评估形态特征进化，以优化贝叶斯树上的特征，并重建可能的祖先状态。
系统发育研究的结果证实了该属的单系性，同时总体上支持基于种子形态的现有种下分类。分析表明亚属 Microsemineum 和 Macrosemineum 是多系的和并系的。形态特征分析表明茎大小减小、刺的数量和硬度减小、种子大小增大、棒状根发育以及多汁和多彩果实变为干燥和绿色果实的趋势。
Gymnocalycium saglionis 是 Microsemineum 唯一的物种，需要一个新的名称来识别包括剩余 Microsemineum 物种的分支；我们提议使用 Scabrosemineum 这个名称，与种子形态一致。识别形态趋势和环境特征可以更好地理解可能影响属多样化的事件。
