M. australis

M. australis may refer to:
 * Malacosteus australis, the Southern stoplight loosejaw, a small, deep-sea dragonfish species
 * Marsdenia australis, the bush banana, silky pear or green vine, a plant species native to Australia
 * Megascolides australis, the giant gippsland earthworm, an earthworm species native to Australia
 * Mentha australis, the river mint, native mint, native peppermint and Australian mint, a mint species native of eastern Australia
 * Microcavia australis, the Southern mountain cavy, a rodent species found in Argentina, Bolivia and Chile
 * Micromesistius australis, the southern blue whiting, a cod species found in the southern oceans
 * Mirandia australis, a jumping spider species found in Paraguay
 * Morus australis, the Chinese mulberry, a flowering plant species found in South-East Asia
 * Myliobatis australis, the Australian bull ray or southern eagle ray, a large ray species of temperate waters of Australia
 * Myrsine australis, the red matipo or mapou, a shrub species endemic to New Zealand