Forms of the West Tocharian copular verb ste and the Proto-Indo-European mediopassive endings / Формы западнотохарского глагола-связки ste и окончания праиндоевропейского медиопассива

The mediopassive endings of the Tocharian B copula forms ste, star-(3 sg.) and skente , skentar-(3 pl.) are in complementary distribution: -tar- and -ntar- were used before suffixed pro-nouns, -te and -nte at the end of words. In this article an attempt is made to reconstruct the prehistory of the Tocharian mediopassive in a way that would make it possible to derive the difference between -(n)tar-(reflex of *- (n)tr̥-) and - (n)te (going back to *- (n)to ) from a regular alternation. According to the proposed scenario, r -less secondary middle endings are innovations of several Indo-European dialects which developed after the split of the proto-language: these dialects lost *- r at the end of finite verb forms after vowels (initially only in utterance-final position, where the verb was placed in line with the basic word order).