Triturus pygmaeus (Wolterstorff, 1905)

Arntzen, Jan W., 2024, Morphological and genetic diversification of Old-World marbled newts, with the description of a new and ‘ not-at-all-cryptic’ subspecies from the Iberian Peninsula (Triturus, Salamandridae), Contributions to Zoology 93 (2), pp. 127-152 : 149

Triturus pygmaeus

The description of the species’ external morphology below largely follows García-París et al. (1993: 5), albeit that in my terminology marbled newts have a dark dorsal side with a green colouration pattern. The male crest is lowered over the pelvic area and males from the northern part of the species range (with the reticulated colour pattern) were found to have not shorter but longer digits that those in the south.

Large head, longer than wide, gradually sharpened, ending abruptly in a narrow, blunt nose. Small eyes placed in a forward position. Gular fold moderately conspicuous. Elongated body with long, thin legs. Digits long, especially in males. Toe webbing absent. Relatively short tail, its cross-section being almost cylindrical at the base and progressively compressed towards the tip. Finely granulated skin, ridged in the gular region, with large granules unevenly spread over the dorsal surface. A general north to south decrease in overall size, be it that individuals of extremely small size have been reported in and around the Doñana National Park, irrespective of intraspecific taxonomic affiliation.

During the terrestrial phase the dorsal colour pattern consists of an irregular pattern of olive-green spots on a dark background. These spots can create a reticulum covering the side of the body or be sparse or absent in the middle, to the effect of a dark, more or less wide band running along the side of the body (fig. 3). In females, the dorsal midline appears as a continuous orange stripe whereas males have a line with alternating orange-yellow and black narrow bands. The dorsal part of the tail shows the same colour as the dorsum. Ventrally, the colouration is that of an offwhite, crème to grey background, sometimes with an orange hue towards the cloaca, on which large blackish spots and small white dots may be found. These white dots may show a higher density on the flanks and occasionally completely cover the background colouration. White dots are also present on the base of the flanks, spreading over the sides of the neck and the cheeks, here alternating with black spots. The ventral black spots are usually large and roundish in males and small and more elliptically shaped in females. The ventral background colour continues over the gular region, often at a lighter shade of pale. The distribution of black and white dots does not seem to follow any obvious geographical trend (fig. 3, Appendix fig. A1). Juveniles show a brighter colour than adults, frequently with a conspicuous, fluorescent-like orange dorsal line and fluorescent-like green dorso-lateral colouration, and a yellowish ventral colouration.

During the breeding period the males have a moderately high dorsal crest, which continues along the tail with an inflexion in the pelvic area. Male crest blotched by alternating black and white vertical bands. In the female, the mid-dorsal line usually shows orangeyellowish, or greyish tones. Male cloaca exposed, swollen and deep black. Female cloaca walnut-shaped, bordered with papillae. Well-developed labial folds during the aquatic phase, especially in females. While the intensity of the dorso-lateral colouration pattern may change during the aquatic phase, especially in males, the reticulation itself remains. Some individuals may become very dark and melanic in appearance, with the colouration pattern difficult to discern. Post-metamorphic juveniles are rarely if ever found in the water.