Myxophaga: Difference between revisions

{{short description|Suborder of beetles}}

{{automatic taxobox

| taxon = Myxophaga

| fossil_range = {{Geological range|Carnian|Recent}}

| image = Delevea kurosawai (cropped).jpg

| image_caption = ''[[Satonius]] kurosawai'' ([[Torridincolidae]])

| image2 =

| image2_caption =

| authority = [[Roy Crowson|Crowson]], 1955

| subdivision = [[Hydroscaphidae]]<br/>

[[Torridincolidae]]<br />

†[[Triamyxidae]]

'''Myxophaga''' is the second-smallest suborder of the [[beetle|Coleoptera]] after [[Archostemata]], consisting of roughly 65 species of small to minute [[beetle]]s in four families. The members of this suborder are [[aquatic insect|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 tubule system|malpighian tubules]] and the testes are tube-like and coiled.<ref>{{cite encyclopedia|title=Band 4 Part 38: Arthropoda, Hälfte: Insecta, Coleoptera, Beetles|encyclopedia=Handbuch der Zoologie/Handbook of Zoology|publisher=[[Walter de Gruyter]]|date=2005|volume=1|isbn=3-11-017130-9|last2=Leschen|first2=R.|last1=Beutel|first1=R.|chapter=Morphology and Systematics (Archostemata, Adephaga, Myxophaga, Polyphaga partim)}}</ref>

Beetles of this suborder are adapted to feed on algae. Their mouthparts are characteristic in lacking [[Insect mouthparts#Maxilla|galeae]] and having a mobile tooth on their left mandible.<ref>{{harvnb|Beutel|Leschen|2005|page=43}}</ref>

There are four extant families in the suborder Myxophaga divided between two superfamilies,<ref>{{cite web |url=http://tolweb.org/Myxophaga/8871 |title=Myxophaga |publisher=Tree of Life Web Project |date=2007 |access-date=2017-05-26}}</ref> containing about 65 described species,<ref>{{Cite journal |last=Mesaros |first=Gabor |title=Sphaeriusidae (Coleoptera, Myxophaga): A new beetle family to the fauna of Serbia |url=http://scindeks.ceon.rs/Article.aspx?artid=1820-95211306071M |journal=Bulletin of the Natural History Museum |issue=6 |pages=71–74 |doi=10.5937/bnhmb1306071m|year=2013 |doi-access=free }}</ref> and at least one extinct family.{{efn|† Denotes that the group is extinct}}

Superfamily [[Lepiceroidea]] <small>[[H. E. Hinton|Hinton]], 1936</small>

*Family [[Lepiceridae]] <small>[[H. E. Hinton|Hinton]], 1936</small>

**''[[Lepicerus]]'' <small>[[Victor Motschulsky|Motschulsky]], 1855</small>

**†''[[Lepiceratus]]'' <small>Jałoszyński et al. 2020<ref name=":1" /></small>

Superfamily [[Sphaeriusoidea]] <small>[[Wilhelm Ferdinand Erichson|Erichson]], 1845</small>

*Family [[Hydroscaphidae]] <small>[[John Lawrence LeConte|LeConte]], 1874</small>

** ''[[Hydroscapha]]'' <small>LeConte, 1874</small>

** ''[[Scaphydra]]'' <small>Reichardt, 1973</small>

** ''[[Yara (beetle)|Yara]]'' <small>Reichardt & Hinton, 1976</small>

**''[[Confossa]]'' <small>Short, Joly, García & Maddison, 2015</small>

*Family [[Sphaeriusidae]] <small>[[Wilhelm Ferdinand Erichson|Erichson]], 1845</small>

**''[[Sphaerius]]'' <small>[[Joseph Waltl|Waltl]], 1838</small>

**''[[Bezesporum]]'' <small>Fikáček et al. 2022<ref name=":2" /></small>

**†''[[Burmasporum]]'' <small>Kirejtshuk 2009<ref name=":3" /></small>

**†''[[Crowsonaerius]]'' <small>Li & Cai in Li et al. 2023<ref name=":4" /></small>

*Family [[Torridincolidae]] <small>[[August Wilhelm Steffan|Steffan]], 1964</small>

