PALEOMYRTINAEA, A NEW GENUS OF PREMINERALIZED MYRTACEOUS FRUITS AND SEEDS FROM THE EOCENE OF BRITISH-COLUMBIA AND PALEOCENE OF NORTH-DAKOTA

Paleomyrtinaea princetonensis gen. et sp. nov. Pigg, Stockey & Maxwell is described from the Middle Eocene Princeton Chert of British Columb ia, Canada. Anatomically preserved fruits are berries up to 1.6 x 0.78 cm with a fleshy fruit wall that consists of a three-layered pericarp . The exocarp is composed of a uniseriate epidermis of tabular cells a nd an outer hypodermis of small cells and die mesocarp is aerenchymato us. Some seeds are invested in a pulpy endocarp. The seeds are campylo tropous, 1.8 mm long and 1.6 mm wide, and contain a curved embryo cavi ty about 1.5 mm long and 0.64 mm wide. Four distinct integumentary zon es can be recognized, an outermost zone two to three cells thick of ta ngentially elongate cells, a second zone, constituting the bulk of the integument, of small, isodiametric cells, a third zone of uniseriate, columnar cells that extends into the germination valve, and an innerm ost zone of five to six layers of tangentially elongate cells. The gen us is also represented by fruits and seeds from the Upper Paleocene Se ntinel Butte Formation, Almont, North Dakota. Affinities of these frui ts are with the berrylike guavas of the Myrtaceae, tribe Myrteae, subt ribe Myrtinae, and in particular, with the closely related genera Mosi era Small and Psidium L. A brief review of the fossil record of the My rtaceae is also presented.