Enochrus melanocephalus, copyright Donald Hobern.

Belongs within: Hydrophiloidea.
Contains: Hydrophilinae, Anacaenini, Chaetarthriini, Acidocerinae.

The Hydrophilidae are a group of beetles in which the majority of species are aquatic though many members of the subfamily Sphaeridiinae are terrestrial. Aquatic species swim by alternate movements of the hind legs and usually breathe using a bubble of air covering the ventral surface of the abdomen (Van Tassell 2001). Distinctive features of the Hydrophilidae include well developed maxillary palps and antennae with a three-segmented club preceded by a small cup-like segment or cupule. Larvae are phytophagous or saprophagous but the adults are predators (Lawrence & Britton 1991).

Several subfamilies are recognised with some historical disagreement over the family’s circumscription. Hydrophilids sensu stricto have five-segmented tarsi but species of the genus Spercheus have four-segmented tarsi and are often treated as a distinct family (Lawrence & Britton 1991). The Enochrinae are small species with a projecting lamina on the mesosternum (Van Tassell 2001). The Chaetarthriinae largely lack stria or other systematic punctures on the elytra.

Characters (from Lawrence & Britton 1991): Antennae usually short, 7- to 9-segmented, with 3-segmented pubescent club preceded by glabrous cup-like segment (cupule); clypeus large, frontoclypeal suture more or less angulate, often attached to median line (endocarina); maxillary palps well developed, usually longer than antennae. Larvae with six stemmata on each side, usually possessing metapneustic respiratory system with only eighth spiracles function and located in respiratory chamber (atrium) at end of abdomen.

Hydrophilidae [Hydrophilini, Sphaeridiidae]
| | `--ChaetarthriinaeMF15
| | |--AnacaeniniMF15
| | `--ChaetarthriiniM74
| `--Spercheus [Spercheidae, Spercheinae]LC20
| |--S. emarginatus Schaller 1783B14
| |--S. mulsanti Perr. 1864M96
| |--S. platycephalus Laporte de Castelnau 1840LC40
| |--S. priscusM96
| `--S. senegalensis [incl. S. costatus]LC40
|--Cymbiodyta Bedel 1880MF15, VT01 [incl. Hydrocombus Sharp 1882VT01]
`--Enochrus Thomson 1859 (see below for synonymy)VT01
|--‘Philydrus’ aequalis Sharp 1882 [incl. P. circumcinctus]FS90
|--‘Philydrus’ affinisLC40
|--‘Philydrus’ bicolorLC40
|--‘Philhydrus’ burrundiensis Blackburn 1889M96
|--‘Philydrus’ dermestoidesLC40
|--E. deserticolaPH10
|--E. elongatusPH10
|--‘Philhydrus’ eyrensis Blackb. 1895M96
|--‘Philydrus’ grisescens [incl. P. torquatus]LC40
|--‘Philydrus’ griseus [incl. P. chrysomelinus]LC40
|--‘Philhydrus’ laevigatus Blackb. 1888M96
|--E. maculicepsPH10
|--‘Philydrus’ marginellusLC40
|--E. melanocephalusBP00 [=Philhydrus melanocephalusB89; incl. Philydrus dichrousLC40]
|--E. ochraceusVT01
|--‘Philydrus’ pallidus Laporte de Castelnau 1840LC40
|--E. quadripunctatusBP00
`--‘Philydrus’ testaceusC01 [=Hydrophilus testaceusG89; incl. P. testaceus var. lineatusC01]

Hydrophilidae incertae sedis:
Zetemnes tarsalisP02
Angarolarva aquaticaP02
Hydrobiites crassus Ponomarenko 1985RJ93
|--S. australisPH10
|--S. immarginatusPH10
|--S. marginicollisB70
|--S. rufipesLC40
|--S. solieriLC40
|--S. tenebricosus Blackb. 1888M96
`--S. unicolor Laporte de Castelnau 1840LC40
|--H. australis Blackb. 1888M96
|--H. clypeatus Blackb. 1890M96
|--H. luridusM96
`--H. tristisM96
Notoberosus zietzi Blackb. 1895M96
|--V. aeneusLC40
|--V. inflatusLC40
|--V. punctatus Blackb. 1888M96
`--V. scaphidiformis Fairm. 1879M96
|--C. abdominaleM96
|--C. australis Blackb. 1888M96
`--C. pygmaeumM96
Hydrocharis Lec. 1855FS90
`--H. tenebroides Duv. 1856 [incl. H. anthracinus]FS90
Troglochares Spangler 1981S86
`--T. ashmolei Spangler 1981S86
Regimbartia attenuataPH10
Paranacaena horniPH10
|--B. bipunctatusLC40
|--B. globulus [incl. B. alicantus]LC40
|--B. pallidus Laporte de Castelnau 1840LC40
`--B. similis Laporte de Castelnau 1840LC40
Globaria striatopunctataLC40

Enochrus Thomson 1859 [incl. Agraphilhydrus Kuwert 1888, Lumetus Zaitzev 1908, Methydrus Rey 1885, Philhydriis Brulle 1835 non Brooks 1828, Philydrus Solier 1834 non Duftschmidt 1805]VT01

*Type species of generic name indicated


[BP00] Bellini, R., F. Pederzani, R. Pilani, R. Veronesi & S. Maini. 2000. Hydroglyphus pusillus (Fabricius) (Coleoptera Dytiscidae): its role as a mosquito larvae predator in rice fields. Boll. Ist. Ent. “G. Grandi” Univ. Bologna 54: 155–163.

