Monday, December 22, 2014

[Herpetology / Behaviour • 2014] Jelly Secretion by a Foam-nesting Tree Frog Chiromantis simus (Anura: Rhacophoridae): An Unreported Behaviour

Figure 5. Nineteen males of Chiromantis simus (15 are in picture frame and 4 just out side) surrounding a polyandrous foam nest, waiting for the female to join in amplexus. One old foam nest is also visible on the left side.

Chiromantis simus, a foam-nesting rhacophorid frog, previously considered extinct from India, was re-discovered in 1998. Surprisingly it is abundant at the village of Rajpur and its surroundings. This species is a true monsoon breeder and produces foam nests between June and October. Generally, during foam-nesting the female initially lays an egg mass without foam coating (i.e., “uncovered”). Later, she produces a foamy liquid and evenly covers the egg mass with it. I collected an uncovered egg mass before a female went to the water source below to absorb water. After returning, the female waited for 4 hours when she did not find the egg mass near the twig and then, by a process of continuous rubbing of her hind limbs, she secreted a thick jelly-like substance from the cloaca, instead of the foamy substance. Additional observations on the egg laying behaviour showed that uncovered egg masses were always attacked by ants, while those egg masses covered by foam were never attacked. Chiromantis simus foam-nesting is mostly polyandrous but, when a female has to deal with too many males in amplexus, she leaves the egg mass without depositing an additional foam coating, which may be why some clutches can be found uncovered.

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Figure 1. Foam nests of Chiromantis simus:
  A. an uncovered egg mass freshly laid and attached to a leaf; it is irregular in shape and with some eggs exposed;
B.
sectional view of a foam nest after additional layering:thickness of the outer foam cover is 3 to 4 mm ‘red outline’.

Ananda Banerjee. 2014. Jelly Secretion by a Foam-nesting Tree Frog Chiromantis simus (Anura: Rhacophoridae): An Unreported Behaviour. Alytes. 31(3-4); 77-82.

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