Crossopriza lyoni

Tailed cellar spider
Crossopriza lyoni
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Class:	Arachnida
Order:	Araneae
Infraorder:	Araneomorphae
Family:	Pholcidae
Genus:	Crossopriza
Species:	C. lyoni
Binomial name
Crossopriza lyoni (Blackwall, 1867)
C. lyoni estimated distribution.[1]
Synonyms[2][3][4]
Species synonymy Crossopriza brasiliensis Mello-Leitão, 1935 Crossopriza mucronata Mello-Leitão, 1942 Crossopriza francoisi Millot, 1946 Crossopriza stridulans Millot, 1946 Crossopriza lyoni Pocock, 1900 Crossopriza lyoni Simon, 1893 Pholcus lyoni Blackwall, 1867 Smeringopus lyoni Thorell, 1895 Tibiosa caracensis González-Sponga, 2006 Tibiosa casanaimensis González-Sponga, 2006 Tibiosa coreana González-Sponga, 2006 Tibiosa guayanesa González-Sponga, 2006 Tibiosa moraensis González-Sponga, 2006

Crossopriza lyoni is a widespread

The original

Crossopriza lyoni

Left: Male tailed cellar spiders are recognizable by the enlarged pedipalps. Right: Female tailed cellar spider. (Both specimens from the Philippines)

C. lyoni are sexually dimorphic. Females of C. lyoni are about 3 to 7 mm (0.12 to 0.28 in) in length. Males are slightly smaller, at about 2.5 to 6 mm (0.098 to 0.236 in) in length, and have prominent pedipalps. Both sexes possess extremely long fragile legs. Males have slightly longer legs than females. The first pair of legs in larger male individuals can reach up to 6 centimetres (2.4 in) in length. The legs are gray to amber in color and covered with numerous small longitudinal brown spots. The 'knee joints' are brown, and the ends of the femur and tibiae are girdled with white.^[9] Males also possess a series of 20 to 25 spines (macrosetae) on their femur. Their leg formula is I, II, IV, III - the front pair of legs being the longest and the third pair being the shortest.^[10]

The cephalothorax is wider than it is long, greyish-white to pale amber in color. The carapace is subcircular. In the middle of the upper surface is a deep depression (called the thoracic fovea) and a darker longitudinal band of color. C. lyoni, like most other cellar spiders, has eight eyes. They are pearly-white in color and located at the tip of the cephalothorax in two lines.

The abdomen (the opisthosoma) is gray with white lateral stripes and various dark and light patches on the sides and the upper surface. An irregular darker stripe runs lengthwise at the bottom surface. The abdomen is angular and somewhat box-shaped, with a small conical hump on the upper back.^[11]

They also possess two types of

C. lyoni can be distinguished from other members of the genus through several ways: by the characteristic boxy shape of their abdomens (C. cylindrogaster has a cylindrical abdomen); by the presence of two apophyses (jutting structures) in the chelicerae of males (C. pristina, C. semicaudata, and C. soudanensis all possess only one apophysis on each chelicera);^[10] or simply by geographic distribution (C. lyoni can be found globally and is the only species of Crossopriza in the New World, while the other species like C. johncloudsleyi and C. nigrescens are restricted to Africa or the Middle East).^[2][10]

Diagnostic images for Crossopriza lyoni (male)^[12]

Dorsal view.
(Note: two left front legs are missing)

Close up of the male pedipalps

Ventral view.

Ecology and life cycle

A single male C. lyoni is able to copulate with several females. Mating is accomplished with the male inserting both his pedipalps into the genital orifice of the female and transferring a previously prepared packet of sperm into her spermathecae.^[13] Because of the relative shortness of the male pedipalps in comparison to the sheer length of the legs of both males and females of the species, the spiders have to bring their bodies close together, giving the impression of 'snuggling'.^[14] This lasts for about 40 minutes. In rare instances, females may eat the males after copulation.^[13]

The eggs are deposited by the females 5–6 days after copulation. After laying the eggs, females will bind them into a ball with tiny amounts of silk. They then clutch the resulting egg sacs with their mouthparts and carry them around (a behavior common among all cellar spiders). Eggs that somehow fall from the loose bundles do not hatch. The females still feed during this period, setting their burdens aside temporarily while they eat, then picking them up again. They also frequently adjust their grip. Instances of females eating some of their own eggs have been recorded. It is assumed that they only consume the infertile ones, as unfertilized eggs occur at high enough rates among C. lyoni.^[13][15]

5 to 54 spiderlings will eventually hatch from the eggs, 11 to 13 days after egg-laying. Spiderlings do not leave the eggs immediately. They hatch partially, but otherwise remain in the bundle their mothers carry for at least a day. They eventually leave it completely. They remain mostly inactive for 2 to 3 days after hatching until their first molt.^[16] Spiderlings which are separated from their mothers mature more rapidly than those which remained nearby. They become adults approximately 80 days after hatching.^[13] C. lyoni has a lifespan of at least 194 days (around 6 and a half months).^[13]

C. lyoni are active hunters. Hanging upside down, they will quickly capture prey caught in their irregular cobweb-like webs. If hungry enough, they also actively pursue prey that fly close to their webs. They do not use their fangs when hunting, throwing silk over prey instead and then wrapping them loosely using their hind legs. They will only bite them when they start to feed, which can sometimes be as long as six days after capture. They also actively clean their webs by removing carcasses regularly.^[17] When webs become too dirty, they build new ones.^[18]

Newly hatched spiderlings are just as active as adults. 2 to 4 days after their first molt, spiderlings can already overpower mosquitoes four times their own size. Spiderlings may share prey they caught themselves or prey caught by their mother. They may also engage in

Their place of origin is unknown but have been variously posited to be Africa (where their genus has the highest diversity) or somewhere in Asia.[9]^[27]

Relations with humans

C. lyoni are a regulated invasive species in several countries.^[9][27][28]

While doing no appreciable damage to humans, they are sometimes regarded as pests due to the large amounts of unattractive webs they construct inside houses. Unlike most spiders which consume their old webs before building new ones, cellar spiders simply abandon their old webs. There are often hundreds of individuals representing different generations living in close proximity to each other in a given area.^[29]

Methods of controlling them can be as direct as simply using a

Some people regard C. lyoni spiders as beneficial.[30] Adult C. lyoni can consume 12 to 20 mosquitoes (Aedes sp.) a day, in addition to other insect pests.^[9] Their effects on containing the populations of mosquitoes (Aedes, Anopheles, Culex, etc.) and other disease-transmitting arthropods harmful to humans seems to be significant. In areas where mosquito-borne diseases (like dengue fever) are present, it is recommended to avoid removing natural populations of C. lyoni.^[23] Studies have also shown that C. lyoni spiders that eat dengue virus-infected mosquitoes do not seem to acquire the virus themselves.^[13]

A study in 2009 showed that the webs of C. lyoni exhibit antibacterial properties against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and others. Gram-positive bacteria were more vulnerable to the proteins from C. lyoni webs than Gram-negative bacteria.^[31]

C. lyoni and other pholcids are often the subject of a popular urban legend about how they are the most venomous known animals except that 'their fangs are too small to penetrate human skin'. While they do possess potent venom against insects and other spiders (some cellar spiders, for example, prey on deadly redback spiders in Australia), their venom is not harmful to humans.^[6][32]

See also

Wikimedia Commons has media related to Crossopriza lyoni.

Wikispecies has information related to Crossopriza lyoni.

• List of Pholcidae species
• Pholcus phalangioides, another widespread synanthropic cellar spider
• Spider cannibalism

References