Hydrochus

Hydrochus is a genus of water scavenger beetles in the monogeneric family Hydrochidae, sometimes placed in the Hydrophilidae as a subfamily Hydrochinae. The family Hydrochidae includes about 180 species, all of which are placed in the genus Hydrochus. Hydrochus has also been used for a fly genus in the family Dolichopodidae. This junior homonym is a junior subjective synonym of the genus Rhaphium.

Hydrochus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Suborder:	Polyphaga
Superfamily:	Hydrophiloidea
Family:	Hydrochidae Thomson, 1859
Genus:	Hydrochus Leach, 1817
Synonyms
Kiransus Makhan, 1994

Beetles in the genus Hydrochus are found in slow moving streams or stagnant water bodies. The club of the 7 segmented antenna consists of three segments with a cup-like basal segment. The number of tarsi on the legs are usually 5-5-5 or 4-4-4 (a tiny basal segment can be hard to see). The pronotum narrows towards the rear but is narrower than the base of the elytra. They walk around inside water or swim weakly in search of invertebrate prey. They hold air under the elytra. The larvae are also aquatic and predatory. An African species was formerly described under the genus Kiransus, but along with several other African species, they are now placed in Hydrochus.[1] Hydrochids are considered to be an older branch of the Hydrophiloidea. Hydrochids have been suggested as a sister group of the Spercheidae+Hydrophilidae but the relationships are unclear. Molecular phylogenetic comparisons suggest that they are related as a sister group to Helophorus+Georissus.[2]

Species

More than 180 species have been described in the genus. The following list includes some of the species in the genus:[3]

• Hydrochus aljibensis Castro & Delgado, 1999 ^g
• Hydrochus angusi Valladares, 1988 ^g
• Hydrochus angustatus Germar, 1824 ^g
• Hydrochus argutissimus Perkins, 2019
• Hydrochus aschnaae (Makhan, 1994)
• Hydrochus basilaris Perkins, 2019
• Hydrochus bicarinatus Perkins, 2019
• Hydrochus bituberculatus Perkins, 2019
• Hydrochus brevis (Herbst, 1793) ^g
• Hydrochus brevitarsis Knisch, 1922 ^{i c g}
• Hydrochus brianbrowni Makhan, 2005 ^{i c g}
• Hydrochus callosus LeConte, 1855 ^{i c g}
• Hydrochus collaris Perkins, 2019
• Hydrochus conjunctus Perkins, 2019
• Hydrochus corruscans Perkins, 2019
• Hydrochus crenatus (Fabricius, 1792) ^g
• Hydrochus currani Brown, 1929 ^{i c g b}
• Hydrochus debilis Sharp, 1882 ^{i c g}
• Hydrochus denarius Perkins, 2019
• Hydrochus drakei Knisch, 1921 ^g
• Hydrochus elongatus (Schaller, 1783) ^g
• Hydrochus ensifer Hansen, 1998
• Hydrochus excavatus LeConte, 1855 ^{i c g b}
• Hydrochus falsus Hellman in Worthington, Hellman, and Lago 2016[4]
• Hydrochus farsicus ^g
• Hydrochus flavipennis Küster, 1852 ^g
• Hydrochus formosus Perkins, 2019
• Hydrochus foveatus Haldeman, 1852 ^{i c g}
• Hydrochus grandicollis Kiesenwetter, 1870 ^g
• Hydrochus granulatus Blatchley, 1910 ^{i c g b}
• Hydrochus hellmani Perkins, 2019
• Hydrochus ibericus Valladares, Diaz & Delgado, 1999 ^g
• Hydrochus ignicollis Motschulsky, 1860 ^g
• Hydrochus inaequalis LeConte, 1855[4]
• Hydrochus jaechi Makhan, 1995 ^{i c g}
• Hydrochus japonicus Sharp, 1873 ^g
• Hydrochus jiawanae Makhan, 1996 ^{i c g}
• Hydrochus kellymilleri Perkins, 2019
• Hydrochus kirgisicus Motschulsky, 1860 ^g
• Hydrochus lachmoni Makhan, 1996
• Hydrochus leei Perkins, 2019
• Hydrochus lobatus Perkins, 2019
• Hydrochus mauriciogarciai Perkins, 2019
• Hydrochus megaphallus van Berge Henegouwen, 1988 ^g
• Hydrochus minimus Blatchley, 1919 ^{i c g}
• Hydrochus neosquamifer Smetana, 1988 ^{i c g}
• Hydrochus nigeriensis Hansen, 1998
• Hydrochus niloticus Sharp, 1903
• Hydrochus nitidicollis Mulsant, 1844 ^g
• Hydrochus nodulifer Reitter, 1897
• Hydrochus nooreinus Berge Henegouwen & Sainz-Cantero, 1992 ^g
• Hydrochus obscurus Sharp, 1882 ^{i c g}
• Hydrochus octocarinatus Hochhuth, 1871 ^g
• Hydrochus pajnii Makhan, 2000 ^{i c g}
• Hydrochus pallipes Chevrolat, 1863 ^{i c g}
• Hydrochus pictus Perkins, 2019
• Hydrochus pseudosecretus Oliva, 1996
• Hydrochus pseudosquamifer Miller, 1965 ^{i c g b}
• Hydrochus pupillus Orchymont, 1939 ^g
• Hydrochus ramcharani Makhan, 1992
• Hydrochus roomylae Makhan, 2001 ^{i c g}
• Hydrochus rishwani Makhan, 1994
• Hydrochus rufipes Melsheimer, 1844 ^{i c g b}
• Hydrochus rugosus Mulsant, 1844 ^{i c g b}
• Hydrochus sagittarius Perkins, 2019
• Hydrochus scabratus Mulsant, 1844 ^{i c g b}
• Hydrochus schereri Makhan, 1995 ^{i c g}
• Hydrochus setosus Leech, 1948 ^{i c g}
• Hydrochus shorti Perkins, 2019
• Hydrochus simplex Leconte, 1851 ^{i c g b}
• Hydrochus soekhnandanae Makhan 1992
• Hydrochus smaragdineus Fairmaire, 1879 ^g
• Hydrochus spangleri Hellman in Steiner, Staines, McCann and Hellman, 2003 ^{i c g}
• Hydrochus squamifer LeConte, 1855 ^{i c g b}
• Hydrochus subcupreus Randall, 1838 ^{i c g b}
• Hydrochus tariqi Ribera, Hernando & Aguilera, 1999 ^g
• Hydrochus tarsalis Chevrolat, 1863 ^{i c g}
• Hydrochus vagus LeConte, 1852 ^{i c g}
• Hydrochus tuberculatus Hansen, 1998
• Hydrochus variabiloides Perkins, 2019
• Hydrochus variolatus LeConte, 1851 ^{i c g}
• Hydrochus yadavi Makhan, 2000 ^{i c g}

