Hydrophilidae, Latreille, 1802

Minoshima, Yûsuke & Hayashi, Masakazu, 2011, Larval morphology of the Japanese species of the tribes Acidocerini, Hydrobiusini and Hydrophilini (Coleoptera: Hydrophilidae), Acta Entomologica Musei Nationalis Pragae (suppl.) 51, pp. 1-118 : 108-110

publication ID	https://doi.org/10.5281/zenodo.4272324
DOI	https://doi.org/10.5281/zenodo.4334954
persistent identifier	https://treatment.plazi.org/id/039A87CB-FFEC-490C-FF54-FF76FBF2E8EC
treatment provided by	Felipe (2020-11-13 20:12:49, last updated 2024-11-26 05:55:16)
scientific name	Hydrophilidae
status

Treatment

4.4. Key to the known genera of the aquatic Hydrophilidae View in CoL from Japan

Here we provide a preliminary generic key to all known larvae of the aquatic Japanese Hydrophilidae (i.e., representatives of the subfamily Hydrophilinae and the genus Coelostoma Brullé, 1835 of the subfamily Sphaeridiinae ). This key presumably works for all instars. The larvae of the genus Megagraphydrus Hansen, 1999 are unknown; larvae of the Japanese species of the tribe Anacaenini and of the genera Pelthydrus d’Orchymont, 1919 (Laccobiini) and Chasmogenus are also unknown. For Anacaena and Chasmogenus , we refer to previous studies ( RICHMOND 1920; WINTERBOURN 1973; ANDERSON 1976; ARCHANGELSKY 1997, 1999; ARCHANGELSKY & FIKÁČEK 2004). The knowledge on the larva of the genus Pelthydrus is based on the larva described by BERTRAND (1936) as Hydrophilidae genus 1 and only later assigned to Pelthydrus by BERTRAND (1974); moreover, as the larva does not fit other known Laccobiini larvae based on its morphology, its identification is doubtful and the genus Pelthydrus is therefore not included in the key.

1. Labium with well developed hypopharyngeal lobe; legs more or less reduced. Mostly terrestrial species. ...................................................... Subfamily Sphaeridiinae View in CoL (part.)

– Labium without well developed hypopharyngeal lobe; legs sometimes short, but well developed. ..................................................................................................................... 2

2. Both mandibles similar in shape and with same number of inner teeth ( Figs. 33 View Fig C–D, 49B–C, 61B–C). .................................................................................................... 3

– Mandibles strongly asymmetrical, with different number of inner teeth on each mandible ( Figs. 11 View Fig B–C, 15D–E, 57B–C). .................................................................. 14

3. Median lobe of spiracular atrium deeply bifurcate ( HAYASHI 1986: Pl. 8I, HANSEN & RICHARDSON 1998: Fig. 12 View Fig ). Terrestrial species. ........ Subfamily Sphaeridiinae View in CoL (part.)

– Median lobe of spiracular atrium simple, entire ( Fig. 5 View Fig ). ....................................... 4

4. Nasale with only one large tooth medially ( HAYASHI 2009a: Fig. 6A View Fig ). ...................... .......................................................................................... Coelostoma Brullé, 1835 View in CoL

– Shape of nasale variable (straight, weakly rounded, serrate, or with variable number of teeth; e.g., Figs. 13C View Fig , 29C View Fig , 46C View Fig , 55A View Fig , 56C View Fig ), never with a single median tooth. .... .............................................................................................................................. 5

5. Nasale with several distinct teeth ( Figs. 36C View Fig , 46C View Fig , 60C View Fig , 62B View Fig ). .................................... 6

– Nasale without distinct teeth, straight or slightly serrate ( Figs. 52C View Fig , 55A View Fig ). ......... 13

6. Ligula reduced, indistinct. .............................................. Amphiops Erichson, 1843 View in CoL

– Ligula well developed (e.g., Figs. 8F View Fig , 21F View Fig , 30F View Fig , 55H View Fig , 57F View Fig ). .................................. 7

