Pthirus gorillae
Encyclopedia
Pthirus gorillae or gorilla louse is a species
of parasitic sucking louse
that afflicts gorilla
s. It is found in the Africa
n continent specifically in Rwanda
and Democratic Republic of the Congo
. Pthirus gorillae and Pthirus pubis or the crab louse
are the only known species that belong to the genus
Pthirus
, often incorrectly spelled as Phthirus and Phthirius. It is suggested that it is transmitted amongst its hosts
by social grooming
, shared breeding and sexual contact
.
All species of sucking lice feed on blood
. They live in close association with their hosts and complete their entire life cycle
on the host. Pthirus gorillae infests the same parts of the bodies of gorillas as Pthirus pubis does in humans, but since the gorilla is so much more hirsute, the lice tend to range over the whole body. The two also resemble each other with the exception that Pthirus gorillae has large eyes that are placed on large lateral protuberances. A short and broad sucking louse, it is about 2.20 mm long with sprawling legs and not more than 20 small abdominal seta
e. While morphologically these species are indistinguishable, they are clearly different in terms of behaviour
, microhabitat preference and vector status.
It was first identified from specimens of mountain gorillas in 1927 by Henry Ellsworth Ewing during a game hunting trip in what is now the Democratic Republic of the Congo
. Molecular phylogenetics suggests that Pthirus gorillae jumped from gorillas to early humans 3.3 million years ago and diverged
into the present day pubic louse. Some researchers have theorized that humans acquired the parasite not through interspecies sex but while scavenging on gorilla corpses or sleeping in the abandoned sleeping nests of gorillas. A more recent theory based on genetic evidence is that lice evolved alongside humans, and that the crab louse
diverged from Pthirus gorillae some 13 million years ago, as humans diverged from apes.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of parasitic sucking louse
Sucking louse
Sucking lice have around 500 species and represent the smaller of the two traditional suborders of lice. As opposed to the paraphyletic chewing lice, which are now divided among three suborders, the sucking lice are monophyletic.The Anoplura are all blood-feeding ectoparasites of mammals...
that afflicts gorilla
Gorilla
Gorillas are the largest extant species of primates. They are ground-dwelling, predominantly herbivorous apes that inhabit the forests of central Africa. Gorillas are divided into two species and either four or five subspecies...
s. It is found in the Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
n continent specifically in Rwanda
Rwanda
Rwanda or , officially the Republic of Rwanda , is a country in central and eastern Africa with a population of approximately 11.4 million . Rwanda is located a few degrees south of the Equator, and is bordered by Uganda, Tanzania, Burundi and the Democratic Republic of the Congo...
and Democratic Republic of the Congo
Democratic Republic of the Congo
The Democratic Republic of the Congo is a state located in Central Africa. It is the second largest country in Africa by area and the eleventh largest in the world...
. Pthirus gorillae and Pthirus pubis or the crab louse
Crab louse
Crab lice are parasitic insects notorious for infesting human pubic hair. The species may also live on other areas with hair, including the eyelashes. They feed exclusively on blood...
are the only known species that belong to the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Pthirus
Pthirus
Pthirus is a genus of lice. There are only two extant species. Pthirus gorillae infests Gorillas, and Pthirus pubis afflicts humans, and is commonly known as the crab louse or pubic lice....
, often incorrectly spelled as Phthirus and Phthirius. It is suggested that it is transmitted amongst its hosts
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
by social grooming
Social grooming
In social animals, including humans, social grooming or allogrooming is an activity in which individuals in a group clean or maintain one another's body or appearance. It is a major social activity, and a means by which animals who live in proximity can bond and reinforce social structures, family...
, shared breeding and sexual contact
Sexual intercourse
Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...
.
All species of sucking lice feed on blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
. They live in close association with their hosts and complete their entire life cycle
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
on the host. Pthirus gorillae infests the same parts of the bodies of gorillas as Pthirus pubis does in humans, but since the gorilla is so much more hirsute, the lice tend to range over the whole body. The two also resemble each other with the exception that Pthirus gorillae has large eyes that are placed on large lateral protuberances. A short and broad sucking louse, it is about 2.20 mm long with sprawling legs and not more than 20 small abdominal seta
Seta
Seta is a biological term derived from the Latin word for "bristle". It refers to a number of different bristle- or hair-like structures on living organisms.-Animal setae:In zoology, most "setae" occur in invertebrates....
e. While morphologically these species are indistinguishable, they are clearly different in terms of behaviour
Ethology
Ethology is the scientific study of animal behavior, and a sub-topic of zoology....
, microhabitat preference and vector status.
It was first identified from specimens of mountain gorillas in 1927 by Henry Ellsworth Ewing during a game hunting trip in what is now the Democratic Republic of the Congo
Democratic Republic of the Congo
The Democratic Republic of the Congo is a state located in Central Africa. It is the second largest country in Africa by area and the eleventh largest in the world...
. Molecular phylogenetics suggests that Pthirus gorillae jumped from gorillas to early humans 3.3 million years ago and diverged
Speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...
into the present day pubic louse. Some researchers have theorized that humans acquired the parasite not through interspecies sex but while scavenging on gorilla corpses or sleeping in the abandoned sleeping nests of gorillas. A more recent theory based on genetic evidence is that lice evolved alongside humans, and that the crab louse
Crab louse
Crab lice are parasitic insects notorious for infesting human pubic hair. The species may also live on other areas with hair, including the eyelashes. They feed exclusively on blood...
diverged from Pthirus gorillae some 13 million years ago, as humans diverged from apes.
External links
- Apes, lice and prehistory by Robin A Weiss
- Genetic Analysis of Lice Supports Direct Contact between Modern and Archaic Humans by David L. Reed et al.