** ''[[Claudiella]]'' <small>Reichardt & Vanin, 1976</small>

** ''[[Delevea]]'' <small>Reichardt, 1976</small>

** ''[[Iapir]]'' <small>Py-Daniel, da Fonseca & Barbosa, 1993</small>

** ''[[Incoltorrida]]'' <small>Steffan, 1973</small>

** ''[[Satonius]]'' <small>[[Sebastian Endrödy-Younga|Endrödy-Younga]], 1997</small>

** ''[[Torridincola]]'' <small>Steffan, 1964</small>

** ''[[Ytu (beetle)|Ytu]]'' <small>Reichardt, 1973</small>

Family †[[Triamyxidae]] <small>Qvarnström et al. 2021</small>

*†''[[Triamyxa]]'' <small>Qvarnström et al. 2021<ref name=":5" /></small>

Unplaced in family

*†''[[Leehermania]]'' <small>Chatzimanolis et al. 2012<ref name=":1" /></small>

==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.<ref>{{Citation|last1=Sampaio|first1=Brunno H.L.|title=Families Hydroscaphidae and Torridincolidae|date=2018|url=https://linkinghub.elsevier.com/retrieve/pii/B9780128042236000226|work=Thorp and Covich's Freshwater Invertebrates|pages=519–525|publisher=Elsevier|language=en|doi=10.1016/b978-0-12-804223-6.00022-6|isbn=978-0-12-804223-6|access-date=2021-07-26|last2=Short|first2=Andrew E.Z.}}</ref>

