This article was downloaded by: [Nanjing University] On: 06 March 2015, At: 21:25 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Palynology Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tpal20 The Ordovician acritarch Dactylofusa velifera Cocchio 1982: a biostratigraphical and palaeogeographical index species Wenhui Wangac, Thomas Servaisb, Kui Yand, Marco Vecolie & Jun Lid a School of Earth Sciences and Engineering, Nanjing University, No. 163 Xianlin Road, 210023 Nanjing, China b Géosystèmes, UMR 8217 du CNRS, Université Lille 1, Avenue Paul Langevin, Bâtiment SN5, 59655 Villeneuve d’Ascq, France c Key Laboratory of Economic Stratigraphy and Palaeogeography (CAS), Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, East Beijing Road, 210008 Click for updates Nanjing, China d State Key Laboratory of Palaeobiology and Stratigraphy(LPS), Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, East Beijing Road, 210008 Nanjing, China e Saudi Aramco, Biostratigraphy Group, Geological Technical Services Division, EXPEC 2 Building, Dharan 31311, Saudi Arabia Published online: 22 Sep 2014. To cite this article: Wenhui Wang, Thomas Servais, Kui Yan, Marco Vecoli & Jun Li (2015) The Ordovician acritarch Dactylofusa velifera Cocchio 1982: a biostratigraphical and palaeogeographical index species, Palynology, 39:1, 125-141, DOI: 10.1080/01916122.2014.944278 To link to this article: http://dx.doi.org/10.1080/01916122.2014.944278 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. 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Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions Palynology, 2015 Vol. 39, No. 1, 125À141, http://dx.doi.org/10.1080/01916122.2014.944278 The Ordovician acritarch Dactylofusa velifera Cocchio 1982: a biostratigraphical and palaeogeographical index species Wenhui Wanga,c*, Thomas Servaisb, Kui Yand, Marco Vecolie and Jun Lid aSchool of Earth Sciences and Engineering, Nanjing University, No. 163 Xianlin Road, 210023 Nanjing, China; bGeosyst emes, UMR 8217 du CNRS, Universite Lille 1, Avenue Paul Langevin, Batiment^ SN5, 59655 Villeneuve d’Ascq, France; cKey Laboratory of Economic Stratigraphy and Palaeogeography (CAS), Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, East Beijing Road, 210008 Nanjing, China; dState Key Laboratory of Palaeobiology and Stratigraphy(LPS), Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, East Beijing Road, 210008 Nanjing, China; eSaudi Aramco, Biostratigraphy Group, Geological Technical Services Division, EXPEC 2 Building, Dharan 31311, Saudi Arabia Dactylofusa velifera Cocchio 1982 is an easily recognisable, fusiform Ordovician acritarch species with a characteristic membrane. The taxonomy of this taxon is revised based on a literature review and on the investigation of new fossil assemblages from sections in South China. Morphological and biometric studies show that a subdivision into three varieties is justified. The taxonomical rank of Dactylofusa velifera var. brevis Albani 1989 is changed and its diagnosis is emended; Dactylofusa velifera var. velifera is the automatically created autonym. An additional new subspecific taxon is erected: Dactylofusa velifera var. sinensis var. nov. The stratigraphical and palaeogeographical occurrences of Dactylofusa velifera are reviewed, indicating that the species was widely distributed around the peri-Gondwanan margin during the Early Ordovician and early Middle Ordovician. Dactylofusa velifera is of biostratigraphical importance because its First Appearance Datum (FAD) can be used to indicate the late Tremadocian. Palaeobiogeographically, its distribution generally corresponds to that of the Early Ordovician ‘messaoudensis-trifidum’ acritarch assemblage in the peri-Gondwanan region. Keywords: Dactylofusa velifera; EarlyÀMiddle Ordovician; acritarch; palaeogeography; biostratigraphy; taxonomy 1. Introduction been revised in detail. These include Frankea (Servais Graptolite and conodont biostratigraphy has been 1993; Vecoli et al. 1999), Peteinosphaeridium-Lilios- widely used in precise international correlations