Variabilität, Verbreitung und Systematik der Arten und Unterarten in der Gattung Pungitius Coste, 1848 (Pisces, Gasterosteidae)

On the systematics and the evolution of variation and distributional patterns in the species and subspecies of the genus Pungitius Coste, 1848 (Pisces, Gasterosteidae) 1. In the genus Pungitius (similarly as in Gasterosteus) there seems to be of some interest the bony armature, especially from the zoogeographical point of view. These lateral bony shields are developed in the skin (instead of scales which are completely lacking in the family of Gasterosteidae) and are more or less present just as to the provenance of the individuals. 2. Preponderantly with respect to this bony armature several species and subspecies have been distinguished in the genus Pungitius, the variability, distribution and systematics of which are critically reviewed and compared in the present paper on the basis of museum material and data from the literature. 3. For the sake of adequate interpretation of modern distributional patterns there may be assumed an originally fully armoured type at the end of the Tertiary from which (after having escaped the ice by southward migration) during the Pleistocene period in several refugial areas new species or subspecies have derived, partially by reduction of the bony armature under freshwater conditions. During postglacial times these subspecies penetrated different areas but in some localities also produced mixed populations ofter having contacted within the same region. At least in some cases this may have led to subsequent hybridization. 4. The species P. platygaster in its modern distribution in the ponto-caspi-aralic region is now geographically isolated from the holarctic-circumpolarly distributed P. pungitius in its recent subspecies pungitius with reduced bony armature. Of this latter (originally fully armoured) species populations are assumed to have penetrated, at latest during the penultimate (= Riß) glaciation the Caspian Sea and subsequently the Black Sea and Lake Aral. These populations are the assumed ancestors of the nowaday still fully armoured P. platygaster. A decision as to the real degree of differentiation between the recent P. pungitius and P. platygaster has to be left to future crossbreeding experiments the results of which will possibly lead to a subspecies concept only. 5. In contrast to the foregoing the fully plated original type of P. pungitius underwent a serious reduction in its bony armature especially in the Southwest European refugium which led to a total loss of bony shields in the subspecies P. p. laevis. 6. As may be concluded from the now occurring types, this reduction seems to have been generally less pronounced in the East Asiatic refugium. We are confronted here, probably as a result of postglacial spread with the occurrence of three subspecies within the same area, i. e. the fullyarmoured P. p. sinensis on the one hand, and P. p. tymensis with reduced lateral plates (and also reduced lateral processes of the pubic bones in the pelvis girdle) and the holarctic-circumpolarly distributed P. p. pungitius with likewise reduced bony armature on the other hand. Of these subspecies the fully plated sinensis seems in its appearance to approach best what we perhaps may imagine as the original type of P. pungitius at the end of the Tertiary.