A moderate-sized (up to 6 cm) wide-bodied frog. The background colouration is olive with small rectangular patches of darker green. The skin of the dark patches is often raised, and larger individuals can have low spines. There is a prominent pale gland above the lip at the angle of the mouth. The fingers and toes are unwebbed, and females have flanges on the first two fingers for nest construction.
Males call from the base of grass tussocks, sometimes calling from the burrows of freshwater crabs (Holthuisiana). When a pair is in amplexus, the female will raise her hands above the water and bring it down rapidly, trapping air bubbles in her hand with the help of the extra flanges on her first two fingers. By alternating her hands, she eventually constructs a foam nest in this way and eggs are fertilised and laid in to the foam.
A strong high-pitched honk repeated sporadically.
See "Breeding" above.
Tadpoles are completely black and can grow as large as 7 cm.
The specific name convexisculus means "arched rump" referring to their posture.