Spiny softshell turtle
|Spiny softshell turtle|
The spiny softshell turtle (Apalone spinifera) is a species of softshell turtle, one of the largest freshwater turtle species in North America. Both the common name, spiny softshell, and the specific name, spinifera (spine-bearing), refer to the spiny, cone-like projections on the leading edge of the carapace, which are not scutes (scales).
The spiny softshell has a wide range, extending throughout much of the United States, as well as north into the Canadian provinces of Ontario and Quebec, and south into the Mexican states of Tamaulipas, Nuevo León, Coahuila and Chihuahua.
The species was first described by Charles Alexandre Lesueur in 1827. It has been redescribed numerous times, leading to some confusion in its taxonomy. The recognized subspecies differ in the markings on the carapace, on the sides of the head, and on the feet. However, these markings, which are distinct as hatchlings, fade as the turtles grow larger. Adult females of the various subspecies, which grow larger than males, are not easily distinguishable from one another, and sometimes can only be assigned to a particular subspecies based on geography.
Spiny softshells begin mating between ages 8 and 10. A large female turtle may live up to 50 years. The turtles mate in mid-to-late spring in deep water. The male will nudge the female's head while swimming, and if she chooses to mate, the male will swim above the female without clasping her with his claws (unlike other turtles). A few months later, the female turtle quickly lays her eggs along a sunny sandbar or gravel bank in a flask-shaped cavity she has dug close to the water. The turtle nests more than once during a single season. She can lay between 9 and 38 round, calcareous-shelled eggs. The eggs are laid around August and September, and they hatch in the spring. Unlike in other turtles, in the spiny softshell turtle, the sex of the hatchlings is not determined by temperature variations; it is determined by genetics.
- Northern spiny softshell turtle (or Eastern spiny softshell ), A. s. spinifera (Lesueur, 1827)
- Gulf Coast spiny softshell turtle, A. s. aspera (Agassiz, 1857)
- Black spiny softshell turtle or Cuatro Cienegas softshell turtle, A. s. atra (Webb & Legler, 1960)
- Texas spiny softshell turtle, A. s. emoryi (Agassiz, 1857)
- Guadalupe spiny softshell turtle, A. s. guadalupensis (Webb, 1962)
- Pallid spiny softshell turtle, A. s. pallida (Webb, 1962)
A rough draft assembly of the A. spinifera aspera genome was completed in 2013 by The Genome Institute at Washington University - St. Louis. The assembly ASM38561v1 can be accessed via its Genbank accession ID APJP00000000.1 
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