Blue-spotted Salamander
Ambystoma laterale
Summary: Common in wooded portions of the region, especially in Cook and Lake Counties Illinois, and Porter and LaPorte Counties Indiana. Apparently absent west of the Fox River. Polyploid varieties occur in Indiana and at one Illinois locality.
Description: A medium-sized salamander, 10-14 cm total length. Black or blue-black above with pale blue flecks heaviest on the lower sides, sometimes present on the dorsal surfaces as well. The blue-spotted salamander is not easily confused with any other Chicago region salamander.
Polyploid members of the Ambystoma jeffersonianum-Ambystoma laterale complex occur in the eastern part of the region. Formerly thought to be distinct species (Uzzell, 1964), these populations are now considered to be hybrid-derived genotypes with various combinations of chromosome sets from both parental species, the blue-spotted and Jefferson's salamanders (Lowcock et al, 1987). Polyploids are larger (to about 18 cm), lighter in coloration, and have proportionally longer tails and limbs and wider snouts. Polyploids can be distinguished from diploids with 90 percent reliability by measuring snout-vent length and internarial distance (Lowcock et al, 1992). Identification to genotype requires more specialized analysis.
Distribution and Status: Diploid blue-spotted salamanders are common at numerous wooded sites east of the Des Plaines River, and occur more sporadically as far west as the Fox River. They are apparently absent from the extreme western part of the region. In Illinois, the species is known from Cook, Lake, DuPage, and eastern Will Counties, and from a single locality in eastern McHenry County. Anecdotal reports from extreme northeast and southeast Kane County are unverified. In Indiana, diploids are known from Lake, Porter, and Starke Counties. Only polyploid populations are known from LaPorte County, and diploids and polyploids exist in close proximity in northern Porter County. Three ponds in Cook County support polyploids accidentally introduced in the late 1950s.
Habitat:This species inhabits a variety of wooded areas, from 30 to 100 percent canopy cover. Peak abundance is reached at northern flatwoods sites with numerous vernal ponds; the blue-spotted salamander is usually the dominant amphibian species in flatwoods, and is considered characteristic of the community type (White, 1978). Most other upland forest, woodland, and floodplain forest communities are also utilized. Blue-spotted salamanders are present in many black-soil savanna remnants, but are abundant only in a few better quality examples. They are usually rare in northwest Indiana sand savannas, but more common in the more densely wooded parts of the dunes region.
Phenology: First emergence has been reported as early as February 28 and as late as April 15. Breeding activity more typically begins in mid-March, but depends on weather. Males arrive at the ponds first, as soon as the ground has thawed and sometimes before the last of the ice has melted from the surface of the water. Females usually begin to arrive in numbers a few days later. Surface movement peaks on mild rainy nights, but continues at lower levels even under drier conditions. Migration may be interrupted several times by freezing temperatures.
Courtship takes place in the ponds, and 24 to 48 hours later the females deposit single eggs attached to the pond-bottom leaf litter (diploids) or small masses attached to sticks or vegetation (polyploids). Eggs hatch within a few weeks, and the larvae leave the ponds around the beginning of July.
Diploid adults remain surface active longer than most other salamanders, and they can be found under logs during much of April and May, and again in the fall. Polyploids are apparently less tolerant of dry conditions, and they spend much shorter periods of time above ground.
Literature Cited
Lowcock, L. A., H. Griffith, and R. W. Murphy. 1992. Size in relation to sex, hybridity, ploidy, and breeding dynamics in a central Ontario population of the Ambystoma laterale-jeffersonianum complex. J. Herpetol. 26:46-52.
Lowcock, L. A., L. E. Licht, and J. P. Bogart. 1987. Nomenclature in hybrid complexes of Ambystoma: no case for the erection of hybrid "species." Syst. Zool.6:328-336.
Uzzell, T. M. 1964. Relations of the diploid and triploid species of the Ambystoma jeffersonianum complex (Amphibia: Caudata). Copeia 1964:257-300.
White, J. 1978. Illinois Natural Areas Inventory. Technical Report. Illinois Natural Areas Inventory, Urbana, IL. 426p.
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| Updated: October 9, 2007
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