Spotted Turtle
Clemmys guttata
Common Name: |
Spotted Turtle |
Scientific Name: |
Clemmys guttata |
Etymology: |
|
Genus: |
Clemmys is derived from the Greek word klemmys which means "tortoise". |
Species: |
guttata is derived from the Latin word gutta which means "spot". |
Average Length: |
3.5 - 4.5 in. (9 - 11.5 cm) |
Virginia Record Length: |
4.8 in. (12.1 cm) |
Record length: |
5 in. (12.7 cm) |
Systematics: Originally described as Testudo guttata by Johann Gottlob Schneider in 1792 from a specimen that no longer exists. Mittleman (1945a) restricted the type locality to Philadelphia, Pennsylvania. Ritgen (1828) was the first to use the genus Clemmys for this species, although it was then called Testudo punctatus (Iverson, 1992). In the Virginia literature, this species was called Clemmys guttatus by Hay (1902). All other authors have used the current nomenclature. No subspecies are recognized.
Description: A small freshwater turtle reaching a maximum carapace length (CL) of 127 mm (5.0 inches) (Conant and Collins, 1991). In Virginia, known maximum CL is 121 mm, maximum plastron length (PL) is 110 mm, and maximum body mass is 234 g.
Morphology: Carapace smooth without serrations on posterior margin; no median keel; marginals usually 12/12, pleurals 4/4, and vertebrals 5; hingeless plastron 84-91% of CL.
Coloration and Pattern: Carapace black to blue-black with 3-92 (ave. = 32.4 ± 17.9, n = 60) yellow, yellow-orange, or cream spots; spots are transparent areas in epidermal scutes that overlie patches of yellow pigment on shell (Ernst and Barbour, 1972); marginals black above and below; bridge black but may be dark brown in old turtles; plastron yellow, cream, or sometimes light orange with large, black blotches positioned away from midline; skin on head, neck, and limbs dark gray to black with a variable number of yellow spots; undersides of limbs reddish to yellowish in color.
Sexual Dimorphism: Males have a tan chin, brown eyes, and a slightly concave plastron. They do not have elongated foreclaws. Females have yellow chins, orange eyes, and flat plastrons. There is little sexual dimorphism in size. Males averaged 104.2 ± 7.3 mm CL (88-121, n = 80), 89.3 ± 6.1 mm PL (78-110, n = 80), and 144.5 ± 21.5 g body mass (91-189, n = 49). Females averaged 104.0 ± 6.9 mm CL (84-117, n = 73), 94.4 ± 6.5 mm PL (77-108, n = 73), and 164.5 ± 22.9 g body mass (116-234, n = 42). The sexes were equal in body size based on CL, but the sexual dimorphism index was 0.06 based on PL, indicating that carapaces and plastrons grew at different rates in males and females. In males, precloacal distance averaged 17.8 ±1.5 mm (16-20, n = 5) and the cloacal opening extends beyond the posterior margin of the carapace. In females, average precloacal distance was 7.0 ± 2.7 mm (5-11, n = 4) and the cloaca does not extend beyond the carapacial margin.
Juveniles: Juveniles are colored and patterned as adults, but with 1 spot in most pleural and vertebral scutes. There is a broad, irregularly shaped black blotch in the center of the plastron. Hatchling spotted turtles in Virginia were 24.0-32.8 mm CL(ave. = 28.9 ± 2.7, n = 9) and 23.1-26.4 mm PL (ave. = 24.4 ± 1.0), and weighed 4.0-6.4 g(ave. = 5.2 ±1.0).
Confusing Species: Other turtles lack yellow spots on a black shell.
Geographic Variation: There is no discernable geographic variation in body size or number of spots in Virginia populations of spotted turtles. Richmond and Goin (1938) noted that three specimens from New Kent County had fewer spots than found in spotted turtles farther north. The average number of spots on Virginia specimens (32.4) was less than the average reported for a Pennsylvania population (males = 46.9, females = 42.6; Ernst and Barbour, 1972).
