Hygrotus Stephens, 1828

Fery, Hans, 2017, A new classification of the tribe Hygrotini Portevin, 1929 (Coleoptera: Dytiscidae: Hydroporinae), Zootaxa 4317 (3), pp. 499-529 : 521-522

publication ID	https://doi.org/ 10.11646/zootaxa.4317.3.4
publication LSID	lsid:zoobank.org:pub:5Fd492A4-D41D-4F37-A121-Ffa680E7E778
DOI	https://doi.org/10.5281/zenodo.6026857
persistent identifier	https://treatment.plazi.org/id/039C87CE-0F35-FF96-FF1F-661CCD6352E5
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scientific name	Hygrotus Stephens, 1828
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Subgenus Hygrotus Stephens, 1828 View in CoL

Type species: Dytiscus inaequalis Fabricius, 1777: 239 , by subsequent designation of Curtis (1835: pl. 531).

Herophydrus Sharp, 1880 View in CoL : cxlviii; type species: Hydroporus hyphydroides Perris, 1864: 277 (= Herophydrus guineensis (Aubé 1838: 455)) View in CoL , 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 View in CoL ; type species: Herophydrus descarpentriesi Peschet, 1923: 176 , by original designation of Guignot (1950: 150). n. syn.

The newly defined subgenus Hygrotus View in CoL s. str. includes siX species previously included in the former subgenus Hygrotus View in CoL s. str., the single species of former genus Heroceras View in CoL ( H. descarpentriesi ) and all 44 species (one of them bitypic) of the former genus Herophydrus View in CoL (see Fig. 2 View FIGURE 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 View FIGURES 7 – 12 for H. (s. str.) inaequalis and Fig. 17 View FIGURES 13 – 18 for H. (s. str.) descarpentriesi ) and species of former Herophydrus small to large (TL 2.6–7.4 mm) (see Fig. 16 View FIGURES 13 – 18 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 View FIGURES 41 – 48 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 View FIGURES 41 – 48 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 View FIGURES 13 – 18 ). Elytra with margin in lateral view rather strongly ascending to shoulder (similar to Fig. 54 View FIGURES 49 – 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 View FIGURES 49 – 55 ). 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 View FIGURES 19 – 28 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 View FIGURES 29 – 40 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 View FIGURE 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.