Munduruku gen. nov., é proposto para a espécie-tipo Munduruku bicoloratum sp. nov., de Juruti, e Santarém, Pará, Brasil. O principal caráter diagnóstico de Munduruku gen. nov. é a presença de uma quilha subapical lancelotada no bulbo copulatório do macho, único no grupo basal de Theraphosinae com cerdas urticantes do tipo III-IV. A espermateca da fêmea consiste em dois recipientes esferóides com pescoço em forma de funil, cada um dos quais tendo uma área esclerotizada. Em ambos os sexos, o abdômen apresenta um padrão de colorido característico, o que é incomum em adultos de terafosídeos do Novo Mundo. Tanto a quilha lanceolada do bulbo quanto o padrão de colorido do abdômen são hipotetizados como sinapomorfias do gênero.

Munduruku gen. nov. is proposed for the type species Munduruku bicoloratum sp. nov., from Juruti and Santarém, Pará, Brazil. The main diagnostic character of Munduruku gen. nov. is the presence of a subapical, lanceolate keel on the male palpal bulb, which is unique among the basal taxa of Theraphosinae with type III-IV urticating setae. The female spermathecae consist of two spheroid receptacles with funnel-shaped necks, each of which bears a sclerotized area. In both sexes, the abdomen is remarkably patterned, an uncommon feature in adults of New World theraphosids. Both the bulbus lanceolate keel and the abdominal color pattern are hypothesized as synapomorphies of the genus.

The type species of the Neotropical Actinopus, A. tarsalis Perty, 1833, is redescribed based on material from the type locality, the state of Piauí, Brazil. The species appears to be restricted to northeastern Brazil and is newly recorded from the state of Sergipe. An old record from the state of Rio Grande do Sul is rejected. Actinopus tarsalis differs from other species of the genus by details of the male copulatory bulb: tegular apophysis absent, robust embolar base, inserted basally at a right angle (90°); embolar apices apex flattened and expanded, arrow-shaped in dorsal view.