Length 2.5 to 5 cm. Terrestrial slugs can be quite variable in colour and patterning. Generally, scarletback taildropper is reddish in colour (especially dorsally – but not always), grey-buff along the sides, with two conspicuous dark bands running laterally from the mantle to the tail. These bands define a wedge-shaped lighter dorsal area which may enclose a (sometimes faint), dark dorsal stripe at midline. The sole (bottom of foot), is usually cream colored but can be grey. The pneumostome (pore used for air breathing) is located at or in front of the midline of the mantle covering the right side. The tail often has oblique constrictions (not always), that mark the area where autotomy has occurred. A mucus pore usually found on the tail area of other slugs is absent.