Desmognathus fuscus 

INTRODUCTION

• Desmognathus fuscus is a species of amphibian in the family Plethodontidae (lungless salamanders).

• The species is commonly called the dusky salamander or northern dusky salamander to distinguish it from populations in the southern United States which form several distinct species, the southern dusky salamanders (D. auriculatus, D. valentinei).

• They are most common where water is running or trickling.

• They hide under various objects, such as leaves or rocks, either in or near water. Alternatively, they may enter burrows for protection.

• The dusky salamander lays its eggs close to water under moss or rocks, in logs, or in stream-bank cavities. The larval stage which follows is normally aquatic.

DESCRIPTION

• A small but sturdy salamander, the upper body of the northern dusky salamander varies in colour from reddish-brown to gray or olive, with a white or grey underside.

• The body is sparsely covered with dark spots or mottling concentrated on the sides. It also has a light dorsal stripe or two dark stripes that continue on to the first part of the tail.

• Juvenile colouring consists of five to eight pairs of dorsal spots or blotches located between the front and hind legs. Older individuals tend to be uniformly dark brown or black.

•  As with all dusky salamander species, both juveniles and adults have a pale single stripe outlined in black that extends from the eye and runs diagonally to the rear of the jaw.

• Additionally, both have 14 costal grooves, larger hind limbs than forelimbs, and a keeled (knife-like) tail that is triangular in cross-section and compressed laterally at the base.

• The tail is less than half its body length and is normally lighter in colour in comparison to the body.

• Adults attain lengths of up to 14 cm, with the average length of adult males and females being 9.4 cm and 8.6 cm, respectively.

•  Being from the family Plethodontidae, the northern dusky salamander is lungless. It absorbs oxygen through the skin and membranous tissue located in the mouth and throat.

• The dusky salamander also has a naso-labial groove, which aids olfaction, and thus the ability to search out mates and prey through smell.

HABITAT

• The Northern Dusky Salamander (Desmognathus fuscus) primarily inhabits cool, clear streams and their adjacent forested areas.

• They can be found under rocks, logs, and leaf litter, with a preference for moist, riparian zones.

• These semi-aquatic salamanders are highly dependent on clean water sources and are sensitive to environmental contaminants.

REPRODUCTION

• After successful courtship, mating occurs. The male transfers a spermatophore, a packet of sperm, to the female's cloaca, where fertilization takes place. Unlike some other amphibians, Northern Dusky Salamanders do not lay eggs externally.

• Once fertilization occurs, the female retains the fertilized eggs internally. This is in contrast to many other amphibian species that lay eggs in water. The female carries the eggs inside her body until they are ready to hatch.

• The eggs develop within the female's body and hatch into fully formed miniature salamanders, bypassing the free-swimming larval stage that is characteristic of many other amphibians. This process is known as direct development. The young salamanders are often quite advanced at birth, having fully developed limbs and resembling miniature adults.

• When the young salamanders are fully developed, the female gives birth to live offspring. This live birth is a unique reproductive strategy among amphibians. The number of offspring produced in each brood can vary but typically ranges from a few to a dozen or more.

• After birth, the female may provide some level of parental care by guarding the newly born salamanders for a brief period. This behavior helps protect the vulnerable young from potential predators.

• The newborn salamanders are independent from birth and go through a juvenile stage where they continue to grow and mature. They often resemble miniature versions of the adults but may have more vibrant coloration.