River Martin - Taxonomy

Taxonomy

When a specimen of the African River Martin from Gabon was first formally described by German zoologist Gustav Hartlaub in 1861, it was not initially identified as a member of the swallow and martin family. Hartlaub placed it with the rollers, and later authors either put it in its own separate family, or with the woodswallows. It was only following study of the anatomy of the species by Lowe that it was determined to be closely related to the swallows and martins, but sufficiently different to be placed in a separate subfamily Pseudochelidoninae. The genus name Pseudochelidon comes from the Ancient Greek prefix ψευδο/pseudo, "false," and χελιδων/chelidôn, "swallow," reflecting its distinctiveness from the "true" swallows.

For many years the African River Martin was the sole member of its genus and subfamily until the discovery of the White-eyed River Martin, Pseudochelidon eurystomina, by Thai ornithologist Kitti Thonglongya in 1968. Although some authorities follow Brooke in placing that species in a separate genus Eurochelidon due to its significant differences from the African species, it remains a member of the same subfamily. Genetic studies confirmed that the two river martins form a distinct clade from the typical swallows in the Hirundininae subfamily.

The river martins are in some ways intermediate between typical swallows and other passerines: they have stout bills, large feet and relatively strong legs, which is unusual in aerial feeders. They also have a large syrinx (vocal organ) and a different bronchial structure. The extent of their differences from other swallows and the wide geographical separation of these two martins suggest that they are relict populations of a group of species that diverged from the main swallow lineage early in its evolutionary history, and they may be the most primitive of the swallows. Like other early hirundine lineages, they nest in burrows, rather than adopted nest holes or mud nests.