Taxonomy
The Rock Martin was formally described in 1842 as Hirundo fuligula by German physician, explorer and zoologist Martin Lichtenstein and was moved to the new genus Ptyonoprogne by German ornithologist Heinrich Gustav Reichenbach in 1850. Its nearest relatives are the three other members of the genus, the Pale Crag Martin, P. obsoleta of north Africa, the Dusky Crag Martin P. concolor of southern Asia and the Eurasian Crag Martin P. rupestris. The genus name is derived from the Ancient Greek ptuon (φτυον), "a fan", referring to the shape of the opened tail, and Procne (Πρόκνη), a mythological girl who was turned into a swallow. The specific name fuligula means "sooty-throated", from Latin fuligo "soot" and gula "throat".
The three Ptyonoprogne species are members of the swallow family of birds, and are placed in the Hirundininae subfamily, which comprises all swallows and martins except the very distinctive river martins. DNA sequence studies suggest that there are three major groupings within the Hirundininae, broadly correlating with the type of nest built. The groups are the "core martins" including burrowing species like the Sand Martin, the "nest-adopters", which are birds like the Tree Swallow that utilise natural cavities, and the "mud nest builders". The Ptyonoprogne species construct open mud nests and therefore belong to the last group. Hirundo species also build open nests, Delichon house martins have a closed nest, and the Cecropis and Petrochelidon swallows have retort-like closed nests with an entrance tunnel.
The genus Ptyonoprogne is closely related to the larger swallow genus Hirundo, but a DNA analysis showed that a coherent enlarged Hirundo genus should contain all the mud-builder genera. Although the nests of the Ptyonoprogne crag martins resembles those of typical Hirundo species like the Barn Swallow, the DNA research suggested that if the Delichon house martins are considered to be a separate genus, as is normally the case, Cecropis, Petrochelidon and Ptyonoprogne should also be split off.
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