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Abstract Detail

Paleobotanical Section

Bronson, Allison W. [1], Klymiuk, Ashley [2], Stockey, Ruth [3], Tomescu, Alexandru [1].

A perithecial sordariomycete (Ascomycota) of diaporthalean affinity from the Early Cretaceous of Vancouver Island, British Columbia (Canada).

A perithecial ascomycete represented by > 70 fruiting bodies is preserved by cellular permineralization in marine carbonate nodules dated at the Valanginian-Hauterivian boundary (Early Cretaceous, ca. 136 Ma), from Vancouver Island, British Columbia,Canada. Spheroid perithecia with lumina 330-470 µm wide and 220-320 µm high, are preserved at similar developmental stages, close to or at maturity. They are densely distributed and entirely immersed in the tissues of a coniferous leaf. The perithecial wall comprises two layers: an outer layer of large pseudoparenchyma, tightly integrated in and difficult to separate from the host plant tissue, and an inner layer (17-26 µm thick) of thin filamentous nature. Perithecial necks are incompletely preserved, broken at the surface level of host tissues by taphonomic abrasion. They have a bell-shaped chamber (115-140µm in widest diameter and 75-105 µm high) at the base and a narrow (30-35 µm)channel, with longitudinally aligned hyphae, above. The basal chamber is filled with a plug of pseudoparenchyma (cells 8-18 µm in diameter), which subsequently disintegrates to form a peripheral collar; periphyses are present on the basal chamber walls. A hymenium composed primarily of pseudoparenchymatous tissue (cells 12-33 µm in diameter) lines the bottom of perithecia. Asci are clavate to teardrop-shaped and small (ca. 35 µm long and 14 µm wide at the tip), with 0.4-0.8 µm (diameter) punctae ornamenting their surface. They break off from the hymenium to float freely in the perithecium. No unequivocal ascospores were found, although smaller units are present in some of the asci. The combination of immersed perithecia with complex wall structure and a well defined hymenium, absence of paraphyses at maturity, and persistent, detachable inoperculate asci, is consistent with order Diaporthales of class Sordariomycetes. The small asci, delicate spores, and fully immersed perithecia suggest affinity with family Gnomoniaceae, although given the state of flux of current diaporthalean systematics, family Sydowiellaceae cannot be ruled out. Perithecioid ascomata are rare in the fossil record and bona fide perithecia are known with certainty only from the Early Devonian Rhynie Chert, the Eocene of Vancouver Island, and Cenozoic amber. The Apple Bay ascomycete contributes a well characterized Cretaceous occurrence to the fossil record of the group, and a second taxon to the fungal flora of the locality, which also includes a basidiomycete.

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1 - Humboldt State University, Department of Biological Sciences, 1 Harpst Street, Arcata, CA, 95521, USA
2 - University Of Kansas, Biological Sciences, Haworth Hall, 1200 Sunnyside Ave, Lawrence, KS, 66046, Canada
3 - Oregon State University, Department Of Biological Sciences, 2082 Cordley Hall, Corvallis, OR, 97331, USA

fossil fungi

Presentation Type: Oral Paper:Papers for Sections
Session: 9
Location: Union A/Hyatt
Date: Monday, July 9th, 2012
Time: 11:30 AM
Number: 9005
Abstract ID:411

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