Philopterus Nitzsch, 1818: 288.
Docophorus Nitzsch, 1818: 289 (in partim).
Cypseloecus Conci, 1941: 126.
Debeauxoecus Conci, 1941: 126.
Docophorulus Eichler, 1944: 80.
Bitrabeculus Uchida, 1948: 317.
Prunellides Złotorzycka & Eichler, 1984: 219, figs 1–3.
Pediculus ocellatus Scopoli, 1763, ex Corvus corone Linnaeus, 1758, by subsequent designation (Neumann 1906).
As currently circumscribed (Mey 2004), likely global apart from Antarctica, but poorly known in the Southern Hemisphere.
As currently circumscribed (Mey 2004), widely distributed across hosts in the Passeriformes. A single species (Philopterus solus Tendeiro, 1962) has been described from a bucerotiform host, but Mey (2004: 200) doubted the authenticity of this record.
All species described herein key to the genus Philopterus in the key of Mey (2004), based on having both trabecula and coni, an extensive hyaline margin, dorsal anterior plates that are longer than wide, and ventral carinae that are not recurved towards the preantennal nodi. However, other characters are quite variable among the species described here, and ascertaining homologous structures can be difficult, especially in the male genitalia. Moreover, one distinguishing character of Philopterus in Mey’s key is the similarity in the length of the os, pos, and mts1–3; yet, the relative lengths of these setae vary in the species treated here. The number and position of sensilla of the postantennal head also vary between species. Most likely, this variation corresponds to deep divisions between different groups of Philopterus sensu Mey (2004), some of which may ultimately be considered different genera or subgenera.
Many species of Philopterus are inadequately described, with much of the description being based on measurements, and most of the illustrations being of characters of limited taxonomic value (prosternal plates, shape of trabecula, single tergopleurites with only some of the setae illustrated). Finding suitable species to compare potential new species with is, therefore, often difficult. Here, we primarily compare our new species with other species from the same, or a closely related host family. In cases where known species of Philopterus on the same host family are clearly very different (e.g., Philopterus afropari sp. nov.), or where no species of Philopterus were described from the same host family, we expanded our comparison to species from other host families, principally ones in the same geographical region. In some cases (e.g., Philopterus hebes sp. nov.), no closely related species of Philopterus were identifiable.
We also referred to the species groups proposed by Złotorzycka & Lucińska (1976); however, these species group are of limited use as they only include Central European species of Philopterus. Moreover, the morphological characters on which these species groups are based are sometimes hard to interpret, differ somewhat between species groups, and are of limited or unknown phylogenetic utility. Finally, all illustrations and descriptions in Złotorzycka’s publications (e.g., Złotorzycka & Lucińska 1976) are partial and poor, and not all species are illustrated. Nevertheless, the partial revisions of Philopterus in Złotorzycka & Lucińska (1976) and Złotorzycka (1964) are the only published attempts to structure the species in Philopterus.