7. Anterior corners of mentum strongly projecting anteriad ( Figs. 61F View Fig , 63G View Fig ); legs long, with fringes of long swimming hairs ( Fig. 64D View Fig ). ............ Sternolophus Solier, 1834 View in CoL

– Anterior corners of mentum not projecting anteriad ( Fig. 30F View Fig , 47B View Fig ); legs rather short to moderately long, without fringes of long swimming hairs ( Figs. 45 View Fig , 50C View Fig ). ....... 8

8. Proscutum with lateral lobes ( ARCHANGELSKY & FIKÁČEK 2004: Figs. 9 View Fig , 11 View Fig ); posterior margin of dorsal plate of abdominal segment 8 slightly to strongly trifid ( ARCHANGELSKY & FIKÁČEK 2004: Figs. 10 View Fig , 12 View Fig ). ..................................................................................... 9

– Proscutum without lateral lobes ( Figs. 3 View Fig , 6 View Fig ); posterior margin of dorsal plate of abdo- minal segment 8 straight to sinuate ( Figs. 32B View Fig , 41B View Fig , 48B View Fig ). ................................. 10

9. Inner edge of antennal socket with fringe-like seta ( ARCHANGELSKY & FIKÁČEK 2004: Fig. 3 View Fig ); proscutum with rounded lateral lobes ( ARCHANGELSKY & FIKÁČEK 2004: Fig. 9 View Fig ); abdominal segments without finger-like lateral projections ( ARCHANGELSKY & FIKÁČEK 2004: Fig. 1 View Fig ). .................................................... Anacaena Thomson, 1859 View in CoL

– Inner edge of antennal socket with trichoid seta; proscutum with flat lateral lobes ( ARCHANGELSKY & FIKÁČEK 2004: Fig. 11 View Fig ); abdominal segments with finger-like lateral projections ( ARCHANGELSKY 1997: Fig. 37A View Fig ). ............................. Crenitis Bedel, 1881 View in CoL

10. Frontal lines not converging towards base of head capsule (the lines widely separated at the base of head capsule) or widely U-shaped ( ARCHANGELSKY 1997: Fig. 34B; WIN- View Fig TERBOURN 1973: Fig. 4 View Fig ). ................................................ Paracymus Thomson, 1867 View in CoL

– Frontal lines converging towards base of head capsule, V-shaped or lyriform ( Figs. 29A View Fig , 35A View Fig , 48A View Fig ). .................................................................................................................. 11

11. Nasale strongly asymmetrical ( Figs. 38C View Fig , 42A View Fig ); mandibles with two inner teeth, distal one large, basal one smaller ( Figs. 42 View Fig C–D); head capsule with long scale-like setae ( Figs. 29 View Fig , 36 View Fig , 38 View Fig ). .......................................................... Helochares Mulsant, 1844 View in CoL

– Nasale slightly asymmetrical ( Fig. 46C View Fig ); mandibles with three inner teeth, distal two large, basal one smaller ( Figs. 49 View Fig B–C); head capsule without long scale-like setae ( Fig. 46 View Fig ). ............................................................................................................. 12

12. Dorsal and lateral surface of head capsule with densely arranged, strong tooth-like cuticular projections; abdominal segments with transverse rows of tubercles. ......... .................................................................................... Hydrocassis Fairmaire, 1878 View in CoL

– Dorsal and lateral surface of head capsule smooth, without densely arranged, strong tooth-like cuticular projections ( Fig. 48A View Fig ); abdominal segments without transverse rows of tubercles ( Figs. 1G View Fig , 6C View Fig ). ........................................ Hydrobius Leach, 1815 View in CoL

13. Abdominal segments with long lateral projections ( Fig. 51A View Fig ); spiracular atrium with long prostyli ( Fig. 54B View Fig ). .............................................. Hydrochara Berthold, 1827 View in CoL

– Thoracic and abdominal segments with several pairs of long setiferous projections ( HAYASHI 2009a: Figs. 10 View Fig A–B); spiracular atrium without distinct prostyli (e.g., Figs. 5 View Fig , 32B View Fig ). ......................................................................... Regimbartia Zaitzev, 1908 View in CoL

