Mesoderus ovatus, Prokin, Alexander A., Petrov, Pyotr N., Wang, Bo & Ponomarenko, Alexander G., 2013

Prokin, Alexander A., Petrov, Pyotr N., Wang, Bo & Ponomarenko, Alexander G., 2013, New fossil taxa and notes on the Mesozoic evolution of Liadytidae and Dytiscidae (Coleoptera), Zootaxa 3666 (2), pp. 137-159 : 147

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.

Figures

FIGURES 8 – 11. Mesoderus punctatus sp. n.: (8) photo of holotype, (9) line drawing of holotype; arrow indicates penis; Mesoderus ovatus sp. n.: (10) photo of holotype, (11) line drawing of holotype.