Salamandrella tridactyla (Nikolskii, 1906)
Because this is a cryptic species recently separated from Salamandrella keyserlingii, its conservation status is not known (Berman et al., 2005; Poyarkov & Kuzmin, 2008; Matsui et al., 2008)
Brown salamander with moderately long, flattened tail; usually 11-12 costal grooves; four toes; a light dorsal band and darker sides.
Almost indistinguishable from Salamandrella keyserlingii based on external morphology. In populations of S. tridactyla from Primorye the number of costal grooves (11-12) is lower than in S. keyserlingii (11-14/15) and the number of trunk vertebrae is lower (Litvinchuk & Borkin, 2003). Whereas in S. keyserlingii the egg sacs are spiraled, the clutches belonging to populations of S. tridactyla in the Primorye and Khabarovsk regions contain egg sacs which are just bended in banana-form (Kuzmin & Maslova, 2003).
The following description is largely identical to that of S. keyserlingii. Moderately sized, inconspicuous brown salamander One fold between digits when limbs are laid against the body. Head oval; paratoid glands well developed; gular fold present. Skin smooth. Limbs well developed; four fingers and (usually) four toes. Tail sometimes longer, equal to or shorter than snout-vent length. Flattened laterally and a dorsal keel throughout, ventral keel in distal two-thirds. Vent formed by three slits converging with apex forwards, median longest. Vomerine teeth beginning behind inner edge of nares, in V-shaped series. Lungs present (Dunn, 1923; Kuzmin & Maslova, 2003; Borkin, 1999). Males have relatively longer and higher tails, a larger cloaca (both in length and width), relatively longer forelegs than females. These differences are more pronounced during the reproductive period (Kuzmin, 1999). Color dull grayish brown, lighter below; a broad gold-colored band runs from snout to tip of tail. Inside this band, a thin dark stripe runs from neck to tail base. The golden band becomes dark and indistinct in males in the breeding season (Goris & Maeda, 2004). Total length 12 to 16 cm (Kuzmin, 1999).
Mitochondrial data suggest that S. tridactyla from Primorye and S. keyserlingii from other regions form two reciprocally monophyletic clades, with ~10% divergence (Berman et al., 2005). Salamandrella tridactyla is also characterized by a higher intraspecific divergence compared to S. keyserlingii (Berman et al., 2005).
Primorye (Lazovsky, Vladivostok and other localities), southern Khabarovsk area. The precise border between the ranges of S. tridactyla and S. keyserlingii is not yet known (Matsui et al., 2008).
In the Primorye region the salamander lives in river valleys, groves, bushes, areas with dark-coniferous taiga, and meadows. Reproduction takes place in a broad range of waters, from temporary, shallow puddles to permanent lakes. Although generally a lowland species, breeding in standing water, in Primorye the salamander also breeds in roadside ditches and shallow brooks with running water. It inhabits mountainous terrain up to about 900 m altitude (Kuzmin & Maslova, 2003).
The animals enter the water after hibernation. In Khabarovsk and Primorye the breeding season starts early April ending in May-June. Courtship behavior probably is similar to that of S. keyserlingii. Egg laying, hatching of the larvae and metamorphosis is earlier than in S. keyserlingii from southern Sakhalin, Zabaykalskiy, central Yakutia and northern Mongolia. Juvenile salamanders of this taxon are much smaller than of S. keyserlingii (Sato, 1993). The female produces a pair of egg sacs, connected to one another with a short mucous stalk, by which the clutch is attached to twigs and grasses. The clutches belonging to populations of S. tridactyla in the Primorye and Khabarovsk regions contain egg sacs which are just bended in banana-form (Kuzmin & Maslova, 2003). These egg sacs contain in general fewer eggs than the spiraled ones, with egg sacs from the Khabarovsk area containing 106 to 131 eggs on average (Sato, 1993).