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 Its "head" bears a pair of tentaculate, horseshoe-shaped branchiae ("gills"), and can be withdrawn into the body; it is surrounded by a cage of spines interpreted as chaetae, equivalent to those of the flabelligerid "cage worms".[1]
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[4] – an interpretation that was soon thrown into question.[5] 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.[1]
Previous comparisons to ecdysozoan worms such as Louisella.[6] have been ruled out based on the construction of the anterior region and other morphological details.[1] 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.[1]
Occurrence
Iotuba has been reported from the Chengjiang biota, with a possible additional occurrence in the Haiyan Lagerstätte[7]
^Ma, Xiaoya; Hou, Xianguang; Baines, David (2010). "Phylogeny and evolutionary significance of vermiform animals from the Early Cambrian Chengjiang Lagerstätte". Science China Earth Sciences. 53 (12): 1774–1783. Bibcode:2010ScChD..53.1774M. doi:10.1007/s11430-010-4084-y. S2CID84720166.
^Chen, J.-Y.; Zhou, G.-Q. (1997). "Biology of the Chengjiang Fauna". Bull. Natl. Museum Nat. Sci. 10: 11–105.
^DY Huang; J Vannier; JY Chen (2004). "Anatomy and lifestyles of Early Cambrian priapulid worms exemplified by Corynetis and Anningvermis from the Maotianshan Shale (SW China)". Lethaia. 37: 21–33. doi:10.1080/00241160410005088.