Korovchinsky N.M.1, Boikova O.S. 2023. Orders Haplopoda and Onychopoda (Crustacea: Branchiopoda: Cladocera) do not form a monophyletic group: morphological evidence // Arthropoda Selecta. Vol.32. No.3: 256–280 [in English].
A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, Leninsky prospect 33, Moscow, 119071 Russia. 1 E-mail: nmkor@yandex.ru
doi: 10.15298/arthsel.32.3.04
ABSTRACT. G.O. Sars was the first who united the tribes (now orders) Onychopoda (family Polyphemidae) and Haplopoda (family Leptodoridae) in the taxon (“divisio”) Gymnomera. The later researcher’s view on this taxon was controversial — one of them followed Sars’ hypothesis, others rejected it and offered their own solution regarding the relationship between orders. Generally, the idea of the rejection of the taxon Gymnomera prevailed for about a century until the 1990s when some researchers proposed to restore the taxon Gymnomera, although, without much evidence, as a monophyletic. They based both on morphological and molecular-genetic data which looked rather poor and superficial. The authors of the present paper collected and analyzed a large set of morphological data concerning the external and internal structure, as well as the features of the reproduction and development of the representatives of Haplopoda and Onychopoda, based on the innovative traditional, not cladistic, approaches and methods of evolutionary biology and systematics. It has been clearly shown that although the features of the representatives of the orders seem superficially similar, in fact they are mostly substantially different. All morphological similarities of Haplopoda and Onychopoda are purely adaptive, associated with a predatory lifestyle, and therefore, these orders do not form a monophyletic group. Recently, this conclusion was confirmed by molecular-genetic studies.
KEY WORDS: Onychopoda, Haplopoda, comparative morphology, reproductive peculiarities, phylogeny, monophyly, affinity.