Taxonomic Synonyms: Amblystoma aterrimum (Cope, 1868), Amblystoma aterrium (Boulenger, 1882), Chondrotus aterrimus (Cope, 1887), Dicamptodon aterrimus (Dunn, 1823)
Vernacular Names: Idaho Giant Salamander, Rocky Mountain Salamander 

D. aterrimus are large, robust salamanders, reaching between 7.0-10.0 inches in total length (Petranka, 1998). The dorsum is darkish brown mottled with a lighter brown that give the appearance of a marbled surface. In some individuals, there is an absence of mottling about the mid-dorsal region (Stebbins, 2003). D. aterrimus are the darkest of the four species. The tail is thick, and laterally compressed at the distal portion in adults. Neoteny is apparent in some individuals. Neotenes are smaller than metamorphosed adults, reaching up to 4.5 inches in total length.  

Larvae are stream type, with short gills, streamlined bodies, and low tail fins. Larvae possess little mottling, and can be differentiated from D. tenebrosus by their darker color. A faint yellow stripe is usually present behind the eyes. The tail tip is mildly darker than the dorsal coloration, but not as contrasting as in D. tenebrosus. Larvae >60mm lack the dark tail tip, have gray colored ventral surfaces, and brownish-purple dorsal surfaces with little marbling (Petranka, 1998). Larvae are abundant in streams above 975 m (Maughan et al., 1976). Larvae are thought to metamorphose during their third year, when they measure around 140-180 mm (Petranka, 1998). Larvae may mature into neotenes when as small as 107 mm (Petranka, 1998).

D. aterrimus are found in the Rocky Mountains of north and central Idaho, and extreme western Montana, from Salmon River to the Coeur d'Alene drainage (Stebbins, 2003). 

D. atterimus was described based on molecular data that showed a significant difference between coastal populations and Rocky Mountain populations of D. enstatus (Daugherty et al., 1983). The Rocky Mountain type were then re-classed as D. aterrimus.

Taxonomic Synonyms: Dicamptodon copei (Nussbaum, 1970)
Vernacular Names: Cope's Giant Salamander 

D. copei rarely metamorphose, but are capable of doing so. Metamorphosed individuals are rare, with only a handful of accounts of natural occurrences. In the lab, even those treated with thyroxin rarely transform (Petranka, 1998). Neotenes are medium brown mottled with yellowish gold coloration, although some are unpatterned. Adults may reach 4.5-8.0 inches in total length. Conspicuous poison glands are found at the base of the tail in neotenes, and both larvae and neotenes lack eyelids. Young individuals possess a white ventral surface that turns bluish-gray with age. The head is notably narrower than the other species, and palatopterygoid teeth are absent (Petranka, 1998). 

Larvae and gilled adults are stream type, with short gills, streamlined bodies, and low tail fins. Like all Dicamptodondids, the gills of larvae and neotenes are bushy, and colored red. The dorsal surface of larvae is similar to the adult coloration, consisting of a medium to dark brown mottled with yellowish gold coloration, unpatterned. Larvae lack the black tail tip characteristic of D. tenebrosus. 

D. copei are found from the Olympic Peninsula, Washington, south through the Cascade Mountains and Willapa Hills to drainage streams of the Columbia River in Oregon (Stebbins, 2003). Populations may reside as at elevations as high as 1372 m (Petranka, 1998). Clear, cold streams in coniferous forests are the primary habitat, although mountain lakes and ponds are also inhabited. Larvae actually leave the water and crawl about on rocks and land near their water source during very wet nights.

D. copei are sympatric with larval D. tenebrosus over a large range, but are reproductively isolated (Daugherty et al., 1983). 

Courtship and reproduction strategy are poorly known, however, eggs are found throughout the year, with the exception of the winter season. Eggs are attached singly on the undersides of rocks and other debris by a short pedicel in subterranean hiding spots, where the female remains to guard clutches until hatching (Petranka, 1998). Clutch size is variable, and may be anywhere between 25-115 eggs. Females are thought to breed every other year. Like all animals that show parental care, females guarding eggs are highly aggressive toward potential predators, including conspecifics that may prey on the eggs. Egg robbing by conspecifics is common and contributes to the mortality rate of D. copei, as evidenced by battle scars and the high frequency of missing eggs from nests (Petranka, 1998).

