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A group of Amazonian harvestmen is recognized and described as Amazochroma gen. nov. This taxon includes Discocyrtus carvalhoi Mello-Leitão, 1941 (type species), the only species of Discocyrtus previously thought to occur in Amazonia, and Amazochroma pedroi gen. et sp. nov., described here from the Brazilian states of Acre and Rondônia. New records are added for Amazochroma carvalhoi gen. et comb. nov, expanding its distribution from the Brazilian state of Mato Grosso northwards also to Pará and Amazonas in Brazil and additionally French Guiana and Suriname. Diagnostic features of Amazochroma gen. nov. include: trichromatic pattern of legs, dry marks on the dorsal scutum and base of legs and diastema in the row of macrosetae C of the penis ventral plate. A morphological maximum parsimony analysis (1022 scorings; 16 taxa; 64 characters) is performed to test whether Amazochroma gen. nov. is a member of Discocyrtus and if the traditional allocation of Discocyrtus in Pachylinae is defendable. A clade is retrieved containing three groups: Amazochroma carvalhoi gen. et comb. nov, here described as a new subfamily of Gonyleptidae - Roeweriinae subfam. nov. Discocyrtanus Roewer, 1929 and Roeweria Mello-Leitão, 1923 are accordingly here transferred from Pachylinae to Roeweriinae subfam. nov.
The genus Lacronia Strand, 1942 is herein revised, and a maximum parsimony phylogenetic analysis of morphological characters (30 taxa, 115 characters, 2962 scorings) is performed to test its monophyly. As a result, Lacronia is herein made monophyletic by means of the inclusion of Discocyrtus boraceae B. Soares, 1942, Discocyrtus niger Mello-Leitão, 1923 and Discocyrtus tenuis Roewer, 1917. Lacronia including those species is the sister group of Discocyrtus s. str. inside the DRMN-clade, and should be removed from Pachylinae Sørensen, 1884, although without a new subfamilial assignment for now. Four new junior subjective synonyms are detected for the first time (Discocyrtus rarus B. Soares, 1944 = Discocyrtus fazi Piza, 1942 = Discocyrtus niger Mello-Leitão, 1923; Discocyrtus infelix Mello-Leitão, 1940 = Discocyrtus nigrolineatus Mello-Leitão, 1923 = Discocyrtus tenuis Roewer, 1917). Accordingly, the following new combinations are proposed: Lacronia boraceae (B. Soares, 1942) comb. nov., Lacronia nigra (Mello-Leitão, 1923) comb. nov. and Lacronia tenuis (B. Soares, 1942) comb. nov. Lacronia is endemic to the Atlantic province of Brazil, with verified records from the states of Rio de Janeiro, Santa Catarina and São Paulo. As a geographic note, the record of ‘D. fazi’ for Chile is here discussed and considered incorrect.