Dysdera

Dysdera Temporal range: Palaeogene–present PreꞒ Ꞓ O S D C P T J K Pg N
Dysdera erythrina
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Class:	Arachnida
Order:	Araneae
Infraorder:	Araneomorphae
Family:	Dysderidae
Genus:	Dysdera Latreille, 1804[1]
Type species
D. erythrina (Walckenaer, 1802)
Species
285, see text

Dysdera is a genus of woodlouse hunting spiders that was first described by Pierre André Latreille in 1804.^[2] They originated from Central Asia to Central Europe.

The family has gained many common names from their individual species, including the "European garden spider", the "slater-eating spider", the "sow-bug killer", the "woodlouse hunter", and the "woodlouse spider".^[3]

A bite from one of these spiders can be painful due to their large fangs and wide jaw. It may leave an itchy, swollen, or red bump, but the venom from one of their bites is not harmful to humans.^[3]

Description[]

Adults have a reddish-brown body and legs, and can grow up to 2 centimetres (0.79 in) long. Females are generally larger growing from 1.1 to 1.5 centimetres (0.43 to 0.59 in), while males are about 0.9 to 1 centimetre (0.35 to 0.39 in).^[4] Their six eyes are close together in an oval shape, and they have eight reddish legs, the second pair facing backward.^[3]

Dysdera live in natural shelters, which they wrap by totally white silk. The inhabitants of hot and humid forest will take any potential shelter on or close to the ground. The shelters are used to hide from predators as well as for keeping the spider warm. During the day, they are commonly found taking shelter under objects like gravel with organic material covering it, stones, bark, and occasionally in suburban gardens.^{[citation needed]}

Diet[]

Dysdera are one of the few known arthropods to hunt and prey on woodlice, one of their main food sources. These spiders have wide jaws and large fangs to help to overcome the solid armor-like shells of woodlice. It makes them powerful predators for their size, allowing them to dominate or kill competitors, such as centipedes or other spiders. D. crocata is the only species from the Dysdera family known to prey on other spiders.^[5]

They can also excrete certain enzymes that neutralize the chemical defenses of potential prey, allowing them to subsist on other common ground-dwelling invertebrates, including silverfish, earwigs, millipedes, and small burying beetles. is considered the most remarkable case of troglomorphism (adaptation to cave life) in the genus Dysdera.^{[citation needed]}

Mating[]

Mating is mainly done during the month of April. The female is the main caregiver for the young. After mating, the male has minimal to no role in the child rearing process.^[5] Before laying the eggs, females will make a silk pouch to protect and give them shelter. She can lay up to seventy eggs at once,^[4] and will stay in the silk pouch with the eggs, protecting them and waiting for them to hatch.

Distribution[]

The D. crocata, , , , and are the five species still found in Central Europe after the last glacial period.^[5] They are also abundantly found in North African countries like Morocco and Egypt, but also in Ethiopia, the Iberian Peninsula, and Australia. In the United States, Dysdera crocata is found from New England down to Georgia, and all the way across the country in California. At least two species inhabit South America: in Colombia- possibly a relict species from the post-miocene era- and in Brazil, Uruguay, and the central area of Chile.

Canary Islands[]

Dysdera inhabits all of the Macaronesian archipelagos, but the most drastic variety is in the Canary Islands, a 22 million year old volcanic archipelago nearly 100 kilometres (62 mi) off the northwestern coast of Africa. These islands house over forty endemic species of Dysdera, thirty-six of which likely descended from a single ancestor, and six of which are associated with the oldest eastern island.^[6] On Lanzarote and Fuerteventura, the spider populations are limited to the highest elevation.

The most likely reason that these spiders are so abundant on the Canary Islands is due to the abundance of species on the nearby Iberian Peninsula and North Africas. Groups like Dysdera crocata and Dysdera erythrina, found on two neighboring lands, are found more often than and Dysdera longirostris, found also in North Africa and Iberia.^[6] Over time, these spiders either made their way to the islands, then began evolving separately, or were separated when the islands broke off from the greater land masses.

In total, two to four colonization events are assumed. This probably happened by rafting, or even more likely by transport on floating islands, for Dysdera is not known to use ballooning. Dydera lancerotensis is the only species where an independent origin from continental ancestors is unquestionable; it was originally described as a subspecies of Dysdera crocata. While some of the remaining Macaronesian archipelagos have been colonized from the Canaries, the Azores have been independently colonized from the continent.

The radiation of Dysdera is surpassed on the Canary Islands only by the snail genus Napaeus, the millipede genus Dolichoiulus, and the beetle genera Attalus and Laparocerus.

Species[]

As of May 2019 it contains 285 species.^[1]

A study published in 2021 used an integrative approach combining morphological and molecular evidence to describe 8 species new to science as well as re-describing and synonymising some existing species.^[7]

References[]

External links[]

• Dysdera at BugGuide

Further reading[]

• Arnedo, M.A.; P. Oromí & C. Ribera (2001). "Radiation of the spider genus Dysdera (Araneae, Dysderidae) in the Canary Islands: cladistic assessment based on multiple data sets". Cladistics. 17 (4): 313–353. doi:10.1006/clad.2001.0168.
• Rezác Milan; Pekár Stano (2007). "Evidence For Woodlice-Specialization In Dysdera Spiders: Behavioural Versus Developmental Approaches". Physiological Entomology. 32 (4): 367–371. doi:10.1111/j.1365-3032.2007.00588.x.