Bryozoans of the genus Stomatoporopsis Illies, 1981 (Tubuliporina, Stenolaemata), with the first records from the Maastrichtian of the middle Volga River region and Mangyshlak

The first records of the bryozoan genus Stomatoporopsis from the Maastrichtian of the middle Volga River region and Mangyshlak are described: S. multigemmans (Illies, 1974), S. arguta sp. nov., S. illiesae sp. nov., S. mirabilis sp. nov., and S. caudata sp. nov. The diagnosis of the genus Stomatoporopsis Illies, 1981 is supplemented. "Marginal tubes" are interpreted as "marginal reptozooecia." The first instance of bilateral ramification in the family Stomatoporidae is given. Much attention is given to the adaptive significance of the dichotomous, lateral ramification, which developed as early as the initial stages of astogeny in the genus Stomatoporopsis.