It is a small urodelo amphibian (with tail), slender and rounded in appearance. The total length of males varies between 6.7 and 7.5 cm, and that of females between 7 and 10 cm. The head is longer than wide, with a rounded snout and small, prominent eyes, with a golden iris and a black band on both sides of the pupil. The parotid glands are small and clearly visible. It has small legs and no palmeadura between its fingers. Its tail is longer than the length of the head and body combined, is very compressed on the sides and has small ridges both above and below and ends in a point, with a small filament called “flow rate”. The skin is smooth in the water and grainy on land, with a longitudinal furrow along the back. The colour of the back of males is greyish with a yellowish background, while that of females is darker. On this background there are numerous scattered black spots. During the mating season, the back usually turns light brown or olive and and a conspicuous white line appears on the sides that delimits the belly and extends in females from the mouth to the cloaca, and in males it reaches the end of the tail. The colour of the belly is orange or red throughout the year, and can become a very bright colour, sometimes yellowish, with small black spots lined up on both sides of the belly. During the oestrus period, the back is light brown or olive, with irregular black patches. When moulting in the terrestrial phase, the colour is almost uniform black. The female is larger than the male, with a broad head and rounded snout, and a cone-shaped cloaca; in contrast, the male is smaller, with a narrower head, a sharper snout, a more laterally compressed tail, and a rounded cloaca.

It lives mainly in small or medium water mass devoid of vegetation and with clear and cold waters. It is frequently seen in streams, washing places and pylons, fountains, streams, ponds, reservoirs, etc. It also likes to enter caves or abandoned mines and, in summer, come out of the water to hide under stones. It can be found at an altitude of 1,600 metres. It is a western Iberian endemism, and in Spain it is present only in Galicia and in parts of the western half, occupying Salamanca, Extremadura, the Montes de Toledo, part of Asturias, the Central System and the western part of Andalusia. In Portugal, it is present in practically the whole territory. It is quite frequent within its area of distribution, being victims of being run over especially when the first rains of autumn begin. The heat period takes place between January and May, and is carried out either day or night. During mating, the male is placed inversely to the female to move the tail to her side for a long time, then the male deposits a packet containing the sperm, for the female to collect. Females from February to early June begin to lay between 100 to 250 eggs about 2 mm in diameter, fixed between the vegetation or, in the absence of vegetation, on any other object, independently of each other. The hatching of the eggs, which are greyish-brown above and whitish below, takes place within a few weeks, depending on the temperature of the area. At the time of hatching, newborns measure about 8 mm. and are very light yellow in colour, with darker areas; later they become light brown with many dark dots on the back and no pigmentation on the belly. They have a kind of crest on the back and tail (dorsocaudal crest), which is highly developed and starts just behind the head. The tail ends abruptly, with a not very visible terminal appendage. The legs have rather short toes. As metamorphosis approaches, the colour of the back becomes duller and darker, the crest is reduced, the gills become rudimentary and the legs become quite developed. At the end of metamorphosis they resemble adults in the terrestrial phase and measure 2 to 3 cm LT (total length including tail). They lead a strictly terrestrial life for several years, until they reach sexual maturity.

Adults eat larvae of Diptera, Diptera, Odonata, Coleoptera, Heteroptera, Oligochaetes, Ostracoda, small insects, larvae of other amphibians, and others that fall into the water. During the winter, they catch invertebrates on land that are not excessively hard. It is the most aquatic of all the newts, although it has two phases, the terrestrial phase, which always takes place depending on the area and climate, from mid-summer until November, and the aquatic phase, the rest of the year. They are nocturnal during the terrestrial phase, being easy to observe in the water during the day, although the largest populations are observed at night. It is very agile in the water and on the contrary clumsy on land, moving slowly with oscillations. When it is in the water, it comes to the surface to breathe, and does so quickly, allowing itself to sink slowly. With the first rains of autumn, they increase their activity. Among the animals that feed on the Iberian newt are water snakes (Natrix natrix), collared snakes (Natrix maura) and vipers (genus vípera).