Putting the cart before the horse: taxonomy of the species of Philopterus (Phthiraptera: Ischnocera: Philopteridae) of the goldcrest, Regulus regulus (Linnaeus, 1758) (Aves: Passeriformes: Regulidae)

The concept of “type host” denotes the host with which the holotype (or equivalent) of a parasitic species was associated at the time of collection. This concept is often erroneously conflated with the concept of a “natural host(s)”, which refers to the host(s) with which the parasite species is naturally and normally associated in the wild. In cases where these two concepts are not kept apart, and when parasites like lice (Phthiraptera) are believed to be strictly host specific, a culture of  identification by host association may develop. Here, I look at the consequences of such a case, the recent rejection of Philopterus reguli Denny, 1842 as the valid name of the louse species that normally parasitizes Regulus regulus (Linnaeus, 1758), and the erection of a new name for this taxon, which was subsequently synonymized with the new name based on a proposed neotype for Ph. reguli. I discuss the history of Philopterus reguli, the known specimens of this species, and the present controversy, as well as the validity of the neotype designation. In conclusion, the neotype designation of Ph. reguli is rejected, as it has not been shown that the syntype is unidentifiable, suspicious, or otherwise invalid, and a change in nomenclature has not been shown to be a problem for the stability of taxonomy. Moreover, the neotype designation is invalidated by at least three separate violations of the International Code of Zoological Nomenclature. I call for more care in both specimen identification and louse taxonomy and open up for a discussion about how the louse research community can move forward together on the issue of poorly described species.