New fossil taxa and notes on the Mesozoic evolution of Liadytidae and Dytiscidae (Coleoptera) Author Prokin, Alexander A. Author Petrov, Pyotr N. Author Wang, Bo Author Ponomarenko, Alexander G. text Zootaxa 2013 3666 2 137 159 journal article 10.11646/zootaxa.3666.2.2 930d392c-8720-4820-85eb-501985209cf3 1175-5326 220466 1F8D4E8A-2447-4556-9B98-D8229D858194 Mesoderus ovatus sp. n. Etymology : The Latin ovatus (egg-shaped); adjective in the nominative singular. Material : Holotype NIGP 154569, counter impression of beetle; China , Liutiaogou; Early Cretaceous , Yixian Formation. Description ( Figs. 10, 11 ): Light coloured beetle. Maximum body width situated at middle of metacoxae. Pronotum 3.3 times as wide as long, 1.5 times as wide basally as at its anterior margin. Mesocoxae widely separated. Mesofemur with anterior margin straight and posterior margin convex, slightly protruding beyond body sides; mesotibia straight, with holes at bases of setae on ventral surface. Metacoxal plate 1.7 times as long as lateral lobe of metaventrite (LC/LV = 1.7). Metacoxal processes extended to level of abdominal ventrite 2. Metafemur and metatibia dilated towards their apices, metatibia slightly shorter than metafemur. First metatarsomere 1.8 times as long as metatarsomere 2 and equal in length to metatarsomeres 2 and 3 together; metatarsomeres 3 and 4 equal in length; metatarsomere 5 slightly shorter. Measurements : Body length, 10.8 mm ; body width, 6.3 mm ; elytron length, 8.7 mm . Comparison : Similar to M. ventralis Prokin & Ren, 2010 in size, but differs from it in the ratio of the length of the metacoxal plate and lateral lobe of the metaventrite, longer metacoxal processes, shape of meso- and metafemora and metatibia, and shorter metatarsomere 1.