Department of Invertebrate Zoology, Faculty of Biology and Soil Sciences, St. Petersburg State University, Universitetskaja nab. 7/9, 199034 St. Petersburg, Russia.
Eur J Protistol. 2010 Aug;46(3):159-63. doi: 10.1016/j.ejop.2010.01.003. Epub 2010 Feb 12.
Three new species of centrohelid heliozoans Acanthocystis crescenta, A. kirilli, and Choanocystis minima from two freshwater lakes of Valamo Island (North-Western Russia) were studied using light- and scanning electron microscopy. The main apomorphy of A. kirilli are slightly branched radial scales. Acanthocystis crescenta has characteristic radial scales with crescent-like structures on their tips. Cell diameter of these two species does not exceed 10 microm. Radial scales of C. minima have truncated tips and lack apical teeth; plate scales of this species are oviform, without lateral notches or central rib. The latter organism is the smallest heliozoan species known; the diameter of its body is about 3 microm. The possible domination of small heliozoans in the cryptic diversity of centrohelids is discussed.
三种来自俄罗斯西北部瓦拉莫岛（Valamo Island）两个淡水湖的新型中缢虫（centrohelid heliozoans）——新月形中缢虫（Acanthocystis crescenta）、基里利中缢虫（A. kirilli）和微小中缢虫（Choanocystis minima），利用光学显微镜和扫描电子显微镜进行了研究。基里利中缢虫的主要独特特征是略微分枝的辐射状鳞片。新月形中缢虫具有特征性的辐射状鳞片，其尖端呈新月形结构。这两个物种的细胞直径都不超过 10 微米。微小中缢虫的辐射状鳞片尖端截断，缺乏顶端齿；该物种的板状鳞片呈卵形，没有侧凹口或中央肋条。后一种生物是已知的最小的原生动物；其体长约 3 微米。讨论了小型原生动物在中缢虫隐种多样性中的可能主导地位。
