Tailed Cellar Spider

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. 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. 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. …

C. lyoni are synanthropic, preferring to live inside or near human-made structures. They usually build large irregular webs in corners of rooms, basements, cellars, and beneath ceilings. They are readily transported by human activity, especially as hitchikers in ships. As a result, C.lyoni has been introduced to most of the world, including Australia, Asia, Africa, Europe, North and South America, and some Pacific islands. 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.

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. 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'. This lasts for about 40 minutes. In rare instances, females may eat the males after copulation.

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. 5 to 54 spiderlings will eventually hatch from the eggs, 11 to 13 days after egg-laying. …