Aquatic Ecohealth Group, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
Laboratory of Marine Biodiversity and Global Change, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, PR China.
Eur J Protistol. 2014 Apr;50(2):205-11. doi: 10.1016/j.ejop.2013.12.003. Epub 2013 Dec 24.
Difflugia is a morphologically diverse genus of testate amoebae, which are common components of freshwater ecosystems. We observed a new morphotype similar to Difflugia tuberspinifera but without spine in four Xiamen reservoirs, Fujian Province, southeast China. We investigated its morphology and biometry using light and scanning electron microscopy. The linear discriminant analysis and principal component analysis of biometric characters revealed that the spiny and spineless forms of D. tuberspinifera differed only in the presence or absence of spine. Shell height, shell diameter, aperture diameter and collar height did not differ significantly between the two morphotypes. The number of conical spines varies from 0 to 8. However, the distribution of spine numbers showed two main modes at 0 (spineless form 45.1% of individuals) and 4-6 (38.9%), suggesting the possible existence of two genetically distinct lineages. Spines may have ecological and evolutionary significance. Our results suggested that the spiny and spineless morphotypes of D. tuberspinifera represent either a single variable taxon with different ecotypes or sibling species. Further morphological studies on clonal variations and molecular approaches are needed to clarify if the spineless morph represents an independent species or not.
有棘变形虫是形态多样的有壳变形虫属，是淡水生态系统的常见组成部分。我们在中国东南部福建省的四个厦门水库中观察到了一种与有棘变形虫相似但没有刺的新形态。我们使用光学显微镜和扫描电子显微镜研究了它的形态和生物计量学。生物计量学特征的线性判别分析和主成分分析表明，有棘和无刺的有棘变形虫形态仅在刺的存在与否上有所不同。壳高、壳径、口孔直径和颈环高度在两种形态之间没有显著差异。圆锥形刺的数量从 0 到 8 不等。然而，刺的数量分布显示出两个主要模式，分别为 0（无刺形态个体的 45.1%）和 4-6（38.9%），这表明可能存在两个具有遗传差异的谱系。刺可能具有生态和进化意义。我们的结果表明，有棘变形虫的有刺和无刺形态可能代表具有不同生态型的单一可变量分类群，或者是姐妹种。需要进一步进行关于无性系变异的形态学研究和分子方法，以澄清无刺形态是否代表一个独立的物种。