Biology: Spotted Turtles have been found in ponds, ditches, flooded fields, creeks, the floodplain of meandering creeks, bogs, marshy pastures, and forested wetlands. Populations also occur in upper marshes of some tidal creeks (Dunson, 1986). Woods are often nearby or, in the case of flood-plains and low areas, overhead. Aquatic macrophytes or grasses are abundant components of the habitat during the summer. This species is the most aquatic member of the genus, but it is usually not found in deep water. The seasonal activity period begins as soon as the late-winter to early-spring thaw occurs. This turtle is seen primarily in the early spring but seldom beyond the month of June. Of the Virginia records, 72.4% occur March-May, 14.1% in June, and 13.5% in other months. The earliest observation in Virginia was on 19 February (Wells, 1966). On Carroll Island, Maryland, spotted turtles occupied wet areas in fields and wood-marsh ecotones during March to early May, dispersed under vegetative areas during May-July, dug deeper in aestivation sites under vegetation August-October, and returned to flooded puddles in November-February, where they overwintered underwater (Ward et al., 1976). Body temperatures of turtles caught in April in shallow water were 22.6-23.0°C (n = 3), 1° cooler than the water temperature (23.5-24.(PC). In Pennsylvania, spotted turtles overwintered in the mud, in muskrat burrows, and under banks of creeks (Ernst, 1976). Terrestrial activity occurs during the nesting season and sporadically at other times.
Spotted turtles are primarily carnivorous, although plants are sometimes consumed (Ernst and Barbour, 1989a). Surface (1908) found several types of insects, worms, slugs, snails, crayfish, spiders, and millipedes in specimens he examined in Pennsylvania. Several species of insects were found in the stomach of one Virginia specimen. Predators of these turtles are raccoons (Procyon lotor), dogs, and Snapping Turtles (Chelydra serpentina). Raccoons, skunks (Mephitis, Spilogale), foxes (Urocyon, Vulpes), and small mammals prey on eggs in the nest. Some unknown proportion of Virginia's spotted turtles are killed each year on highways.
Reproduction in this species has not been thoroughly studied. In Virginia, known clutch size is 3-4 eggs (ave. = 3.4 ± 0.5, n = 5). Ernst (1970) reported clutch sizes of 3-5 for a Pennsylvania population. Size at maturity for both sexes was about 77 mm PL. Mating occurs in spring in shallow water. K. A. Buhlmann (pers. comm.) observed mating in Virginia on 7 March and 2 April. Virginia females had eggs in their oviducts 1 May, 31 May, 7 June, and 10 June. Nesting dates for Virginia have not been reported, but elsewhere in its range nesting dates are in June (Ernst and Barbour, 1989a). In Virginia, eggs averaged 32.3 ± 1.6 x 17.5 ± 0.8 mm in size (length 30.4-37.8, width 16.8-19.0; n = 18) and weighed 6.4 ± 0.8 g (4.6- 8.1). Laboratory incubation time of three clutches was 61-70 days (ave. = 66.0 ± 4.6), and hatching occurred 6-16 August. Natural hatching occurred August-September in Pennsylvania (Ernst, 1970), but most hatchlings overwintered in the nest (Ernst, 1976).
The population biology of this species in Virginia is unknown. In a Pennsylvania population, densities were 16-32 per acre (40-79 per hectare), movements were less then 250 m, most of the population was comprised of turtles over 10 years of age, and maximum known age was 19 years (Ernst, 1976).
Basking occurs frequently, especially early in the activity season. Basking sites include logs, stumps, grass mats, and tussocks. Aggression occurs between males during the mating season. K. A. Buhlmann (pers. comm.) observed two Virginia males chasing and biting a female and each other on 7 March 1988.
Remarks: A vernacular name used in Virginia is "speckled tortoise" (Hay, 1902; Mitchell, 1990b).
The pattern of distribution in the Virginia Piedmont is puzzling. Is this a product of human alteration of the landscape in this area, a natural distribution pattern, or the collection pattern of herpetologists?
A male collected from Hog Island by M, K. Brady (1927) had a kyphotic shell. Two females collected in the Dismal Swamp in 1895 were missing limbs. Variations in scute numbers, abnormalities, and deformities occurred in 19% of 74 museum specimens examined by me.
Conservation and Management: The status of this species is unknown, largely because of the lack of information on the extent of populations in threatened wetlands. The primary cause of population decline and local extirpation is habitat loss from destruction of wetlands. A more-thorough inventory of spotted turtle populations in Virginia needs to be conducted in conjunction with an evaluation of the threats to the wetlands they occupy. Continued loss of local populations could cause this turtle to be afforded legal protection. An unknown number of this native species has been lost to the pet trade. Regional and national herpetological societies have sponsored resolutions seeking a halt in all commercial take of wild Spotted Turtles and more protection of the wetlands in which they occur.
References for Life History
Photos:
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