Do Malaysian Myrmarachne associate with particular species of ant?

Ant-mimicry has evolved in numerous families of spiders. Although some mimics resemble ants very precisely in their morphology and behaviour, others have only a superficial resemblance to ants. In the present study, each of at least seven (and probably ten) out of 11 species of Myrmarachne from peninsular Malaysia associates with one particular species or genus of ant that it specifically resembles; these are therefore ‘good’ or ‘specific’ mimics. Myrmarachne malayana lives in the foraging ranges of a variety of ants and shows no specific resemblance to any one genus of ant, and it is best considered as a ‘poor’ or ‘general’ mimic. A species of Castianeira (Corinnidae) with a much less precise similarity to ants (a ‘poor’ mimic) was associated with Polyrhachis ants. It had previously been suggested that Orsima ichneumon (Salticidae) is an ant or insect mimic in reverse; in the present study, it was associated with Polyrhachis ants but is not considered to be an ant-mimic. Two recent theoretical models show how a poor ant-mimic may be better protected than a good mimic under certain circumstances. These data provide some support for the multimodel hypothesis, although not for Sherratt's hypothesis. However, a realistic test of these hypotheses requires more information than that provided here on both mimics and models.