208 Included in this probably paraphyletic or even polyphyletic suborder of about 1750

species are two large families. The paraphyletic PHILOPTERIDAE, a cosmopolitan group with about 1460 species, is the largest family of the order. Its members are parasitic on birds and include a number of pest species found on poultry, for example, Cuclutogaster heterographus (the chicken head louse). The cosmopolitan family TRICHODECTIDAE (290 species), which is restricted to placental mammals, contains a number of species found on domesticated animals, for example, Damalinia (Bovicola) bovis (cattle) (Figure 8.3C), D. ovis (sheep), D. equi (horses), Felicola subrostratus (cats), and Trichodectes canis (dogs), which can serve as an intermediate host for the dog tapeworm, Dipylidium caninum. The GONIODIDAE, formerly included in the Philopteridae, are found on galliform and columbiform birds. The family includes some major poultry pests, for example, Chelopistes meleagridis (large turkey louse) (Figure 8.3B), Goniodes gigas (large chicken louse) and G. dissimilis (brown chicken louse).

Suborder Rhyncophthirina

Members of the suborder Rhyncophthirina have the following characteristics: head prolonged into a rostrum, mandibles at apex of rostrum, and labium and maxillae vestigial.

This suborder contains only two species, Haematomyzus elephantis, a parasite of both Indian and African elephants, and H. hopkinsi, which infests warthogs. It has been suggested that this group may resemble the ancestors of the Anoplura. Certainly, the two groups share a number of primitive characters (Lyal, 1985).

Suborder Anoplura

Members of the suborder Anoplura are recognized by their relatively small head, styli-form mouthparts, and lack of mandibles.

The approximately 530 species of Anoplura were arranged by Kim and Ludwig (1978) in 15 families, of which 8 contain 4 or fewer species, The features of the seven largest families, plus the Pediculidae and Phthiridae, which have special significance for humans, are summarized below, The ECHINOPHTHIRIIDAE (12 species) are parasites of Pinnipedia (seals, sea lions, and walruses) and theriver otter (Lutra canadensis). Their body is covered with strong spines or scales that retain a film of air over the body when submerged. It is evident that many of these lice must be very long-lived, as their hosts spend most of their life at sea, coming ashore to breed (when presumably transfer of parasites occurs) for only a short time each year. The cosmopolitan LINOGNATHIDAE (70 species) parasitize dogs (Linognathus setosus), hyraxes, and ruminants, including sheep (L. ovillus and L. pedalis), cattle (L. vituli) (Figure 8.3D), and goats (L. stenopsis). The HAEMATOPINIDAE (22 species) form a cosmopolitan group whose members parasitize ungulates, including several domesticated forms on which they may become serious pests. Haematopinus eurysternus (Figure 8.3E) occurs on cattle, H. suis on pigs, and H. asini on horses. The HOPLOPLEURI-DAE (about 130 species) are also a large group whose hosts are mainly rodents and rabbits, but also include moles and shrews. The largest anopluran family is the POLYPLACIDAE, a cosmopolitan group whose 175 species very largely parasitize rodents, though some are found on primates (lemurs, lorises, and galagos), rabbits, moles, and shrews. The ENDER-LEINELLIDAE (50 species) are another rodent-infesting group, specifically parasitizing Sciuridae (squirrel family). The family is widespread though not represented in Australia, Madagascar, and southern South America. PEDICINIDAE (16 species) infest Old World monkeys. The PEDICULIDAE (2 species) live on primates. The genus Pediculus is found on humans (as P. humanus and P. capitis) and other hominoids as well as New World monkeys. P. capitas (the head louse) and P. humanus (the body louse) (Figure 8.3F) differ in size and habits. The smaller head louse attaches its eggs to hair, whereas the body louse or "cootie" lays its eggs on clothing to which it usually remains attached. Until recently, P. humanus and P. capitis were considered sibling species. However, a recent molecular study (Leo et al., 2002) indicated that head and body lice are conspecific, despite their differences. Certainly, they interbreed readily in the laboratory. This discovery is significant given that the two forms are generally believed to be very different in their roles as disease vectors. Thus, the body louse is an important vector of diseases such as endemic typhus and trench fever, caused by blood-borne rickettsias. Relapsing fever, caused by a spirochete, is also spread by the louse. By contrast, the head louse is not usually considered a disease vector (but see Robinson et al., 2003). Included in the PHTHIRIDAE are Phthirus gorillae, found on gorillas, and P. pubis, the pubic or crab louse (Figure 8.3G) found on humans. Unlike the body louse, the crab louse does not appear to be a disease vector.

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