in the phaeridium-Cycloposphaeridium (Playford et al. 1995), Ordovician. Based on the published biozonations, time Dicrodiacrodium (Servais et al. 1996), Arkonia-Striato- slices (TS) and stage slices (SS) provide precise interna- theca (Servais 1997), Aureotesta (Brocke et al. 1997), tional correlations for all major palaeocontinents Arbusculidium (Fatka & Brocke 1999), Pachysphaeri- (Webby et al. 2004; Bergstrom€ et al. 2009). However, dium (Ribecai & Tongiorgi 1999), Sacculidium (Ribecai in sequences where graptolites and conodonts are et al. 2002), Veryhachium (Servais et al. 2007), Coryphi- absent, organic-walled microfossils, such as acritarchs dium (Servais et al. 2008), Ampullula (Yan et al. 2010) and Rhopaliophora (Li et al. 2014, Forthcoming) (for Downloaded by [Nanjing University] at 21:25 06 March 2015 or chitinozoans, may provide useful data for biostrati- graphical correlations. Some acritarch taxa have been more discussion see Yan et al. 2010). Other taxa are shown to have First Appearance Datums (FAD) at dif- still not well understood and in need of detailed revi- ferent stratigraphical levels in the EarlyÀMiddle Ordo- sion of their taxonomy, biostratigraphy, palaeogeogra- vician. These are thought to have strong potential for phy and palaeoecology. the correlation of Global Stage boundaries in the Early Dactylofusa velifera Cocchio 1982 belongs to the and Middle Ordovician, not only for Gondwana, but fusiform acritarchs. It can easily be distinguished also for correlations between different palaeoconti- because of its characteristic veil/membrane (‘velifera’) nents (Li et al. 2003, 2010; Molyneux et al. 2007). The and its short central body (var. ‘brevis’), compared to fundamental, and also the most time-consuming, part most other fusiform acritarchs. This species is easy to of correlation work is to carry out a thorough review recognise and thus has the potential for high biostrati- of the taxonomy of the stratigraphically significant graphical and palaeogeographical importance. First taxa. During the past two decades, several EarlyÀMid- occurrences are reported in the late Tremadocian Ara- dle Ordovician acritarch taxa with biostratigraphical neograptus murrayi graptolite Biozone (TS 1c of and/or palaeogeographical significance have therefore Webby et al. 2004) in South China and North Africa *Corresponding author. Email: [email protected] Ó 2014 AASP À The Palynological Society 126 W. Wang et al. (Brocke 1996; Vecoli & Le Herisse 2004; Wang et al. margin and upper slope mud-carbonate belt during 2013a). Palaeobiogeographically, Dactylofusa velifera the EarlyÀearly Middle Ordovician (Zhang et al. is a common taxon of the ‘messaoudensis-trifidum’ acri- 2002; Yan et al. 2011;Wangetal.2013b). All speci- tarch assemblage from the latest TremadocianÀearliest mens of Dactylofusa velifera were recovered from Floian along the peri-Gondwanan margin. four local EarlyÀMiddle Ordovician-age formations. Well-preserved material from several sections in Lithologically, the Meitan Formation in the Hon- South China allow a detailed investigation of large ghuayuan section from Tongzi is composed of grey- Dactylofusa velifera populations in the assemblages ish-yellow and greyish-green shales intercalated with recovered. This paper revises the taxonomy of Dactylo- nodular limestone beds in the lower-middle part, and fusa velifera based on the new material and a complete thin-bedded sandstones in the upper part. The Dacao literature review, in order to obtain greater precision Formation in the Houping section of Chengkou con- of its biostratigraphical and palaeogeographical sists of muddy limestones and bioclastic limestones, distribution. interbedded with yellow-green and grey-green to dark grey shales. The overlying Yingpan Formation consists of dark grey to black or grey-green shales 2. Material and methods intercalated with bioclastic limestone lenses. The The material analysed in this study is from three locali- Yinchufu Formation in the Nanba section is charac- ties in South China: the Honghuayuan section in terised by grey micritic