New Ant-Mimic Spider Sneaks Into Vermont

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December 5, 2020 by Nathaniel Sharp

A small, metallic-black arthropod with a head, thorax, abdomen, and two waving antennae – your classic picnic-robbing ant right? Take a closer look at Michael Sundue’s photos at the Vermont Atlas of Life on iNaturalist and you’ll see that in fact this little critter only has two distinct body segments, and those waving antennae up front are actually a pair of legs! Michael Sundue, a botanist at the University of Vermont’s Pringle Herbarium, not only knew to take photos of this interesting arachnid to upload to the Vermont Atlas of Life on iNaturalist, but even correctly identified this ant-mimicking spider to species in his iNaturalist post. This species identification was then verified by one of the leading experts of ant-mimic spider identification on iNaturalist, user Jeremy Hussell, making this the first verified observation of Myrmarachne formicaria in Vermont.

Those familiar with the Vermont Atlas of Life likely know by now the power of iNaturalist when it comes to discovering new records of species in the state. These photos of Myrmarachne formicaria, taken in Burlington’s Battery Park, bring to mind another discovery of a new spider species in the state, the Black-palped Jumping Spider recently discovered in Burlington by a UVM student.

A macro photograph of (Myrmarachne formicaria) by iNaturalist user pierrebornand.

Taking a look at the iNaturalist range map for Myrmarachne formicaria quite clearly shows how this species has expanded its non-native range into North America. While most of the species in the genus Myrmarachne are found in the tropics, this species has a palearctic distribution, and was first discovered as an introduced species in the United States in 2001 in Ohio. Since then, it has expanded its range eastward through Pennsylvania and New York, and has now arrived in Vermont. Now that this species’ presence has been documented in Vermont, curious naturalists should be advised to take an extra-close look at the next ant they see, just in case it might be one of these convincing mimics! As always, submit your finds – ants, spiders, and everything else – to the Vermont Atlas of Life on iNaturalist.