Higher Taxon Phthiraptera

Phthiraptera

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Higher Taxon Phthiraptera

Lice

Compiler and date details

2006 - updated by ABRS

1996 - R.L. Palma, Museum of New Zealand, Wellington, New Zealand; S.C. Barker, Department of Parasitology, University of Queensland, Brisbane, Queensland, Australia

Introduction

Phthiraptera, or lice, are one of the least known orders of Australian insects. They are wingless, highly modified, flat-bodied insects that are external parasites of birds and mammals. Adults range in length from less than 0.5 to 11 mm, and have diversified into a great variety of morphological types. They are obligate parasites, i.e. they spend their complete life cycle on the host, cementing their eggs onto feathers or hairs, and are totally dependent on the heat, humidity and secretions produced by the host. Both adults and nymphs have a similar diet which, depending on the species, may be blood, feathers, skin debris, mucus or serum (Marshall 1981). As permanent parasites, their geographical distribution (with some notable exceptions, see Clay 1976; Barker & Close 1990), is often that of their hosts. Therefore, the identity of the host is an important piece of ecological information associated with a louse. A list of host-lice associations for the Australian fauna is given in below.

There is no recent comprehensive publication on Australian lice. The first lists of Australian lice, which include several introduced species, were compiled by Johnston & Harrison (1912a, 1912b, 1913). Thompson & Plomley (1938) listed 104 species from native Australian birds and mammals. Subsequently, Murray et al. (1990, 1993) listed the lice recorded from some groups of birds; they also included many species from non-Australian localities. At a regional level, the lice from Tasmania are better known than those from any other part of Australia (Green & Palma 1991). Descriptions of new species and references to Australian lice are scattered over a great range of publications, mainly written by authors outside Australia. This is a reflection of two factors: the cosmopolitan nature of most louse genera and many species (especially those from birds), and the absence of a resident Australian phthirapterist working on bird lice (about 80% of known species in Australia parasitise birds).

About 500 species of lice have been recorded from Australia, representing approximately 15% of the species known from the world. However, since this group of parasitic insects has not been collected from many potential Australian hosts, the total number of species is likely to be much higher. Fourteen families of lice (52% of the total number of families in the world) are represented in Australia; seven of these are introduced. Three of the native families (Menoponidae, Philopteridae and Boopiidae) contain almost 90% of the known species. Endemicity for any given area of the world is low, and Australia is no exception. None of the seven native families is restricted to Australia. Even the Boopiidae, which is confined mainly to Australian and Papuan marsupial hosts, contains one cosmopolitan species, Heterodoxus spiniger (Enderlein) (Calaby & Murray 1991)).

On the basis of close morphological similarities with free living Psocoptera or "book-lice", the Phthiraptera are regarded as having been derived from a psocopteran ancestor which probably inhabited the nest of a bird or a mammal sometime during the Cretaceous (Lyal 1985; Rothschild & Clay 1952; Waage 1979; Barker 1994). The present pattern of host distribution shown by some louse species indicates that many are highly host specific, having evolved and speciated with their hosts. Hence, an analysis of the phylogeny of a group of lice may help to elucidate the phylogenetic relationships of their hosts (Clay 1949, 1951, 1957; Hafner & Nadler 1988; Hellenthal & Price 1991; Hopkins 1942, 1957; Kim 1985, but see Barker 1994).

The most important means of louse dispersal is by direct contact among host individuals of the same species, e.g. in social groups, at copulation or during the care of the young (Marshall 1981). Usually, different host species do not come into direct contact, thus lice are mainly transferred through the generations of the same host species. However, accidental exchange of lice between different host species (also known as straggling) may occur in a variety of circumstances, such as hosts breeding in close proximity, during predator-prey contact, in communal roosts and through phoresy (Durden 1990; Horning et al. 1980; Keirans 1975). Most lice that transfer to "foreign" hosts die, but a few may adapt and become established. Eventually, the lice that have switched to a new host may diverge from the original type to become a separate species. This is a type of secondary infestation or host-switching (Clay 1957; Rôzsa 1993). The Australian louse fauna includes a notable example of a secondary infestation: Austrogoniodes metoecus Clay, 1971 is parasitic on the musk duck, whereas all other known species of Austrogoniodes Harrison are found exclusively on all species of penguins (Clay 1967, 1971).

