Disclaimer:

The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Big-headed Turtle

Taxonomy: available through www.itis.gov

Identification: Platysternon megacephalum have extremely large, flat-topped heads, half the width of the carapace and protected by a bony scute which can resemble a helmet and a poweful hooked beak. The yellowish or olive-brown carapace is elongated and flat, sometimes with a slight keel, and a powerful tail as long as the carapace (Ernst and Barbour 1989, Bonin et al. 2006). Juveniles are more brightly colored than adults, with a keeled shell and serrated posterior scutes, and may feature a colorful stripe behind the eye (Bonin et al. 2006, Rhodin et al. 2021).

Size: Carapace length up to 25.5 cm for males and 21.0 cm for females (Rhodin et al. 2021)

Native Range: Cambodia, China, Laos, Myanmar, Thailand, and Vietnam (Rhodin et al. 2021)

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Platysternon megacephalum are largely noctural, living in cooler, high-elevation streams in Southeast Asia where they spend the day hiding in the rocky substrate and are seldom seen basking. Although poor swimmers, they are adept climbers, facilitated by their powerful jaws and strong tails. Their diet consists largely of fishes, mollusks, and crustaceans, and they may forage terrestrially along the stream bank. Females typically lay one or two white, ellipsoidal (37 x 22 mm) eggs (Ernst and Barbour 1989, Bonin et al. 2006).

Means of Introduction: This was likely an escaped pet

Status: Not known to be established in the United States

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. Research is required to evaluate effects before conclusions can be made.

References: (click for full references)

Bonin, F., B. Devaux, and A. Dupre. 2006. Turtles of the World. The John Hopkins University Press, Baltimore, MD.

Ernst, C.H. and R.W. Barbour. 1989. Turtles of the world. Smithsonian Institution Press, Washington, D.C.

Rhodin, A.G.J., J.B. Iverson, R. Bour, U. Fritz, A. Georges, H.B. Shaffer, and P.P. van Dijk. 2021. Turtles of the world: annotated checklist and atlas of taxonomy, synonymy, distribution, and conservation status. In: Conservation biology of freshwater turtles and tortoises: a compilation project of the IUCN/SSC tortoise and freshwater turtle specialist group. Volume 8. 9th edition. Chelonian Research Foundation and Turtle Conservancy, Arlington, VT. https://iucn-tftsg.org/wp-content/uploads/crm.8.checklist.atlas_.v9.2021.e3.pdf

Author: Jonathan Freedman

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.