Abstract: The confirmed discovery of an adult female of an as yet undescribed species of the genus Nesiotinus (Phthiraptera, Ischnocera, Philopteridae sensu lato) on a Kerguelen Diving-petrel appears to provide the first certain parasitophyletic evidence for a phylogenetic relationship between penguins (Sphenisciformes) and tubenoses (Procellariiformes). An over-view of the hospital distribution of chewing lice genera parasitising penguins and tubenoses is given.