In Australia, the number of louse species recorded from each host species varies from one to seven, usually two to seven on birds and one to three on mammals. In general, those louse species belong to different genera, often placed in two, and sometimes three families. Their ecological requirements are also diverse so, typically, each species occupies a specific region of the host's body (Murray 1990; Nelson & Murray 1971).

Host—Lice Interactions
Lice are obligate parasites, consequently their ecology, behaviour and evolution are intimately linked to those of the host (Barnard & Behnke 1990; Loye & Zuk 1991; Nelson et al. 1975). Lice have developed several adaptations to the ectoparasitic way of life, especially those which assist them in holding onto the host. Some are morphological, such as a flattened body, strong legs or claws, powerful mandibles and numerous setae, while others are behavioural, such as negative phototropy and the capacity to avoid being dislodged or killed by the grooming activities of their host (Clayton 1991; Marshall 1981).

Lice are detrimental to host health and fitness, either as a result of their own activities or by acting as vectors of organisms which cause disease (Bartlett 1993; Booth et al. 1993; Cohen et al. 1991; Marshall 1981). Also, lice have been found to influence the choice of reproductive mates among pigeons with possible effects on host sexual selection (Clayton 1990). Similarly, hosts have evolved diverse behavioural (e.g. grooming, anting, dusting) morphological (e.g. bill shape) and physiological (e.g. natural resistance) adaptations to control their lice (Clayton & Cotgreave 1994; Clayton & Vernon 1993; Marshall 1981; Murray 1990). Thus, hosts and lice exert reciprocal selection pressures which may lead to coevolution (Clayton 1991).

Medical and Economic Significance
Human lice feed on blood and therefore can cause irritation and anaemia, but they are most damaging to human health as vectors of a variety of microorganisms which cause disease (Marshall 1981; Roberts & Strand 1977). The most notorious is epidemic typhus which, transmitted by the human body louse, has caused the death of many millions of people (Busvine 1976; Marshall 1981). In Australia, louse-borne epidemic typhus has been absent since early European settlement (Calaby & Murray 1991).

All species of domestic birds and mammals living in Australia are hosts to one or more species of lice. Roberts (1952) reviewed the veterinary importance of lice in Australia. Lice are responsible for the loss of livestock production in the meat, wool, leather, dairy and poultry industries adding up to millions of dollars every year (De Vaney 1976; Kettle & Pearce 1974; Marshall 1981; Steelman 1976). For an excellent account of the lice affecting sheep, cattle, goats and horses in Australia, see Arundel & Sutherland (1988).

Higher Classification
An historical account of the suprageneric classification of the Phthiraptera, including a useful list of many taxa was given by Lakshminarayana (1976). While there is general consensus at the family level (see Hopkins & Clay 1952; Kim 1982), there is as yet no agreement on the ordinal and subordinal classification of the lice. One arrangement, supported by Kim & Ludwig (1978, 1982), maintains the traditional division of lice into two orders: the Mallophaga (chewing lice) and the Anoplura (sucking lice). An alternative arrangement, proposed by Königsmann (1960) and supported by Clay (1970), Haub (1980), Lyal (1985) and Barker (1994) recognises a single order: the Phthiraptera, subdivided into four suborders: Amblycera, Ischnocera, Rhyncophthirina and Anoplura. This latter classification which seems to reflect phylogenetic relationships (see Barker 1994) is adopted here. All the suborders are represented in Australia, with the exception of the Rhyncophthirina which includes only three species parasitic on elephants and African wart-hogs (Emerson & Price 1988).Subordinal placement of families occurring in Australia is outlined in Table 1.

