PERMINERALIZED FRUITS OF DIPLOPANAX (CORNACEAE, MASTIXIOIDEAE) FROM THE MIDDLE EOCENE PRINCETON CHERT OF BRITISH-COLUMBIA

Over 80 specimens of a permineralized fruit referable to the Cornaceae (Mastixioideae) have been recovered from the middle Eocene Princeton chert (Allenby Formation) of British Columbia, Canada. Specimens were studied using a modified cellulose acetate peel technique using hydrof luoric acid. Diplopanax eydei Stockey, LePage et Pigg sp. nov has frui ts with endocarps up to 11 mm long and 10 mm in diameter that have a s mooth stone surface, a single locule that is U-shaped in cross section , and a germination valve that extends nearly the full length of the f ruit. An epicarp (exocarp + mesocarp) composed of thin-walled parenchy matous cells, 1.2-1.5 mm thick, is preserved on one specimen. Remnants of an apical disc with possible perianth scars are seen in three spec imens. The endocarp is composed of interlocking fibers with scattered resin ducts and vascular tissue that parallels the edges of the valve. Seed integuments consist of a single external layer of large cells wi th brown contents and an inner zone of two to four thin-walled cells o f smaller diameter lacking contents. Numerous septate fungal hyphae ar e usually present in the integumentary layers. These fruits represent the first reported fossils of the genus Diplopanax Handel-Mazzetti, an d the northernmost known mastixioids in North America. The fruits are compared to those of other living and fossil mastixioids including Mas tixicarpum Chandler and add to our knowledge of the diversity and dist ribution of the North American mastixioids during the Tertiary. (C) 19 98 Elsevier Science B.V. All rights reserved.