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Family Eucnemidae - False Click Beetles

Eucnemid adult! - Dirrhagofarsus ernae Cross-grain eucnemid - Melasis pectinicornis ID help? - Dirrhagofarsus ernae Xylophilus crassicornis Muona - Xylophilus crassicornis False Click Beetle Deltometopus amoenicornis - Deltometopus amoenicornis Eucnemid - Deltometopus amoenicornis Eucnemids - Nematodes penetrans Elateridae: Anelastes desertorum - Anelastes desertorum
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Coleoptera (Beetles)
Suborder Polyphaga
No Taxon (Series Elateriformia)
Superfamily Elateroidea
Family Eucnemidae (False Click Beetles)
Other Common Names
Eucnemid Beetles
Pronunciation
yook-NEM-ih-dee
Synonyms and other taxonomic changes
Melasidae (includes Phylloceridae, Perothopidae, and Anischiidae)
Explanation of Names
Eucnemidae Eschscholtz 1829
Numbers
>100 spp. in our area, ~2000 total; numerous additions to our fauna may be expected, esp. in FL and along the south border
7 out of 10 subfamilies and 14 out of 29 tribes are represented in our area(1)

Family EUCNEMIDAE Eschscholtz, 1829
Subfamily PEROTHOPINAE Lacordaire, 1857
Genus Perothops Eschscholtz, 1838
Perothops cervinus Germar, 1839
Perothops muscidus (Gyllenhal, 1817)
Perothops witticki LeConte, 1857 - type

Subfamily PHYLLOCERINAE Reitter, 1905
Tribe Anelastini Reitter, 1921
Genus Anelastes Kirby, 1818
Anelastes drurii Kirby, 1818 - Type Synonymized Type (A. latreillei)

Subfamily SCHIZOPHILINAE Muona, 1993
Genus Schizophilus Bonvouloir, 1871
Schizophilus subrufus (Randall, 1838)

Subfamily PALAEOXENINAE Muona, 1993
Genus Palaeoxenus Horn, 1891
Palaeoxenus dohrnii (Horn, 1878) - Type

Subfamily MELASINAE Fleming, 1821
Tribe Melasini Fleming, 1821
Genus Isorhipis Boisduval & Lacordaire, 1835
Isorhipis nubila (Bonvouloir, 1871)
Isorhipis obliqua (Say, 1839)
Genus Melasis Olivier, 1790
Melasis pectinicornis Melsheimer, 1846
Melasis rufipalpis Chevrolat, 1835
Melasis rufipennis Horn, 1886 - Type
Melasis tsugae Hopping, 1926
Tribe Hylocharini Jacquelin du Val, 1859
Genus Hylochares Laporte, 1834
Tribe Xylobiini Reitter, 1911
Genus Xylophilus Mannerheim, 1823
Tribe Epiphanini Muona, 1993
Genus Epiphanis Eschscholtz, 1829
Epiphanis cornutus Eschschultz, 1829 - Type Synonymized Type (E. cristatus)
Genus Hylis des Gozis, 1866
Hylis californicus (Van Dyke, 1932)
Hylis frontosus (Say, 1836)
Hylis irvinei Muona, 2000
Hylis terminalis (LeConte, 1866) - Type
Tribe Dirhagini Reitter, 1911
Genus Protofarsus Muona, 1993
Genus Arrhipis Bonvouloir, 1871
Arrhipis lanieri (Guérin-Méneville, 1843)
Genus Entomophthalmus Bonvouloir, 1871
Entomophthalmus rufiolus (LeConte, 1866) - Type
Genus Rhagomicrus Fleutiaux, 1902
Rhagomicrus thomasi Muona, 2000
Genus Golbachia Cobos, 1955
Golbachia impressicollis (Bonvouloir, 1872)
Golbachia wrighti (Knull, 1946)
Genus Adelothyreus Chevrolat, 1867
Adelothyreus barrae Muona, 2000
Adelothyreus dejeani Bonvouloir, 1872
Genus Microrhagus Dejean, 1833
Microrhagus audax Horn, 1886
Microrhagus opacus Otto, 2015
Microrhagus pectinatus LeConte, 1866 - Type
Microrhagus subsinuatus LeConte, 1852 - Type; 2nd Type Synonymized Type (D. imperfectus)
Microrhagus vulcanicus Wickham - Extinct, Miocene Florissant fossil in Colorado
Genus Dirrhagofarsus Fleutiaux, 1935 - five adventive
Dirrhagofarsus ernae Otto, Muona & McClarin 2014
Dirrhagofarsus lewisi (Fleutiaux, 1900)
Dirrhagofarsus modestus (Fleutiaux, 1923)
Dirrhagofarsus unicolor (Hisamatsu, 1960)
Genus Sarpedon Bonvouloir, 1871
Sarpedon scabrosus Bonvouloir, 1875

