Haynes and McKown, 1974
Cagle's map turtle
Recognition
This map turtle has a cream-colored transverse bar on the chin and a yellow V-shaped mark on the dorsal surface of its head. Its somewhat flattened carapace (to 16 cm) is elliptical (wider posteriorly), serrated posteriorly, and bears a medial keel of sharp spinelike projections. Vertebrals are also raised in the center, giving the carapace a "lumpy" appearance. The carapace is olive to brown; each scute has yellow, contourlike markings, and the posterior midline of each vertebral is brown or black. The plastron is well-developed with a posterior notch. Its scute formula is: abd > an > fem > pect > gul > hum. The cream-colored plastron has a dark seam-following pattern; each scute may also contain black flecks. The cream-colored bridge is crossed by four black longitudinal bars, as also are the undersurfaces of the 5th to 8th marginals. The head is narrow. Its snout is somewhat pointed, and the triturating surfaces of the jaws are not greatly enlarged. The head is black and contains seven cream-colored stripes on the dorsal surface, with the medial stripe widest. Another broad stripe arises on each side of the head below and in front of the orbit and runs backward and upward forming a complete crescent-shaped mark around the orbit and meeting the stripe from the opposite side at the midline just behind the orbits to produce a V-shaped mark (viewed from above). Several other narrower stripes also follow this path, but do not meet. A cream-colored bar extends transversely across the lower jaw. Neck, limbs and tail are black with numerous cream to yellow stripes.
The diploid number of mitotic chromosomes is 50: 11 pairs of metacentric or submetacentric and two pairs of acrocentric macrochromosomes, and 12 pairs of microchromosomes (McKown, 1972; Killebrew, 1977a).
Adult males are 7-11 cm in carapace length, have longer vertebral spines and longer, thicker tails with the vent beyond the carapacial rim. Adult females have larger (to 16 cm) and more rounded carapaces with low vertebral spines. The female tail is shorter with the vent under the carapace.
Distribution
Graptemys caglei is restricted to the Guadalupe and San Antonio river drainages in south-central Texas.
Habitat
The streams in which Graptemys caglei lives are generally shallow with moderate currents. It has been taken in small and large pools with depths to 3 m, and with both limestone and mud bottoms (Haynes and McKown, 1974).
Natural History
Clutches contain 1-6 oval eggs (Wibbels et al., 1991), which are deposited near the water in a cavity approximately 15 cm deep (Vermersch, 1992). Possibly two or three clutches may be laid by a single female each year (Vermersch, 1992). Haynes and McKown (1974) collected hatchlings from September through November, indicating a late spring to early summer nesting season. Courtship, mating, and nesting have not been described.
Cagle's map turtle is predominantly insectivorous, although females also eat snails. Plant remains found in stomachs may have been incidentally ingested.
This turtle is a confirmed basker, often being observed on rocks, logs, and cypress knees. Haynes and McKown (1974) commented that logs that had fallen into the river but were still connected to the bank were shunned as basking platforms. When approached, basking Graptemys caglei quickly escaped into the water.
IUCN Red List Status (1996)
Vulnerable (A1c, B1+2c).