Palaeodytes Ponomarenko, 1987

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 : 149

Palaeodytes Ponomarenko, 1987

Type species: Palaeodytes sibiricus Ponomarenko, 1987 .

Notes: The genus is characterized by a short band-like pronotum and short head, together about 1/3 as long as the elytra; metacoxal plates longest in their lateral third (lateral of the external margins of the mesocoxae); lateral lobe of metaventrite half as long as metacoxal plate, median platforms of mesocoxae separated from the anterior margins of mesocoxae by a line, rounded apically and notched laterally; and dilated and flattened metatibia and metatarsus, the latter longer than the former.

It differs from members of the subfamily Liadytiscinae in the shorter lateral lobe of the metaventrite, shorter and more dilated metatibia and metatarsus, and short pronotum; from Sinoporus it differs in the metaventrite with concave posterior margins of the lateral lobe (cf. Figs 17 and 23 ).

The new species described below belongs to this genus according to the combination of two characters: metacoxa nearly twice as long as the lateral lobe of the metaventrite (LC/LV ≈ 2), and absence of an elevated laterally limited area of the metaventrite.

Figures

FIGURES 16 – 18. Palaeodytes baissiensis sp. n.: (16) photo of holotype, direct impression, (17) line drawing of holotype, (18) photo of holotype, counter impression.

FIGURES 22 – 24. (22) Ilybius adygheanus Petrov, Shapovalov & Fery, 2010: metaventrite and metacoxa, with measurements WC, WS, LC and LV shown; modified from Petrov et al. (2010); (23) Sinoporus lineatus Prokin & Ren, 2010: holotype in ventral view, redrawn and modified from original description with LC and LV shown (in this case the longest point of the lateral lobe of the metaventrite is at the very base of the lobe; it has been measured immediately lateral of the posterior margins of the mesocoxa, i. e., at the very base of the lobe, if we define the lobe as the part of the metaventrite lateral of the mesocoxa); (24) Lancetes lanceolatus (Clark, 1863): metaventrite of recent specimen from Lake Cronin (Western Australia); arrow indicates impression at lateral margin of median elevated area of metaventrite.