Table 1: The subordinal placement of Phthiraptera families recorded in the Australian fauna. Suborder
AMBLYCERA
Boopiidae
Gyropidae
Laemobothriidae
Menoponidae
Ricinidae
Suborder ISCHNOCERA
Philopteridae
Trichodectidae
Suborder ANOPLURA
Echinophthiriidae
Haematopinidae
Hoplopleuridae
Linognathidae
Pediculidae
Polyplacidae
Pthiridae

Bird Lice
Lice have been found on members of all major bird groups and on virtually every species which has been properly searched (Clay 1950). Of the total number of louse species recorded from Australia, about 400 (or 80%) are parasitic on birds. However, the hosts of those species comprise only 272 (or merely 37%) of the 730 plus species of Australian birds estimated by Condon (1975). If a conservative estimate is made on the basis of one additional louse species for each as yet unrecorded host species, the total number of bird louse species is expected to be over 850. Lice from Australian marine birds are better known than those from terrestrial hosts, and among the latter, lice from the Passeriformes (songbirds or perching birds) are the least known. Only 39 species and subspecies of lice have been recorded from 38 (or 11.8%) of the 323 plus passeriform species referred to by Condon (1975).

To say that the present knowledge of the Australia bird louse fauna is poor is without doubt an understatement. It is to be hoped that this work and this database will encourage both entomologists and administrators alike to support further studies of Australian bird lice.

The level of endemicity among Australian bird lice is extremely low in all supraspecific ranks. There is only one endemic genus, Dahlemhornia Kéler, represented by one species from the Emu. There are, however, many endemic species from other endemic hosts, in particular those from the native Galliformes (mound-builders), Columbiformes (doves and pigeons), Psittaciformes (parrots and cockatoos), Cuculiformes (cuckoos), and Passeriformes. The zoogeographic relationships of the Australian bird louse fauna resemble those of their hosts, the strongest links being with New Zealand and New Guinea.

Mammal Lice
Ninety-two species of lice from 10 families have been recorded from mammals in Australia. Three families infest native mammals predominantly: Boopiidae (47 species) on marsupials, Hoplopleuridae (8 species) on rodents, and Echinopthiriidae (5 species) on seals. Species from the remaining seven families infest people and introduced mammals. Most introduced mammals carry at least one, but up to four, species of lice. This, however, is not the case for indigenous Australian mammals: lice have not been recorded from possums, gliders, koalas, bats or monotremes.

Regarding the authenticity of host records in the early literature, we have followed the principles applied by Calaby & Murray (1991). Records that are likely to be from hosts held in zoos require confirmation by authentic field records. Similarly, apparent misidentifications of hosts abound in the early literature. Those records judged by Calaby & Murray (1991) to be dubious are treated accordingly here.

Acknowledgements

R.L. Palma wishes to thank: Dr Christopher H.C. Lyal (Natural History Museum, London) and Ms Nancy Adams (Smithsonian Institution, Washington) for their assistance in providing data from the collections under their care; Professor Roger D. Price (Fort Smith, Arkansas) for information on the present status of some louse taxa; the staff of the Hector Library (Museum of New Zealand, Wellington) for providing copies of many references; and especially Mr Philip J. Sirvid (Museum of New Zealand, Wellington) for his excellent assistance in the compilation of this section of the database.

S.C. Barker thanks Ms Margaret McDonald and Glenys Corbett for assistance with inter-library loans and preparation of the manuscript respectively.

We acknowledge the financial support of the Australian Biological Resources Study. Also we are indebted to Dr Alice Wells for her editorial support during the preparation of this work.

