Dytiscidae
Creators: name: Prokin, Alexander A.
name: Petrov, Pyotr N.
name: Wang, Bo
name: Ponomarenko, Alexander G.
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Dytiscidae

description: Key to the genera of Mesozoic Dytiscidae (adults)
1. Metaventrite with straight posterior margins of lateral lobes, converging posteriad at obtuse angle (Fig. 23); elytra with dark stripes (subfamily incertae sedis).................................................................. Sinoporus.
- Metaventrite with concave posterior margins of lateral lobes (e.g., as in Fig. 20); elytra without dark stripes............. 2.
2. LC/LV (ratio of maximum length of metacoxal plate and lateral lobe of metaventrite, both measured longitudinally, as in Fig. 22) around 1–1.7 (Liadytiscinae).......................................................................... 5
- LC/LV around 2 or greater (subfamily incertae sedis).......................................................... 3
3. Posterior and anterior margins of lateral lobe of metaventrite strongly converging, then slightly diverging again, then converging again near epipleuron; LC/LV around 3............................................. " Palaeodytes " incompletus.
- Posterior and anterior margins of lateral lobe of metaventrite more or less evenly converging towards epipleuron......... 4.
4. LC/LV around 3 (as in Figs 19, 20)................................................................ Cretodytes.
- LC/LV around 2.............................................................................. Palaeodytes.
5. Metacoxal lines weakly diverging anteriad; metacoxal processes with incision between them, conjointly truncate or rounded posteriorly, not narrowed anteriad (as in Figs 6, 7); LC/LV around 1; metatibia narrow and long, longer than metafemur (Liadytiscini)........................................................................................ 6.
- Metacoxal lines strongly diverging anteriad; metacoxal processes slightly narrowed anteriad, with posterior margins rounded (as in Figs 8–11, 12, 14); LC/LV around 1.2–1.7; metatibia subequal in length to or shorter than metafemur (Mesoderini trib. n.)................................................................................................. 8.
6. Metacoxal processes conjointly truncate posteriorly, with incision between them; metaventrite with laterally limited elevated median area triangular......................................................................... Liadytiscus.
- Metacoxal processes conjointly truncate apically, with incision between them, or rounded with incision; metaventrite with elevated median area rounded or without such elevated area..................................................... 7.
7. Metacoxal processes more or less conjointly truncate posteriorly, with posterior margins appearing somewhat sinuate, with incision between them (as in Figs 6, 7)...................................................... Liadyxianus gen. n.
- Metacoxal processes rounded.................................................................. Liadroporus.
8. Metaventrite with rounded laterally limited elevated median area (Figs 8–11)............................... Mesoderus.
- Metaventrite without laterally limited elevated median area (Figs 12, 14)............................. Mesodytes gen. n.
description: Published as part of 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), pp. 137-159 in Zootaxa 3666 (2) on pages 153-154, DOI: 10.11646/zootaxa.3666.2.2, http://zenodo.org/record/220466