Genus of ants
Mystrium is a rare genus of ants in the subfamily Amblyoponinae. First described by Roger (1862) with the description of the queen of "M. mysticum", the genus contains 14 species, all of which occur in the rainforests of the Old World with over half of the species endemic to the Malagasy region.
Distribution.
All species occur in the rainforests of the Old World, with most found in tropical Africa: ten of them are restricted to Madagascar (and its adjacent islands) and one is recorded from continental Africa ("M. silvestrii"). "M. camillae" is widespread in the Indo-Australian region, and "M. leonie" and "M. maren" are known from Indonesia.
Taxonomic history.
After Roger (1862) established "Mystrium" with a single species from Madagascar, "Mystrium mysticum", Forel described five additional species in the Malagasy region between 1895 and 1899. The first record of "Mystrium" outside the Malagasy region was "Mystrium camillae" from Myanmar, and the second was "Mystrium silvestrii" from Cameroon. A subspecies was later established under "Mystrium camillae", "Mystrium camillae javana"; however, this subspecies was synonymized with "Mystrium camillae" by Brown (1960). Outside the Malagasy region, "Mystrium oculatum", was described from China, and "Mystrium leonie" and "Mystrium maren" from West Papua, Indonesia. "Mystrium oculatum" was synonymized with "Mystrium camillae" by Bihn and Verhaagh (2007). Yoshimura and Fisher (2014) described six new Malagasy species and synonymized two existing names, "Mystrium fallax" and "M. stadelmanni" with "M. voeltzkowi" and "M. mysticum", respectively.
Description.
The genus is morphologically very peculiar within the poneromorph subfamily group and has the following combination of characteristics: the very wide head; spatulate or squamate hairs on the head; and long, narrow mandibles with a double row of teeth on the inner margins. Monophyly of the genus is strongly supported by a recent molecular phylogenetic study by Saux "et al". (2004).
Mandible snap.
In December 2018, researchers from the University of Illinois, North Carolina State University and the Smithsonian Museum of Natural History conducted studies which found that ants of the species "Mystrium camillae" (also known as Dracula ants) can snap their jaws at speeds of up to 200 mph, making it the fastest recorded animal movement. Their research, published in the peer-reviewed Royal Society Open Science journal, noted that the jaw structure was different from other strong-jawed ants in that "instead of using three different parts for the spring, latch and lever arm, all three are combined in the mandible." They achieve this speed by pressing the tips of their mandibles together, in a spring-loading action (thereby continuously increasing tension), until one slides over the other in a snapping motion, similar to a human finger snap.
Biology.
Besides their bizarre morphology "Mystrium" ants have also evolved some unique biological traits. They have a unique defense mechanism in which they snap their mandibles to generate a powerful strike (Gronenberg "et al". 1998; Moffett 1986). Molet "et al". (2006) demonstrated that, in some species of "Mystrium" known from Madagascar, normal queens are replaced by wingless reproductives which are smaller than workers. Because "Mystrium" are rarely encountered, information on their general biology, ecology and behavior remains sparse. They are presumably predaceous like other species of the subfamily Amblyoponinae, although no direct evidence is available. Species in Madagascar show two distinct reproductive strategies and relevant colony structures. In some species each colony has a single dealate queen with a larger thorax than workers but with mandibles similar to those of the workers. In colonies of other species winged queens are missing and half of the female adults belong to wingless reproductives which are smaller and allometrically distinct from workers.
Species.
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References.
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