Database Notes

The information on the Australian Faunal Directory site for the Phthiraptera is derived from the Zoological Catalogue of Australia database compiled on the Platypus software program. It incorporates changes made to the work published on 22 May 1996 as (Palma, R.L. & Barker, S.C., 1996)

Taxa ranking from suborder to subspecies are listed in alphabetical order, with the exception of nominate subgenera and subspecies which are given priority. Family classification within the Amblycera and Ischnocera follows Hopkins & Clay (1952).

Many louse genera and species have large numbers of synonyms. The synonymies listed in the Catalogue are only those names which either have been applied to an Australian louse record or have been associated with an Australian host (excluding occasional visitors and introduced animals). The taxonomy and nomenclature of the birds follow Christidis & Boles (1994), but subspecies are taken from Condon (1975).

In the geographic distributions of bird louse species, only the standard Zoological Catalogue of Australia descriptors of geographical and political areas have been used because the geographical distribution of a bird louse species is essentially that of its host, and birds tend to be highly mobile animals.

Information on the geographic ranges of lice that infest mammals is invariably fragmentary and consequently misleading; in many cases no one has looked in several states and territories, yet it is likely that the ranges of species extend beyond the known distributions. Geographic distributions of only the species from the Heterodoxus octoseriatus group (Boopiidae) are known in detail. For this group the limits of the geographic ranges of species were mapped, in some cases to within several kilometres, and distributions were found to be parapatric.

It has not been possible to find actual records from any Australian locality for 33 louse species, and their distributions are qualified as "host record only". However, that qualification only applies to species:
a. where the hosts are regular visitors to, or breed within, the Australian political areas as defined in the Catalogue and the lice are relatively common on the same hosts in other regions; or
b. which have been published in any Australian list and are still recognised as valid.

The term "syntypes (probable)" is given where the original description does not indicate the number of specimens examined by the author and no further information is available from subsequent sources. The term "(probable)" has been used in conjunction with the names (acronyms) of depository institutions taken from the original descriptions or other sources when, for various reasons, it has not been possible to confirm that they still hold the types listed.

Often in early literature, when a type species was designated by the author of a genus or subsequently designated by a reviser, the species name was given in several incorrect forms (e.g. in the new combination of the nominator; with the authorship/date attributed erroneously; as a junior synonym, etc.). For such cases, we have followed the standard format, giving the names of the type species in the original binomen of the senior synonym followed, in parentheses, by the form used by the nominator or reviser. For example, the type of Nirmus Nitzsch, 1818, is given thus: Type species: Nirmus discocephalus Burmeister, 1838 (as Degeeriella discocephalus Nitzsch).

All the species described from birds by Burmeister (1838) and Denny (1842) were originally placed in two genera and several subgenera. However, Hopkins & Clay (1952) interpreted the latter as genera, an action which, although not strictly correct, was followed by all subsequent authors. To maintain nomenclatural stability, the original citations of Burmeister's and Denny's species names are given in the binomial form as in Hopkins & Clay (1952).

Limital Area

Distribution data in the Directory is by political and geographic region descriptors and serves as a guide to the distribution of a taxon. For details of a taxon's distribution, the reader should consult the cited references (if any) at genus and species levels.

Australia is defined as including Lord Howe Is., Norfolk Is., Cocos (Keeling) Ils, Christmas Is., Ashmore and Cartier Ils, Macquarie Is., Australian Antarctic Territory, Heard and McDonald Ils, and the waters associated with these land areas of Australian political responsibility. Political areas include the adjacent waters.

Terrestrial geographical terms are based on the drainage systems of continental Australia, while marine terms are self explanatory except as follows: the boundary between the coastal and oceanic zones is the 200 m contour; the Arafura Sea extends from Cape York to 124 DEG E; and the boundary between the Tasman and Coral Seas is considered to be the latitude of Fraser Island, also regarded as the southern terminus of the Great Barrier Reef.

Distribution records, if any, outside of these areas are listed as extralimital. The distribution descriptors for each species are collated to genus level. Users are advised that extralimital distribution for some taxa may not be complete.