Terrapene nelsoni

Stejneger, 1925b
Spotted box turtle

The narrow to oval carapace (to 15 cm) is domed, but somewhat flattened dorsally, with a poorly developed (sometimes absent) medial keel. Vertebrals are broader than long; posterior marginals are unserrated but flared over the hindlimbs. The carapace ranges from yellowish to tan to dark or greenish brown and often contains a pattern of scattered small brown to yellow spots. The plastron is large and well-developed with no posterior notch on the anal scutes. The plastral formula is: an > abd > gul > pect > fem > hum. Axillary scutes are usually absent, but when present, are at the 5th marginals. The dark brown plastron is yellow bordered and may contain yellow spots and streaks. The head is large with a strongly hooked upper jaw. In the skull, no process arises from the postorbital bone, and the postorbital bar is absent. Skin of the head, neck, limbs, and tail is yellow to brown with brown or yellow spots. Four webbless toes are present on the hind foot.
The plastron is shallowly concave in males and flat or convex in females. The first toe of the male hind foot is capable of medial rotation. Males also have thicker and longer tails than females.

Terrapene nelsoni occurs in disjunct populations in southern Sonora, Sinaloa, and Nayarit in western Mexico.

Geographic Variation
Two subspecies are recognized. Terrapene nelsoni nelsoni Stejneger, 1925b, the southern spotted box turtle, is restricted to the vicinity of Pedro Pablo, Nayarit, Mexico. Its carapace is straw-colored to tan or dark brown and the light spots are larger and less numerous. The interhumeral seam and the interpectoral seam lengths average 16 and 35%, respectively, of the anterior plastral lobe length (Iverson, 1982b). Also, its 1st vertebral scute is concave in shape. T. n. klauberi Bogert, 1943, the northern spotted box turtle, occurs in southwestern Sonora and near Terreros in northwestern Sinaloa (Hardy and McDiarmid, 1969). Its carapace is tan to dark brown or greenish-brown with numerous, smaller light spots than in T. n. nelsoni. Its interhumeral seam and interpectoral seam lengths average 18 and 33%, respectively, of the anterior plastral lobe length (Iverson, 1982b). Its 1st vertebral is flattened. Spotting may be absent from either subspecies.

This species inhabits hill country covered with savannah, oak woodlands, or dry scrub forest. T. n. nelsoni has been collected only at elevations over 1050 m, while T. n. klauberi is known only from elevations below this. Hardy and McDiarmid (1969) found numerous burrows on a hillside where they collected T. n. klauberi in Sinaloa, and attributed some of these to box turtles.

Natural History
Nothing is known of courtship and mating in Terrapene nelsoni, but the rotating first hind toe is probably used to clasp the female, as in T. ornata. Milstead and Tinkle (1967) dissected female T. n. nelsoni and found the number of eggs to range from one to four with three the usual number. They found no evidence of second clutches. The elongated eggs averaged 47 x 27 mm.
Captives are omnivorous, feeding on various vegetables, worms, insects, and canned dog food.

IUCN Red List Status (1996)
Data deficient.