Hygrotus sensu Stephens 1828
Creators: name: Fery, Hans
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Dytiscidae
Hygrotus

description: Subgenus Hygrotus Stephens, 1828
Type species: Dytiscus inaequalis Fabricius, 1777: 239, by subsequent designation of Curtis (1835: pl. 531).
Herophydrus Sharp, 1880: cxlviii; type species: Hydroporus hyphydroides Perris, 1864: 277 (= Herophydrus guineensis (Aubé 1838: 455)), by monotypy. n. syn.
Dryephorus Guignot, 1950: 150; type species: Coelambus nodieri Régimbart, 1895: 37, by original designation of Guignot (1950: 150). n. syn.
Heroceras Guignot, 1950: 150; type species: Herophydrus descarpentriesi Peschet, 1923: 176, by original designation of Guignot (1950: 150). n. syn.
The newly defined subgenus Hygrotus s. str. includes siX species previously included in the former subgenus Hygrotus s. str., the single species of former genus Heroceras (H. descarpentriesi) and all 44 species (one of them bitypic) of the former genus Herophydrus (see Fig. 2 and Table 1).
Diagnosis. Body shape short oval to moderately elongate oval (TL/MW ca. 1.7–1.8); species of former Hygrotus s. str. and Heroceras small (TL 2.8–3.6 mm) (see Fig. 8 for H. (s. str.) inaequalis and Fig. 17 for H. (s. str.) descarpentriesi) and species of former Herophydrus small to large (TL 2.6–7.4 mm) (see Fig. 16 for H. (s. str.) guineensis). Head of species of former Hygrotus with anterior clypeal margin evenly and semicircularly rounded, border produced forwards and with complete bead (see Figs 44 and 45 for H. (s. str.) inaequalis); species of former Herophydrus and Heroceras with anterior clypeal margin truncate, straight or slightly emarginated, border not produced forwards; bead present, but in many species narrowed in medial part (see Fig. 43 for H. (s. str.) guineensis), in others medially obsolete or widely reduced eXcept before eyes (cf. AppendiX). Antennomeres simple, not broadened eXcept in H. (s. str.) descarpentriesi, with antennomeres of both seXes, but especially males, strongly dilated (Fig. 17). Elytra with margin in lateral view rather strongly ascending to shoulder (similar to Fig. 54); epipleuron comparably broad, broader than mesotibia distally; carina meeting inner margin of epipleuron forming a comparably small angle (<ca. 135°; similar to Fig. 49). Elytral pattern diverse (vittate, dotted or uniform); venter black or brown. Last abdominal ventrite without deep depression.
Aedeagus with median lobe robust, distal part very diverse in ventral view, more or less symmetric (see Figs 22 and 27 for H. (s. str.) inaequalis and H. (s. str.) guineensis) or at most slightly asymmetric in some former Herophydrus (see figures in Biström & Nilsson 2002); parameres with condylar process generally short, forming an obtuse angle with distal part (see Fig. 32 and 39 for H. (s. str.) inaequalis and H. (s. str.) guineensis). Male metatarsal claws of equal length.
Distribution. Palaearctic, Nearctic, Ethiopian and Oriental. Species of the former subgenus Hygrotus (the H. (Hygrotus) inaequalis -group in Fig. 2) are distributed in Europe, northern Africa, Asia and northern America (reaching northern MeXico); species of former Herophydrus occur mainly in Africa, with five species in the Palaearctic, one (H. (s. str.) musicus) reaching the Oriental region and H. (s. str.) morandi (Guignot, 1952) known from Cambodia only; H. (s. str.) descarpentriesi is endemic to mountainous regions in south-eastern Madagascar.
Main habitat types. The subgenus includes species typical of lentic and lotic freshwater environments; some species can be found in inland mineralised or coastal brackish waters, such as for eXample H. (s. str.) musicus (Millán et al. 2006). The latter species can also be found in mineral and thermal spring-pools (pers. communication by J. Hájek, Prague, Czech Republic). The habitat of most African species of the subgenus is poorly known.
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 521-522, DOI: 10.11646/zootaxa.4317.3.4, http://zenodo.org/record/884766