Iotuba

{{Short description|Cambrian taxon}} {{Speciesbox | fossil_range = {{Fossil range|Chengjiang}} | genus = Iotuba | species = chengjiangensis | image = Iotuba_chengjiangensis.tif | image_caption = Complete specimen of ''Iotuba'' from Chengjiang. | image2 = Iotuba_reconstruction.jpg | image2_caption = Reconstruction of ''Iotuba'': head and anterior trunk | authority = Zhang et Smith 2023 <ref name=zhang/> }}

'''''Iotuba chengjiangensis''''' (sometimes mis-spelt ''Lotuba''<ref>{{Cite journal |doi= 10.1007/s11430-010-4084-y |title= Phylogeny and evolutionary significance of vermiform animals from the Early Cambrian Chengjiang Lagerstätte |journal= Science China Earth Sciences |volume= 53 |issue= 12 |pages= 1774–1783 |last1= Ma |first1= Xiaoya |last2= Hou |first2= Xianguang |last3= Baines |first3= David |date= 2010|bibcode= 2010ScChD..53.1774M |s2cid= 84720166 }} </ref>) is a 515 million year old Cambrian worm known from the Chengjiang biota.<ref>[https://www.spacedaily.com/reports/Ancient_fossils_shed_new_light_on_evolution_of_sea_worm_999.html Ancient fossils shed new light on evolution of sea worm]</ref> Originally interpreted as a phoronid, the organism is now recognized as an annelid cage worm affiliated with the Flabelligeridae and Acrocirridae, which Zhang ''et al'' grouped together in the new superfamily Flabelligeroidea.<ref name=zhang/>

== Anatomy == Iotuba was a couple of centimetres long and half a centimetre in width. Internally it is characterized by a through gut flanked by a pair of boudinaged tubes interpreted as nephridia ("kidneys"). Its trunk is adorned with small conical papillae ("microspines"). Its "head" bears a pair of tentaculate, horseshoe-shaped branchiae ("gills"), and can be withdrawn into the body; it is surrounded by a cage of spines interpreted as chaetae, equivalent to those of the flabelligerid "cage worms".<ref name=zhang/>

== History of interpretation ==

''Iotuba'' was originally interpreted as a phoronid based on a misinterpretation of the single then-available specimen as harbouring a U-shaped gut and tentacles<ref name=chen>{{cite journal|author1=Chen, J.-Y.|author2=Zhou, G.-Q.|year=1997|title=Biology of the Chengjiang Fauna|journal=Bull. Natl. Museum Nat. Sci.|volume=10|pages=11–105}}</ref> – an interpretation that was soon thrown into question.<ref>{{Cite journal |title=Anatomy and lifestyles of Early Cambrian priapulid worms exemplified by ''Corynetis'' and ''Anningvermis'' from the Maotianshan Shale (SW China) |author1=DY Huang |author2=J Vannier |author3= JY Chen |journal= Lethaia |volume=37 |pages= 21–33 |year=2004 |issue=1 |doi= 10.1080/00241160410005088 |bibcode=2004Letha..37...21H }}</ref> The holotype was independently named – by the same author – as ''Eophoronis'', but as neither of these nomenclatural acts contained a diagnosis, they were invalid under the International Code of Zoological Nomenclature until formally defined by Zhang ''et al''. in 2023.<ref name=zhang>{{Cite journal | title = The Cambrian cirratuliform ''Iotuba'' denotes an early annelid radiation | year = 2023| doi = 10.1098/rspb.2022.2014| last1 = Zhang| first1 = Zhifei| last2 = Smith| first2 = Martin R.| last3 = Ren| first3 = Xinyi| journal = Proceedings of the Royal Society B: Biological Sciences| volume = 290| issue = 1992| pmid = 36722078| pmc = 9890102}}</ref>

Previous comparisons to ecdysozoan worms such as ''Louisella''.<ref>{{cite journal |author= Conway Morris, S. |date=2006 |title= Darwin's dilemma: the realities of the Cambrian 'explosion' |journal= Philosophical Transactions of the Royal Society B: Biological Sciences |volume=361 |number=1470 |pages=1069–1083 |doi= 10.1098/rstb.2006.1846 |pmid= 16754615 |pmc= 1578734}} {{open access}}</ref> have been ruled out based on the construction of the anterior region and other morphological details.<ref name=zhang /> Instead, the organism has been linked with the cirratliform annelids, specifically Flabelligeridae – an interpretation that fits in with morphological and molecular data in a phylogenetic context.<ref name=zhang />

== Occurrence ==

''Iotuba'' has been reported from the Chengjiang biota, with a possible additional occurrence in the Haiyan Lagerstätte<ref>{{cite journal | doi = 10.1038/s41559-021-01490-4| title = A juvenile-rich palaeocommunity of the lower Cambrian Chengjiang biota sheds light on palaeo-boom or palaeo-bust environments| year = 2021| last1 = Yang| first1 = Xianfeng| last2 = Kimmig| first2 = Julien| last3 = Zhai| first3 = Dayou| last4 = Liu| first4 = Yu| last5 = Kimmig| first5 = Sara R.| last6 = Peng| first6 = Shanchi| journal = Nature Ecology & Evolution| volume = 5| issue = 8| pages = 1082–1090| pmid = 34183806| bibcode = 2021NatEE...5.1082Y| s2cid = 235674619}}</ref>

==References== {{Reflist}}

Category:Cambrian fossil record Category:Fossil taxa described in 2023 Category:Polychaete genera Category:Monotypic prehistoric annelid genera