Mesoderus punctatus, 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 : 145-147

Mesoderus punctatus sp. n.

Etymology: The Latin punctatus (spotted); adjective in the nominative singular.

Material: Holotype NIGP 0 5622, counter impression of beetle; China, Liutiaogou; Early Cretaceous , Yixian Formation.

Description ( Figs. 8, 9 ): Light coloured beetle. Maximum body width situated at middle of abdominal ventrite 2. Elytron light, with dark spots, distance between spots twice as great as their diameter. Head length equal to width at posterior margin of eyes. Pronotum three times as wide as long, 1.6 times as wide basally as distally. Profemur narrowed towards apex; protarsal claws equal in length. Mesocoxae slightly separated. Mesofemur with anterior margin straight and posterior margin convex, slightly protruding beyond sides of body; mesotibia straight, with setose anterior margin. Metacoxal plate 1.2 times as long as lateral lobe of metaventrite (LC/LV = 1.2). Metafemur dilated towards apex. Metatibia straight, slightly shorter than metafemur, with swimming setae. Metatarsomere 1 with swimming setae, equal in length to metatarsomere 2; metatarsomere 2 equal in length to metatarsomeres 3 and 4 together; metatarsomere 5 short, only half as long as metatarsomere 4; claws of metatarsus equal in length, twice as long as metatarsomere 5. Penis pointed and curved (see arrow in Fig. 10 ).

Measurements: Body length, 14.6 mm; body width, 7.5 mm; elytron length, 10.5 mm.

Comparison: Similar to M. magnus Prokin & Ren, 2010 in size and in the pointed and curved penis, but differs from it in the dorsal coloration, LC/LV, longer metacoxal processes, shape of meso- and metafemora, 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.