Myrmarachne formicaria

(De Geer, 1778)

Ant-mimicking jumping spider

Myrmarachne formicaria is an -mimicking (Salticidae) to the Palearctic region and to North America. It is one of few Myrmarachne found outside the tropics. The species exhibits sophisticated locomotor , with all eight legs while adopting ant-like postures and movement patterns. It was first recorded in the United States in Ohio in 2001 and has since spread to multiple states.

Myrmarachne formicaria 92685782 by Zygy. Used under a CC0 license.Myrmarachne formicaria 92685347 by Zygy. Used under a CC0 license.Myrmarachne formicaria 76646045 by spidereyes. Used under a CC0 license.

Pronunciation

How to pronounce Myrmarachne formicaria: /ˌmɜːrməˈrækni fɔːrmɪˈkɛəriə/

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Identification

Distinguished from non-mimicking by -like and . Forelegs are raised like when stationary. Exhibits winding trajectories with characteristic short pauses (~100 ms). Unlike true ants, walks with all eight legs using a salticid alternating gait rather than the six-legged gait of ants. present; males and females differ in morphology. Gynandromorphic individuals have been documented.

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Habitat

Specific natural requirements are not well documented. Collected in field conditions near human-modified environments in the Ithaca, New York area. Laboratory specimens maintained at 23±2°C in individual containers.

Distribution

to Palearctic region including Austria, Central Europe, Macaronesia, Turkey, Caucasus, Russia (European, Caucasus, and Far East regions), Iran, China, Korea, and Japan. to North America; first recorded in Trumbull County, Ohio, USA on 16 August 2001. Established now present in Pennsylvania, New York, and Canada.

Diet

In laboratory conditions, fed (Drosophila melanogaster) and domestic (Acheta domesticus). Natural diet in the wild is not documented.

Behavior

Exhibits quantitative locomotor of : with all eight legs using typical salticid alternating gait, but raises forelegs like ant only when stationary. Produces winding trajectories with wavelength of 5–10 body lengths, resembling ants engaged in -trail following despite absence of chemical cues. Makes characteristically short pauses of approximately 100 ms, which create ant-like appearance to observers with slow visual systems. Males exhibit toward females and agonistic toward other males.

Ecological Role

Batesian mimic: palatable that avoids by mimicking unpalatable or unprofitable . Subject to predation by , , birds, and other visually oriented . Behavioral experiments with predatory spiders support the protective hypothesis.

Human Relevance

Non- in North America with expanding range; first detected in 2001. Used as a model organism in studies of locomotor and protective mimicry systems.

Similar Taxa

  • Myrmarachne spp.Other -mimicking in the same ; M. formicaria distinguished by its temperate distribution and specific locomotor patterns including foreleg-raising only when stationary and characteristic winding trajectories
  • True ants (Formicidae) target; distinguished by six-legged , , and constriction between and that M. formicaria only approximates through posture and movement

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Sources and further reading