番荔枝科研究35.Guatteria类群和有关属的系统发育

Guatteria类群由4个新热带的属组成,即Guatteria,Guatteriopsis,Guatteriella和Heteropetalum。不同的作者基于不同的证据得出的它在番荔枝中的地位各不相同。基于宏观和微观的形态特征,对该类群进行了表型和分支分析。分支分析表明,所研究属的系统发育分支方式仅由极少数共同衍征支持,同型现象非常明显,所获得的唯一的最简约分支图可分为两个基本部分,即一个(假)合生心皮分支和一个离生心皮grade。在表征聚类图和主成分分析的三维构象图中同样可以区分出离生心皮和(假)合生心皮两个表征群,表征分析表明Guatteria类群处在其它离生心皮类和(假)合生心皮类的中间位置。然而分支分析表明Guatteria类群与番荔枝科中最进化的(假)合生心皮类有姊妹群关系。Guatteria类群是离生心皮类中最进化的一类。番荔枝科中离生心皮类和(假)合生心皮类在漫长的进化过程中经历了强烈的形态分化而显示出极大的形态差异,然而在系统发育上它们可以通过Guatteria类群作为纽带而联系起来。

Studies in Annonaceae. XXXV. Phylogeny of the Guatteria-group and Related Genera

The Guatteria-group consists of four neotropical genera, Guatteria, Guatteriopsis, Guatteriella, and Heteropetalum. Its systematic position within Annonaceae, interpreted by different authors based on various sources of evidence, is quite questionable. In this paper phylogenetic and phenetic analyses were carried out by using 44 phylogenetically informative characters from morphology, leaf and wood anatomy, as well as palynology of 38 annonacaeous genera with Magnoliaceae as outgroup. The phylogenetic analysis indicates that the phylogeny of selected genera in Annonaceae is weakly supported with branching patterns determined by few, mostly homoplasious, characters. Homoplasy in the studied genera is pervasive. The single most parsimonious tree obtained can be divided into two basic parts, i.e., a (pseudo)syncarpous clade and an apocarpous grade. The corresponding two phenons, i.e., the apocarpous vs. (pseudo)syncarpous ones, are also recognized in the phenogram and in the three-dimensional plot of the first three principal coordinates. On the base of our data set, the phenetic analyses agree broadly with the view of van Setten & Koek-Noorman (1992) that the Guatteria-group takes an intermediate position between other apocarpous genera and the (pseudo)syncarpous genera. Our phylogenetic analyses strongly suggest a sister group relation of the Guatteria-group with the most derived (pseudo)syncarpous genera in Annonaceae. It also indicates that the Guatteria-group is the most derived one among the apocarpous genera. Though the apocarpous and the (pseudo)syncarpous genera have undergone drastic morphological divergence in the long history and thus exhibit high superficial dissimilarities, they can possibly be related to each other phylogenetically via the Guatteria-group as a link.