The Burmese Peacock Softshell Turtle (Nilssonia formosa), endemic to the Ayeyarwady, Sittaung, and Thanlwin rivers in Myanmar, is one of the least-studied and most enigmatic of Asian trionychids.
WCS and Turtle Survival have recently examined 14 neonate N. formosa at the Yadanabon Zoological Gardens in Mandalay, Myanmar. Although virtually nothing is known regarding reproduction in N. formosa, we suggest that like other chelonians inhabiting large rivers in Myanmar (e.g., B. trivittata) laying occurs as sandbanks become exposed by falling water levels during the early to mid-dry season (November through March), and hatchlings emerge at the onset of heavy monsoonal rains in late May and June. To our knowledge, this is the first successful reproduction of N. formosa in captivity.
The adaptive significance of conspicuous orange coloration in hatchling N. formosa remains unknown, although bright colors in hatchlings of other turtles often signal an effective aposematic antipredator mechanism. However, aposematic coloration in most
hatchling turtles is displayed on the plastron as a defense against fish rather than the carapace, which tends to be cryptically colored as concealment from avian predators.
The number of ocelli was highly variable among the 14 neonates we examined. Our sample included individuals with four (N = 5), five (N = 4), six (N = 3), and seven (N = 2) ocelli. Additional (> 4) ocelli were reduced in size relative to the four primary ocelli, and often (but not always) positioned peripherally on the carapace. These additional ocelli persist into adulthood until fading to dark olive in very large adults.
We thank the Ministry of Environmental Conservation and Forestry for granting us permission to conduct research in Myanmar, and staff of the Yadanabon Zoological Gardens for assistance with this project.
This is an excerpt from our full reporting: Steven G. Platt, et al., Herpetological Review 47(1), 2016, pp. 125-126.