The Find-a-Spider Guide

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Ant-mimicking spider

Fact Box
Myrmarachne erythrocephala (QM)
(formerly M.simoni and M. cognata and similar to M. luctuosa)
Body length:
female: 7 mm
male: 9 mm
Any surface where ants can be found. The spiders often hide under loose bark but also run with ants along established ant pathways
Probably harmless to humans
Myrmarachne erythrocephala
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A male
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Another view
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Underneath female
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The female

The distinguishing feature of this species is the partial constriction of the cephalothorax and/or the abdomen into two segments to produce an ant-like body shape. The very large porrect (forward pointing) chelicerae on the male are another striking feature. The female's palps are long and thin with paddle-shaped ends. At least on some Myrmarachne species the cephalothorax appears to have a helmet-like shape. Note that the colour of Myrmarachne species seems to vary, at least partly, with the colour of the ants they are running with.

The apparent differences among the images shown on this page may indicate that more than one species is presented. It should also be pointed out that the taxonomy of the Australian Myrmarachne genus is currently being revised, the most recent example of this being the following paper: Pekar S., Petrakiva L., Corcobado G., and Whyte R. (2017) "Revision of eastern Australian ant-mimicking spiders of the genus Myrmarachne (Araneae, Salticidae) reveals a complex of species and forms" Zoological Journal of the Linnean Society, 197(3), 642-676.

Myrmarachne erythrocephala appears to have been badly named since 'erythrocephala' implies a red head region which it rarely, if ever, has. It is a species that has been found from South Queensland through NSW and probably even into Victoria. Most early specimens collected in South Queensland and NSW were initially named Myrmarachne simoni but a few were instead called Myrmarachne cognata. Neither of these names is now considered valid but the specimens found in Southern Queensland have been subdivided into M. erythrocepahala daemeli and M. erythrocephala erato.

Known range: Believed to be in Cairns, Rockhampton (and well inland from there) and down to South-east Queensland but rare or absent in the rest of Australia.

Spider(s) with a very similar appearance: Many other Myrmarachne species.

Email Ron Atkinson for more information.    Last updated 2 February 2022.