Raillietiella trachea n. sp., a pentastomid from the trachea of an oriental white-backed vulture Gyps bengalensis taken in Pakistan, with speculation about its life-cycle.

A cephalobaenid pentastomid, Raillietiella trachea n. sp., from the trachea of a fledgling oriental white-backed vulture Gyps bengalensis taken in Punjab Province, Pakistan, is described. This is the first record of a pentastomid from a fully terrestrial bird. Overall, gross morphology was typical of Raillietiella Sambon, 1910 in most respects. However, the hooks of R. trachea were of equal size, whereas in other members of the genus anterior hooks are smaller than the posterior hooks. The diagnosis of R. trachea was made on the basis of four near-patent females, all of which contained relatively few eggs (c.570), all at the same stage of maturity. Comparison with the only other genus known to infect birds (two species of Reighardia Ward, 1899 from the air-sacs of marine birds) revealed striking parallels in this aspect of the functional anatomy of the female reproductive tract. As far as we know, this mode of egg-production is not found in other raillietiellids. Extrapolating primarily from the experimental life-cycle studies of Reighardia sternae (Diesing, 1864) Ward, 1899, we surmise that the life-cycle of R. trachea has to be direct and that parasite behaviour is an integral part of parasite transmission. The evidence suggests that transmission is from vulture-to-vulture, per os.