Spiny softshell turtle

Spiny softshell turtle
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Class:	Reptilia
Order:	Testudines
Suborder:	Cryptodira
Family:	Trionychidae
Subfamily:	Trionychinae
Genus:	Apalone
Species:	A. spinifera
Binomial name
Apalone spinifera (Lesueur, 1827)[1]
Synonyms[2]
Apalone spinifera spinifera Trionyx nasica Rafinesque, 1822 (nomen suppressum) Trionyx spiniferus LeSueur, 1827 Apalone hudsonica Rafinesque, 1832 Gymnopus spiniferus — A.M.C. Duméril & Bibron, 1835 Trionyx annulifer Wied, 1839 Tyrse argus Gray, 1844 Trionyx annulatus Gray, 1856 Trionyx argus — Gray, 1856 Gymnopodus spiniferus — A.H.A. Duméril, 1856 Aspidonectes nuchalis Agassiz, 1857 Aspidonectes spinifer — Agassiz, 1857 Gymnopus spinifer — Agassiz, 1857 Trionyx spinifer — Agassiz, 1857 Gymnopus olivaceus Wied, 1865 Callinia spicifera Gray, 1869 Callinia spinifera — Gray, 1870 Platypeltis nuchalis — Baur, 1893 Platypeltis spinifer — Baur, 1893 Tyrse spinifera — O.P. Hay, 1904 Amyda spinifera — O.P. Hay, 1905 Platypeltis spinifera — O.P. Hay, 1907 Amyda spinifer — Potter, 1920 Amyda spinifera spinifera — Stejneger & T. Barbour, 1939 Trionyx spinifera spinifera — Cagle, 1941 Amyda ferox spinifera — Neill, 1951 Trionyx ferox spinifera — Schmidt, 1953 Trionyx spinifer spinifer — Schwartz, 1956 Trionyx spiniferus spiniferus — Wermuth & Mertens, 1961 Apalone spinifera — Meylan, 1987 Apalone spiniferus — Meylan & Webb, 1988 Apalone spinifera spinifera — Ernst & R. Barbour, 1989 Apalone spinifera spinifera — Stubbs, 1989 Trionix spiniferus — Richard, 1999

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).

Geographic range

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.^[1]

Taxonomy

The species was first described by Charles Alexandre Lesueur in 1827.^[1] It has been redescribed numerous times, leading to some confusion in its taxonomy.^[3] 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.^[4]

Reproduction

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.^[5]

Subspecies

Six subspecies of Apalone spinifera are recognized, including the nominate subspecies:^[6]

• Northern spiny softshell turtle (or Eastern spiny softshell^[7] ), A. s. spinifera (Lesueur, 1827)^[1]
• Gulf Coast spiny softshell turtle, A. s. aspera (Agassiz, 1857)^[1]
• Black spiny softshell turtle or Cuatro Cienegas softshell turtle, A. s. atra (Webb & Legler, 1960)^[1]
• Texas spiny softshell turtle, A. s. emoryi (Agassiz, 1857)^[1]
• Guadalupe spiny softshell turtle, A. s. guadalupensis (Webb, 1962)^[1]
• Pallid spiny softshell turtle, A. s. pallida (Webb, 1962)^[1]

A previously recognized subspecies, Apalone spinifera hartwegi (Conant & Goin, 1941), has been synonymized to A. s. spinifera as of 2011.^[1]

Genomics

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

Gallery

• 
  A spiny softshell turtle.
• 
  A spiny softshell turtle basking in the sun.

References

Bibliography

• Rhodin, Anders G.J.; van Dijk, Peter Paul; Iverson, John B.; Shaffer, H. Bradley; Bour, Roger (2011-12-31). "Turtles of the world, 2011 update: Annotated checklist of taxonomy, synonymy, distribution and conservation status". Chelonian Research Monographs. 5. Archived from the original (PDF) on 2012-01-22. 
• Fritz, Uwe; Havaš, Peter (2007). "Checklist of Chelonians of the World". Vertebrate Zoology. 57 (2): 149–368. Archived from the original (PDF) on 2010-12-17. 

Further reading

• Behler JL, King FW (1979). The Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Alfred A. Knopf. 743 pp. ISBN 0-394-50824-6. (Trionyx spiniferus, pp. 485-486 + Plates 270, 271).
• Boulenger GA (1889). Catalogue of the Chelonians, Rhynchocephalians, and Crocodiles in the British Museum (Natural History). New Edition. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). x + 311 pp. + Plates I-III. (Trionyx spinifer, pp. 259-260).
• Lesueur CA (1827). "Note sur deux espèces de tortues, du genre Trionyx de M[onsieur]. Geoffroy-Saint-Hilaire ". Mémoires du Muséum d'Histoire Naturelle, Paris 15: 257-268 + Plates 6-7. (Trionyx spiniferus, new species, pp. 258–263 + Plate 6). (in French).
• Smith HM, Brodie ED Jr (1982). Reptiles of North America: A Guide to Field Identification. New York: Golden Press. 240 pp. ISBN 0-307-13666-3. (Trionyx spiniferus, pp. 31-33).

External links

• Drawing of skull of Spiny Softshell Turtle

Turtle family Trionychidae
Genus	Species of the subfamily Cyclanorbinae
Cyclanorbis	Nubian flapshell turtle Senegal flapshell turtle
Cycloderma	Aubry's flapshell turtle Zambezi flapshell turtle
Lissemys	Burmese flapshell turtle Indian flapshell turtle Sri Lankan flapshell turtle
	Species of the subfamily Trionychinae
Amyda	Asiatic softshell turtle
Apalone	Florida softshell turtle Smooth softshell turtle Spiny softshell turtle
Chitra	Asian narrow-headed softshell turtle Burmese narrow-headed softshell turtle Indian narrow-headed softshell turtle
Dogania	Malayan softshell turtle
Nilssonia	Black softshell turtle Burmese peacock softshell Indian softshell turtle Indian peacock softshell turtle Leith's softshell turtle
Palea	Wattle-necked softshell turtle
Pelochelys	Cantor's giant softshell turtle New Guinea giant softshell turtle Northern New Guinea giant softshell turtle
Pelodiscus	Chinese softshell turtle Hunan softshell turtle Lesser Chinese softshell turtle Northern Chinese softshell turtle
Rafetus	Euphrates softshell turtle Yangtze giant softshell turtle
Trionyx	African softshell turtle
Phylogenetic arrangement based on turtles of the world 2011 update: annotated checklist.