Theridion attritum
Encyclopedia
Theridion attritum is a spider from Western Australia
. While it was formerly placed in the families Araneidae and Theridiosomatidae' in 1967 it was found to belong to the family Theridiidae
, and indeed to the genus Theridion. While all members of the first two families have a large colulus, while T. attritum lacks one altogether. It is not to be confused with Anelosimus attritus, which was for a time known as Theridion attritum.
T. attritum is 2.2mm long. It has a yellowish carapace
with a black line all around. The sternum is yellow-orange with gray pigment, the legs are yellow with darker marks. The top of the abdomen
is whitish with a median darker longitudinal band, irregular in outline and bordered on each side by a white band. The venter is black with a white transverse pigment band. The species is surprisingly similar to Theridion melanurum and Theridion varians, but much smaller.
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...
. While it was formerly placed in the families Araneidae and Theridiosomatidae' in 1967 it was found to belong to the family Theridiidae
Theridiidae
Theridiidae is a large family of spiders, also known as the tangle-web spiders, cobweb spiders and comb-footed spiders. The diverse family includes over 2200 species in over 100 genera) of three-dimensional space-web-builders found throughout the world...
, and indeed to the genus Theridion. While all members of the first two families have a large colulus, while T. attritum lacks one altogether. It is not to be confused with Anelosimus attritus, which was for a time known as Theridion attritum.
Description
Carapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
with a black line all around. The sternum is yellow-orange with gray pigment, the legs are yellow with darker marks. The top of the abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
is whitish with a median darker longitudinal band, irregular in outline and bordered on each side by a white band. The venter is black with a white transverse pigment band. The species is surprisingly similar to Theridion melanurum and Theridion varians, but much smaller.