Metaxyonycha is a genus of leaf beetles in the subfamily Eumolpinae.
Taxonomy
Metaxyonycha was first named by Louis Alexandre Auguste Chevrolat in 1836, with the spelling "Metazyonycha", in Dejean's Catalogue of Coleoptera. According to Bousquet et al. in 2013, Metaxyonycha is an incorrect subsequent spelling of Metazyonycha. However, because the subsequent spelling is in prevailing usage and is attributed to the original spelling's publication, "Metaxyonycha" is considered the correct spelling.
In some publications for the Neotropical realm, Metaxyonycha is also known as "Colaspis". This was because the Czech entomologist Jan Bechyné had synonymised Metaxyonycha with Colaspis, after incorrectly assuming the two had the same type species, while splitting the species of Colaspis in the Junk-Schenkling catalog into a separate genus known as "Maecolaspis". As a result, Bechyné was using the name Colaspis for what was actually Metaxyonycha.