See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/330432279 Coralline red algae from the Silurian of Gotland indicate that the order Corallinales (Corallinophycidae, Rhodophyta) is much older than previously thought Article in Palaeontology · January 2019 DOI: 10.1111/pala.12418 CITATIONS READS 4 487 3 authors: Sebastian Teichert William J. Woelkerling Friedrich-Alexander-University of Erlangen-Nürnberg La Trobe University 29 PUBLICATIONS 249 CITATIONS 149 PUBLICATIONS 4,804 CITATIONS SEE PROFILE SEE PROFILE Axel Munnecke Friedrich-Alexander-University of Erlangen-Nürnberg 201 PUBLICATIONS 5,073 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Cephalopod Taphonomy: from soft-tissues to shell material View project Reef recovery after the end-Ordovician extinction View project All content following this page was uploaded by Sebastian Teichert on 23 January 2019. The user has requested enhancement of the downloaded file. [Palaeontology, 2019, pp. 1–15] CORALLINE RED ALGAE FROM THE SILURIAN OF GOTLAND INDICATE THAT THE ORDER CORALLINALES (CORALLINOPHYCIDAE, RHODOPHYTA) IS MUCH OLDER THAN PREVIOUSLY THOUGHT by SEBASTIAN TEICHERT1 , WILLIAM WOELKERLING2 and AXEL MUNNECKE1 1Fachgruppe Pal€aoumwelt, GeoZentrum Nordbayern, Friedrich-Alexander-Universit€at Erlangen-Nurnberg€ (FAU), Erlangen, Germany; [email protected] 2Department of Ecology, Environment & Evolution, La Trobe University, Kingsbury Drive, Bundoora, Victoria 3086, Australia Typescript received 30 August 2018; accepted in revised form 3 December 2018 Abstract: Aguirrea fluegelii gen. et sp. nov. (Corallinales, within the family Corallinaceae and order Corallinales. Corallinophycidae, Rhodophyta) is described from the mid- Extant evolutionary history studies of Corallinophycidae Silurian of Gotland Island, Sweden (Hogklint€ Formation, involving molecular clocks now require updating using new lower Wenlock). The holotype is of dimerous construction calibration points to take account of the much earlier and includes a uniporate conceptacle with a sporangium, unequivocal mid-Silurian record of uniporate conceptacle- thus providing evidence that taxa of the Corallinales/Coralli- bearing taxa of Corallinales/Corallinaceae as well as the naceae existed at least 300 million years earlier than previ- parallel record of Graticula, a genus attributed to the ously documented. Aguirrea fluegelii cannot be unequivocally Sporolithales. placed in any of seven currently recognized lineages/subfami- lies/groups of the Corallinaceae as not all diagnostic charac- Key words: Aguirrea fluegelii, conceptacles, Corallinaceae, ters are preserved, and thus is accorded incertae sedis status Corallinales, coralline red algae, Gotland. R ED ALGAE (Rhodophyta) in which calcification occurs in Recent taxa of Corallinales/Corallinaceae occur world- the form of calcite are presently grouped into the subclass wide and are found in tidal pools to more than 250 m Corallinophycidae Le Gall & Saunders (2007) and water depth (Foster 2001). They include species that func- comprise four orders: the Corallinales, Hapalidiales, tion as carbonate factories (Basso 2012; Teichert & Frei- Rhodogorgonales and Sporolithales (Le Gall et al. 2010; wald 2014) and as ecosystem engineers that enhance Nelson et al. 2015; Rosler€ et al. 2016, 2017). Species of community biodiversity (Kamenos et al. 2004; Teichert the Corallinales are characterized by the occurrence of 2014). Their function in cementing and strengthening uniporate tetrasporangial conceptacles rather than multi- Cenozoic and modern coral reefs is well known (Castro & porate conceptacles or calcified sporangial compartments, Huber 2010) but compared to corals, their ecological role which respectively occur in the Hapalidiales (Nelson et al. in ecosystems is often neglected, in part due to difficulties 2015) and Sporolithales (Le Gall et al. 2010), two other in reliable taxonomic identification (Aguirre & Braga orders of Corallinophycidae that are known from the fos- 2005), and also because the time of origin of the Coralli- sil record. Within the Corallinales, we follow Basso & nales/Corallinaceae and other Corallinophycidae is not Granier (2018), Caragnano et al. (2018), Cormaci et al. certain. (2017), Kamiya et al. (2017), Nelson et al. (2015) and Prior to this study, the Corallinales/Corallinaceae were Rosler€ et al. (2016, 2017), all of whom place all taxa/lin- thought to have emerged during the late Early Cretaceous eages/groups into a single family, the Corallinaceae. This to early Late Cretaceous (Aguirre et al. 2010; Rosler€ et al. contrasts with Athanasiadis (2016, p. 292) and Townsend 2017; Yang et al. 2016), about 15–30 myr after the oldest & Huisman (2018, pp. 86–87), who recognized more than known unequivocal records of taxa of Sporolithaceae one family within the Corallinales. (Tomas et al. 2007; Woelkerling et al. 2014) from the © The Palaeontological Association doi: 10.1111/pala.12418 1 2 PALAEONTOLOGY upper Hauterivian. Another much older group attributed and isotype of Aguirrea fluegelii were gathered at the same to the Sporolithales, the Graticulaceae (Brooke & Riding time from the same outcrop. 