Taxonomic Synonyms: Triton ensatus (Eschscholtz, 1833), Plethodon ensatus (Cope, 1868), Dicamptodon ensatus (Strauch, 1870), Ambystoma ensatum (Grinnell & Camp, 1917)
Vernacular Names: California Giant Salamander, Eschscholtz's Lizard, Marbled Salamander, Pacific Giant Salamander 

D. ensatus are very large, with adults measuring 8-12 inches in total length. The head is rather large, and can be used to distinguish transformed D. ensatus from similar D. tenebrosus. In metamorphosed adults, the dorsal coloration is rusty or dark brown overlain with copper coloration. Marbling is notable in southern populations. Marbling may also extend to the throat, and undersides of forearms (Mahoney, 2004). The ventral surface is typically whitish in southern counties, dull yellow in remaining areas, and lacking mottling or spotting. The tail is increasingly compressed toward the distal end. D. ensatus lack tubercles on the soles of the feet. Neotenes are found in some populations. 

D. ensatus are similar in appearance to D. tenebrosus, but differ in having larger heads, longer limbs, and more teeth in the upper jaw. D. tenebrosus also lack marbling about the throat and undersides of limbs. 

Larvae are stream type with short gills, streamlined bodies, and low tail fins. The gills are bushy, and dull red colored. There may be a light yellow stripe behind the eyes, and the tail tip is not as mottled as in D. tenebrosus. The dorsal coloration is medium to dark brown, often mottled with lighter brown. The ventral surface is cream colored or white.

D. ensatus are found in coastal ranges of California, including the counties of Sonoma and Napa, south to Santa Cruz County (Stebbins, 2003). Geographic isolates occur in Monterey County, near Little Sur River.

Transformed adults are found in moist forests near clear streams and seepages. Adults are mostly terrestrial, hiding under rocks and logs, or walking out in the open. Climbing is apparent but minimal, and usually restricted to shrubs and tree trunks. 

Breeding occurs in the spring and fall, when eggs are deposited in subterranean spots in clear flowing waters. Streams, seepages, and creeks are the preferred aquatic habitat, although lakes are also used. D. ensatus have one of the longest incubation period of all caudate species. From the early tail bud stage, development continues for nearly 5 months before the yolk supply is close to exhaustion (Petranka, 1998). Larvae hatch in winter, and may take up to 2 years to metamorphose. During their first year, larvae may grow 8-12 mm per month during the warmer months, reaching a maximum of 100 mm by the end of the 12th month (Petranka, 1998).

D. ensatus hybridizes with D. tenebrosus in a narrow zone of approximately 6 miles where habitats overlap in Mendocino Co. (Stebbins, 2003). Gene flow in this area is minimal because inhabited streams are disconnected and flow directly into the Pacific Ocean (Petranka, 1998).

Conspecifics are the primary predator, with larger individuals preying on smaller individuals. Other animals, such as fish, birds, shrews, mice, and snakes also prey on juveniles and larvae. D. ensatus are unique among all other caudate taxa in that they can emit a squeaking sound when disturbed.

D. ensatus. Adult from Santa Cruz Co., Calif. Photo © Gary Nafis, California Reptiles and Amphibians	D. ensatus. Adult from Santa Cruz Co., Calif. Photo © Gary Nafis, California Reptiles and Amphibians	D. ensatus. Adult from Santa Cruz Co., Calif. Photo © Gary Nafis, California Reptiles and Amphibians
D. ensatus. Photo © R.D. Bartlett	D. ensatus. Larva from Sonoma Co., Calif. Photo © Gary Nafis, California Reptiles and Amphibians	D. ensatus. Larva. Photo © Suzanne L. Collins, Center for North American Herpetology

For more photos, go to the Dicamptodon ensatus gallery

Taxonomic Synonyms: Amblystoma tenebrosum (Baird & Girard, 1852), Xiphonura tenebrosa (Girard, 1858), Amblystoma tenebrosum (Cope, 1868), Chondrotus tenebrosus (Cope, 1887), Ambystoma tenebrosum (Stejneger & Barbour, 1917), Dicamptodon tenebrosus (Good, 1989)
Vernacular Names: Pacific Giant Salamander, Oregon Salamander, Coastal Giant Salamander 

D. tenebrosus are similar in appearance to D. ensatus, with brown and copper colored marbling about the dorsum, but with a notably smaller head. D. tenebrosus also possess shorter limbs, and fewer upper teeth than D. ensatus. Fine grain marbling is present on the dorsum, but usually does not extend to the throat and undersides of limbs, as in D. ensatus. New morphs are colored brightly with golden markings, which become duller with age. Very old individuals may become completely pattern-less, except on the head (Petranka, 1998). The distal portion of the tail is laterally compressed. D. tenebrosus is the largest Dicamptodontid, reaching up to 13.5 inches in total length. Many populations contain gilled and transformed adults, while certain populations lack neotenous individuals entirely (Petranka, 1998).  

