With fifteen genera and thirty species, the family Trionychidae occurs throughout most of the world. These distinctive turtles have a range that includes North America, Africa, southern and eastern Asia, and the East Indies to New Guinea. Fossil records from the late Jurassic Period provide evidence that this family’s distribution once included what is now Europe and South America.
One genus and four species comprise the soft-shelled turtle diversity in North America. In general, North American soft-shelled turtles are moderately sized. The Florida soft-shelled turtle (Apalone ferox) attains the largest size at 25 inches (63 centimeters). This species has a distribution that includes southern South Carolina, central Georgia, eastern Alabama, and Florida. It is sometimes found in Texas as released pets, but to date none are known to have become established here.
In Texas there are two species of native soft-shelled turtles. The smooth soft-shelled turtle (Apalone mutica) is one of two species inhabiting the central United States and reaches 14 inches (35 centimeters) in carapace length. Unlike its cogener, the spiny soft-shelled turtle (A. spinifera), this species lacks tubercles on the anterior portion of its carapace.
The spiny soft-shelled turtle has the widest range of all the North American soft-shelled turtles. This species has a geographic distribution that includes southern Ontario and Quebec, Canada, to northern Florida westward to Montana and southeastern California. It also occurs south of the Rio Grande in Juarez, Coahuila, Nuevo Leon, and Tamaulipas, Mexico.
Two species of soft shell turtle occur in Texas.