Karanovic Tomislav, Djurakic Marko, Eberhard Stefan M
Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 440-746, Korea; Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia;
Department of Biology and Ecology, Faculty of Science, University of Novi Sad, Trg Dositeja Obradovića 2, Novi Sad 21000, Serbia;
Syst Biol. 2016 Mar;65(2):304-27. doi: 10.1093/sysbio/syv088. Epub 2015 Nov 24.
Discovery of cryptic species using molecular tools has become common in many animal groups but it is rarely accompanied by morphological revision, creating ongoing problems in taxonomy and conservation. In copepods, cryptic species have been discovered in most groups where fast-evolving molecular markers were employed. In this study at Yeelirrie in Western Australia we investigate a subterranean species complex belonging to the harpacticoid genus Schizopera Sars, 1905, using both the barcoding mitochondrial COI gene and landmark-based two-dimensional geometric morphometrics. Integumental organs (sensilla and pores) are used as landmarks for the first time in any crustacean group. Complete congruence between DNA-based species delimitation and relative position of integumental organs in two independent morphological structures suggests the existence of three distinct evolutionary units. We describe two of them as new species, employing a condensed taxonomic format appropriate for cryptic species. We argue that many supposedly cryptic species might not be cryptic if researchers focus on analyzing morphological structures with multivariate tools that explicitly take into account geometry of the phenotype. A perceived supremacy of molecular methods in detecting cryptic species is in our view a consequence of disparity of investment and unexploited recent advancements in morphometrics among taxonomists. Our study shows that morphometric data alone could be used to find diagnostic morphological traits and gives hope to anyone studying small animals with a hard integument or shell, especially opening the door to assessing fossil diversity and rich museum collections. We expect that simultaneous use of molecular tools with geometry-oriented morphometrics may yield faster formal description of species. Decrypted species in this study are a good example for urgency of formal descriptions, as they display short-range endemism in small groundwater calcrete aquifers in a paleochannel, where their conservation may be threatened by proposed mining.
利用分子工具发现隐存物种在许多动物类群中已很常见，但很少伴随着形态学修订，这在分类学和保护方面引发了持续的问题。在桡足类动物中，在大多数使用快速进化分子标记的类群中都发现了隐存物种。在西澳大利亚州耶利里的这项研究中，我们利用条形码线粒体COI基因和基于地标点的二维几何形态测量学，对属于猛水蚤属Schizopera Sars（1905年）的一个地下物种复合体进行了研究。在任何甲壳类动物类群中，体表器官（感觉器和小孔）首次被用作地标点。基于DNA的物种界定与体表器官在两个独立形态结构中的相对位置完全一致，这表明存在三个不同的进化单元。我们将其中两个描述为新物种，采用了适合隐存物种的简化分类格式。我们认为，如果研究人员专注于使用明确考虑表型几何形状的多变量工具来分析形态结构，那么许多所谓的隐存物种可能并非隐存。我们认为，在检测隐存物种方面分子方法被视为具有优势，是分类学家之间投资差异以及形态测量学近期未被利用的进展所致。我们的研究表明，仅形态测量数据就可用于找到诊断性的形态特征，这给任何研究体表坚硬或有外壳的小动物的人带来了希望，尤其是为评估化石多样性和丰富的博物馆藏品打开了大门。我们预计，同时使用分子工具和以几何为导向的形态测量学可能会更快地对物种进行正式描述。本研究中解密的物种是正式描述紧迫性的一个很好例子，因为它们在古河道中的小型地下水钙质含水层中显示出短距离特有性，而在那里它们的保护可能会受到拟议采矿的威胁。
