中国水韭属两个四倍体新种

水韭属(Isoëtes)是起源最为古老的水生维管植物,全属物种均被列为国家一级重点保护植物。通过对全国水韭属植物的调查和研究发现,不同产地的四倍体植株在形态上存在显著差异。基于形态学、孢粉学和细胞学证据,将分布于中国湖南省长沙地区和怀化地区的四倍体居群分别命名为隆平水韭(Isoëtes longpingii)和湘妃水韭(I. xiangfei),并详细描述了其形态特征。隆平水韭形态上与中华水韭(I. sinensis)相似,不同之处在于其大孢子具小的瘤状或冠状纹饰,叶细长而柔弱,长达60 cm; 该种也与六倍体东方水韭(I. orientalis)相似,不同之处在于其染色体44条,大孢子具瘤状或冠状纹饰。湘妃水韭的大孢子纹饰虽与二倍体云贵水韭(I. yunguiensis)相似,但在小孢子纹饰、孢子囊形状和染色体数目方面却不同。隆平水韭仅少数植株生长于湖南省宁乡市一处池塘,完全沉水生长,而湘妃水韭则分布于怀化市通道县和会同县的湿地。由于这两个新种的分布区狭窄,野生居群数量和个体数较少,栖息地环境受到人为干扰,因此根据IUCN红色名录评估标准,将隆平水韭评为极危(CR)等级,湘妃水韭评为易危(VU)等级。所编制的中国已知水韭属物种的分种检索表,为本属物种的鉴定和保护工作提供了重要参考。

Two new tetraploid quillwort species, Isoëtes longpingii and I. xiangfei from China(Isoëtaceae)

Two new tetraploid quillwort species, Isoëtes longpingii and I. xiangfei, from China are described and illustrated. I. longpingii is a fully submerged plant found in a small pond of Hunan Province. It is morphologically similar to I. sinensis, but differs in its small and tuberculate-cristate megaspores and soft slender leaves that grow up to 60 cm. It is also similar to hexaploid I. orientalis, but differs in its 44 chromosomes and tuberculate-cristate megaspores. I. xiangfei is most similar to diploid I. yunguiensis in megaspore ornamentation, but differs in its microspore ornamentation, oblong sporangium, and 44 number of chromosomes. There are a few individuals of I. longpingii found in Ningxiang City of Hunan Province, and I. xiangfei is distributed in the wetlands of Tongdao and Huitong counties of Hunan Province. Because of their limited geographic ranges, small populations, fewer individuals and disturbed habitats, I. longpingii and I. xiangfei are evaluated as critically endangered(CR)and vulnerable(VU)category, respectively, according to the IUCN Red List criteria. A key to all the current known Chinese quillworts is also provided for further taxonomic identification and conservation of these rare and endangered plants in China.