Larvae are stream type, with short gills, streamlined bodies, and low tail fins. The gills of larvae are bushy and red, and the ventral surface is bright cream colored. Larvae possess a distinct black tail tip, and mottling on the upper portion of the tail fin (Petranka, 1998). A yellowish stripe is usually present behind the eye. Black, cornified tips are present on the digits of larvae and neotenes, which aid in locomotion and remaining stationary in moving streams. As larvae age, the copper mottled coloration becomes more apparent about the dorsum, and the blotching on the tail and the black tail tip become less apparent (Petranka, 1998). 

D. tenebrosus are found from Chilliwack Valley, British Columbia, Canada, south through western Washington, excluding the Olympic Peninsula, western Oregon, and northwestern California to Mendocino Co. (Stebbins, 2003). East of the Cascade crest at Sears Creek, Wenatchee Lake, Chelan Co., and the north side of Kachess Lake, Kittitas Co., Washington, and at Oak Springs near Maupin, Wasco Co., Oregon (Stebbins, 2003). Also found coastally to Willapa Hills (north of Willapa River), Washington (Stebbins, 2003). California range includes inland to near Shasta Reservoir, Shasta Co., and McCloud, Siskiyou Co. (Stebbins, 2003). 

D. tenebrosus can be found in and near permanent and semi-permanent streams, rivers, and high elevation ponds and lakes (Stebbins, 2003). The terrestrial habitat consists of mesic and humid coniferous forests, especially coastal redwood and douglas fir forests, where adults can be found under rocks and logs, out in the open, or in nearby water sources. D. tenebrosus may climb several feet up tree trunks and other surface to forage for food. D. tenebrosus often burrow underground, and have been found at depths of up to 20 feet. The average elevation is typically <960m, but have been observed at elevations as high as 2160 m (Petranka, 1998). 

Breeding occurs primarily during spring and fall. Courtship is thought to occur in aquatic crevices, or under logs, where eggs are subsequently deposited. Females guard the eggs, which are attached singly to the surface of the subterranean retreat, or to rocks and other debris. Eggs are unpigmented, and attached with a pedicel (Petranka, 1998). The incubation period is extraordinarily long, lasting as long as 6-7 months. 

The length of the larval period and size at metamorphosis are influenced by the seasonality of the water source they inhabit. Those inhabiting smaller permanent and semi-permanent streams transform 18-24 months after hatching, while those in larger permanent streams are provided with adequate water levels to remain aquatic year-round, and may take up to 3 years to transform (Petranka, 1998). In large, permanent streams, neoteny is more frequent.

D. ensatus hybridizes with D. tenebrosus in a narrow zone of approximately 6 miles where habitats overlap in Mendocino Co. (Stebbins, 2003). Gene flow in this area is minimal because inhabited streams are disconnected and flow directly into the Pacific Ocean (Petranka, 1998).

D. tenebrosus are voracious feeders, taking invertebrates, other amphibians, and even small mammals such as mice and shrews. In the lab, larvae will consume conspecifics, and Ambystoma gracile larvae, but will avoid Taricha granulosa larvae (the most toxic newt species) (Petranka, 1998). 

D. tenebrosus is also capable of emitting a low growling sound when disturbed.

D. tenebrosus. Adult, Del Norte Co., Calif. Photo © Gary Nafis, California Reptiles and Amphibians	D. tenebrosus. Photo © Henk Wallays, Henk.Wallays@pandora.be	D. tenebrosus. Neotenic adult. Photo © Henk Wallays, Henk.Wallays@pandora.be
D. tenebrosus. Larva. Photo © Henk Wallays, Henk.Wallays@pandora.be	D. tenebrosus. Larva, Del Norte Co., Calif. Photo © Gary Nafis, California Reptiles and Amphibians	D. tenebrosus. Neotenic adult, Siskiyou Co., Calif., 5,000 ft. Photo © Gary Nafis, California Reptiles and Amphibians

For more photos, go to the Dicamptodon tenebrosus gallery