Convergent Defensive Behavior of Two Leaf-Litter Frogs of Southeastern Brazil

Abstract

The microhylid Stereocyclops parkeri and the leptodactyloid Proceratophrys appendiculata are terrestrial frogs of the coastal rainforest in southeastern Brail, living in the litter accumulated on the floor and spending most of the time half-buried among fallen leaves. Besides the cryptic appearances of both these species, I observed a defensive behavior which enhances their resemblances to fallen leaves and may cause a frog to be confused with a casually dislodged Typically, when the leaf-litter in the immediate vicinity is disturbed, the frog makes a short leap, landing with its legs stretched backwards (fig. 1), and remains remarkably still. It may be touched without its changing the posture, keeping the legs stiff and body flat. Placed with its belly up, the frog turns with an almost imperceptible movement of one arm and resumes being a leaf. The immobility may last as long as 30 minutes if there is some activity nearby but on some occasions the frog may move forwards a litde with a quick movement of the feet, this displacement resembling that of a flicked