Pthirus gorillae and Pthirus pubis (the crab louse) are the only known species that belong to the genus Pthirus, often incorrectly spelled as Phthirus (the Latin for louse is phthir).
Further research showed that the major transmission method was not louse bites but excrement: lice infected with typhus turn red and die after a couple of weeks, but in the meantime they excrete a large number of microbes.
Although the relationship between a specific species of whale louse and a specific species of whale is more pronounced with baleen whales than with toothed whales, almost every species of whale has a louse species that is unique to it.