Calymeninae Milne Edwards, 1840

Adrain, Jonathan M., Karim, Talia S. & McAdams, Neo E. B., 2020, Atlanticalymene, a new genus of Middle Ordovician (Darriwilian) calymenine trilobites, and revision of the calymenoidean genus Protocalymene Ross, Zootaxa 4859 (1), pp. 1-55 : 7

Subfamily Calymeninae Milne Edwards, 1840

=Flexicalymeninae Siveter, 1977

Discussion. Siveter (1977) restricted Calymeninae to those taxa with fixigenal buttresses to the glabellar lobes and assigned the remainder of taxa to his new Flexicalymeninae. While it appears likely that Calymeninae as thus restricted is monophyletic (though the concept has never been explored analytically), it is equally apparent that Flexicalymeninae is expressly paraphyletic, a grade left over by removal of Calymeninae . Hence we elect not to formally recognize it and follow Adrain (2013, pp. 309–310) in regarding all of the taxa in question as Calymeninae .

The early history of putative members of the subfamily Calymeninae Milne Edwards, 1840 , is sparsely known. Three formally named species are known from the Floian, all from Gondwanan Armorica and assigned to Platycalymene Shirley, 1936 , by Courtessole et al. (1983). No named calymenine species are known from the Dapingian, and nine occur globally in the Darriwilian. The subfamily became increasingly more common thereafter and at least 58 Katian species have been named. No potential Floian calymenines have been reported from Laurentia, but several Dapingian and lower Darriwilian occurrences have been described, though not always recognized as such. These are assigned herein to an unnamed, monotypic, new Dapingian genus and to the Darriwilian Atlanticalymene n. gen. (to which a Dapingian species from Tarim is also tentatively assigned).