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.[1]
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.[2]
Taxonomy
There are four extant families in the suborder Myxophaga divided between two superfamilies,[3] containing about 65 described species,[4]
Little about the fossil record of Myxophaga is known. Fossils from the early Late Cretaceous (Cenomanian) aged Burmese amber from Myanmar, have been assigned to the extant genus Lepicerus within Lepiceridae.[5][6] As well as Burmasporum, which belongs to Sphaerusidae.[7] No impression fossils of myxophagan beetle were described until 2012, probably because of their small body size and specialized habitat.[8] A fossil specimen, assigned to the living genus Hydroscapha in Hydroscaphidae, is known from the Yixian Formation in the Jehol Biota, dating from the Early Cretaceous.[8] In 2018, Leehermania from the Late Triassic (Norian) Cow Branch Formation of North Carolina, which had previously been interpreted as the oldest known rove beetle was reinterpreted as an early diverging relative of the family Hydroscaphidae, making it the then oldest known Myxophagan.[9] In 2021, numerous specimens of a new myxophagan were described from a coprolite found in Late Triassic (Carnian) aged sediments in Poland. The new taxon Triamyxa, was placed in its own monotypic family Triamyxidae, and was resolved as either the most basal myxophagan or sister to Hydroscapidae.[10]
^Beutel, R.; Leschen, R. (2005). "Morphology and Systematics (Archostemata, Adephaga, Myxophaga, Polyphaga partim)". Band 4 Part 38: Arthropoda, Hälfte: Insecta, Coleoptera, Beetles. Handbuch der Zoologie/Handbook of Zoology. Vol. 1. Walter de Gruyter. ISBN3-11-017130-9.
^Kirejtshuk, A. G.; Poinar, G. (2006). "Haplochelidae, a new family of cretaceous beetles (Coleoptera: Myxophaga) from Burmese amber". Proceedings of the Entomological Society of Washington. 108: 155–164.
^ abCai, C.; Short, A. E. Z.; Huang, D. (2012). "The First Skiff Beetle (Coleoptera: Myxophaga: Hydroscaphidae) from Early Cretaceous Jehol Biota". Journal of Paleontology. 86 (1): 116–9. doi:10.1666/11-050.1. S2CID140170420.