Kingdom: Animalia
Phylum: Arthropoda
Class: Arachnida
Order: Araneae
Suborder: Araneomorphae
Superfamily: Araneoidea
Family: Linyphiidae
Subfamily: Erigoninae (Dwarf Spiders)
Genus: Ostearius
Species: O. melanopygius
Binomial name: Ostearius melanopygius
Ostearius melanopygius is a cosmopolitan dwarf spider and is found in many parts of the world. This spider may have first been described from NZ before anywhere else. It is often associated with man-made objects which have allowed it to establish itself in many countries from Europe to Africa, Brazil, Hawaii and Australia and New Zealand.
Its uniformly orange-red abdomen is its most distinctive characteristic. There are no other spiders with a similar appearance. An Ostearius melanopygius male has a 2mm body length which is smaller than the female with a 3mm body length. They have a small web and can be found resting under a great variety of surfaces. They are too small to harm humans.
Visit http://www.bumblebee.org/invertebrates/Araneae.htm for details of a spiders anatomy.
Photo of Ostearius melanopygius showing its narrow pedicel (waist)
Photo of the underside of this spider in its near invisible web. One strand can be seen top left
Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/
