About Aneides lugubris (Hallowell, 1849)
Aneides lugubris (Hallowell, 1849), commonly called the arboreal salamander, measures 6.5–10 cm (2.6–3.9 in) in snout-vent length (SVL). It has a plain purplish-brown base color, and is usually dorsally spotted with gold or yellow, though some individuals are unspotted. Juveniles are overall dark, clouded with a greyish tone and marked with fine yellow speckling on the back. Males of this species can be distinguished by their broad triangular head, with the front jaw teeth extending beyond the bottom lip. Compared to most other salamanders in the order Urodela, this species has longer and sharper teeth; compared to most other plethodontid salamanders, it also has much more developed teeth and jaws. After the second year of development, the anterior section of the skull becomes heavily ossified and bulbous; teeth increase in size but decrease in number to make the overall jaw more robust. In contrast, the body's long bones and pelvic plate never complete ossification over the salamander's entire lifespan. The tail is prehensile. Large adults can deliver a painful bite. As a plethodontid (family Plethodontidae) salamander, this species is lungless, and breathes through its skin as well as membranes in its mouth and throat. Aneides lugubris is insectivorous, and has been recorded eating beetles, caterpillars, sow bugs, ants, and centipedes. It is an excellent climber and difficult to capture. It is nocturnal, and spends daylight hours and dry periods in oak tree cavities, often gathered with many other individuals of its own species. Because it primarily lives in trees, the arboreal salamander has been observed deliberately using its body to protect itself from falls. When falling, it can use its limbs to glide or parachute, creating a controlled, directional fall to minimize injury. This aerial behavior is thought to have evolved through generations of adaptation to falling from its arboreal habitat. This species has relatively low rates of water loss, which may be due to its rapid water intake and postural adaptation of curling its body and tightly coiling its tail. It can produce sounds that have been compared to the faint bark of a dog. All members of the genus Aneides are characterized by the loss of the aquatic larval stage common to most salamanders, as well as their unusual arboreal and climbing tendencies. Aneides lugubris is the largest species in its genus, and one of three Aneides species found in Western North America. Arboreal salamanders are nearly endemic to California, and occupy coastal woodlands, conifer forests, and shrublands. They are found from Humboldt County, California down to northern Baja California, Mexico, and also live on the offshore islands of South Farallon, Los Coronados, Catalina, Ano Nuevo, and San Francisco. They thrive in moist terrestrial habitats, which limits their terrestrial activity to periods of elevated humidity. They spend most of their time under forest floor leaf litter, and retreat to tree cavities during summer to stay moist. This species has a unique reproductive strategy. Females lay eggs in moist burrows (or in holes of live oak trees, or under rocks, logs, or other ground cover under dirt), and eggs are laid and guarded in these burrows. Clutch size ranges from 5 to 24 eggs, and laying occurs in late spring or early summer. Embryos hatch after 3–4 months, in August and September. After hatching, hatchlings enter the moist burrows where they were laid. Adult salamanders stay near their eggs to shield them from predators and environmental hazards, providing parental care that increases the hatchlings' chance of survival. Hatchlings measure 24 mm in SVL. Age at maturity is 2.69 years, and the average adult age is 8–11 years. Annual survival probability increases with age, rising from 0.363 at age 0 to 0.783 for individuals older than 4 years.
