UNCORRECTED PROOF 1 2 Taxonomic revision of the Palaeozoic marattialean fern 3 Acitheca Schimper 4 Erwin L. Zodrow a, ⁎ , Zbyněk Šimůnek b , Christopher J. Cleal c , 5 Jiří Bek d , Josef Pšenička e 6 a University College of Cape Breton, Sydney, Nova Scotia, Canada B1P 6L2 7 b Czech Geological Survey, Klárov 3, 118 21 Prague 1, Czech Republic 8 c Department of Biodiversity and Systematic Biology, National Museum and Galleries of Wales, Cardiff, CF10 3NP, UK 9 d Laboratory of Palaeobiology and Palaeoecology, Academy of Sciences of the Czech Republic, Rozvojová 135, 165 00 Prague 6, Czech Republic 10 e West Bohemian Museum in Plzeň, Kopeckého sady 2, 301 36 Plzeň, Czech Republic 11 Received 7 January 2005; received in revised form 9 September 2005; accepted 25 January 2006 12 Abstract 13 The Pennsylvanian genus Acitheca Schimper, 1879 is revised based on re-examination of the sterile types, plus evidence from 14 well-preserved fertile and sterile material from Canada and the Czech Republic (n = 750 specimens). Acitheca was an arborescent 15 marattialean fern about 3.5 m high with large, tripinnate or quadripinnate fronds which produced Caulopteris-like frond scars on the 16 trunk. Although its reproductive structures are similar to those of Asterotheca Presl, Acitheca differs in a number of characters of 17 the sterile foliage (especially the venation), and its palynology. The veins fork at least twice (except in the smallest pinnules): after 18 the first dichotomy, the upper branch divides and then the lower branch divides, producing polymorphopterid veining pattern. 19 Synangia occur in two rows, one on either side of the midvein, and usually consist of four elongate sporangia that extend beyond 20 the pinnule margin. Recovered in situ spores show a much greater ontogenetic variability than any other known Pennsylvanian 21 marattialean; the size varies from 34 μm to 116 μm, and exine ornamentation from laevigate (immature spores), finely 22 microgranulate to scabrate (intermediate spores), to microverrucate–microgranulate (mature spores). Three species are described in 23 the paper: Acitheca polymorpha (Brongniart) Schimper, Acitheca ambigua (Sternberg) Němejc, and a new species Acitheca alii sp. 24 nov. Distributional evidence suggests that Acitheca probably originated in eastern North America and Western Europe in middle 25 Pennsylvanian, and towards the end of it its geographical range had extended to Eastern Europe, the Caucasus, and into Permian of 26 China. 27 © 2006 Elsevier B.V. All rights reserved. 28 29 Keywords: Permo-Carboniferous; Acitheca; Marattiales; epidermis; in situ spores 30 31 1. Introduction 32 The marattialean ferns have an essentially continuous 33 fossil history from the Pennsylvanian to the Recent, and 34 offer significant opportunities to study evolutionary 35 patterns over long geological intervals (Bower, 1963; 36 Liu et al., 2000). The Palaeozoic members of the Review of Palaeobotany and Palynology xx (2006) xxx – xxx + MODEL PALBO-02737; No of Pages 42 www.elsevier.com/locate/revpalbo ⁎ Corresponding author. E-mail addresses: Erwin_Zodrow@uccb.ca (E.L. Zodrow), simunek@cgu.cz (Z. Šimůnek), chris.cleal@nmgw.ac.uk (C.J. Cleal), mrbean@gli.cas.cz (J. Bek), Jpsenicka@zcm.cz (J. Pšenička). 0034-6667/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.revpalbo.2006.01.007 ARTICLE IN PRESS