Mesodytes rhantoides, 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 : 147-149

Mesodytes rhantoides sp. n.

Etymology: From the generic name Rhantus ; adjective in the nominative singular. Material: Holotype NIGP 154570, counter impression of beetle; China, Liutiaogou; Early Cretaceous , Yixian Formation.

Description ( Figs. 12–15 ): Beetle with light underside. Head length 0.7 times as great as head width at level of posterior margins of eyes; obscured behind eyes, with two small dark spots in front of clypeus. Pronotum three times as wide as long, 1.4 times as wide basally as at its anterior margin; with rounded sides and angles, with basal angles slightly protruding posteriad; with broad dark stripe basally, broadly connected medially with narrow dark stripe running along entire anterior margin, narrowing and reaching or almost reaching anterior angles. Maximum body width situated at level of abdominal ventrite 2. Procoxae and mesocoxae closely set. Metacoxal plate approximately 1.2 times as long as lateral lobe of metaventrite (LC/LV ≈ 1.2). Metafemur not dilated towards apex. Abdominal ventrites more or less equal in length; abdominal segments 3, 4, and 5 sublaterally with large oval spiracles. Penis evenly curved, with apex rounded and base dilated (see arrows in Fig. 15 ). Elytron translucent, with wing venation partly visible under elytron; with dark sutural and apical margin and at least 20 rows of dark spots. Elytral epipleuron translucent, without spots, wide; its internal margin forming sharp angle with lateral margin of elytron, starting at base of abdomen and ending at posterior edge of abdominal ventrite 4; maximum width situated at level of abdominal ventrite 2. Abdominal tergites 4, 5, and 6 with round spiracles dorsally.

Measurements: Body length, 16.0 mm (17.7 mm including protruding genitalia); body width, 7.5 mm; elytron length, 10.1 mm.

Figures

FIGURES 12 – 15. Mesodytes rhantoides sp. n.: (12) photo of holotype, (13) line drawing of holotype in dorsal view, (14) line drawing of holotype in ventral view, (15) photo of holotype (fragment, 3 × enlarged): male genitalia; arrows indicate base, dorsal margin and apex of penis.