Red Triangle Slug

Red triangle slugs are easily recognized by their two tentacles; unlike many other slugs, they do not have four. Like other leaf-vein slugs, they also have a distinctive indented pattern on their back that resembles the veins of a leaf. These slugs can grow up to 14 centimeters in length. They are highly variable in color. Individuals can appear white, off-white, yellow, light or dark grey, beige, pink, red, or olive green. Regardless of color, all adults display a red (sometimes orange, magenta, or maroon) triangular mark on the mantle around the breathing pore (pneumostome), as well as a red line along the edge of the foot. The texture of their backs can also differ: some are smooth, while others are rough. Juvenile slugs look quite different from the adults. They lack the red markings but instead have three dark grey stripes running down their backs and a grey outline around the triangular mantle shield. Scientists are currently studying whether some of these different color forms might actually belong to separate species or subspecies.

This slug species is native to the east coast of Australia, where it ranges from New South Wales to Queensland. A closely related and brightly colored pink form, referred to as Triboniophorus aff. graeffei, is found only on Mount Kaputar in New South Wales. In 1959, malacologist Alan Solem suggested the species might have been introduced to the New Hebrides (now Vanuatu), although no specimens were available to confirm this at the time.