Myxophaga is the second-smallest suborder of the Coleoptera after Archostemata, consisting of roughly 65 species of small to minute beetles in four families. The members of this suborder are aquatic and semiaquatic, and feed on algae. Description Myxophaga have several diagnostic features: the antennae are more or less distinctly clubbed with usually fewer than nine segments, mesocoxal cavities are open laterally and bordered by a mesepimeron and metanepisternum, the hind wings are rolled apically in the resting positions. Internally, they are characterised by the presence of six malpighian tubules and the testes are tube-like and coiled. Beetles of this suborder are adapted to feed on algae. Their mouthparts are characteristic in lacking galeae and having a mobile tooth on their left mandible. Taxonomy There are four extant families in the suborder Myxophaga divided between two superfamilies, containing about 65 described species, and at least one extinct family. Superfamily Lepiceroidea Hinton, 1936 Family Lepiceridae Hinton, 1936 Lepicerus Hinton, 1936 †Lepiceratus Jałoszyński et al. 2020 Superfamily Sphaeriusoidea Erichson, 1845 Family Hydroscaphidae LeConte, 1874 Hydroscapha LeConte, 1874 Scaphydra Reichardt, 1973 Yara Reichardt & Hinton, 1976 Confossa Short, Joly, García & Maddison, 2015 Family Sphaeriusidae Erichson, 1845 Sphaerius Waltl, 1838 Bezesporum Fikáček et al. 2022 †Burmasporum Kirejtshuk 2009 †Crowsonaerius Li & Cai in Li et al. 2023 Family Torridincolidae Steffan, 1964 Claudiella Reichardt & Vanin, 1976 Delevea Reichardt, 1976 Iapir Py-Daniel, da Fonseca & Barbosa, 1993 Incoltorrida Steffan, 1973 Satonius Endrödy-Younga, 1997 Torridincola Steffan, 1964 Ytu Reichardt, 1973 Family †Triamyxidae Qvarnström et al. 2021 †Triamyxa Qvarnström et al. 2021 Unplaced in family †Leehermania Chatzimanolis et al. 2012 Distribution Living members of Lepiceridae are confined to northern South America and Central America. Members of Sphaeriusidae occur on all continents except Antarctica, while Hydroscaphidae occurs on all continents except Australia and Antarctica. Torridincolidae occurs in Africa, Asia, and South America. Fossil record The fossil record of myxophagan beetles is sparse, likely due to their small size limiting preservation potential. The currently oldest myxophagan is Triamyxa, described in 2021 from numerous specimens of found in a coprolite found in Late Triassic (Carnian) aged sediments in Poland. It was placed in its own monotypic family Triamyxidae, and was resolved as either the most basal myxophagan or sister to Hydroscaphidae. The next oldest is Leehermania from the Late Triassic (Norian) Cow Branch Formation of North Carolina, which had previously been interpreted as the oldest known rove beetle but in