2000), dates from the Wenlock epoch of the Silurian. The raw material was formatized using a low speed dia- Further details on the evolutionary history of the Coralli- mond rock saw. Sample surfaces were ground using carbon nales/Corallinaceae are summarized by Rosler€ et al. (2017, silicide in 120, 220, 400 and 800 graining and mounted on â pp. 570–573). glass surfaces with Biresin (https://advanced-resins.sika. In this study, we show that species of Corallinales/ com/gbr/en/group.html). Microphotography in normal and Corallinaceae much older than the Cretaceous with char- fluorescent transmitted light was done with a Zeiss Axio acteristic spore-bearing uniporate conceptacles unequivo- Imager 2 equipped with a Zeiss Axiocam MRc5. High reso- cally existed. Our material, belonging to the newly lution images were captured on a Zeiss LSM800 confocal described fossil-genus and species, Aguirrea fluegelii, was laser scanning microscope. Both devices were operated using found in the lower Wenlock Stage (c. 430–434 Ma) of the the Zeiss ZEN software package. We examined 30 newly pre- Silurian of Gotland Island, Sweden, a region well-known pared 5 9 5 cm thin sections from the Gutev€agen material, (Munnecke & Servais 2008) for its outstanding fossil two of which contained one specimen of A. fluegelii each, quality. We provide a detailed taxonomic account and representing the holotype and the isotype. All sections are discuss the implications for the evolutionary history of now housed at GZN except for the two sections containing the Corallinales/Corallinaceae. the holotype and isotype of A. fluegelii, which are housed at SNSB-BSPG under the inventory numbers SNSB-BSPG 2017 I 53 (holotype) and SNSB-BSPG 2017 I 54 (isotype). MATERIAL AND METHOD Sample material Geological setting, facies and palaeoenvironment Samples were collected from the lower part (c. 1.5 m Gotland Island is composed of a series of stacked Silurian above base) of a roughly 8 m section in Visby (Gutev€agen 2; tropical carbonate platforms ranging in age from late 57°37046.8″N18°16050.9″E) on the west coast of Gotland Llandovery to late Ludlow (Calner et al. 2004). The east- Island, Sweden by AM in 2000 (Fig. 1A, B). The holotype ern part of Gotland is dominated by shallow-water A C B FIG. 1. Geographical and lithological context. A, map of the island of Gotland, Sweden, indicating the outcrop area in Visby (Gutev€agen 2; 57°37046.8″N18°16050.9″E). B, sketch map of the outcrop area. C, profile of the study site, sampling horizon is c.30cm below the position of the hammer, lithology according to Riding & Watts (1981). TEICHERT ET AL.: CORALLINALES FROM THE SILURIAN OF GOTLAND 3 lagoonal and backreef deposits whereas the western part and thus the taxonomic affinities of Aguirrea fluegelii to the is mainly composed of limestones and marls of an open Corallinales could only be elucidated from evident shelf environment (Samtleben et al. 1996). morpho-anatomical features (see below). The taxonomic The samples containing A. fluegelii belong to the Hog-€ disposition of Aguirrea fluegelii within the Corallinales/ klint Formation (Fig. 1C, lower Wenlock, lowermost Corallinaceae is considered further in the Discussion. Ozarkodina sagitta rhenana Conodont Zone (Riding & Watts 1981; Jeppsson 2008). The outcrop represents a Institutional abbreviations. GZN, GeoZentrum Nordbayern, Fach- shallowing-upward sequence of reef-derived bioclastic rud- gruppe Pal€aoumwelt, Friedrich-Alexander-Universit€at Erlangen- stones (5 m thick), mostly composed of remnants of Nurnberg€ (FAU), Erlangen, Germany; SNSB-BSPG, Staatliche crinoids, bryozoans, tabulate corals, brachiopods, stromato- Naturwissenschaftliche Sammlungen Bayerns, Bayerische € € poroids and calcareous algae. These deposits are overlain Staatssammlung fur Palaontologie und Geologie, Staatliche Natur- wissenschaftliche Sammlungen Bayerns, Munchen,€ Germany. by a prograding biostromal stromatoporoid reef (3 m thick), and an encrusted reef crest on top (0.3 m thick) mainly composed of specimens of ‘Solenopora’(later SYSTEMATIC PALAEONTOLOGY described as Graticula by Brooke & Riding (1998, 2000) and further assessed by Nose et al. (2006)), Parachaetetes by William Woelkerling, Sebastian Teichert and Axel and Hedstroemia (?cyanobacteria) (Riding & Watts