Ecology Section, Department of Evolutionary Biology, Ecology and Environmental Sciences, Faculty of Biology, University of Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain..
A.N. Severtsov Institute of Ecology and Evolution, Leninsky Prospect 33, Moscow 119071, Russia..
Zootaxa. 2021 May 19;4974(1):146. doi: 10.11646/zootaxa.4974.1.1.
Species of the genus Ceriodaphnia Dana, 1853 (Crustacea: Cladocera: Daphniidae) are present in the plankton of many freshwater bodies all around the World. However, the taxonomy of the genus is still poorly developed. Most species have been described in the nineteenth century and data on their morphology and distribution should be revised according to current standards. Currently, due to lack of reliable morphological and genetic data, almost all nominal species of Ceriodaphnia are considered as species groups rather than separate biological species, complicating the detection and description of new species of the genus. Here, we redescribe the morphology of Ceriodaphnia quadrangula (O.F. Müller, 1785) based on material close to the type locality in Denmark, and describe a new species of Ceriodaphnia from the Mediterranean region. Also, we provide a phylogenetic analysis using existing and novel sequences of mitochondrial DNA of the commonest species of the genus. Ceriodaphnia smirnovi sp. nov. can be easily distinguished from C. quadrangula via presence of the head pore and the structure of the second thoracic limb, the postabdomen and the ephippium. From other species of Ceriodaphnia known to date C. smirnovi sp. nov. can also be separated on ephippium structure and some other fine morphological features. Although distribution range of C. smirnovi sp. nov. must be clarified in the future based on analysis of more sampling points, most likely, it is restricted to the Mediterranean region. The phylogenetic analyses showed high divergence among 16 different clades (mean clade separation of 13±2.3 % (mean ± SD) and 20.7±2.1% for 16S and COI respectively). These clades belonged to 11 described species and 5 undescribed. The high intraspecific variability of some species indicates the possible existence of more undescribed species within present species groups.
戴氏真枝角类（属）物种（甲壳纲：枝角目：真枝角科）广泛存在于世界各地的许多淡水浮游生物中。然而，该属的分类学仍然不够发达。大多数物种都是在 19 世纪描述的，其形态和分布数据应根据当前标准进行修订。目前，由于缺乏可靠的形态学和遗传数据，几乎所有名义上的 Ceriodaphnia 物种都被认为是物种群，而不是独立的生物物种，这使得该属新物种的检测和描述变得复杂。在这里，我们根据丹麦接近模式产地的材料重新描述了四角真枝角类（O.F. Müller，1785）的形态，并描述了一种来自地中海地区的新 Ceriodaphnia 物种。此外，我们还使用该属最常见物种的现有和新的线粒体 DNA 序列进行了系统发育分析。通过头部孔和第二胸肢、后腹部和卵囊的结构，很容易将 Ceriodaphnia smirnovi sp. nov. 与 Ceriodaphnia quadrangula 区分开来。与迄今为止已知的其他 Ceriodaphnia 物种相比，Ceriodaphnia smirnovi sp. nov. 也可以通过卵囊结构和一些其他精细形态特征来区分。尽管 Ceriodaphnia smirnovi sp. nov. 的分布范围必须在未来基于更多采样点的分析来澄清，但它很可能仅限于地中海地区。系统发育分析表明，16 个不同分支（平均分支分离度为 13±2.3%（平均值±标准差）和 16S 和 COI 分别为 20.7±2.1%）之间存在高度分化。这些分支属于 11 个已描述的物种和 5 个未描述的物种。一些物种的高度种内变异性表明，目前的物种群中可能存在更多未描述的物种。
