Costal grooves well-developed, 11-12 on each side of the body. Body elongated and slender. Tail usually longer than body with head. Adults are able to autotomize and regenerate the tail. Coloration black, dark-brown or brown-orange with oval yellow dorsal and lateral spots arranged in two more or less regular rows. Belly brownish. The extent of the yellow spot development is subject to variation. In contrast to females, the males possess a spike-shaped protuberance on the dorsal surface of the tail base and nuptial pads on the forelegs which are best developed during the breeding season. Mertensiella caucasica displays a high extent of morphological and, probably, genetic polymorphisms. In particular, specimens from Mtirala Mountain near Batumi Town, Georgia, have light, earthworm-like coloration and spots are reduced. There are also some altitudinal variations in the salamander morphometrics, including coloration, body proportions, etc.
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Georgia, Turkey
The salamander is found in Western Georgia and adjacent parts of Turkey. In Georgia, it inhabits the western spurs of the Trialeti Mountain Ridge, Meskhetian and Lazistanian ridges. The range margin runs eastwards approximately along the line Batumi Town - Kintrishi and Borzhomi District - Nedzura River, then south-westwards to Abastumani Town - Goderdzi Mountain Pass. In Turkey, the most south-western localities are Rize, Gunugoren, Tutuncu, and Giresun. The species lives mainly in the beech, coniferous, and mixed forests, in the subalpine belt and in alpine meadows. The salamander tends to avoid large streams and lives mainly near the 2nd through 4th order tributaries of rivers, usually no more than 1-1.5 m in width and about 20-30 cm in depth in spring. Such brooks flow in dense shade and their banks are covered with dense arboreal and herbaceous vegetation. Summer water temperatures are about 12ºC, and increase from a brook's source to its mouth. Postmetamorphic salamanders live in very wet conditions on stream banks in places with seepages, under stones, logs, snags, and roots. They also occur in the forest at long distances from the water, up to 200-300 m.
Life History, Abundance, Activity, and Special Behaviors
Mertensiella caucasica is a rare species with uneven spatial distribution. In suitable places, numerous individuals may be encountered. Maximum density is observed in places where there are logs and wooden blocks, combined with stone conglomerations, and a lot of small pools and shelters under tree roots. However, elsewhere, even in "visibly suitable" habitats, the salamander is absent. Such local populations inhabit relatively small plots, from 200-500 m along stream banks with the maximum concentration of sites suitable for shelter and reproduction. The larvae are more frequent in the headwaters of streams, probably because salamanders reproduce there. Sometimes the larvae drift downstream and occur in shallow swampy puddles. As in the majority of other brook salamanders, M. caucasica prefers cool conditions, probably about 15 -18ºC. According to data collected from medium elevations (Borjomi District of Georgia), the first active adults appear in early May and the last ones in September. Evidently, this reflects the start and the end of hibernation. However, in the warmest region (Batumi District of Georgia) and in highlands the hibernation period may be different. Breeding occurs in the late spring - summer. The reproductive behavior is generally similar to that of Salamandra salamandra. Mating occurs on land or in water. The spike on the male's tailbase probably has no special role in courtship and amplexus. The interval from copulation to egg deposition varies from 3 days to 2 months. The only clutch (or few clutches?) found in nature contained 92 eggs and was deposited on leaves and other submerged plants in a small hole in a stream bottom. Probably, newly hatched larvae stay in their hatching places before the next spring and then appear in streams. The development from fertilized egg to completed metamorphosis seems to take about 2 to 4 years. Metamorphosis evidently occurs throughout the summer. Larvae prey on stream invertebrates, Gammaridae, and larval insects. Adults eat mainly terrestrial invertebrates: Oniscidae, Arachnoidea and insects (Coleoptera, larval Diptera, etc.).
Trends and Threats
Overall situation with this species is unclear, but declines of some populations are documented.
Relation to Humans
Anthropogenic alteration of habitat is one of the main threats for M. caucasica. Destruction of forests (tree felling), the use of the salamander brooks as roads for the transportation of cut trees and destruction of habitats by cattle are known as causes of population declines. In general, this species avoids the human neighborhood and its populations do not live in anthropogenically altered landscapes.
Possible reasons for amphibian decline
General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
The two species in the genus Mertensiella, M. caucasica and M. luschani, are not sister taxa based on molecular sequence data. Some authors recommend including M. luschani in the genus Salamandra, while M. caucasica is more closely related to Chioglossa lusitanica. See Titus and Larson (1995) and Veith et al. (1998) for phylogenetic analyses and discussion.
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Titus, T.A., and Larson, A. (1995). ''A molecular phylogenetic perspective on the evolutionary radiation of the salamander family Salamandridae.'' Systematic Biology, 44, 125-151.
Veith, M., Steinfartz, S., Zardoya, R., Seitz, A., and Meyer, A. (1998). ''A molecular phylogeny of 'true' salamanders (family Salamandridae) and the evolution of terrestriality of reproductive modes.'' Journal of Systematics and Evolutionary Research, 36, 7-16.
Written by Sergius L. Kuzmin, modified by Meredith J. Mahoney (ipe51 AT yahoo.com), Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow
First submitted 1999-10-03
Edited by Meredith J. Mahoney
Species Account Citation: AmphibiaWeb 1999 Mertensiella caucasica: Caucasian Salamander <http://amphibiaweb.org/species/4255> University of California, Berkeley, CA, USA. Accessed Jul 23, 2019.
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Citation: AmphibiaWeb. 2019. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 23 Jul 2019.
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