14. Abdominal segments with long lateral tracheal gills ( HAYASHI 2009a: Figs. 10 View Fig C–D); spiracular atrium reduced. ............................................................ Berosus Leach, 1817 View in CoL

– Abdominal segments without tracheal gills; spiracular atrium developed (e.g., Fig. 5 View Fig ). ............................................................................................................................. 15

15. Epistomal lobes strongly extended anteriorly; left lobe with dense series of stout setae on anterior margin, right lobe without setae ( ARCHANGELSKY 1997: Fig. 45A View Fig ). ......... ........................................................................................ Laccobius Erichson, 1837 View in CoL

– Epistomal lobe not or moderately extended anteriorly, setation of both lobes more or less the same ( Figs. 10C View Fig , 20C View Fig , 56C View Fig ). ................................................................... 16

16. Nasale almost straight, without distinct teeth or serrate margin ( Fig. 56C View Fig ); frontal lines U-shaped ( Fig. 58A View Fig ); anterior corners of mentum strongly projecting anteriad ( Fig. 57F View Fig ); abdominal segments without spinose prolegs. ........................................ .................................................................................... Hydrophilus Geoffroy, 1762 View in CoL

– Nasale not straight, with distinct teeth or serrate margin ( Figs. 10C View Fig , 15A View Fig ); frontal lines V-shaped to lyriform ( Figs. 9A View Fig , 25A View Fig ); anterior corners of mentum not projecting anteriad ( Fig. 26G View Fig ); abdominal segments with spinose prolegs ( Figs. 12 View Fig A–B, 28). ................ 17

17. Nasale serrate, with only one or two teeth ( Figs. 17A View Fig , 22C View Fig ). .......................................... ............................................................................................... Enochrus Thomson, 1859 View in CoL

– Nasale with several distinct teeth, without serrate margin ( Figs. 7C View Fig , 10C View Fig ). ............... 18

18. Nasale almost symmetrical ( ANDERSON 1976: Fig. 9 View Fig ). ........ Chasmogenus Sharp, 1882 View in CoL

– Nasale strongly asymmetrical ( Figs. 7C View Fig , 10C View Fig ). ............ Agraphydrus Régimbart, 1903

References

ANDERSON J. M. E. 1976: Aquatic Hydrophilidae (Coleoptera). The biology of some Australian species with descriptions of immature stages reared in the laboratory. Journal of the Australian Entomological Society 15: 219 - 228.

ARCHANGELSKY M. 1997: Studies on the biology, ecology, and systematics of the immature stages of New World Hydrophiloidea (Coleoptera: Staphyliniformia). Ohio Biology Survey Bulletin, New Series 12: 1 - 207.

ARCHANGELSKY M. 1999: Immature stages of Paracymus rufocinctus Bruch, 1915 and Enochrus (Methydrus) vulgaris (Steinheil, 1869) (Coleoptera: Hydrophilidae: Hydrophilinae). Elytron 13: 87 - 99.

ARCHANGELSKY M. & FIKACEK M. 2004: Descriptions of the egg case and larva of Anacaena and a review of the knowledge and relationships between larvae of Anacaenini (Coleoptera: Hydrophilidae: Hydrophilinae). European Journal of Entomology 101: 629 - 636.

BERTRAND H. 1936: Larves de Coleopteres aquatiques de l'Expedition Limnologique Allemande en Insulinde. Archiv fur Hydrobiologie, Supplement Band XIV Tropische Binnengewasser, Band VI 6: 193 - 285 + pls. I-XI.

BERTRAND H. 1974: Larves et nymphes des Coleopteres aquatiques (2 e note). Bulletin de la Societe Entomologique de France 79: 53 - 63.

HANSEN M. & RICHARDSON B. A. 1998: A new species of Omicrus Sharp (Coleoptera: Hydrophilidae) from Puerto Rico and its larva, the first known larva of Omicrini. Systematic Entomology 23: 1 - 8.

