Agelenopsis, commonly known as the American grass spiders, is a genus of funnel weavers described by C.G. Giebel in 1869. They weave sheet webs that have a funnel shelter on one edge. The web is not sticky, but these spiders make up for that by running very rapidly. The larger specimens can grow to about 19 mm in body length. They may be recognized by the arrangement of their eight eyes into three rows. The top row has two eyes, the middle row has four eyes, and the bottom row has two eyes. They have two prominent hind spinnerets, somewhat indistinct bands on their legs, and two dark bands running down either side of the cephalothorax.
Crevice weaver spiders (Filistatidae) comprise cribellate spiders with features that have been regarded as "primitive" for araneomorph spiders. They are weavers of funnel or tube webs. The family contains 18 genera and more than 120 described species worldwide.
Liocranidae is a family of araneomorph spiders first described by Eugène Simon in 1897. They are one of several groups called "sac spiders". The holarctic genus Agroeca is the best-known, but it also includes various genera of more obscure spiders that still lack a diagnosis. Two species in the North American genus Neoanagraphis are found in the extremely dry conditions in the Mojave, Sonoran and Chihuahuan deserts. Females live in animal burrows while males wander and are the ones most often caught in pitfall traps.
The Tooth Cave spider, formerly Neoleptoneta myopica, now Tayshaneta myopica, is a 1.6 mm long spider in the family Leptonetidae. It is endemic to limestone caves near Austin, Texas in the United States and is considered an endangered species.
The Tasmanian pygmy possum, also known as the little pygmy possum or tiny pygmy possum, is the world's smallest possum. It was first described by Oldfield Thomas in 1888, after he identified that a museum specimen labelled as an eastern pygmy possum in fact represented a species then unknown to science. The holotype resides in the Natural History Museum in London.
Dwarf sheet spiders (Hahniidae) is a family of araneomorph spiders, first described by Philipp Bertkau in 1878. Their bodies are about 2 millimetres (0.079 in) long, and they build extremely delicate webs in the form of a sheet. Unlike many spiders the web does not lead to a retreat. The silk used in these webs is so fine that they are difficult to spot unless they are coated with dew. They greatly favor locations near water or near moss, and are often found in leaf litter and detritus or on the leaves of shrubs and trees.
Psechridae is a family of araneomorph spiders with about 70 species in two genera. These are among the biggest cribellate spiders with body lengths up to 2 centimetres (0.79 in) and funnel webs more than 1 metre in diameter.
The anatomy of spiders includes many characteristics shared with other arachnids. These characteristics include bodies divided into two tagmata, eight jointed legs, no wings or antennae, the presence of chelicerae and pedipalps, simple eyes, and an exoskeleton, which is periodically shed.
Maevia inclemens or the dimorphic jumping spider is a relatively common and colorful jumping spider of North America. In the males there are two forms, a very rare phenomenon in zoology. These use different courting displays, and differ in appearance: the "tufted" morph has a black body and pedipalps ("palps"), three black tufts across its "head", and pale legs; and the "gray" morph has black and white stripes all over its body and legs, orange palps, and no tufts. However, each form accounts for 50% of the adult males, and they are equally successful in mating. A female of Maevia inclemens is 6.5 to 8.0 millimetres long, while males are 4.75 to 6.50 millimetres long.
The Tasmanian masked owl is a bird in the barn owl family Tytonidae that is endemic to the island state of Tasmania, Australia. It is the largest subspecies of the Australian masked owl, the largest Tyto owl in the world, and is sometimes considered a full species. The subspecific name castanops, meaning "chestnut-faced", comes from the colouring of the facial disc. It was first described by John Gould, who wrote about it in his Handbook to the Birds of Australia as:
"…a species distinguished from all the other members of its genus by its great size and powerful form. Probably few of the Raptorial birds, with the exception of the Eagles, are more formidable or more sanguinary in disposition."
"Forests of large but thinly scattered trees, skirting plains and open districts, constitute its natural habitat. Strictly nocturnal in its habits, as night approaches it sallies forth from the hollows of the large gum-trees, and flaps slowly and noiselessly over the plains and swamps in search of its prey, which consists of rats and small quadrupeds generally."
Cicurina madla is a rare species of spider in the family Dictynidae known by the common name Madla Cave meshweaver. It is endemic to Texas, United States, where it is known to originate from only eight or nine caves in Bexar County. This is one of a small number of invertebrates endemic to the karst caves of Bexar County that were federally listed as endangered species in the year 2000. Another spider from the caves was described as Cicurina venii, and given the common name Braken Bat Cave meshweaver. In 2018, it was synonymized with C. madla.
The two palpal bulbs – also known as palpal organs and genital bulbs – are the copulatory organs of a male spider. They are borne on the last segment of the pedipalps, giving the spider an appearance often described as like wearing boxing gloves. The palpal bulb does not actually produce sperm, being used only to transfer it to the female. Palpal bulbs are only fully developed in adult male spiders and are not completely visible until after the final moult. In the majority of species of spider, the bulbs have complex shapes and are important in identification.
Synotaxus is a genus of araneomorph spiders in the family Synotaxidae that was first described by Eugène Louis Simon in 1895. Originally placed with the tangle web spiders, it was moved to the family Synotaxidae in 2017.
Hentziectypus is a genus of comb-footed spiders that was first described by Allan Frost Archer in 1946. Originally placed with Theridion, it was moved to Achaearanea in 1955, and to its own genus in 2008. These spiders most resemble members of Cryptachaea, but are distinguished by a median apophysis that is broadly attached to the tegulum. Spiders of Parasteatoda have a median apophysis attached to the embolus, while those of Achaearanea have a hooked paracymbium on the pedipalps of males.
Philodromus cespitum is a species of running crab spider in the family Philodromidae. It is found in North America, Europe, North Africa, and parts of the Middle East and Asia. P. cespitum is a foliage-dweller, and is the most abundant species found in European fruit orchards. It acts as a biological control by preying on orchard pests. P. cespitum is a diurnal ambush hunter and preys on aphids, insects, and occasionally competitor spider species. Males court females by tapping on the females’ bodies with their forelegs. They then insert a genital plug into the female during copulation. Unlike in many other spider species, subsequent males can mate with plugged females by removing part of the plug prior to copulation. Males discriminate among females based on virginity and plug size, and can determine these factors using the females’ draglines and plug samples.
Tupua is a genus of Tasmanian araneomorph spiders in the family Physoglenidae that was first described by Norman I. Platnick in 1990.
Stalita taenaria is an araneomorph spider species in the family Dysderidae. The species is classified as a member of troglofauna, more precisely a troglobiont species, meaning such spiders are obligate cave-dwellers adapted to living in dark surroundings. Stalita taenaria is a species of a few European countries. The spider is thought to be the first described species of true (eyeless) cave spider in the world.
Nesticus cellulanus, also known as the cavity spider or comb-footed cellar spider, is a species of scaffold web spider. It is found throughout Europe and Turkey, and has been introduced to North America.
Tayshaneta microps, synonym Neoleptoneta microps, is a rare species of spider in the family Leptonetidae known by the common name Government Canyon bat cave spider. It is endemic to Texas in the United States, where it is known to be found in two caves in Bexar County. It is a troglobite, an animal which spends its entire life in caves. It is one of nine Bexar County troglobites which were listed as endangered species in 2000.
