Are these two Temnothorax species, or one Temnothorax and one Protomognathus?
Last year, a team of Antweb-affiliated myrmecologists published an evolutionary study concluding, among many results, that a slate of socially parasitic genera had evolved from within their host genera. The names of parasitic genera were subsequently sunk. Inclusion of derived groups in their parent genera has been standard practice for decades as a way to keep names consistent with ancestry.
But a number of myrmecologists do not approve of their favorite ants losing their names, and struck back with a strongly worded opinion in Insectes Sociaux this week:
We contend that banning all paraphyletic groups while simultaneously executing binominal Linnaean nomenclature results in a taxonomy going off the rails.
The dissenting authors make a lengthy argument about information content, evolution, and practicality, but the logic distills to, “the sunk genera look different, and we feel it more useful that the difference is reflected in a unique name.” If this argument looks familiar, it is the same case put forth by Ernst Mayr’s “Evolutionary Taxonomy” school in the 1960s and 70s. This was not a winning argument. Most biologists found disagreements about trait differences subjective compared to the relatively clarity of ancestry, and taxonomists today generally agree that recognizing paraphyletic groups is more confusing than the alternatives.
I have little personal experience with the genera in question. From my perspective as an outsider, I had to look up Epimyrma in Bolton’s catalogue to figure out what kind of an ant it was. Formicine? Myrmicine? Had I known it was basically a parasitic Temnothorax, I’d have been that much ahead of the game. Monophyly is information; paraphyly less so. But utility is a question of perspective and context, I suppose, and I can empathize with those who regularly work with these ants. Treating these distinct species as congeners may be as awkward as attending a party where everyone is named Jayden.
Still, given the volumes of vituperative ink spilled a half-century ago in the cladism wars, and the weight of the pro-monophyly consensus among all biologists, I suspect this renegade group of ant scientists will be fighting an uphill battle.
Disclosure: I eclosed as a myrmecologist from Phil Ward’s lab, so of course I am not without my allegiances.
Sources: Seifert, B. et al 2016. Banning paraphylies and executing Linnaean taxonomy is discordant and reduces the evolutionary and semantic information content of biological nomenclature. Insectes Sociaux doi: 10.1007/s00040-016-0467-1
Ward, P.S. et al 2015. The evolution of myrmicine ants: phylogeny and biogeography of a hyperdiverse ant clade (Hymenoptera: Formicidae). Systematic Entomology, 40: 61–81. doi: 10.1111/syen.12090