HANSEN M. 1999: World Catalogue of Insects 2: Hydrophiloidea (s. str.) (Coleoptera). Apollo Books, Amsterdam, 416 pp.

HAYASHI N. 1986: IV. Taxonomy and Phylogeny. 3. Key to family of larval stage of Coleoptera from Japan. Pp. 202 - 218 + pls. 1 - 113. In: MORIMOTO K. & HAYASHI N. (eds.): The Coleoptera of Japan in Color Vol. 1. Hoikusha Publishing Co., Ltd., Osaka (in Japanese, with English book title).

HAYASHI M. 2009 a: (Aquatic Hydrophilidae of Shimane prefecture). Bulletin of Hoshizaki Green Foundation 12: 87 - 121 (in Japanese, with English title and abstract).

RICHMOND E. A. 1920: Studies on the biology of the aquatic Hydrophilidae. Bulletin of the American Museum of Natural History 42: 1 - 94 + pls. 1 - 16.

WINTERBOURN M. J. 1973: The larva of Anacaena tepida (Coleoptera: Hydrophilidae) from a Rotorua hot spring. New Zealand Entomologist 5: 171 - 174.

Figures

Fig. 33. Helochares (Helochares) pallens (MacLeay, 1825), third instar.A – clypeolabrum, dorsal view; B – antenna, dorsal view; C–D – mandibles, dorsal view; E – maxilla, dorsal view; F – maxilla, ventral view; G – labium, dorsal view; H – labium, ventral view.

Fig. 11. Head appendages of Agraphydrus narusei (Satô, 1960), third instar.A – antenna, dorsal view; B–C – mandibles, dorsal view; D – maxilla, dorsal view; E – maxilla, ventral view; F – labium, dorsal view; G – labium, ventral view.

Fig. 12. Agraphydrus narusei (Satô, 1960).A–B – prolegs, ventral view:A – first instar; B – third instar. C–D – shape of setae, dorsal view: C – median part of parietale, third instar, dorsal view; D – thoracic segments, first instar, dorsal view. Seta on PA8 and PA13 missing. Photographs were taken with compound light microscope.

Fig. 5. Spiracular atrium of Enochrus japonicus (Sharp, 1873). A – dorsolateral view; B – lateral view.

Fig. 6. Habitus of third instar larvae of the Acidocerini and Hydrobiusini, dorsal view.A – Enochrus umbratus Sharp, 1884; B – Helochares nipponicus Hebauer, 1995; C – Hydrobius pauper Sharp, 1884.

Fig. 13. Head capsule of Enochrus (Holcophilydrus) simulans (Sharp, 1873), first instar.A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 29. Head capsule of Helochares (Helochares) pallens (MacLeay, 1825), first instar.A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 46. Head capsule of Hydrobius pauper Sharp, 1884, second instar.A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 55. Hydrochara affinis (Sharp, 1873), third instar. A – clypeolabrum, dorsal view; B – antenna, dorsal view; C – antenna, detail of outer membranous area on pedicel; D–E – mandibles, dorsal view; F – maxilla, dorsal view; G – maxilla, ventral view; H – labium, dorsal view; I – labium, ventral view.

Fig. 56. Head capsule of Hydrophilus acuminatus Motschulsky, 1854, first instar.A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 36. Head capsule of Helochares (Hydrobaticus) anchoralis Sharp, 1890, first instar.A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 60. Head capsule of Sternolophus (Sternolophus) rufipes (Fabricius, 1792), first instar. A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 62. Sternolophus (Sternolophus) rufipes (Fabricius, 1792), third instar, dorsal view. A – head; B – detail of anterior margin of head capsule; C – spiracular atrium.

Fig. 52. Head capsule of Hydrochara affinis (Sharp, 1873), first instar.A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 8. Head appendages of Agraphydrus narusei (Satô, 1960), first instar. A – antenna, dorsal view; B–C – mandibles, dorsal view; D – maxilla, dorsal view; E – maxilla, ventral view; F – labium, dorsal view; G – labium, ventral view.