== Fossil record ==

The fossil record of myxophagan beetles is sparse, likely due to their small size limiting [[preservation potential]].<ref name=":1">{{Cite journal |last1=Fikáček |first1=Martin |last2=Beutel |first2=Rolf G. |last3=Cai |first3=Chenyang |last4=Lawrence |first4=John F. |last5=Newton |first5=Alfred F. |last6=Solodovnikov |first6=Alexey |last7=Ślipiński |first7=Adam |last8=Thayer |first8=Margaret K. |last9=Yamamoto |first9=Shûhei |date=January 2020 |title=Reliable placement of beetle fossils via phylogenetic analyses – Triassic Leehermania as a case study (Staphylinidae or Myxophaga?) |url=https://onlinelibrary.wiley.com/doi/10.1111/syen.12386 |journal=Systematic Entomology |language=en |volume=45 |issue=1 |pages=175–187 |doi=10.1111/syen.12386 |bibcode=2020SysEn..45..175F |s2cid=203407211 |issn=0307-6970}}</ref> 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.<ref name=":5">{{Cite journal |last1=Qvarnström |first1=Martin |last2=Fikáček |first2=Martin |last3=Vikberg Wernström |first3=Joel |last4=Huld |first4=Sigrid |last5=Beutel |first5=Rolf G. |last6=Arriaga-Varela |first6=Emmanuel |last7=Ahlberg |first7=Per E. |last8=Niedźwiedzki |first8=Grzegorz |date=June 2021 |title=Exceptionally preserved beetles in a Triassic coprolite of putative dinosauriform origin |journal=Current Biology |volume=31 |issue=15 |language=en |pages=3374–3381.e5 |doi=10.1016/j.cub.2021.05.015 |pmid=34197727 |doi-access=free}}</ref> 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 2019 was reinterpreted as an early diverging relative of the family Hydroscaphidae.<ref name=":1" /> A fossil impression assigned to the living genus ''[[Hydroscapha]]'' in Hydroscaphidae is known from the [[Yixian Formation]] in the [[Jehol Biota]], dating from the [[Early Cretaceous]] ([[Aptian]]).<ref name="firstskiff">{{cite journal |author1=Cai, C. |author2=Short, A. E. Z. |author3=Huang, D. |date=2012 |title=The First Skiff Beetle (Coleoptera: Myxophaga: Hydroscaphidae) from Early Cretaceous Jehol Biota |journal=Journal of Paleontology |volume=86 |issue=1 |pages=116–9 |doi=10.1666/11-050.1 |bibcode=2012JPal...86..116C |s2cid=140170420}}</ref> Fossils from the early Late Cretaceous ([[Cenomanian]]) aged [[Burmese amber]] from Myanmar, have been assigned to the extant genus ''[[Lepicerus]]'' and extinct genus ''[[Lepiceratus]]'' within Lepiceridae,<ref>{{cite journal |author1=Kirejtshuk, A. G. |author2=Poinar, G. |date=2006 |title=Haplochelidae, a new family of cretaceous beetles (Coleoptera: Myxophaga) from Burmese amber |journal=Proceedings of the Entomological Society of Washington |volume=108 |pages=155–164}}</ref><ref>{{cite journal |author1=Ge, S. Q. |author2=Friedrich, F. |author3=Beutel, R. G. |date=2010 |title=On the systematic position and taxonomic rank of the extinct myxophagan dagger Haplochelus (Coleoptera) |url=http://booksandjournals.brillonline.com/content/journals/10.1163/187631210x537385 |journal=Insect Systematics and Evolution |volume=41 |issue=4 |pages=329–338 |doi=10.1163/187631210X537385}}</ref><ref name=":0">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). {{doi|10.1080/14772019.2020.1747561}}</ref> as well as the extant ''[[Sphaerius]]'' and ''[[Bezesporum]]'' and the extinct ''[[Burmasporum]]'' and ''[[Crowsonaerius]]'', belonging to Sphaerusidae.<ref name=":3">{{cite journal |author1=Kirejtshuk, A. G. |date=2009 |title=A new genus and species of Sphaeriusidae (Coleoptera, Myxophaga) from Lower Cretaceous Burmese amber |url=http://www.zobodat.at/stable/pdf/DENISIA_0026_0099-0102.pdf |journal=Denisia |volume=26 |pages=99–102}}</ref><ref name=":4">{{Cite journal |last1=Li |first1=Yan-Da |last2=Ślipiński |first2=Adam |last3=Huang |first3=Di-Ying |last4=Cai |first4=Chen-Yang |date=2023-01-11 |title=New fossils of Sphaeriusidae from mid-Cretaceous Burmese amber revealed by confocal microscopy (Coleoptera: Myxophaga) |journal=Frontiers in Earth Science |volume=10 |pages=901573 |doi=10.3389/feart.2022.901573 |issn=2296-6463|doi-access=free |bibcode=2023FrEaS..10.1573L }}</ref><ref name=":2">{{Cite journal |last1=Fikáček |first1=Martin |last2=Yamamoto |first2=Shûhei |last3=Matsumoto |first3=Keita |last4=Beutel |first4=Rolf G. |last5=Maddison |first5=David R. |date=2022-12-07 |title=Phylogeny and systematics of Sphaeriusidae (Coleoptera: Myxophaga): minute living fossils with underestimated past and present-day diversity |url=https://onlinelibrary.wiley.com/doi/10.1111/syen.12571 |journal=Systematic Entomology |volume=48 |issue=2 |language=en |pages=233–249 |doi=10.1111/syen.12571 |s2cid=254440169 |issn=0307-6970}}</ref>

== Gallery ==

{{gallery|Sphaerius minutus (10.3897-zookeys.808.30600) Figures 1–9 (cropped).jpg|Specimen of ''[[Sphaerius]] minutus'' (Sphaeriusidae) in various views|Hydroscapha natans01.jpg|Specimens of ''[[Hydroscapha]] natans'' ([[Hydroscaphidae]])|Lepicerus_inaequalis.jpg|Specimen of ''[[Lepicerus]] inaequalis'' (Lepiceridae)|||||||||width=300|height=180|align=center}}

*{{cite web |title=Myxophaga |work=Atlas of Living Australia |url=https://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:afd.taxon:3717c802-bced-437f-b3da-94087e7ac12c}}

{{DEFAULTSORT:Myxophaga}}