Ancylometes

Description

Members of Ancylometes are among the largest araneomorph spiders, with a typical body length of 1.5 to. They are sometimes referred to as "giant fishing spiders" to distinguish them from Dolomedes, a genus of smaller spiders also called "fishing spiders". The largest species is A. rufus, with females that grow to a body length of 5 cm and a leg span of 12 cm. Males of the species only grow up to 3 cm in body length, but usually have longer legs than the females. Both sexes are brown with dark spots on the abdomen, and males have two thin lines along their carapace.

They have a 2-4-2 eye pattern and a reduced third claw, characteristics of the Ctenidae and Pisauridae, respectively. Members of this genus can be distinguished from all others by ventral spines found on the tarsi of the third and fourth legs.

Ancylometes and the more fully aquatic Argyroneta are the only known genera of spiders that can spin webs in water. Though these webs can catch fish, they mostly prey on fish by diving down or lying in wait until prey passes within striking distance. Once caught, these spiders will bring their prey back to the surface before eating it.

During mating, the male wraps the female with silk, and the female enters an immobile state. After about a week, she produces a cocoon and carries it with her fangs. After a month, she builds a nursery web above the ground, about 10 cm in diameter. Over one hundred baby spiders will hatch inside this egg case, each only about 2 mm long. The baby spiders take about a year to mature. Males only live for sixteen months at most, while females can live for more than two years.

The venom of Acyclomete sp, has effects on muscle contraction and preparation of the phrenic nerve diaphragm muscle, 50 μg causes depolarization of the diaphragm muscle fiber membranes. These studies indicate that the Ancylometes venom activates voltage-gated sodium channels. All of these effects of Ancylometes sp. venom on this nerve muscle preparation increase in twitch tension.

Species

, this genus includes ten species:

• Ancylometes amazonicus Simon, 1898 – Peru, Brazil
• Ancylometes bogotensis (Keyserling, 1877) – Honduras to Bolivia
• Ancylometes concolor (Perty, 1833) – Brazil, Bolivia, Paraguay, Argentina
• Ancylometes hewitsoni (F. O. Pickard-Cambridge, 1897) – Bolivia, Brazil
• Ancylometes japura Höfer & Brescovit, 2000 – Brazil
• Ancylometes jau Höfer & Brescovit, 2000 – Brazil
• Ancylometes pantanal Höfer & Brescovit, 2000 – Brazil
• Ancylometes riparius Höfer & Brescovit, 2000 – Brazil
• Ancylometes rufus (Walckenaer, 1837) – Northern South America
• Ancylometes terrenus Höfer & Brescovit, 2000 – Brazil

References

References

1. "Gen. Bertkau, 1880". World Spider Catalog.
2. Bertkau, P.. (1880). "Verzeichniss der von Prof. Ed. van Beneden auf seiner im Auftrage der Belgischen Regierung unternommen wissenschaftlichen Reise nach Brasilien und La Plata im Jahren 1872-73 gensammelten Arachniden.". Mémoires Couronnés et Mémoires des Savants Étrangers de l'Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique.
3. "Ancyclometes". intute.
4. (March 1999). "The neuromuscular action of Ancylometes sp. spider venom in the rat phrenic nerve-diaphragm preparation". Toxicon.
5. (2000). "A revision of the Neotropical spider genus Ancylometes Bertkau (Araneae: Pisauridae)". Insect Systematics & Evolution.
6. Lehtinen, P. T.. (1967). "Classification of the cribellate spiders and some allied families, with notes on the evolution of the suborder Araneomorpha". Annales Zoologici Fennici.
7. "Ancylometes – introduction". State Museum of Natural History Karlsruhe.
8. (1970). "Consideraciones sobre el género Ancylometes Bertkau 1880 (Araneae: Pisauridae)". Acta Zoologica Lilloana.
9. "Family: Ancylometidae Hazzi, Wood & Hormiga, 2025". Natural History Museum Bern.