中国西南地区地图衣属一新种——四川地图衣

Rhizocarpon sichuanense, a new species from Southwest China

关键词:  巴巴酸, 地图衣科, 地衣型子囊菌, 地衣型真菌, 分类学

Key words:  barbatic acid, Rhizocarpaceae, lichenized ascomycetes, lichenized fungi, taxonomy

摘要:

为明确地图衣属部分物种的分类地位,该研究以中国西南地区为研究区域,采用表型特征(形态学、解剖学和化学特征)和基因型特征(ITS序列)相结合的方法,对地图衣属(Rhizocarpon Ramond ex DC.)地衣物种进行分类学研究,初步探讨该属物种表型与基因型的对应关系。通过研究,我们发现了该属1新种——四川地图衣(Rhizocarpon sichuanense Y. M. Zhang, L. Hu & W. C. Wang, sp. nov.),该新种与相近种黑灰地图衣(Rhizocarpon cinereonigrum Vain.)和中华地图衣(Rhizocarpon sinense Zahlbr.)的主要区别:地衣体裂片较为分散,表面呈龟裂或者亚鳞叶状; 下地衣体黑色,明显; 孢子较大,为[(27～)32～42.5] μm×[12.5～17.5(～20)] μm,TLC检测含有巴巴酸。在系统发育中,该新种与黑红地图衣 [Rhizocarpon badioatrum(Flörke ex Spreng. )Th. Fr. ]在同一个进化分枝上,但黑红地图衣的地衣体裂片连续不分散,孢子明显较小[(23～36)μm×(13～16)μm],地衣体中含有地弗地衣酸或不含化学物质。通过系统发育分析,结果表明:(1)该新种——四川地图衣属于褐地衣体亚属中的Badioatrum group;(2)仅依据解剖学特征(孢子的大小和分隔类型)对地图衣属部分类群的划分存在不合理性,还需结合化学特征进行综合分析。该文提供了新种的分类学描述以及形态、解剖和化学的高分辨率图片。利用新种的ITS序列构建的系统发育树,为建立更趋自然合理的分类系统提供基础数据。此外,该文对世界范围内褐地衣体亚属中子囊孢子为棕色1隔的类群(Badioatrum group)编写了详细的物种检索表,为该类群的进一步研究提供了资料支持。

Abstract:

In this paper, we study in Rhizocarpon Ramond ex DC. species by the method of combining phenotypic characteristics(morphology, anatomy and chemistry)with genotypic characteristics(ITS sequence). The aims of this present paper are to clarify the status of some species and explore the relationship between phenotype and genotype in Rhizocarpon. During the study on Rhizocarpon species from southwest China, R. sichuanense Y. M. Zhang, L. Hu & W. C. Wang sp. nov. is described as a new species in this genus. The new species is morphologically similar to R. cinereonigrum Vain and R. sinense Zahlbr., which also produces brown thallus, medulla I-, 8-spored ascus and brown ascospores with 1-septa. But it can be distinguished by the scattered, areolate to subsquamulose thallus, a distinct black prothallus, large ascospores are [(27-)32-42.5] μm × [12.5-17.5(-20)] μm and the presence of barbatic acid is in the thallus. In phylogenetic trees, it is also similar to R. badioatrum(Flörke ex Spreng. )Th. Fr. which can be distinguished by the more continuous thallus with diffractaic acid or without secondary products, and the smaller spores [(23-36)μm ×(13-16)μm] than this new species. The phylogenic results are as follows:(1)The new species R. sichuanense belongs to badioatrum group which belongs to Rhizocarpon subg. Phaeothallus;(2)It is unsuitable to classify some groups only based on anatomical characteristics(spore size and separation type)in Rhizocarpon, the chemical characteristics should also be considered. In this paper, the achievement of ITS sequences provide the basic data for an establishment of a more reasonable and natural classification system. In addition, we provide high resolution pictures of morphological, anatomical and chemical characteristics as well as detailed descriptions of the new species. The key to the species of Rhizocarpon subg. Phaeothallus with 1-septa brown spore(Badioatrum group)in the world is also provided, which will provide basic data for the further studies in this group.