Department of Botany, Connecticut College, New London, CT 06320, USA.
Skoklefall Terrasse 82, 1452 Nesoddtangen, Norway.
Eur J Protistol. 2022 Feb;82:125857. doi: 10.1016/j.ejop.2021.125857. Epub 2021 Dec 6.
Rotosphaerids are unicellular, heterotrophic, eukayotic protists that have filopodia, an exterior covering consisting of highly ornamented siliceous scales, and are classified in the Rotosphaerida within the opistokont lineage. Given their appearance as relatively large spherical cells with protruding filopodia and a silica scale covering, they are often mistaken for centrohelid heliozoans. Even though these organisms are widely distributed in both marine and freshwater environments, many species are rarely reported, and none have been reported from the fossil record. We report extensive remains of a new species of Rabdiophrys, R. giraffensis, from an ancient waterbody that was situated near the Arctic Circle in northern Canada during the Eocene. The new species has both plate and spine scales that are similar in morphology, but significantly larger than its closest modern congeners, R. monopora and R. anulifera. The waterbody in which the new species grew and thrived is inferred to have been a moderately deep, circumneutral pond, with moderate concentrations of nutrients and dissolved humic material.
旋盘虫是一种单细胞、异养、真核原生动物，具有纤毛，外部覆盖着高度装饰的硅质鳞片，被分类为旋盘虫门中的后口动物谱系。由于它们的外观为相对较大的球形细胞，具有突出的纤毛和硅质鳞片覆盖，因此它们经常被误认为是中心体鞭毛虫类原生动物。尽管这些生物广泛分布于海洋和淡水环境中，但许多物种很少被报道，也没有从化石记录中报道过。我们报道了一种来自加拿大北部北极圈附近的古代水体中新的 Rabdiophrys 物种（R. giraffensis）的广泛遗迹。该新物种既有板状鳞片又有棘状鳞片，在形态上相似，但比其最接近的现代同属种（R. monopora 和 R. anulifera）明显更大。推断该新物种生长和繁荣的水体是一个中等深度、近中性的池塘，具有适度浓度的营养物质和溶解的腐殖质。
