Marpissoida: Dendryphantinae

The genus Eris is one of several representative groups of New World dendryphantines. A dozen Eris species range across North America and the Caribbean and south to Panama, Colombia, and Equador. Four Eris species are widely distributed in North America; three* of these occurs in Massachusetts. Eris militaris is one of the more abundant and widespread salticids in North America and will likely be encountered early on by naturalists cultivating an interest in jumping spiders. Eris, the mischievous goddess who threw the contested apple that began a chain of events leading to the Trojan War, was for the Greeks the personification of discord and strife. As it turned out Eris militaris (previously Eris marginata) was the subject of some discord and even more confusion until Wayne Maddison sorted out the taxonomy and described various identifying characteristics in 1986. However, it seems that at least some of the mischief spread by the goddess Eris continues to be in play. While Maddison's efforts clarified one problem, distinguishing E. militaris from E. flava may still be problematic. In addition, Kaston (1973) described a new species Metaphidippus pineus now known as Eris rufa for which few records exist; its described characteristics are similar to E. floridana a fairly widespread eastern species.
*In summary, this genus is in need of revision. Until various taxonomic uncertainties are clarified the suggested identification characteristics for individual species should be used with caution.
Hill 1978, 2008; Maddison, 1986; Hill and Edwards, 2013

Some Eris species are superficially similar to jumping spiders in the genus Pelegrina. These images illustrate several differences.