The new colonial dendrophylliid coral genus Cairnsipsammia is described from the Lower Cretaceous Schrattenkalk Formation (upper Barremian–lower Aptian) of western Austria (Vorarlberg). The new genus is characterized by plocoid to submeandroid types of polyp integration, compact to porous costosepta, and corallites that are united by their perithecal walls or embedded in a narrow (up to 2 mm wide) porous, reticulate and costate coenosteum with granular surfaces. It represents the oldest colonial genus of the family Dendrophylliidae. The occurrence of Cairnsipsammia in a shallow-water, reefal environment (Schrattenkalk Formation), in combination with both the relatively high degree of corallite integration (submeandroid) and massive growth form points to the hypothesis that Cairnsipsammia may have been zooxanthellate.