Helochares, Mulsant, 1844

Jia, Fenglong & Tang, Yu-dan, 2018, A revision of the Chinese Helochares (s. str.) Mulsant, 1844 (Coleoptera, Hydrophilidae), European Journal of Taxonomy 438, pp. 1-27 : 22

A key to the species of Helochares (s. str.) of China

1. Elytra with 10 striae and scutellary stria, punctures in striae coarser than systematic punctures ..... .............................................................................................Subgenus Hydrobaticus MacLeay, 1871

– Elytra without striae or series of punctures except for the rows of systematic punctures, without scutellary stria ......(Subgenus Helochares (s. str.) Mulsant, 1844)..................................................2

2. Size small, 2.8–3.4 mm in length. Dorsum yellowish or reddish brown with dark labrum and frons ( Figs 32, 34 ), pronotum and elytra never dark brown or black. Mesoventrite only simply convex posteromedially, without a transverse ridge or process pointed posteriorly ( Fig. 39 ) ........ ................................................................................................................ H. pallens ( MacLeay, 1825)

– Size over 3.6 mm in length. Dorsum dark brown or black, if yellowish or reddish brown, then size over 4.9 mm. Mesoventrite with a transverse ridge or a process ( Figs 7 , 15 , 24 , 30 )...............3

3. Dark brown or black with very fine ground punctures, clypeus with systematic punctures distinctly larger than ground punctation. Mesoventrite with a stout, backward pointing projection ( Fig. 24 ). Parameres with 3 branches on apical third ( Figs 50–51 ) ............................... ........................................................................................................... H. atropiceus Régimbart, 1903

– Dorsum yellowish brown, dark brown or black with coarser ground punctures, systematic punctures on clypeus almost of the same size as ground punctures. Mesoventrite with a transverse ridge ( Figs 7 , 15 , 30 ), without backward projection. Parameres without branches ( Figs 47–48, 52–55 ).......................................................................................................................4

4. Yellowish or reddish brown with dark brown labrum, never dark brown or black ( Fig. 26 ). Clypeus at most slightly expanded, not impressed in front of eyes. Elytra usually with some longitudinal rows of black spots ( Fig. 26 ). Dorsum with coarser punctures, systematic punctures usually somewhat indistinct ( Figs 26, 28 ). Median lobe of aedeagus with spiniform apex ( Figs 53–55 ) ........................................................................................... H. obscurus ( Müller, 1776)

– Dark brown or black, pronotum with yellowish brown lateral margin ( Figs 1 , 9 ). Clypeus more expanded, distinctly impressed in front of eyes ( Figs 4 , 14 ). Elytra without longitudinal rows of black spots. Median lobe of aedeagus with broad apex ( Figs 47–49 )........................5

5. Body length 4.8–5.3 mm. Lateral margin of clypeus and elytra with same colour as disc ( Figs 1, 3–4 ); pronotum and elytra more coarsely punctate; maxillary palps dark brown or black, each palpomere clearly lighter ( Fig. 4 ). Aedeagus slender, parameres ca 10 × as long as width of apex, apex with a small dent inwards ( Figs 48–49 ) ...................................................... H. songi sp. nov.

– Body length 3.6–4.3 mm. Clypeus and elytra with light colour laterally ( Figs 11, 14 ); pronotum and elytra with finer and sparser punctures; maxillary palps uniformly yellowish brown ( Figs 12–14 ). Length of parameres ca 6.5 × width of apex, subparallel, apex without small dent inwards ( Fig. 47 ); median lobe expanded subapically, abruptly narrowed apically ( Fig. 47 ) .. ..................................................................................................... H. fuliginosus d’Orchymont, 1932

Figures

Figs 32–40. Helochares pallens (MacLeay, 1825). 32–34. Habitus. 32. Dorsal. 33. Ventral. 34. Lateral. 35. Head and pronotum. 36. Pronotum, dorsolateral. 37. Head, ventral. 38. Prosternum. 39. Mesoventrite with legs. 40. Abdomen.

Figs 1–8. Helochares songi sp. nov. 1–3. Habitus. 1. Dorsal. 2. Ventral. 3. Lateral. 4. Head and pronotum. 5. Head and prosternum. 6. Pronotum, lateral. 7. Mesoventrite. 8. Abdomen.

Figs 9–17. Helochares fuliginosus d’Orchymont, 1932. 9–11. Habitus. 9. Dorsal. 10. Ventral. 11. Lateral. 12–13. Head and pronotum. 12. Dorsal. 13. Dorsolateral. 14. Head, dorsal. 15. Mesoventrite. 16. Head and prosternum. 17. Abdomen.

Figs 18–25. Helochares atropiceus Régimbart, 1903. 18–20. Habitus. 18. Dorsal. 19. Ventral. 20. Lateral. 21. Head and pronotum. 22. Head and prosternum. 23. Pronotum, dorsolateral. 24. Mesoventrite. 25. Abdomen.

Figs 26–31. Helochares obscurus (Müller, 1776). 26–27. Habitus. 26. Dorsal. 27. Ventral. 28. Head and pronotum. 29. Head and prosternum. 30. Mesoventrite. 31. Abdomen.

Figs 47–55. Aedeagi in species of Helochares Mulsant, 1844. 47. H. fuliginosus d’Orchymont, 1932. 48–49. H. songi sp. nov. 50–51. H. atropiceus Régimbart, 1903. 50. From Guangxi. 51. From Hong Kong. 52. H. pallens (MacLeay, 1825). 53–55. H. obscurus (Müller, 1776). 53. From Xinjiang. 54–55. After Hansen (1987).