Two new jewel-eyed tree frog species discovered in Taiwan, display strange reproductive behavior

Researchers have identified two new species of tree frogs with jewel-colored eyes on the Island of Taiwan.
The tadpoles of these frogs display a strange reproductive behavior: the tadpole embryos feed on their mother’s unfertilized eggs, while still inside the mother’s womb.
Team suspects that Taiwan could be home to several other new amphibian species.

In the island country of Taiwan, researchers have identified two new species of tree frogs with jewel-colored eyes. The tadpoles of these frogs display a strange reproductive behavior: the tadpole embryos feed on their mother’s unfertilized eggs, while still inside the mother’s womb.

Both species of tree frogs — Kurixalus berylliniris and Kurixalus wangi — lay eggs in tree holes, researchers write in a study published in ZooKeys, but at different times of the year.

“To our knowledge, this is the first comprehensive report of the genus Kurixalus on the island of Taiwan,” researchers note.

The team led by Dr. Shu-Ping Wu of University of Taipei found Kurixalus berylliniris among the leaves of moist forests in eastern Taiwan. The slim-bodied frog has emerald colored iris (berylliniris is Latin for “green-colored” iris), and dark green or deep tan colored body with white, and sometimes faintly speckled, belly and throat. The females, measuring around 41 mm in length, are slightly bigger than the males that measure around 35 mm in length. The frog’s tadpoles are dark brown or black in color.

Researchers discovered emerald-eyed tree frog called Kurixalus berylliniris in eastern Taiwan. Photo credit: Dr. Shu-Ping Wu

The team discovered the second new species in the shrubs of secondary forests and lowland broad-leaved forests in southern Taiwan at lower elevations. They named it Kurixalus wangi in honor of herpetologist Ching-Shong Wang “for his pioneering work and contributions to the herpetology of Taiwan”.

These frogs have a golden-yellow iris, and are smaller in size than Kurixalus berylliniris. The females measure an average 34 mm in length, while the males are around 30 mm long.

Researchers found the golden-eyed tree frog, Kurixalus wangi, in lower elevations of southern Taiwan. Photo credit: Dr. Shu-Ping Wu

Inside the bellies of some tadpoles of both the tree frog species, the team found a yellow “yolky” substance, suggesting that the tadpoles had eaten some of their mother’s eggs, the researchers write.

They conclude that based on several different characteristics, including different mating call characteristics, difference in timing of their mating calls, and different morphology and genetic composition, the two frog populations in eastern and southern Taiwan are two distinct species.

The team suspects that Taiwan could be home to several other new amphibian species.

“The actual amphibian species diversity on the island of Taiwan is likely higher than currently thought, given the diverse habitats and the dynamic history of geographic events,” the researchers note in the paper. “Although Taiwan is a highly developed island with significant alterations to the natural landscape and destruction of critical habitats for amphibians, it is noteworthy that during the last fifty years, six of the seven newly described frog species in Taiwan were treefrogs inhabiting forested areas.”

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