Assassin Spiders: Archaeidae and Mecysmaucheniidae

Assassin Spiders

Families Archaeidae and Mecysmaucheniidae

Hannah Marie Wood

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Assassin spiders were first discovered as Baltic Amber fossils in the 1800's. It wasn't until 30 years after their initial discovery that these spiders were found living in the forests of Madagascar. To date, there are 62 known species of living assassin spider restricted to small habitats in the southern hemisphere. There are approximately 30 more species that will be named and described in the future. Furthermore, there are likely more species that still remain to be discovered. These organisms possess traits, like strange morphologies, restricted distributions, complex behaviors, low dispersal ability, and a fossil record, that makes them an important and fascinating group for scientific research. In addition these small creatures inspire curiosity, awe and creativity. Click on the links above to learn more about assassin spiders and my research. To see 3D animations of assassin spiders, click here.

♀ mecysmaucheniid spider from Nahuelbuta Parque Nacional, Chile. (Mecysmauchenius sp.)	Assassin spiders, also called pelican spiders, are comprised of two families, Mecysmaucheniidae and Archaeidae. These families are believed to be sister clades, meaning they are very closely related to each other. Archaeids are found in Madagascar, South Africa and Australia, while mecysmaucheniids are found in New Zealand and southern South America. Assassin spiders seem to prefer cold, moist montane habitats and can be found in leaf litter on the forest floor, in vegetation, and in moss. Fossil assassin spiders are known from Baltic and Burmite amber.
♀ archaeid spider from Nosy Be, Madagascar. (Eriauchenius gracilicollis) Photo by J. Miller	The bizarre appearance of these spiders illustrates the power of evolution. Spider bodies consist of two main segments, an abdomen and a cephalothorax, which contains the legs, eyes, mouth and jaws. In most spiders the cephalothorax is a rounded plate, but in assassin spiders this plate and the jaws (chelicerae) are greatly elongated giving the spider the appearance of a 'neck' and 'head,' almost making them look bird-like (they are called pelican spiders in Australia). There is a huge amount of variety in the shape of the 'neck,' which can appear thick and robust, as in the upper image, or it can be a long, slender stalk, as in the image to the left. In this image the assassin spider has just captured another spider and is holding this prey away from its body on one extended chelicera (the jaw), which insures that the prey won't cause injury to the assassin spider. Some assassin spiders are capable of moving their chelicerae independently and at 90° away from the body.

Contact Information
Hannah M. Wood Center for Macroecology, Evolution & Climate -and- Zoological Museum Universitetsparken 15 2100, Copenhagen Denmark hannah.wood@snm.ku.dk

Research supported by NSF DDIG grant