Belongs within: Byrrhoidea.
Contains: Elmini.
The Elmidae are a group of mostly aquatic beetles (invariably aquatic as larvae) that feed on decaying vegetation and algae. They are mostly found in well-oxygenated habitats with rocky bottoms and clear waters. Larvae breath through retractile anal gills until the last instar when they develop functional spiracles and leave the water to pupate. Adults carry an air bubble when going underwater. In members of the subfamily Elminae, this air bubble is carried on a ventral plastron of hairs with the beetle’s dorsum being glabrous or only sparsely pubescent. Members of the subfamily Larainae lack the ventral plastron but are densely pubescent above (Lawrence & Britton 1991).
Certain members of the Elminae are specialised for subterranean habitats, including Anommatelmis botosaneanui and Lemalelmis species from Haiti and Troglelmis leleupi from the Democratic Republic of the Congo (Spangler 1986). Ancyronyx variegatus is conspicuously coloured in black and yellow or orange and bears tarsal claws with a basal tooth (Shepard 2002).
Characters (from Lawrence & Britton 1991): Small to minute, darkly pigmented, with moderately short, slender or slightly incrassate antennae, moderately to widely separated coxae, long legs with simple tarsi and long claws. Larvae onisciform to cylindrical, with movable operculum and paired hooks on S9 and three pairs of retractile anal gills. Adult Elminae glabrous or sparsely pubescent above but have ventral tomentose tracts that serve as a plastron; adult Larainae densely pubescent but lack a plastron.
<==Elmidae [Elminthidae, Helminthidae, Limniidae]
| i. s.: Urumaelmis uenoi (Nomura 1961) [=Zaitzevia uenoi]S86
| Coxelmis v-fasciataB70, M85
| HydrethusB70
|--LarainaeMW15
| |--Potamodytes schoutedeni Delève 1937B14
| |--Stetholus elongatusLB91
| |--HydoraLB91
| |--OvolaraLB91
| |--PotamophilinusLB91
| |--Phanocerus Sharp 1882S02
| | `--P. clavicornis Sharp 1882S02
| `--Lara LeConte 1852O08
| |--*L. avara LeConte 1852O08
| `--L. gehringi Darlington 1929O08
`--ElminaeMW15
| i. s.: Austrolimnius waterhouseiLB91
| SimsoniaLB91
| |--S. tasmanicaC91
| `--S. wilsoniM85
| NotriolusLB91
| KingolusLB91
| Homalosolus hospitalisKB11
| LimniusKB11
| |--L. tuberculatus Müll. 1806 (see below for synonymy)G89
| `--L. volckmariKB11
| Macron quadrituberculatusKB11
| Anommatelmis Spangler 1981S86
| `--A. botosaneanui Spangler 1981S86
| Troglelmis Jeannel 1950S86
| `--T. leleupi Jeannel 1950S86
| Lemalelmis Spangler 1981S86
| |--L. fontana Spangler 1981S86
| `--L. minyops Spangler 1981S86
|--ElminiS02
|--Ancyronyx Erichson 1847 [Ancyronychini]S02
| `--A. variegatus (Germar 1824)S02
`--MacronychiniS02
|--Zaitzevia Champion 1923S02
| |--Z. parvulaB72
| `--Z. rufa Nomura & Baba 1961I92
`--Macronychus Mueller 1806S02
|--M. glabratus Say 1825S02
|--M. quadrituberculatusR26
`--M. variegatusLC40
Limnius tuberculatus Müll. 1806 [incl. L. dargelasi Latr. 1807, L. fuscipes Reiche 1879, L. interruptus Fairm. 1884, L. subparallelus Fairm. 1863]G89
*Type species of generic name indicated
References
[B72] Bell, L. N. 1972. Notes on dry-season survival in two species of Elmidae (Coleoptera). Pan-Pacific Entomologist 48 (3): 218–219.
[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.
[C91] Chapman, R. F. 1991. General anatomy and function. In: CSIRO. The Insects of Australia: A textbook for students and research workers 2nd ed. vol. 1 pp. 33–67. Melbourne University Press: Carlton (Victoria).
[G89] Grouvelle, A. 1889. Divers renseignements relatifs au groupe des Helmis et la diagnose d’un Riolus nouveau. Annales de la Société Entomologique de France, 6e série 9: lxxix–lxxx.
[I92] Iwahashi, J. (ed.) 1992. Reddo Deeta Animaruzu: a pictorial of Japanese fauna facing extinction. JICC: Tokyo.
[KB11] Kundrata, R., & L. Bocak. 2011. The phylogeny and limits of Elateridae (Insecta, Coleoptera): is there a common tendency of click beetles to soft-bodiedness and neoteny? Zoologica Scripta 40: 364–378.
[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).
[M85] Matthews, E. G. 1985. A Guide to the Genera of Beetles of South Australia. Part 4. Polyphaga: Byrrhoidea, Buprestoidea, Dryopoidea, Elateroidea, Cantharoidea, Derodontoidea, and Bostrichoidea. South Australian Museum: Adelaide.
[MW15] McKenna, D. D., A. L. Wild, K. Kanda, C. L. Bellamy, R. G. Beutel, M. S. Caterino, C. W. Farnum, D. C. Hawks, M. A. Ivie, M. L. Jameson, R. A. B. Leschen, A. E. Marvaldi, J. V. McHugh, A. F. Newton, J. A. Robertson, M. K. Thayer, M. F. Whiting, J. F. Lawrence, A. Ślipiński, D. R. Maddison & B. D. Farrell. 2015. The beetle tree of life reveals that Coleoptera survived end-Permian mass extinction to diversify during the Cretaceous terrestrial revolution. Systematic Entomology 40 (4): 835–880.
[O08] Özdikmen, H. 2008. Nomenclatural changes for some preoccupied harvestman genus group names (Arachnida: Opiliones). Turkish Journal of Arachnology 1 (1): 37–43.
[R26] Risso, A. 1826. Histoire naturelle des principales productions de l’Europe méridionale et particulièrement de celles des environs de Nice et des Alpes maritimes vol. 5. F.-G. Levrault: Paris.
[S02] Shepard, W. D. 2002. Elmidae Curtis 1830. In: Arnett, R. H., Jr, M. C. Thomas, P. E. Skelley & J. H. Frank (eds) American Beetles vol. 2. Polyphaga: Scarabaeoidea through Curculionoidea pp. 117–120. CRC Press.
[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.