Kinosternon alamosae

Berry and Legler, 1980
Alamos mud turtle

This medium-sized (to 13.5 cm) mud turtle has a narrow, oval, rounded or flat-topped, keelless carapace. Its scutes are imbricate, and the 1st vertebral does not usually touch the 2nd marginals. The 10th and 11th marginals are higher than the rest, with the 10th highest. The posterior margin of the carapace is straight and often vertical, but not flared or recurved. The carapace is tan or brown to olive with dark seams; often the sutures of the underlying bones can be seen through the translucent scutes. The plastron is double hinged, and the movable anterior and posterior lobes are extensive, closing or nearly closing the shell completely so the head, limbs, and tail are hidden. If present, the anal notch is very small. The plastral scute formula is: abd > an > gul > hum > fem > pect. The plastron is yellowish with brown seams and growth annuli. The bridge is long, 26-33% of the carapace length, and the axillary and inguinal are widely separated. The inguinal touches the 6th marginal, but not the 5th. On the broad head are a short snout and a slightly hooked upper jaw. The rostral shield is neither concave posteriorly nor V-shaped. Two yellow barbels occur on the chin. Dark spotting occurs dorsally and mottling laterally on the gray heads. A pale stripe extends from the orbit to the corner of the mouth. The jaws are cream to gray and are faintly streaked with brown in males. The neck is gray dorsally and yellow ventrally. No vinculae occur on the thighs or crura, but the tail ends in a spine.
Males are slightly larger but narrower than the females, and have concave plastra and long, thick tails. The females have flat to slightly concave plastra and short tails.

Kinosternon alamosae occurs on the Pacific coastal lowlands of Mexico from the vicinity of Hermosillo, Sonora, southward into Sinaloa to at least Guasave. It is found at elevations ranging from sea level to 1000 m in the Sierra de Alamos.

The Alamos mud turtle lives in aquatic habitats which are seasonally dry, particularly ponds (Kinosternon alamosae biotope). During these dry periods it apparently aestivates under the dried mud.

Natural History
Female maturity is reached at a carapace length of 90-95 mm in 5-7 years (Iverson, 1989a). Iverson (1989a) observed courtship and mating in July. Berry and Legler (1980) and Iverson (1989a) examined the reproductive tracts of several females and concluded that a clutch comprises 3-5 eggs and that some females may lay more than one clutch per season. Clutch size is not correlated to female size. They hypothesized that follicular development begins when the females become active early in the wet season and that nesting is probably completed by the end of the wet season in October or November (females had oviducal eggs 20 July to 27 August).
The eggs are relatively small, averaging 27.2 mm in length (24.6-29.4) and 15.2 mm in width (13.5-16.5); average egg mass is estimated to be 3.7 g (Iverson, 1989a).
Natural foods include insects, clam shrimps, centipedes, scorpions, anurans, and some plant material (mainly seeds) (Iverson, 1989a). This is a shy species that withdraws into its shell and never bites.
K. alamosae is very tolerant of water temperatures as high as 42°C (Iverson, 1989a). It is most active during the wet months, July through September, a very short annual activity period with the turtle spending most of the year in aestivation.

IUCN Red List Status (1996)
Not listed.