A perithecial ascomycete, Spataporthe taylori gen. et sp. nov., represented by >70 sporocarps is preserved by
cellular permineralization in marine carbonate concretions dated at the Valanginian-Hauterivian boundary (Early
Cretaceous) from Vancouver Island, British Columbia, Canada. The spheroid perithecia with lumina 330–470 µm
wide and 220–320 µm high are densely distributed and entirely immersed in the tissues of a coniferous leaf. The
perithecial wall consists of an outer layer of large pseudoparenchyma and an inner layer of thin filamentous
nature. Perithecial necks are incompletely preserved due to taphonomic abrasion; they have a bell-shaped chamber
at the base and a narrow channel, with longitudinally aligned hyphae above. The basal chamber of the neck is
filled with a plug of pseudoparenchyma, which subsequently disintegrates to form a peripheral collar; periphyses
are present on the basal chamber walls. A pseudoparenchymatous hymenium lines the bottom of perithecia. Asci
are clavate, with thinly tapered bases, and small (30–47 µm long and 12–20 µm wide at tip), ornamented with
minute papillae. They become detached 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, and persistent,
detachable inoperculate asci is consistent with order Diaporthales of class Sordariomycetes. The small clavate asci
are comparable to those found in family Gnomoniaceae. Perithecioid ascomata are rare in the fossil record, and
bona fide perithecia are known with certainty only from the Early Devonian Rhynie Chert and Cenozoic amber.
Spataporthe taylori contributes a well-characterized Early Cretaceous occurrence, which is also the oldest to date,
to the scarce fossil record of the Sordariomycetes and a second taxon to the fungal flora of the locality, which also
includes a basidiomycete. As the oldest representative of the Diaporthales, Spataporthe provides a minimum age
(136 Ma) for the order and a direct calibration point for studies of divergence times in the ascomycetes.This is the publisher’s final pdf. The published article is copyrighted by the University of Chicago Press and can be found at: http://www.press.uchicago.edu/index.html.Keywords: Gnomoniaceae, Ascomycota, Diaporthales, Cretaceous, Spataporthe, Sordariomycete