The first ptychanthoid Lejeuneaceae in Miocene Mexican amber

Abstract

Two inclusions of leafy liverworts in Miocene Mexican amber are tentatively assigned to the extant genus Mastigolejeunea (Lejeuneaceae subfam. Ptychanthoideae). Both specimens share complicate bilobed leaves with a rounded lobe apex, a lobule with an oblique free margin continuing into the ventral margin of the leaf lobe, elongated leaf cells, a broad ventral merophyte, and undivided underleaves with a truncate to slightly emarginated, recurved apex. The lack of generative structures prevents a more thorough taxonomic treatment. Nevertheless, the inclusions represent the first ptychanthoid Lejeuneaceae from Mexican amber.