Jurassic Cladocera (Crustacea, Branchiopoda) with a description of an extinct Mesozoic order Author Kotov, Alexey A. text Journal of Natural History 2007 2007-02-16 41 1 - 4 13 37 http://dx.doi.org/10.1080/00222930601164445 journal article 10.1080/00222930601164445 1464-5262 4669488 Leptodorosida gen. nov. Type species. Leptodorosida zherikhini sp. nov. Etymology Leptodora Lilljeborg, 1861 is the type (single) genus of the family Leptodoridae Lilljeborg, 1861 of the gymnomeran order Haplopoda ; Sida Straus, 1820 is the type genus of the family Sididae, Baird 1850 of the ‘‘calyptomeran’’ order Ctenopoda . Among all cladocerans, AII of Leptodorosida gen. nov. is maximally similar with one of Leptodora , while general body shape is similar with sidids. Diagnosis Body elongated with expressed postero-dorsal angle. Distal extremity of head protruding anteriorly, posterior portion of head inflated. AII with proximal segment of endopod long and proximal segment of exopod of moderate length, second segment of exopod shorter than 3 + 4 segments. Each of segments 3–4 of endopod with a series of setae. Differential diagnosis Leptodorosida gen. nov. differs from the second known genus from the order Cryptopoda ord. nov. , Leposida gen. nov. , in elongated body and large proximal segments of antennal branches.