Coleoptera
Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
after
Archostemata
The Archostemata are the smallest suborder of beetles, consisting 45 living species in five families. They are an ancient lineage with a number of primitive characteristics. Antennae may be thread-shaped (filiform) or like a string of beads (mon ...
, consisting of roughly 65 species of small to minute
beetle
Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
s in four families. The members of this suborder are aquatic and semiaquatic, and feed on
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
.
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
The Malpighian tubule system is a type of excretory and osmoregulatory system found in some insects, myriapods, arachnids and tardigrades.
The system consists of branching tubules extending from the alimentary canal that absorbs solutes, water, ...
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
''Lepicerus'' is a genus of myxophagan beetles containing three described species in the family Lepiceridae; it is the only extant genus in the family, with another genus, '' Lepiceratus'' only known from fossils.Jałoszyński, Paweł; Luo, Xiao- ...
Lepiceridae
''Lepicerus'' is a genus of myxophagan beetles containing three described species in the family Lepiceridae; it is the only extant genus in the family, with another genus, '' Lepiceratus'' only known from fossils.Jałoszyński, Paweł; Luo, Xiao- ...
Lepicerus
''Lepicerus'' is a genus of myxophagan beetles containing three described species in the family Lepiceridae; it is the only extant genus in the family, with another genus, '' Lepiceratus'' only known from fossils.Jałoszyński, Paweł; Luo, Xiao- ...
Hydroscapha
''Hydroscapha'' is a genus of beetles endemic to Europe and the United States. It contains these species:
'' LeConte, 1874
** ''
Scaphydra
''Scaphydra'' is a genus of beetles in the family Hydroscaphidae, containing the following species:
'' Reichardt, 1973
** ''
Yara Yara may refer to:
People
* YARA (girl group), a Filipino girl group
* Yara (given name)
* Yara (surname), a Japanese surname
* Yara (singer) (born 1983), Lebanese pop singer
* Yara (footballer) (born 1964), Brazilian footballer
Locations
* Y ...
Sphaerius
''Sphaerius'' is a genus of beetles, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on algae; they occur on all continents ex ...
Torridincolidae
The Torridincolidae are a small family of beetles in the suborder Myxophaga. It contains these genera:Steffan, 1964
** '' Claudiella'' Reichardt & Vanin, 1976
** '' Delevea'' Reichardt, 1976
** ''
Iapir
''Iapir'' is a genus of beetles in the family Torridincolidae, containing these species:Incoltorrida
''Incoltorrida'' is a genus of myxophagan water beetles from Madagascar in the family Torridincolidae
The Torridincolidae are a small family of beetles in the suborder Myxophaga. It contains these genera:Satonius
''Satonius'' is a genus of beetles in the family Torridincolidae. It is native to East Asia. The type species, ''S. kurosawai'', was originally described as a species of ''Delevea
''Delevea'' is a genus of beetles in the family Torridincolida ...
Torridincola
''Torridincola'' is a genus of beetles in the family Torridincolidae
The Torridincolidae are a small family of beetles in the suborder Myxophaga. It contains these genera:Ytu'' Reichardt, 1973
Family †
Triamyxidae
''Triamyxa'' is an extinct genus of myxophagan beetle in the monotypic family Triamyxidae from the Carnian stage of Late Triassic, approximately 230 million years ago. It was found in the Keuper Claystone of Poland. The type species is ''T. ...
Qvarnström et al. 2021
*†''
Triamyxa
''Triamyxa'' is an extinct genus of myxophagan beetle in the monotypic family Triamyxidae from the Carnian stage of Late Triassic, approximately 230 million years ago. It was found in the Keuper Claystone of Poland. The type species is ''T. ...
'' 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
Little about the fossil record of Myxophaga is known. Fossils from the early Late Cretaceous (
Cenomanian
The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...
) aged Burmese amber from Myanmar, have been assigned to the extant genus ''
Lepicerus
''Lepicerus'' is a genus of myxophagan beetles containing three described species in the family Lepiceridae; it is the only extant genus in the family, with another genus, '' Lepiceratus'' only known from fossils.Jałoszyński, Paweł; Luo, Xiao- ...
'' and extinct genus '' Lepiceratus'' within Lepiceridae,Jałoszyński, Paweł; Luo, Xiao-Zhu; Hammel, Jörg U.; Yamamoto, Shûhei & Beutel, Rolf G. (2020). "The mid-Cretaceous †''Lepiceratus'' gen. nov. and the evolution of the relict beetle family Lepiceridae (Insecta: Coleoptera: Myxophaga)". ''Journal of Systematic Palaeontology''. 18 (13). as well as '' Burmasporum'', which belongs to Sphaerusidae. No impression fossils of myxophagan beetle were described until 2012, probably because of their small body size and specialized habitat. A fossil specimen, assigned to the living genus ''
Hydroscapha
''Hydroscapha'' is a genus of beetles endemic to Europe and the United States. It contains these species:
Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
Geology
Pro ...
(
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...
). In 2019, '' Leehermania'' from the Late Triassic (
Norian
The Norian is a division of the Triassic Period. It has the rank of an age (geochronology) or stage (chronostratigraphy). It lasted from ~227 to million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.
Stratigraphic defi ...
)
Cow Branch Formation
The Cow Branch Formation is a Late Triassic (Carnian to Norian, or Tuvalian in the regional stratigraphy) geologic formation in the eastern United States.rove beetle
The rove beetles are a family (Staphylinidae) of beetles, primarily distinguished by their short elytra (wing covers) that typically leave more than half of their abdominal segments exposed. With roughly 63,000 species in thousands of genera, the ...
was reinterpreted as an early diverging relative of the family Hydroscaphidae, making it the then oldest known Myxophagan. In 2021, numerous specimens of a new myxophagan were described from a
coprolite
A coprolite (also known as a coprolith) is fossilized feces. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour (in this case, diet) rather than morphology. The name is de ...
found in Late Triassic ( Carnian) aged sediments in Poland. The new taxon ''
Triamyxa
''Triamyxa'' is an extinct genus of myxophagan beetle in the monotypic family Triamyxidae from the Carnian stage of Late Triassic, approximately 230 million years ago. It was found in the Keuper Claystone of Poland. The type species is ''T. ...
,'' was placed in its own monotypic family Triamyxidae, and was resolved as either the most basal myxophagan or sister to Hydroscaphidae.