[B89] Blackburn, T. 1889. Notes on Australian Coleoptera, with descriptions of new species. Part III. Proceedings of the Linnean Society of New South Wales, series 2, 4 (2): 445–482.

[B14] Bouchard, P. (ed.) 2014. The Book of Beetles: A lifesize guide to six hundred of nature’s gems. Ivy Press: Lewes (United Kingdom).

[B70] Britton, E. B. 1970. Coleoptera (beetles). In: CSIRO. The Insects of Australia: A textbook for students and research workers pp. 495–621. Melbourne University Press.

[C01] Csiki, E. 1901. Bogarak [Coleopteren]. In: Horváth, G. (ed.) Zichy Jenő Gróf Harmadik Ázsiai Utazása [Dritte Asiatische Forschungsreise des Grafen Eugen Zichy] vol. 2. Zichy Jenő Gróf Harmadik Ázsiai Utazásának Állattani Eredményei [Zoologische Ergebnisse der Dritten Asiatischen Forschungsreise des Grafen Eugen Zichy] pp. 75–120. Victor Hornyánszky: Budapest, and Karl W. Hierseman: Leipzig.

[FS90] Fleutiaux, E., & A. Sallé. 1890. Liste des coléoptères de la Guadeloupe et descriptions d’espèces nouvelles. Annales de la Société Entomologique de France, 6e série 9: 351–484.

[LC40] Laporte de Castelnau, F. 1840. Histoire Naturelle des Insectes Coléoptères vol. 2. P. Duménil: Paris.

[LB91] Lawrence, J. F., & E. B. Britton. 1991. Coleoptera (beetles). In: CSIRO. The Insects of Australia: A textbook for students and research workers 2nd ed. vol. 2 pp. 543–683. Melbourne University Press: Carlton (Victoria).

[LC20] Lü, L., C.-Y. Cai, X. Zhang, A. F. Newton, M. K. Thayer & H.-Z. Zhou. 2020. Linking evolutionary mode to palaeoclimate change reveals rapid radiations of staphylinoid beetles in low-energy conditions. Current Zoology 66 (4): 435–444.

[M96] Masters, G. 1896. Catalogue of the described Coleoptera of Australia. Supplement, part II. Dytiscidae, Gyrinidae, Hydrophyllidae, Staphylinidae, Pselaphidae, Paussidae, Silphidae, Scaphididae, Histeridae, Phalacridae, Nitidulidae, Trogositidae, Colydiidae, Cucujidae, Cryptophagidae, Lathridiidae, Mycetophagidae, Dermestidae, Byrrhidae, Parnidae, Heteroceridae. Proceedings of the Linnean Society of New South Wales 21 (Suppl.): 695–754.

[MF15] McKenna, D. D., B. D. Farrell, M. S. Caterino, C. W. Farnum, D. C. Hawks, D. R. Maddison, A. E. Seago, A. E. Z. Short, A. F. Newton & M. K. Thayer. 2015. Phylogeny and evolution of Staphyliniformia and Scarabaeiformia: forest litter as a stepping stone for diversification of nonphytophagous beetles. Systematic Entomology 40: 35–60.

[M74] Miller, D. C. 1974. Revision of the New World Chaetarthria (Coleoptera: Hydrophilidae). Entomologica Americana 49 (1): 1–123.

[PH10] Pinder, A. M., S. A. Halse, R. J. Shiel & J. M. McRae. 2010. An arid zone awash with diversity: patterns in the distribution of aquatic invertebrates in the Pilbara region of Western Australia. Records of the Western Australian Museum Supplement 78 (1): 205–246.

[P02] Ponomarenko, A. G. 2002. Superorder Scarabaeidea Laicharting, 1781. Order Coleoptera Linné, 1758. The beetles. In: Rasnitsyn, A. P., & D. L. J. Quicke (eds) History of Insects pp. 164–176. Kluwer Academic Publishers: Dordrecht.

[RJ93] Ross, A. J., & E. A. Jarzembowski. 1993. Arthropoda (Hexapoda; Insecta). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 363–426. Chapman & Hall: London.

[S02] Sinitshenkova, N. D. 2002. Ecological history of the aquatic insects. In: Rasnitsyn, A. P., & D. L. J. Quicke (eds) History of Insects pp. 388–426. Kluwer Academic Publishers: Dordrecht.

[S86] Spangler, P. J. 1986. Insecta: Coleoptera. In: Botosaneanu, L. (ed.) Stygofauna Mundi: A Faunistic, Distributional, and Ecological Synthesis of the World Fauna inhabiting Subterranean Waters (including the Marine Interstitial) pp. 622–631. E. J. Brill/Dr W. Backhuys: Leiden.

[VT01] Van Tassell, E. R. 2001. Hydrophilidae Latreille, 1802. In: Arnett, R. H., Jr & M. C. Thomas (eds) American Beetles vol. 1. Archostemata, Myxophaga, Adephaga, Polyphaga: Staphyliniformia pp. 187–208. CRC Press: Boca Raton.

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