Although typically treated as a distinct taxon, there has been considerable uncertainty on the assignment of this name with respect to other myllokunmingiid specimens. Hou and colleagues in 2002 argued that
Haikouichthys is a subjective junior synonym of this taxon (using the
principle of the first reviser due to the two taxa being described on the same date) on the basis of the apparent presence of fin rays in
Haikouichthys specimens being
lithological artifacts, the gill structures missing from specimens referred to both genera being present in the specimen they studied, and the argued triviality of the difference in shapes between them. However, subsequent studies led by the British paleontologist
Simon Conway Morris identified both genera to be distinct on the basis of different gill arrangement, the absence of branchial rays in
Myllokunmingia and the myomeres having a more acute shape in
Haikouichthys. Nevertheless, Hou
et al. in 2017 in their book,
The Cambrian Fossils of Chengjiang, China, suggested that specimens referred to
Myllokunmingia,
Haikouichthys and
Zhongjianichthys may be
taphonomic variants (i.e., of the same animal but in different states of decay) and due to what they argue to be the lack of certainty in the reliability of the distinguishing characters between the three taxa, they follow the opinion of Hou
et al., 2002, and use
Myllokunmingia for all of them. ==See also==