Martínez-Millán Marcela, Crepet William L, Nixon Kevin C
L. H. Bailey Hortorium, Department of Plant Biology, 412 Mann Library Building, Cornell University, Ithaca, New York 14853-4303 USA.
Am J Bot. 2009 May;96(5):933-49. doi: 10.3732/ajb.0800347.
The study of fossil flowers in the last 25 years has greatly increased our understanding of angiosperm diversification. Following that tradition, we here describe a new fossil taxon from the Late Cretaceous of New Jersey, Pentapetalum trifasciculandricus Martínez-Millán, Crepet et Nixon gen. et sp. nov. It includes actinomorphic pentamerous flowers with quincuncial calyx, imbricate corolla, numerous stamens of markedly different heights, and a superior tricarpellate ovary, which are morphologically consistent with the flowers of the Theaceae s.l. and of members of the order Theales sensu Cronquist. Cladistic analyses including 45 extant taxa plus the fossil, 61 morphological characters, and different combinations of the molecular markers rbcL, matK, trnL-trnF, matR, and ITS support its inclusion in the order Ericales sensu APG. Comparison with extant taxa using traditional methods of identification suggests a relation with the Theaceae s.s. (Stewartia), but the phylogenetic analyses do not support this view. Instead, the phylogenetic analysis suggests some relation to the Ternstroemiaceae/Pentaphylacaceae (Theaceae s.l.), exemplifying the importance of evaluating identifications in a phylogenetic context. The description of Pentapetalum further adds to the ample diversity of Ericales in the Late Cretaceous.
在过去25年中，对化石花的研究极大地增进了我们对被子植物多样化的理解。遵循这一传统，我们在此描述一种来自新泽西州晚白垩世的新化石分类群，五瓣花三叶雄蕊花（Pentapetalum trifasciculandricus Martínez-Millán, Crepet et Nixon），新属新种。它包括辐射对称的五基数花，其花萼呈交互对生，花冠呈覆瓦状，有许多高度明显不同的雄蕊，以及一个上位的三心皮子房，在形态上与广义茶科和克朗奎斯特分类系统中茶目成员的花一致。包含45个现存分类群加该化石、61个形态特征以及分子标记rbcL、matK、trnL-trnF、matR和ITS的不同组合的分支分析支持将其归入APG分类系统中的杜鹃花目。使用传统鉴定方法与现存分类群进行比较表明它与狭义茶科（紫茎属）有关系，但系统发育分析并不支持这一观点。相反，系统发育分析表明它与厚皮香科/五列木科（广义茶科）有一定关系，这例证了在系统发育背景下评估鉴定结果的重要性。五瓣花的描述进一步丰富了晚白垩世杜鹃花目的多样性。
