Moskalenko Victoria N, Neretina Tatiana V, Yampolsky Lev Y
Zoological Museum of Moscow State University, B. Nikitskaya 6, 125009 Moscow, Russia.
Zootaxa. 2020 Apr 21;4766(3):zootaxa.4766.3.5. doi: 10.11646/zootaxa.4766.3.5.
Extraordinarily diverse morphologically and ecologically, Lake Baikal's two endemic gammaroidean amphipod clades are both firmly placed within the paraphyletic genus Gammarus, based both on morphological and molecular characters. However, the exact placement of the two Baikal clades remains elusive, making reconstruction of the ancestral state of Baikal endemic radiation difficult. We sequenced 2 mitochondrial and 3 nuclear genes from several species of each of the two clades aiming to represent early branches of the radiation. We also describe two new species of Baikal gammarids, Eulimnogammarus etingovae sp. nov. and Eulimnogammarus tchernykhi sp. nov., with some morphology suggestive of basal position within the radiation. We confirm the two previously demonstrated Baikal clades, but cannot unequivocally support any of the previous hypotheses about affinities of the two Baikal clades within palearctic Gammarus species. Rather, it appears that the two Baikal endemic radiations separated from the rest of freshwater Palearctic forms early and rapidly, probably as part of gammarid diversification during colonization of fresh waters in Middle Eocene.
贝加尔湖的两个地方性钩虾亚目十足目甲壳动物分支在形态和生态上极为多样，基于形态学和分子特征，它们都被稳固地置于并系的钩虾属中。然而，这两个贝加尔湖分支的确切位置仍然难以确定，这使得重建贝加尔湖地方性辐射的祖先状态变得困难。我们对这两个分支的几个物种的2个线粒体基因和3个核基因进行了测序，旨在代表辐射的早期分支。我们还描述了两种新的贝加尔湖钩虾，即新物种埃氏真钩虾（Eulimnogammarus etingovae sp. nov.）和切尔内赫氏真钩虾（Eulimnogammarus tchernykhi sp. nov.），它们的一些形态表明其在辐射中处于基部位置。我们证实了之前所证明的两个贝加尔湖分支，但无法明确支持之前关于这两个贝加尔湖分支在古北区钩虾物种中的亲缘关系的任何假设。相反，似乎这两个贝加尔湖地方性辐射早期就与淡水古北区的其他形式迅速分离，这可能是始新世中期淡水殖民化过程中钩虾多样化的一部分。
