Hyalinobatrachium colymbiphyllum

The Cricket Glass Frog is one of the most spectacular Glass Frog species one can hope to encounter in Costa Rica. It is a true Glass Frog amongst Glass Frogs.

It's underside lacks any pigment, as can be seen in the photograph on the left, and all of the frog's internal organs are clearly visible. The red heart lacks a lining and is visible near the frog's throat.

Below the heart is the liver, which is covered by a white visceral lining. This can be clearly distinguished on the photograph below. The green gall bladder can be seen to the left, just below the liver and the ventral vein points downward, from the liver towards the digestive tract. The digestive tract, like the liver, is also covered by a white visceral lining. The red area to the right of this individual's gall bladder is a bit of a mystery. This area should be white on Cricket Glass Frogs. Despite the anomaly, we have found two individuals with the same characteristics in Drake Bay.

Individuals from southwest Costa Rica have light green skin scattered with very fine, yellow and black spots throughout their upper surface.

According to Brian Kubicki's Glass Frogs of Costa Rica, there is an isolated population in Monteverde which differs in size, call, coloration and in the shape of their egg masses. They are still classified as Hyalinobatrachium colymbiphyllum, but Kubicki speculates that it could be a completely different species altogether. 

Cricket Glass Frogs are uncommon and small, with adults measuring between 23 and 28 millimeters. As with other Glass Frogs, females are normally larger than males. On humid nights, male frogs call from the top or, more commonly, from the underside of leaves bordering streams in primary or secondary forests. Males generally call from one to six meters above the surface of the stream.

Its common name is due to its call, described as a single note, a rather musical "brrrrrrrt", which closely resembles that of a cricket. The call serves to advertise to females as well as to demark the male's territory.

Like the closely related Reticulated Glass Frog (Hyalinobatrachium valerioi), Cricket Glass Frogs are extremely territorial. If an intruder invades another male's territory, the confrontation could turn physical and wrestling matches may ensue. The battle will rage until the victor pins his opponent and holds him down for a short time. After it is clear which frog will get to keep the calling perch, the loser is released and will retreat to find another leaf to call from.

Once a male has secured his perch, he will resume calling until he attracts a female. The female will approach the male and they will mate right at the calling site. She will lay her eggs on the underside of the calling site leaf, often near its center. Egg clutches contain between 50 and 75 eggs.

After the eggs have been deposited, the male will continue his advertising call. If another female is drawn in by his call, they will mate and she will also lay her eggs on the underside of his calling perch.

Males will guard the eggs during the night and individual males have been recorded guarding up to eight egg clutches in different stages of development. Throughout the night, the male will occasionally climb on top of the egg clutches and empty his bladder, protecting them from dehydration. The egg masses absorb the water and become noticeably swollen.

Once dawn arrives, the males will retreat into the canopy, leaving their egg clutches unprotected. This results in a high mortality rate. Wasps commonly raid the egg clutch. The eggs are carried away one by one, often until the entire egg mass is gone. At night, the males return to their perches and resume their post.

 Cricket Glass Frogs are only know to exist in three countries: Costa Rica, Panama, and Colombia.

References:

Kubicki, B.  2007  Costa Rica Glass Frogs  Editorial INBio

Savage, J.  2002  The Amphibians and Reptiles of Costa Rica   University of Chicago Press