M. nigricans

M. nigricans may refer to:
 * Makaira nigricans, the Atlantic blue marlin, a fish species endemic to the Atlantic Ocean
 * Mantella nigricans, the Guibé's mantella, a frog species endemic to Madagascar
 * Melanogaster nigricans, a hoverfly species in the genus Melanogaster
 * Melinda nigricans, a fly species in the genus Melinda
 * Micropterus salmoides, the largemouth bass, a fish species found in the United States of America
 * Milax nigricans, Philippi, 1836, a land slug species in the genus Milax
 * Molossus nigricans, a bat species in the genus Molossus
 * Myotis nigricans, the black myotis, a bat species from South and Central America
 * Mucuna nigricans, a plant species in the genus Mucuna