Davies K L, Stpiczynska M
School of Earth, Ocean and Planetary Sciences, Cardiff University Main Building, Park Place, Cardiff CF10 3YE, UK.
Ann Bot. 2006 Dec;98(6):1215-31. doi: 10.1093/aob/mcl204. Epub 2006 Sep 28.
The two closely related subtribes Bifrenariinae Dressler and Maxillariinae Benth. are easily distinguished on morphological grounds. Recently, however, molecular techniques have supported the inclusion of Bifrenariinae within a more broadly defined Maxillariinae. The present paper describes the diverse labellar micromorphology found amongst representatives of Bifrenariinae (Bifrenaria Lindl., Rudolfiella Hoehne, Teuscheria Garay and Xylobium Lindl.) and compares it with that found in Maxillaria Pabst & Dungs and Mormolyca Fenzl (Maxillariinae).
The labella of 35 specimens representing 22 species of Bifrenariinae were examined by means of light microscopy and scanning electron microscopy and their micromorphology compared with that of Maxillaria sensu stricto and Mormolyca spp. The labellar epidermis of representatives of Bifrenaria, Xylobium and Mormolyca was tested for protein, starch and lipids in order to ascertain whether this tissue is involved in the rewarding of pollinators.
The labella of Bifrenaria spp. and Mormolyca spp. are densely pubescent but those of Xylobium, Teuscheria and Rudolfiella are generally papillose. However, whereas the trichomes of Bifrenaria and Mormolyca are unicellular, those found in the other three genera are multicellular. Hitherto, no unicellular trichomes have been described for Maxillaria, although the labella of a number of species secrete a viscid substance or bear moniliform, pseudopollen-producing hairs. Moniliform hairs and secretory material also occur in certain species of Xylobium and Teuscheria and these genera, together with Maxillaria, are thought to be pollinated by stingless bees (Meliponini). Differences in the labellar micromorphology of Bifrenaria and Mormolyca are perhaps related to Euglossine- and/ or bumble bee-mediated pollination and pseudocopulation, respectively. Although Xylobium and Teuscheria share a number of labellar features with Maxillaria sensu stricto, this does not necessarily reflect taxonomic relationships but may be indicative of convergence in response to similar pollinator pressures.
两个亲缘关系密切的亚族，比弗瑞纳瑞亚族（Dressler）和马克西拉里亚族（Benth.），基于形态学依据很容易区分。然而，最近分子技术支持将比弗瑞纳瑞亚族归入更广义的马克西拉里亚族。本文描述了在比弗瑞纳瑞亚族（比弗瑞纳瑞亚属Lindl.、鲁道夫瑞亚属Hoehne、特舍瑞亚属Garay和木瘤兰属Lindl.）代表植物中发现的多样的唇瓣微观形态，并将其与马克西拉里亚属（Pabst & Dungs）和莫莫利卡属（Fenzl）（马克西拉里亚族）中的唇瓣微观形态进行比较。
通过光学显微镜和扫描电子显微镜检查了代表比弗瑞纳瑞亚族22个物种的35个标本的唇瓣，并将它们的微观形态与狭义的马克西拉里亚属和莫莫利卡属物种的唇瓣微观形态进行比较。对比弗瑞纳瑞亚属、木瘤兰属和莫莫利卡属代表植物的唇瓣表皮进行了蛋白质、淀粉和脂质检测，以确定该组织是否参与对传粉者的回报。
比弗瑞纳瑞亚属和莫莫利卡属的唇瓣密被柔毛，但木瘤兰属、特舍瑞亚属和鲁道夫瑞亚属的唇瓣通常具乳头状突起。然而，比弗瑞纳瑞亚属和莫莫利卡属的毛状体是单细胞的，而其他三个属中的毛状体是多细胞的。迄今为止，虽然许多马克西拉里亚属物种的唇瓣分泌粘性物质或具念珠状、产生假花粉的毛，但尚未描述过该属的单细胞毛状体。念珠状毛和分泌物质也出现在某些木瘤兰属和特舍瑞亚属物种中，这些属与马克西拉里亚属一起被认为是由无刺蜂（Meliponini）传粉的。比弗瑞纳瑞亚属和莫莫利卡属唇瓣微观形态的差异可能分别与 Euglossine 蜂和/或熊蜂介导的传粉和拟交配有关。尽管木瘤兰属和特舍瑞亚属与狭义的马克西拉里亚属有一些唇瓣特征相同，但这不一定反映分类关系，可能表明是对类似传粉者压力的趋同反应。