Subfamily EUCNEMINAE Eschscholtz, 1829
Tribe Proutianini Muona, 1993
Genus Proutianus Muona, 1993
Proutianus americanus (Horn, 1886) - Type
Tribe Dendrocharini Fleutiaux, 1920
Genus Dendrocharis Guérin-Méneville, 1843
Dendrocharis flavicornis (Guérin-Méneville, 1843)
Tribe Mesogenini Muona, 1993
Genus Vitellius Bonvouloir, 1871
Vitellius texanus Knull, 1957
Genus Stethon LeConte, 1866
Stethon pectorosus LeConte, 1866 - Type
Tribe Eucnemini Eschscholtz, 1829
Genus Eucnemis Ahrens, 1812
Eucnemis americana Horn, 1886 - Type
Genus Idiotarsus Bonvouloir, 1871
Idiotarsus errans (Horn, 1886) - Type

Subfamily MACRAULACINAE Fleutiaux, 1922
Tribe Echthrogasterini Cobos, 1964
Genus Hemiopsida MacLeay, 1872
Hemiopsida robusta (Van Dyke, 1943)
Tribe Euryptychini Mamaev, 1976
Genus Euryptychus LeConte, 1852
Euryptychus arizonicus (Van Dyke, 1945)
Euryptychus ulkei (Horn, 1886) - Type
Tribe Macraulacini Fleutiaux, 1902
Genus Diphytaxis Horn, 1890
Genus Onichodon Newman, 1838
Onichodon canadensis (Brown, 1940)
Onichodon downiei Muona, 2000
Onichodon orchesides Newman, 1838
Onichodon rugicollis (Fall, 1925) - Type
Onichodon wappesi Muona, 2000
Genus Serrifornax Fleutiaux, 1926
Serrifornax infelix (Horn, 1886) - Type
Genus Fornax Laporte, 1835
Fornax bicolor (Melsheimer, 1844)
Fornax dixiensis Otto, 2017
Fornax floridana Otto, 2020
Fornax knulli Muona, 2000
Fornax melsheimeri Otto, 2020
Fornax relictus Wickham - Extinct, Miocene Florissant fossil in Colorado
Genus Isarthrus LeConte, 1852
Isarthrus calceatus (Say, 1836) - Type Synonymized Type (I. spretus)
Isarthrus rufipes (Melsheimer, 1844)
Genus Absensiugum Otto, Muona & Cordoba-Alfaro, 2023
Absensiugum teres (Horn, 1886) - Type; 2nd Type Synonymized Type (N. pavidus)
Genus Dromaeolus Kiesenwetter, 1858
Dromaeolus badius (Melsheimer, 1844)
Dromaeolus californicus Bonvouloir, 1875 - Type
Dromaeolus punctatus (LeConte, 1878) - Type
Dromaeolus salsus Bonvouloir, 1871
Dromaeolus striatus (LeConte, 1852) - Type
Dromaeolus turnbowi Muona, 2000
Genus Asiocnemis Mamaev, 1976
Asiocnemis basalis (LeConte, 1866) - Type
Asiocnemis boharti Muona, 2000
Asiocnemis hospitalis (Blanchard, 1904) - Type
Asiocnemis mcclayi Muona, 2000
Asiocnemis nitens (Horn, 1886) - Type
Genus Thambus Bonvouloir, 1871
Thambus horni Muona, 2000 - Type Replaced name (D. pusillus)
Genus Deltometopus Bonvouloir, 1871
Deltometopus fossilis Wickham - Extinct, Miocene Florissant fossil in Colorado
Tribe Nematodini Leiler, 1976
Genus Nematodes Berthold, 1827
Nematodes atropos (Say, 1836)
Nematodes collaris Bonvouloir, 1872
Nematodes humpreyi Muona, 2000
Nematodes penetrans (LeConte, 1852) - Type
Genus Trigonopleurus Bonvouloir, 1871
Trigonopleurus cordobaalfaroi Otto, 2024
Size
2.9‒25.0 mm
Identification
ADULTS: in Eucnemidae antennomere 2 is attached subterminally to the scape (vs apically in Elateridae
