Myrmelastes is a genus of passerine birds in the antbird family (Thamnophilidae). The eight recognised species inhabit the understorey of lowland and sub‑montane evergreen forests of the Amazon Basin and the Guiana Shield, from sea level to about 1 200 m. All species regularly follow marching swarms of army‑ants (Eciton spp.), feeding on arthropods flushed by the ants. The generic name, coined by Philip Sclater in 1858, combines the Ancient Greek words for “ant” and “robber.” Molecular data place the genus in the core antbird clade, sister to Hypocnemis. Seven species are currently assessed as Least Concern and one as Near Threatened; nevertheless, progressive deforestation and forest fragmentation are causing local declines .

The generic name Myrmelastes combines the Ancient Greek words μυρμηξ (myrmēx, meaning “ant”) and λῇστης (lēstēs, meaning “robber” or “bandit”). The name reflects the birds’ distinctive ecological habit of following swarms of army ants and feeding on arthropods flushed out by the ants' activity. This behavior is among the most specialized foraging strategies in Neotropical avifauna and underlies the ecological identity of the genus.

The genus Myrmelastes was introduced in 1858 by the British ornithologist Philip Lutley Sclater to accommodate two species but did not specify the type species. In his Latin diagnosis, he highlighted key morphological traits such as the thick, straight bill, strong feet with long toes and a small rounded tail — a set of features still considered diagnostic.

In 1890, Sclater himself designated M. plumbeus as the type species of the genus, confirming its nomenclatural foundation. Subsequently, Myrmelastes was retained by the Austrian ornithologist Carl Eduard Hellmayr in the Catalogue of Birds of the Americas, though closely related genera such as Schistocichla were occasionally treated as separate based on morphological distinctions such as head shape and wing markings. Over the 20th century, however, Myrmelastes fell into disuse as most authors subsumed its members into the broader genus Myrmeciza.

The genus was later revived following advances in phylogenetic studies that clarified the polyphyletic nature of Myrmeciza. Sclater's original diagnosis, once sidelined, regained taxonomic significance in light of congruent genetic and behavioral data.

Modern molecular phylogenetics places Myrmelastes firmly within the core radiation of the antbird family (Thamnophilidae). Mitochondrial cytochrome b and three nuclear gene regions consistently recover Myrmelastes as the sister group to Hypocnemis, a result supported across multiple tree-building methods. This relationship suggests a relatively deep evolutionary split within the tribe Thamnophilini.

A broader multilocus study by Brumfield et al. involving 46 genera indicated that the divergence between Myrmelastes and its sister taxa likely occurred during the late Miocene, a period associated with increased Amazonian diversification due to tectonic uplift and climate fluctuation.

Building upon this foundation, Morton Isler and collaborators carried out a comprehensive revision of the genus Myrmeciza, which had long served as a taxonomic "wastebasket" for many phenotypically similar antbirds. Their integrative approach, combining DNA sequences, vocalizations, plumage patterns, and ecological traits, confirmed that Myrmeciza was polyphyletic. Consequently, they proposed dividing the former genus into 12 monophyletic genera, one of which was Myrmelastes. This revision helped restore evolutionary coherence to antbird classification and better align genera with their natural history attributes.