Idiosoma
Encyclopedia
- Idiosoma is also the terminus for an anatomical structure of miteMiteMites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...
s.
Idiosoma is a genus of trapdoor spiders in the family Idiopidae
Idiopidae
Idiopidae Idiopidae Idiopidae (superfamily Idiopoidea are a mygalomorph spider family. They have a large body that often looks rather like a tarantula.-Description:In some species the males have a spur on their legs, which they will show if provoked....
with three species, found only in Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
.
The genus was transferred from Ctenizidae to Idiopidae in 1985.
Idiosoma nigrum, commonly called the Black rugose trapdoor spider, can grow up to 30 mm long. Males reach a body size of up to 18 mm. The skin of their opisthosoma
Opisthosoma
The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma . It is a distinctive feature of the subphylum Chelicerata...
is hardened, with a flattened end and deep grooves running along the sides. The thickened skin helps to reduce water loss in its dry habitat. It also serves as a kind of plug to shield itself from predators. This phenomen is called phragmosis
Phragmosis
Phragmosis is any method by which an animal defends itself in its burrow by using its own body as a barrier. An example can be seen in the mygalomorph spider Idiosoma nigrum , which protects itself in its burrow by positioning itself so as to block the burrow with its abdomen, which is unusually hard...
and occurs in perfection in the spider genus Cyclocosmia
Cyclocosmia
Cyclocosmia or "trapdoor spider" is a genus of spiders in the Ctenizidae family.The abdomen of spiders in this genus is abruptly truncated and ends in a hardened disc which is strengthened by a system of ribs and grooves. They use this to clog the entrance of their 7 to 15 cm deep vertical...
(Ctenizidae). However, some parasitic wasps have evolved paper-thin abdomens and long, slender ovipositor
Ovipositor
The ovipositor is an organ used by some animals for oviposition, i.e., the laying of eggs. It consists of a maximum of three pairs of appendages formed to transmit the egg, to prepare a place for it, and to place it properly...
s and lay their eggs on the softer skin at the front of the spider's opisthosoma.
Its burrow is up to 32 cm deep, where the temperature is relatively constant during the seasons. When prey trips over one of the trip-lines radiating from the burrow's entrance, the spider runs out of the burrow to capture ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
s, beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s, cockroach
Cockroach
Cockroaches are insects of the order Blattaria or Blattodea, of which about 30 species out of 4,500 total are associated with human habitations...
es, millipede
Millipede
Millipedes are arthropods that have two pairs of legs per segment . Each segment that has two pairs of legs is a result of two single segments fused together as one...
s and moth
Moth
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...
s. This is unlike many trapdoor spiders that very rarely leave their burrow. Males actively look for females, and mating takes place in the female's burrow. She lays her eggs during late spring and early summer. The spiderlings hatch in mid-summer, and stay inside the burrow until early winter, when the climate gets more humid.
Name
The genus name is derived from the GreekAncient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
idios "individual, unique" and soma "body", referring to the distinctive structure of the abdomen.
Species
- Idiosoma hirsutum Main, 1952
- Idiosoma nigrumIdiosoma nigrumIdiosoma nigrum, also called Black rugose trapdoor spider, occurs only in south-western Australia, in dry woodlands east of the Darling Scarp and north to Moore River.Females can reach a length of about 30mm, males about 18mm....
Main, 1952 — Black Rugose Trapdoor Spider - Idiosoma sigillatum (O. P.-Cambridge, 1870)