Clemnius Fery 2017
Creators: name: Fery, Hans
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Dytiscidae
Clemnius

description: Subgenus Clemnius s. str. n. subgen.
Type species: Hyphydrus decoratus Gyllenhal, 1810: XVI, by present designation.
The subgenus Clemnius n. subgen. contains five species of the former genus Hygrotus, subgenera Hygrotus and Coelambus (see Fig. 2 and Table 1).
Diagnosis. Body shape oval, either almost globose (TL/MW ca. 1.6) (see Fig. 10 for C. (s. str.) decoratus) or more elongated, "navicular" (TL/MW 1.7–1.8) (see Fig. 11 for C. (s. str.) laccophilinus (LeConte, 1878)), with MW short behind pronotum and distinctly before mid-length (still somewhat more elongated in C. (s. str.) berneri Young & Wolfe, 1984, with TL/MW ca. 2.05; see Fig. 12 for holotype and its labels; FSCA); body size small (TL 2.1–3.3 mm). Clemnius (s. str.) decoratus and C. (s. str.) hydropicus (LeConte, 1852) with anterior clypeal margin evenly and semicircularly rounded, with border produced forwards and bead complete as in subgenus Hygrotus s. str. In contrast Clemnius (s. str.) laccophilinus, C. (s. str.) berneri and C. (s. str.) sylvanus (Fall, 1917) with anterior clypeal margin truncate and slightly emarginated, with border not produced forwards and bead absent. Antennomeres simple, not broadened. Elytra with margin in lateral view moderately ascending to shoulder (similar to Fig. 55); epipleuron comparably broad, broader than mesotibia distally; carina meeting inner margin of epipleuron forming a comparably small angle (<ca. 135°; similar to Fig. 49). Elytra either dark, uniformly testaceous or with yellowish-brown dots, but not vittate; venter brown or testaceous. Last abdominal ventrite without deep depression.
Aedeagus with median lobe symmetric, robust in C. (s. str.) decoratus (Fig. 21) and C. (s. str.) hydropicus (cf. fig. 13 in Anderson 1971) or distally very narrow in C. (s. str.) berneri (Fig. 20), C. (s. str.) laccophilinus and C. (s. str.) sylvanus (cf. also figs 1A and 2A in Anderson 1976). Parameres with condylar process rather short and forming an obtuse angle with distal part (Figs 30 and 31; cf. also figs 1B and 2B in Anderson 1976). Male metatarsal claws of equal length.
Etymology. From the Greek χλεµµύϛ (klemmys = tortoise); referring to the almost hemispherical body shape of most species. The gender of the generic name is masculine.
Distribution. Palaearctic (Europe, Russia and Kazakhstan), Nearctic and Neotropical (northern part of MeXico).
Main habitat types. The subgenus includes species typical of lentic freshwater environments.
Notes: Within the subgenus there are two clear groups of species according to body shape and genital morphology, one formed by C. (s. str.) decoratus and C. (s. str.) hydropicus (body shape more globular, aedeagus robust with short medial lobe), and the other by C. (s. str.) berneri, C. (s. str.) laccophilinus and C. (s. str.) sylvanus (body shape more elongated, "navicular", aedeagus slender with elongated median lobe). The phylogenetic relationships of the species for which molecular data were available are poorly supported (Fig. 1), but in any case we never recovered these two groups as respectively monophyletic. We thus refrain from splitting Clemnius n. subgen. into two taXa corresponding to these two groups, at least until more evidence becomes available.
description: Published as part of Fery, Hans, 2017, A new classification of the tribe Hygrotini Portevin, 1929 (Coleoptera: Dytiscidae: Hydroporinae), pp. 499-529 in Zootaxa 4317 (3) on pages 517-518, DOI: 10.11646/zootaxa.4317.3.4, http://zenodo.org/record/884766