1) early formation of the mesenchyme mass between the zeugopod bifurcation as the base for the proxi-
modistal differentiation of preaxial, median and postaxial columns;
2) initial connection of the median column with postaxial one in the region of intermedium condensation;
3) early formation of the intermedium condensation in close contact with ulnar / fibular condensation;
4) dominance of the posterior or postaxial branch (ulnarefibulare) in the early limb development;
5) comparatively late formation of the basale commune which arises primarily as a small distal 2 condensation at the base of the digit 2 and later fuses with distal 1 condensation;
6) fusion of the skeletal elements in longitudinal rather than in transverse direction; usually amalgamation of the median elements with postaxial than with preaxial ones;
7) frequent (in 75%) amalgamation of the intermedium with ulnare;
8) presence of two central elements in the standard morphology;
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189Females of Salamandrella keyserlingii with deposited or fertilized eggs from the previous year spawn in the end of April- beginning of May. In females that have not spawned in spring maturing eggs are found in the oviduct by the end of May and copulation takes place in the beginning of July. It seems that both variants of breeding cycle exist side by side. If females could not get spermatozoids during summer then eggs are reserved for the next breeding season.
Differentiation of geographical populations of the Siberian newt Salamandrella keyserlingii throughout the species range was analyzed using a fragment of the cytochrome b gene. The population of the Primorye region (Russian Far East) is separated to the greatest extent; the Japanese and South Kuril populations are the next most separate. These populations are possibly subspecies. Geographical differentiation of populations in the Siberian part of the species range is lower, lacks a clinal variation, and is irregular. The molecular variation of S. keyserlingii supports the hypothesis that several primary vicarious refugia of pre-Pleistocene differentiation of a common ancestor of Salamandrella occurred in the southeastern part of its current distribution range and that northern and western regions were gradually colonized via repeated steps of expansion and retreat in the Siberian part of the modern species range.