Fig. 21. Enochrus (Holcophilydrus) umbratus Sharp, 1884, third instar.A – antenna, dorsal view; B–C – mandibles, dorsal view; D – maxilla, dorsal view; E – maxilla, ventral view; F – labium, dorsal view; G – labium, ventral view.

Fig. 30. Head appendages of Helochares (Helochares) pallens (MacLeay, 1825), first instar. A – antenna, dorsal view; B–C – mandibles, dorsal view; D – maxilla, dorsal view; E – maxilla, ventral view; F – labium, dorsal view; G – labium, ventral view.

Fig. 57. Head appendages of Hydrophilus acuminatus Motschulsky, 1854, first instar. A – antenna, dorsal view; B–C – mandibles, dorsal view; D – maxilla, dorsal view; E – maxilla, ventral view; F – labium, dorsal view; G – labium, ventral view.

Fig. 61. Head appendages of Sternolophus (Sternolophus) rufipes (Fabricius, 1792), first instar. A – antenna, dorsal view; B–C – mandibles, dorsal view; D – maxilla, dorsal view; E – maxilla, ventral view; F – labium, dorsal view; G – labium, ventral view.

Fig. 63. Head appendages of Sternolophus (Sternolophus) rufipes (Fabricius, 1792), third instar. A – antenna, dorsal view; B – detail of outer surface of pedicel, lateral view; C–D – mandibles, dorsal view; E – maxilla, dorsal view; F – maxilla, ventral view; G – labium, dorsal view; H – labium, ventral view.

Fig. 64. Prosternum and mesothoracic legs of Hydrophilini species.A – prosternum of Hydrochara affinis (Sharp, 1873), third instar, ventral view. B–D – mesothoracic legs, first instar, anterior view: B – Hydrochara affinis (Sharp, 1873); C – Hydrophilus acuminatus Motschulsky, 1854; D – Sternolophus rufipes (Fabricius, 1792).

Fig. 47. Head appendages of Hydrobius pauper Sharp, 1884, second instar. A – antenna, dorsal view; B – labium, dorsal view; C – labium, ventral view.

Fig. 45. Mesothoracic legs of Acidocerini species, third instar, anterior view.A – Agraphydrus narusei (Satô, 1960); B – Enochrus umbratus Sharp, 1884; C – Enochrus japonicus (Sharp, 1873); D – Helochares nipponicus Hebauer, 1995.

Fig. 50.Thoracic structures of Hydrobius pauper Sharp, 1884, third instar.A – surface of proscutum; B – prosternum, ventral view; C – mesothoracic leg, anterior view.

Fig. 9. Agraphydrus narusei (Satô, 1960), third instar.A – head, dorsal view; B – spiracular atrium, dorsal view.

Fig. 10. Head capsule of Agraphydrus narusei (Satô, 1960), third instar.A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 3. Larva of Enochrus japonicus (Sharp, 1873) with basic morphological terms. A – dorsal view; B – lateral view; C – ventral view.

Fig. 32. Helochares (Helochares) pallens (MacLeay, 1825), third instar. A – head, dorsal view; B – spiracular atrium, dorsal view.

Fig. 41. Helochares (Hydrobaticus) nipponicus Hebauer, 1995, third instar. A – head, dorsal view; B – spiracular atrium, dorsal view.

Fig. 48. Hydrobius pauper Sharp, 1884, third instar. A – head, dorsal view; B – spiracular atrium, dorsal view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 1. Habitus of the third instar larvae of Acidocerini and Hydrobiusini. A – Agraphydrus narusei (Satô, 1960), dorsal and lateral view; B – Enochrus (Holcophilydrus) simulans (Sharp, 1873), dorsal view; C – E. (H.) umbratus Sharp, 1884, dorsal view; D – E. (Methydrus) japonicus (Sharp, 1873), dorsal view; E – Helochares (Helochares) pallens (MacLeay, 1825), dorsal view; F – H.(Hydrobaticus) nipponicus Hebauer, 1995, dorsal view; G – Hydrobius pauper Sharp, 1884, dorsal and ventral view.

