Belongs within: Byrrhoidea.
The Limnichidae are a group of very small beetles often found in riparian habitats (Lawrence & Britton 1991).
Characters (from Lawrence & Britton 1991): Very small, oval and moderately convex beetles, clothed with decumbent, erect or occasionally minute and pruinose vestiture. Antennae eleven-segmented with three- or four-segmented club, usually slender; frontoclypeal suture present; body with ventral cavities into which legs can be folded; prosternum elongate, extending well in front of coxae; fore coxae transverse, trochantins exposed, coxal cavities externally and internally open; mid coxal cavities widely separated, laterally open; transverse metasternal suture usually present; tarsi usually five-segmented, rarely four-segmented; abdomen with five visible ventrites, three to five connate. Larvae cylindrical, maxillolabial complex consolidated, so cardines are contiguous, maxillary articulating areas absent, postmentum joined to stipites for most of its length.
<==Limnichidae
| i. s.: BabalimnichusB14
| ParalimnichusLB91
| Byrrhinus [incl. Notiocyphon]M85
| `--B. convexusM85
|--Throscinus LeConte 1874 [Cephalobyrrhinae]S02
|--Hyphalus [Hyphalinae]B14
| `--H. insularis Britton 1971B14
|--ThaumastodinaeB14
| |--Acontosceles hydroporoidesS72
| `--+--Mexico Spilman 1972S72
| | |--*M. litoralis Spilman 1972S72
| | `--M. morrisoni Skelley 2005B14
| `--+--Martinius ripisaltatorS72
| `--PseudeucinetusS72
`--LimnichinaeS02
|--Physemus LeConte 1854 [incl. Ditaphrus Casey 1886; Bothriophorini]S02
| `--P. minutus LeConte 1854S02
`--LimnichiniS02
|--Eulimnichus Casey 1889S02
|--Limnichoderus Casey 1889S02
|--Lichminus Casey 1889S02
| `--L. tenuicornis (Casey 1889)S02
|--Limnichites Casey 1889S02
| `--L. nebulosusS02
`--LimnichusKB11
|--L. australisLB91
`--L. pygmaeusKB11 [incl. L. sericeusLC40]
*Type species of generic name indicated
References
[B14] Bouchard, P. (ed.) 2014. The Book of Beetles: A lifesize guide to six hundred of nature’s gems. Ivy Press: Lewes (United Kingdom).
[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.
[S02] Shepard, W. D. 2002. Limnichidae Erichson 1846. In: Arnett, R. H., Jr, M. C. Thomas, P. E. Skelley & J. H. Frank (eds) American Beetles vol. 2. Polyphaga: Scarabaeoidea through Curculionoidea pp. 125–126. CRC Press.
[S72] Spilman, T. J. 1972. A new genus and species of jumping shore beetle from Mexico (Coleoptera: Limnichidae). Pan-Pacific Entomologist 48 (2): 108–115.