(Wagler, 1830)
Mexican rough-footed mud turtle
Recognition
Kinosternon hirtipes has an elongated (to 18.2 cm), somewhat elevated, usually keeled carapace. Three longitudinal keels may be found on the young, but the lateral keels often disappear with age, and the medial keel may become restricted to the posterior portion of the carapace. The 1st vertebral is flared anteriorly, touching the first two marginals on each side, the 2nd through 4th are longer than broad, and the 5th is flared posteriorly. Marginals are narrow except for the 10th, which is elevated, and those posterior to the bridge, which are somewhat flared. The carapace varies from olive or light brown to dark-brown or nearly black; lighter individuals may have dark seams. The hinged plastron is short and narrow, not completely closing the carapacial opening. There is a posterior anal notch. The plastral formula is: abd> an > hum >< gul > fem >< pect. On the short bridge (23% of carapace length in males, 27% in females), the axillary and inguinal scutes are nearly always in broad contact. The plastron is yellow or tan to brown with dark seams (dark staining may cover the plastron of some individuals). The head is of moderate size with a projecting snout and a hooked upper jaw. Its rostral scale may be V-shaped and there are usually three pairs of relatively short chin barbels. Head and neck are tan to black, with light reticulations if black and dark reticulations or spotting if tan. Jaws are tan to gray and may be finely streaked with dark brown or black. Limbs and tail are gray, olive, or brownish.
The diploid chromosome number is 56: 26 macrochromosomes and 30 microchromosomes (Killebrew, 1975b).
Males are longer (to 18.2 cm) than females (to 15.7 cm), with vinculae, long spine-tipped tails, concave plastra, and the posterior marginals more flared.
Distribution
Kinosternon hirtipes ranges southward from the Big Bend region of Texas and adjacent Chihuahua on the Mexican Plateau, at elevations to 2600 m, to Mexico City.
Geographic Variation
Six subspecies are recognized; the following descriptions are taken largely from Iverson (1981a). Kinosternon hirtipes hirtipes (Wagler, 1830), the Valley of Mexico mud turtle, occurs only in the drainages of the Valley of Mexico. Adults have a triangular, rhomboidal, or bell-shaped rostral scale; a mottled head pattern with a light streak extending posteriorly from the corner of the mouth; one or typically two pairs of mental chin barbels with the anterior pair the largest; medium carapace length (both sexes reach 14 cm); a short bridge (17.6% of the carapace length in males, 21.7% in females); a relatively short interfemoral seam length (6.9% of carapace length in males, 7.1% in females); and a relatively long interanal seam length (20.6% of carapace length in males, 25.8% in females). Kinosternon h. murrayi Glass and Hartweg, 1951, the Mexican Plateau mud turtle, ranges from the Big Bend region of Texas and Chihuahua south in Mexico to northern Jalisco, northern Michoacán, and the eastern portion of the state of México. The rostral scale is V-shaped (posteriorly bifurcate); the head pattern is quite variable (mottled to reticulated); there are two pairs of mental chin barbels with the anterior pair largest; the carapace is rather large (males to 18.2 cm, females to 15.7 cm); the bridge is long (20% of carapace length in males, 23.7% in females); and the plastron has a long gular scute (14.7% of carapace length in males, 15.8% in females). The Lake Chapala mud turtle, K. h. chapalaense Iverson, 1981a, is confined to the Chapala and Zapotlan (and possibly the Duero) basins of Jalisco and Michoacán in Mexico. It has a reduced crescent-shaped rostral scale; reduced dark pigment on the head and neck (confined to isolated spots or reticulations dorsally, but sometimes as two dark lateral postorbital stripes); the neck and chin nearly immaculate and the jaws with few dark streaks; one to three pairs of chin barbels present (anterior pair largest); medium carapace length (males 15.2 cm, females 14.9 cm); a long bridge (20.3% of carapace length in males, 25.3% in females); and a long interanal seam (19.1% of carapace length in males, 25.2% in females). The Pátzcuaro mud turtle K. h. tarascense Iverson, 1981a is known only from the Logo de Pátzcuaro basin of Michoacán, Mexico. It has a finely mottled to spotted head; a V-shaped rostral scale; two pairs of chin barbels; small to medium body size (males to 13.6 cm, females to 13.2 cm); a short bridge (18.0% of carapace length in males, 21.4% in females); a short gular length (10.6% of carapace length in males, 12.6% in females), and a long interpectoral seam (10.1% of carapace length in males, 8.5% in females). K. h. magdalense Iverson, 1981a, the San Juanico mud turtle, is endemic in the Magdalena Valley of Michoacán, Mexico. It has a finely mottled to spotted head pattern with little or no jaw streaking; a large V-shaped rostral scale; two pairs of chin barbels; a small carapace (males 9.4 cm, females 9.1 cm); a small plastron; a short bridge (18.5% of carapace length in males, 19.7% in females); short gular scutes (9.9% of carapace length in males, 11.0% in females); and a long interpectoral seam (8.7% of carapace length in males, 11.0% in females). The last subspecies, K. h. megacephalum Iverson, 1981a, the Viesca mud turtle, is known only from two localities in southwestern Coahuila, and may now be extinct since natural water bodies apparently no longer exist in the area. Iverson (1981a) described it as having an enlarged head with broad triturating jaw surfaces and enlarged musculature. Other characters are a V-shaped rostral scale; a head pattern like that of K. h. murrayi; three or four pairs of chin barbels (the anterior pair largest) and another small pair at the level of the anterior edge of the tympanum; small body size (males to 9.9 cm, females to 11.7 cm); a very small plastron; a short bridge (17.3% of carapace length in males, 23.9% in females); short gular scutes (11.0% of carapace length in males, 12.8% in females), and a short interanal seam (15.9% of carapace length in males, 20.9% in females).
Habitat
The rough-footed mud turtle inhabits bodies of water in arid mesquite grasslands. It usually is found in lakes, ponds, streams, or rivers flowing into lakes, but also enters temporary pools, stock ponds, and marshy areas.
Natural History
Females mature in 6-8 years at 95-100 mm carapace lengths (Iverson et al., 1991). Ovulation occurs from late May to late September. Nothing has been reported on the attainment of maturity by males, their sex cycle, or courtship behavior.
Nesting occurs from at least early May to September in Mexico, two to four clutches of 1-7 eggs may be laid each season (most females produce two clutches by July). The eggs are elliptical (24.2-33.2 x 14.6-18.6 mm) and brittle shelled (Iverson, 1981a; Iverson et al., 1991). Eggs undergo embryonic diapause (Ewert, 1985, 1991).
Hatchlings are from 20-27 mm long with a brown carapace and a red or orange, dark-centered plastron.
Kinosternon hirtipes is carnivorous, feeding on a variety of insects, worms, and other small invertebrates, amphibians, and small fish.
It is chiefly nocturnal but sometimes active by day, and seems more aquatic than some other species of Kinosternon; Seidel and Reynolds (1980) found it consistently demonstrated greater evaporative water loss compared to the more terrestrial K. flavescens. Unlike many of its congeners, K. hirtipes and its sister taxon K. sonoriense are not known to aestivate terrestrially (Iverson et al., 1991).
IUCN Red List Status (1996)
Not listed.