Abstract Santaremicaris gen. nov. is proposed to accommodate Santaremicaris amazonensis sp. nov., a new species collected by Noodt from the hyporheic zone of the Amazonas River at Santarém, Brazil, and Parastenocaris santaremensis Noodt, 1963, which is redescribed and designated as the type species of the new genus. The new genus is recorded also from several localities of the Amazonian hydrographic basin. Santaremicaris gen. nov. is well supported by clear autapomorphies, e.g., 1) the absence of distal spinules on the endopod of the second swimming leg of the male, which is ornamented with strong outer spinules along the first 2/3 of the segment and armed with a long distal seta the insertion area of which covers almost the whole width of the segment; 2) the presence of a triangular, short and strongly sclerotized endopod on the fourth swimming leg of the male; and 3) the presence of a long and slim male fifth leg ending in a long distal spiniform process, with irregular margins, armed with only three setigerous elements on the outer margin, and reaching the middle of the subsequent urosomal segment or beyond it. The new genus is closely related to Murunducaris Reid, 1994, with males sharing conspicuous ornamentation on the inner margin of the first swimming leg basis, represented either by an enlarged spinule accompanied by minute accessory spinules or by a row of strong spinules. In addition, the males of both Murunducaris and Santaremicaris gen. nov. share an enlarged intercoxal sclerite with a median process on the fifth leg.