Results
Numerous males were calling in close proximity, frantically grappling with each other, and trying to dislodge
amplectic males. Males expel air from their lungs to produce the moaning call (see Heyer 1971) without changing
the inflation of the immense vocal sac (Fig. 1A). The rotund build of these frogs forces the male to clasp the female
well behind her front legs with what appears to be an insecure grip; his palms are turned outwards, and his fingers
are not clenched (Fig. 1B). Males are glued to the female by chest glands (Zug et al. 1998) as is common in
microhylid frogs that breed in water.
When observations recommenced at 0730 h on 29 April, egg laying was in progress. As is typical of
microhylids, amplectic pairs float head upwards at an angle of about 45° to the surface and then dip forwards
almost vertically to position their vents above the water surface momentary to oviposit a portion of a clutch. This
maneuver allows the extruded eggs to fall from the female’s vent onto the surface without being wetted so that they
will float in a single-layered, coherent film. A dip is initiated solely by rapid paddling by all four legs of the female
just before she dips downwards. A dip to release a raft of eggs lasts for about 6 s (200-300 eggs/raft), and a number
of dips, with about 5 s between dips, are required to oviposit an entire clutch. As the pair dips, the hind feet of the
male are initially positioned parallel on each side of the female’s vent and tightly tucked against her belly (Fig. 1C),
and as soon as she arches her back downwards to bring her vent closer to his, his extended legs splay to the side as
she releases eggs. The raft is pushed away from the pair when the female relaxes her back, and the legs of both the
male and female are splayed apart. Also note the uniform film of evenly spaced coherent eggs caused by the
diameters of the outer jelly layer. There is some evidence in the photographs that the outer egg jelly has a floatation
flange like those of Kaloula (Liu 1950). The ova have a yellow vegetal pole and a darkly pigmented animal pole.
On the morning of 29 April, three dead males and a moribund male in amplexus with a dead female were
found, and a smaller chorus started again at dusk. Potamid crabs (Fig. 2B) predated and scavenged eggs and frogs.
It seemed that the crabs preferred the viscera, and they reached into the opened body cavities to remove pieces of
tissue that looked like pieces of the fat bodies. In one case, a crab began to chew on the right hind leg of a calling
male. The frog made several futile leaps while dragging the crab with him but could not escape until the approach
of a second crab caused the attacker to release its grip. While the two crabs fought, the frog hurriedly escaped into
the forest.