Latrodectus is a broadly distributed genus of spiders with several species that, together, are referred to as true widows. This group is composed of those often loosely called black widow spiders, brown widow spiders, and similar spiders. However, such general "common names" are of limited use as the diversity of species is much greater. A member of the family Theridiidae, this genus contains 32 species, which include several North American "black widows". In addition to these in North America are also the red widow Latrodectus bishopi and the brown widow Latrodectus geometricus, which, in addition to North America, has a much wider geographic distribution. Elsewhere, others include the European black widow, the Australian redback black widow, several different species in Southern Africa that can be called Button spiders, and the South American black widow spiders. Species vary widely in size. In most cases, the females are dark-coloured, but some may have lighter bodies or even reddish. Many can have red, white or brown markings on the upper-side (dorsal) of the abdomen. Some can be readily identifiable by reddish markings on the central underside (ventral) abdomen, which are often hourglass-shaped.
Theridiidae, also known as the tangle-web spiders, cobweb spiders and comb-footed spiders, is a large family of araneomorph spiders first described by Carl Jakob Sundevall in 1833. This diverse, globally distributed family includes over 3,000 species in 124 genera, and is the most common arthropod found in human dwellings throughout the world.
Parasteatoda tepidariorum, the common house spider, referred to internationally as the American house spider, is a spider species of the genus Parasteatoda that is mainly indigenous to the Americas, with P. tepidariorum australis but has achieved a cosmopolitan distribution. American house spiders are synanthropic and build their tangled webs in or near human dwellings, greenhouses or similar, often in secluded areas such as between loose walls and behind open doors and attic windows. Statistically, they are the most often encountered spider by humans in North America, and least likely to adopt defensive behavior in their vicinity. Their prey mechanism is similar to that of the other cobweb spiders: the spider follows disturbances transmitted along the web to entangle and then paralyze its prey, which usually consists of household insects and other invertebrates.
Oonopidae, also known as goblin spiders, is a family of spiders consisting of over 1,600 described species in about 113 genera worldwide, with total species diversity estimated at 2000 to 2500 species. The type genus of the family is OonopsKeyserling, 1835.
Lampshade spiders, family Hypochilidae, are among the most primitive of araneomorph spiders. There are two genera and twelve species currently recognized. Like mygalomorphs, most hypochilids have two pairs of book lungs, but like araneomorphs they have intersecting fangs, with the exception of some species which have chelicerae in an angle that is neither orthognathous or labidognathous. These long-legged spiders build typical "lampshade" style webs under overhangs and in caves. In the United States the fauna is primarily associated with the Appalachian, Rocky and California Mountains. Ten of the known species are found in these ranges, all in the genus Hypochilus. The genus Ectatosticta is found in China.
Velvet spiders are a small group of spiders almost entirely limited to the Old World, with exception of a few species known from Brazil. The characteristics of this family of spiders are that they are entelegyne, eight-eyed araneomorph spiders that build unkempt webs. They are cribellate. Some species are nearly eusocial, lacking only a specialized caste system and a queen. They cooperate in brood rearing, unlike most other spiders except for some African agelenid spiders in the genus Agelena and a few others.
Achaearanea is a genus of comb-footed spiders that was first described by Embrik Strand in 1929.
Araneus is a genus of common orb-weaving spiders. It includes about 650 species, among which are the European garden spider and the barn spider. The genus was erected by Carl Alexander Clerck in 1757.
White-tailed spiders are spiders native to southern and eastern Australia, and so named because of the whitish tips at the end of their abdomens. The body size is up to 18 mm, with a leg-span of 28 mm. Common species are Lampona cylindrata and Lampona murina. Both these species have been introduced to New Zealand.
Marchena is a genus of jumping spiders only found in the United States. Its only described species, M. minuta, dwells on the barks of conifers along the west coast, especially California, Washington and Nevada.
Periegops is a genus of spiders with six eyes instead of the usual eight. It is the only genus in its family (Periegopidae) and has three described species. It was long considered to be members of Sicariidae or Segestriidae until Raymond Forster elevated them to the family level in 1995.
Anapidae is a family of rather small spiders with 231 described species in 58 genera. It includes the former family Micropholcommatidae as the subfamily Micropholcommatinae, and the former family Holarchaeidae. Most species are less than 2 millimetres (0.079 in) long.
Archaeidae, also known as assassin spiders and pelican spiders, is a spider family with about ninety described species in five genera. It contains small spiders, ranging from 2 to 8 millimetres long, that prey exclusively on other spiders. They are unusual in that they have "necks", ranging from long and slender to short and fat. The name "pelican spider" refers to these elongated jaws and necks used to catch their prey. Living species of Archaeidae occur in South Africa, Madagascar and Australia, with the sister family Mecysmaucheniidae occurring in southern South America and New Zealand.
A social spider is a spider species whose individuals form relatively long-lasting aggregations. Whereas most spiders are solitary and even aggressive toward other members of their own species, some hundreds of species in several families show a tendency to live in groups, often referred to as colonies.
Coneweb spiders (Diguetidae) are six-eyed haplogyne spiders that live in tangled space webs, fashioning a cone-like central retreat where they hide and lay eggs. It is a small family, containing only two genera with fifteen species and is confined to the New World, preferring deserts. Members of the genus Diguetia usually build their webs in shrubs or between cactus pads. They have the same eye arrangement as the venomous recluse spiders, but none are known to be harmful to humans.
Trite planiceps, commonly known as the black-headed jumping spider, is a common jumping spider (Salticidae) endemic to New Zealand and one of about 150 species of jumping spiders in New Zealand.
Cryptachaea is a genus of spiders in the Theridiidae family.
Allocosa brasiliensis is a burrowing wolf spider species from southern South America. Long known to science, it remained almost unstudied until its unusual sexual behavior was described in the early 21st century.
Trogloraptor is a genus of large spiders found in the caves of southwestern Oregon. It is the sole genus in the family Trogloraptoridae, and includes only one species, Trogloraptor marchingtoni. These spiders are predominantly yellow-brown in color with a maximum leg span of 3 in (7.6 cm). They are remarkable for having hook-like claws on the raptorial last segments of their legs.
Caponiidae is a family of ecribellate haplogyne spiders that are unusual in a number of ways. They differ from other spiders in lacking book lungs and having the posterior median spinnerets anteriorly displaced to form a transverse row with the anterior lateral spinnerets. Most species have only two eyes, which is also unusual among spiders. A few species of Caponiidae variously have four, six or eight eyes. In some species the number of eyes will increase when the spiderling changes its skin as it grows towards adulthood.