Range
All continents except for Antarctica; most diverse in the tropical and subtropical regions
Habitat
woodlands/forests, especially with a diverse structure, adults in tree canopy and on/under bark, larvae in moist dead wood, hard seasoned wood or in soil near the roots of dead/dying trees (with fungi usually present)
see also(2)
Season
in s.US adults may be seen as early as March; in the Pacific Northwest, as early as April; in Upper Midwest, NE and lower sections of w.NA, since mid-May/early Jun
Food
Larvae may be feeding on fungal mycelia in wood. Larvae bore across the grain.(3)
Life Cycle
Some species undergo a hypermetamorphic lifecycle, with a first instar being a free-living non-parasitic triungulin. It will molt into a completely different larval form later on. Some fifth instar larvae will transition into a prepupal stage, before entering the pupal stage.
Some eucnemid larvae, espcially those similar to elaterid larvae have been observed to bore along the grain of the wood. Other larvae (buprestiform), on the other hand have been known to cut across the grain of the wood, hence the name cross-grain borers. In all observations, these immature beetles are usually found within two to three inches from the surface in the sapwood.
Most Nearctic eucnemid species overwinter as larvae and continue development in the following spring. Many species complete development in one to two years. Some will complete it in three years. Pupal cells are constructed near the surface and larvae have been seen doubled-up in a u-shaped position. Timing in their development hinges on the availability of food sources, moisture and temperature and may arrest its development until suitable conditions are met.
Remarks
The term false click beetle is a misnomer, many eucnemids can click. ―Robert Otto, 3.v.2008
exclusive hosts of Vanhorniidae(4)
See Also
Cerophytidae · Throscidae · Elateridae · Melandryidae (esp. Enchodes, Orchesia and Rushia)
Print References
see (5) for new records not yet reflected in the Guide
Works Cited
1.Family-group names in Coleoptera (Insecta)
Bouchard P, Bousquet Y, Davies A, Alonso-Zarazaga M, Lawrence JF, Lyal CH, Newton A, Reid CA, Schmitt M, Ślipiński SA, Smith A. 2011. ZooKeys 88: 1–972.
2.Review of the phylogeny, classification and biology of the family Eucnemidae (Coleoptera)
Muona J. 1993. Entomologica Scandinavica Suppl. 44: 1-133.
3.The World Beneath our Feet: A Guide to Life in the Soil
James B. Nardi. 2003. Oxford University Press.
4.Hidden Company that Trees Keep: Life from Treetops to Root Tips
James B. Nardi. 2023. Princeton University Press.
5.Additional new records for 35 species of false click beetles (Coleoptera: Eucnemidae) in the Nearctic region
Otto R.L. 2024. Insecta Mundi 1037: 1–16.