Gąsiorek Piotr, Vončina Katarzyna, Nelson Diane R, Michalczyk Łukasz
Department of Invertebrate Evolution, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, Gronostajowa 9, 30-387, Kraków, Poland.
Department of Biological Sciences, East Tennessee State University, Johnson City, TN, 37614, USA.
Zoological Lett. 2021 Nov 20;7(1):13. doi: 10.1186/s40851-021-00181-z.
There are two predominant sources of taxonomically useful morphological variability in the diverse tardigrade family Echiniscidae: the internal structure and surface sculpture of the cuticular plates covering the dorsum (sculpturing) and the arrangement and morphology of the trunk appendages (chaetotaxy). However, since the appendages often exhibit intraspecific variation (they can be reduced or can develop asymmetrically), sculpturing has been considered more stable at the species level and descriptions of new echiniscid species based solely on morphology are still being published. Here, we present a case study in which a detailed analysis of the morphology and multiple genetic markers of several species of the genus Viridiscus shows that cuticular sculpture may also exhibit considerable intraspecific variation and lead to false taxonomic conclusions. In a population collected from the eastern Nearctic, in the type locality of the recently described species V. miraviridis, individuals with transitional morphotypes between those reported for V. viridissimus and V. miraviridis were found. Importantly, all morphotypes within the viridissimus-miraviridis spectrum were grouped in a single monospecific clade according to rapidly evolving markers (ITS-1, ITS-2 and COI). Given the morphological and genetic evidence, we establish V. miraviridis as a junior synonym of V. viridissimus. This study explicitly demonstrates that a lack of DNA data associated with morphological descriptions of new taxa jeopardizes the efforts to unclutter tardigrade systematics. Additionally, V. perviridis and V. viridissimus are reported from Lâm Đồng Province in southern Vietnam, which considerably broadens their known geographic ranges.
在种类繁多的棘影熊虫科中，有两个主要的形态变异来源对分类学很有用：覆盖背部的角质板的内部结构和表面纹饰（纹饰）以及躯干附肢的排列和形态（刚毛序）。然而，由于附肢常常表现出种内变异（它们可能会退化或不对称发育），纹饰在物种水平上被认为更稳定，仅基于形态学对新的棘影熊虫物种进行描述的情况仍在发表。在此，我们展示了一个案例研究，其中对绿影熊虫属几个物种的形态学和多个遗传标记进行详细分析后发现角质纹饰也可能表现出相当大的种内变异，并导致错误的分类学结论。在从近北极东部收集的一个种群中，在最近描述的物种绿影熊虫V. miraviridis的模式产地，发现了具有介于翠绿熊虫V. viridissimus和绿影熊虫V. miraviridis所报道形态之间的过渡形态型个体。重要的是，根据快速进化的标记（ITS - 1、ITS - 2和COI），翠绿熊虫 - 绿影熊虫谱系内的所有形态型都被归为一个单一的单种分支。鉴于形态学和遗传学证据，我们将绿影熊虫V. miraviridis确立为翠绿熊虫V. viridissimus的次异名。这项研究明确表明缺乏与新分类单元形态学描述相关的DNA数据会危及简化熊虫分类学的努力。此外，在越南南部的林同省报道了翠绿熊虫V. perviridis和翠绿熊虫V. viridissimus，这大大拓宽了它们已知的地理范围。