Fig. 37. Head appendages of Helochares (Hydrobaticus) anchoralis Sharp, 1890, first instar. A – antenna, dorsal view; B–C – mandibles, dorsal view; D – maxilla, dorsal view; E – maxilla, ventral view; F – labium, dorsal view; G – labium, ventral view.

Fig. 34. Helochares (Helochares) pallens (MacLeay, 1825), chaetotaxy of head capsule, dorsal view. A – median part of head capsule, second instar. B–D – third instar larva: B – median part of head capsule; C – intraspecific variation of secondary sensilla between PA6 and PA7; D – intraspecific variation of secondary sensilla on outer part of antennal socket. Secondary sensilla are marked by a black rhombus.

Fig.4.General morphology of the head and mouthparts of theAcidocerini,Hydrobiusini and Hydrophilini.A–C – head and anterior part of thorax, schematic:A – dorsal view; B – ventral view; C – lateral view. D–G – head appendages, dorsal view: D – antenna; E – mandible; F – maxilla; G – labium (submentum omitted).

Fig. 35. Helochares (Hydrobaticus) anchoralis Sharp, 1890, first instar.A – head, dorsal view; B – spiracular atrium, dorsal view.

Fig. 38. Head capsule of Helochares (Hydrobaticus) nipponicus Hebauer, 1995, first instar. A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 42. Helochares (Hydrobaticus) nipponicus Hebauer, 1995, third instar.A – clypeolabrum, dorsal view; B – antenna, dorsal view; C–D – mandibles, dorsal view; E – maxilla, dorsal view; F – maxilla, ventral view; G – labium, dorsal view; H – labium, ventral view.

Fig. 49.Head appendages of Hydrobius pauper Sharp, 1884, third instar.A – antenna, dorsal view; B–C – mandibles, dorsal view; D – maxilla, dorsal view; E – maxilla, ventral view; F – labium, dorsal view.

Fig. 51. Habitus of Hydrophilini species, third instar, dorsal view. A – Hydrochara affinis (Sharp, 1873); B – Sternolophus rufipes (Fabricius, 1792).

Fig. 54. Hydrochara affinis (Sharp, 1873), third instar. A – head, dorsal view; B – spiracular atrium, dorsal view.

Fig. 20. Head capsule of Enochrus (Holcophilydrus) umbratus Sharp, 1884, third instar.A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 58. Hydrophilus acuminatus Motschulsky, 1854, third instar. A – head, dorsal view; B – spiracular atrium, dorsal view.

Fig.15. Enochrus (Holcophilydrus) simulans (Sharp, 1873), second instar.A – clypeolabrum,dorsal view; B – antenna, dorsal view; C – antenna, detail of outer membranous area on pedicel, ventral view; D–E – mandibles, dorsal view; F – maxilla, dorsal view; G – maxilla, ventral view; H – labium, dorsal view; I – labium, ventral view.

Fig. 25. Enochrus (Methydrus) japonicus (Sharp, 1873), third instar. A – head, dorsal view; B – spiracular atrium, dorsal view.

Fig. 26. Enochrus (Methydrus) japonicus (Sharp, 1873), third instar. A – clypeolabrum, dorsal view; B – antenna, dorsal view; C–D – mandibles, dorsal view; E – maxilla, dorsal view; F – maxilla, ventral view; G – labium, dorsal view; H – labium, ventral view.

Fig. 17. Enochrus (Holcophilydrus) simulans (Sharp, 1873), third instar.A – clypeolabrum, dorsal view; B – antenna, dorsal view; C–D – mandibles, dorsal view; E – maxilla, dorsal view; F – maxilla, ventral view; G – labium, dorsal view; H – labium, ventral view.

Fig. 22. Head capsule of Enochrus (Methydrus) japonicus (Sharp, 1873), first instar. A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 7. Head capsule of Agraphydrus narusei (Satô, 1960), first instar. A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.