Small ants (about 5 mm) tan, smooth and shiny. The width of the head (HW) 0.66-0.70 mm, the length of the head (HL) 0.79-0.85 mm, the length of the scape of the antennae (SL) 0.78-0.87 mm. The antennae of the workers are 12-segmented with a mace of 3 segments (for males, the antennae are of 13 segments). Formula of mandibular and labial palps of workers 3.2; males - 4.3 or 3.3. Zhval workers with several teeth (about 10). The sting is developed. The stalk between the breast and the abdomen consists of two segments: petiol and postpetiol. Posterothorax without propodeal teeth. The biology of M. nocarina has not been investigated. Some other species of the genus Megalomyrmex are known as specialized social parasites of Attini leaf-cutting ants, in whose nests they live and feed in the mushroom gardens of the host species. A close species of Megalomyrmex mondaboroides is associated with fungi breeders of the genus Trachymyrmex ( C. costatus Mann) and Apterostigma ( A. goniodes Lattke), and M. symmetochus is associated with fungus breeders of the genus Sericomyrmex . The species was first described in 2010 by American worldmecologist John T. Longino ( English John T. Longino ; The Evergreen State College , Olympia , Washington ), and its valid status was confirmed during an audit in 2013 by American worldmecologists Brendon E. Boudinot ), Theodore P. Sumnicht ( Theodore P. Sumnicht ; University of Utah , Salt Lake City , Utah , USA ) and Rachelle Adams (Department of Entomology Smithsonian Institution , Washington , USA). The taxon is included in the species group Megalomyrmex silvestrii- group together with the species M. fungiraptor , M. mondabora , M. adamsae , M. mondaboroides , M. reina , M. silvestrii , M. symmetochus , M. wettereri [1] [2] .