to an ill-resolved clade also including such species as the little shearwater, the Manx shearwater (P. puffinus) or the black-vented shearwater (P. opisthomelas). The little-known Heinroth's shearwater (P. heinrothi) is sometimes considered a subspecies of either Audubon's or the little shearwater. Though it is likely to be another member of that close-knit group, its actual relationships remain uncertain due to lack of specimens. Audubon's shearwater itself has around 10 subspecies. Several have at one time or another been suggested to constitute separate species. For example, the Galápagos Islands population has turned out to be a very distinct species, the Galápagos shearwater (P. subalaris); it is apparently related to the Christmas shearwater (P. nativitatis) and together with it constitutes an ancient lineage without other close relatives in the genus. Other taxa were initially assigned to the little shearwater and later moved to Audubon's. Analysis of mtDNA cytochrome b sequence data – which is of somewhat limited value in procellariiform birds however – indicates that at least three major clades can be distinguished: The lherminieri clade (Atlantic Ocean, Caribbean) Puffinus lherminieri lherminieri Lesson, 1839 – breeds throughout the Caribbean, on the Bahamas and formerly on Bermuda; ranges throughout the Caribbean and up the North American Atlantic coast up to southern Canada, with vagrants having been recorded off north-eastern Canada. A small breeding colony found in 1993 in the Itatiaia Islands off Vila Velha (Espírito Santo, Brazil) probably belongs to this subspecies. Includes loyemilleri. Barolo shearwater, P. baroli (Bonaparte, 1857) – breeds on the Azores and Canary Islands (east Atlantic); ranges throughout east Atlantic around (but mostly north of) the Tropic of Cancer. Boyd's shearwater, Puffinus boydi Mathews, 1912 – breeds on the Cape Verde Islands (east Atlantic); ranges throughout the east Atlantic around (but mostly south of) the Tropic of Cancer. The former two have more white on the face and bluish feet like the little shearwater, with which they were formerly placed Many taxonomists consider both Boyd's and Barolo shearwaters distinct species, depending on whether biogeography and morphological differences or the genetic similarity are considered more significant, and what other lineages are considered distinct from P. lherminieri in a particular treatment. The southern Caribbean birds were separated as P. l. loyemilleri, but are not distinct. The persicus clade (West Indian Ocean) Persian shearwater, Puffinus lherminieri persicus Hume, 1837 – breeds on Khuriya Muriya Islands (Arabian Sea); ranges throughout the Arabian Sea.