Data sources: i = ITIS,[5] c = Catalogue of Life,[6] g = GBIF,[7] b = Bugguide.net[8]

References

1. Hansen, M. (1998). "The systematic status of Kiransus Makhan, 1994, with the description of three new species of Hydrochus Leach, 1817 (Coleoptera: Hydrochidae)". Insect Systematics & Evolution. 29 (2): 223–232. doi:10.1163/187631298x00302.
2. Short, Andrew Edward Z.; Fikáček, Martin (2013). "Molecular phylogeny, evolution and classification of the Hydrophilidae (Coleoptera): Classification of the Hydrophilidae". Systematic Entomology. 38 (4): 723–752. doi:10.1111/syen.12024.
3. Hidalgo-Galiana, A.; Ribera, I. (2011). "Late Miocene diversification of the genus Hydrochus (Coleoptera, Hydrochidae) in the west Mediterranean area". Molecular Phylogenetics and Evolution. 59 (2): 377–385. doi:10.1016/j.ympev.2011.01.018. PMID 21354316.
4. Worthington, Reese J.; Hellman, John L.; Lago, Paul K. (2016). "Hydrochidae (Coleoptera) of Mississippi". Transactions of the American Entomological Society. 142 (2): 167–213. doi:10.3157/061.142.0206. S2CID 88919765.
5. "Hydrochus Report". Integrated Taxonomic Information System. Retrieved 2018-04-22.
6. "Browse Hydrochus". Catalogue of Life. Retrieved 2018-04-22.
7. "Hydrochus". GBIF. Retrieved 2018-04-22.
8. "Hydrochus Genus Information". BugGuide.net. Retrieved 2018-04-22.