CONTENTS Volume 53 Numbers1&2 2007 GENERAL MICROPALEONTOLOGY 1 Ovidiu N. Dragastan and Hans-Georg Herbig Halimeda (green siphonous algae) from the Paleogene of (Morocco) – Taxonomy, phylogeny and paleoenvironment TAXONOMY 73 Christopher W. Smart and Ellen Thomas Emendation of the genus Streptochilus Brönnimann and Resig 1971 (Foraminifera) and new species from the lower Miocene of the Atlantic and Indian Oceans PALEOCLIMATOLOGY 105 Harry J. Dowsett and Marci M. Robinson Mid-Pliocene planktic foraminifer assemblage of the North Atlantic Ocean BIOSTRATIGRAPHY 127 Mahmoud Faris and Aziz Mahmoud Abu Shama Nannofossil biostratigraphy of the Paleocene-lower Eocene succession in the Thamad area, east central Sinai, Egypt 145 Itsuki Suto The Oligocene and Miocene record of the diatom resting spore genus Liradiscus Greville in the Norwegian Sea TAXONOMIC NOTE 104 Elizabeth S. Carter New names for two Triassic radiolarian genera from the Queen Charlotte Islands: Ellisus replaces Harsa Carter 1991 non Marcus 1951; Serilla replaces Risella Carter 1993 non Gray 1840 (1847) ANNOUNCEMENT 160 “Catbox” — Ellis and Messina Catalogues on one DVD Halimeda (green siphonous algae) from the Paleogene of (Morocco) – Taxonomy, phylogeny and paleoenvironment Ovidiu N. Dragastan1 and Hans-Georg Herbig2 1University of Bucharest, Department of Geology and Paleontology, Bd. N. Balcescu No.1, 010041, Bucharest, Romania email: [email protected] 2Universität zu Köln, Institut für Geologie und Mineralogie, Arbeitsgruppe für Paläontologie und Historische Geologie, Zülpicher Strasse 49a, 50674 Köln, Germany email: [email protected] ABSTRACT: Calcareous algae of order Bryopsidales, family Halimedaceae abound in shallow marine ramp facies of the Jbel Guersif Formation (late Thanetian), Ait Ouarhitane Formation (middle – late Ypresian) and Jbel Tagount Formation (latest Ypresian to late Lutetian or latest Bartonian), southern rim of central High Atlas, Morocco. The genus Halimeda includes nine new species, Halimeda erikfluegeli, H. lacunosa, H. barbata, H. marcconradi, H. praetaenicola, H. unica, H. praemacroloba, H. praegoreaui, H. prae- cuneata. Additionally, 14 modern and fossil taxa occur: H. cylindracea, H. incrassata, H. monile, H. opuntia, H. opuntia f. triloba, H. simulans, H. tuna, H. tuna f. platydisca, H. gracilis, H. copiosa, H. scabra, H. fragilis, H. nana, H. praeopuntia. For the first time, gametangia were observed in fossil species. All new species were of short range. Most appeared during adaptive radiation in the late Thanetian, associated with some already known fossil species and an ancient stock of modern Halimeda taxa (H. cylindracea, H. incrassata, H. monile, H. opuntia). The adap- tive radiation was connected with the marine transgression at the southern rim of the central High Atlas and is interpreted as part of the recovery phase after the end-Cretaceous decline of green algal diversity. Mid Ypresian to late Lutetian or latest Bartonian assemblages show minor origination rates but the onset of long-ranging extant species. These assemblages are interpreted to represent the stabiliza- tion phase of Paleogene green algal evolution, dominated by well-adapted species. At the beginning of the Lutetian, already twelve modern taxa of Halimeda were present. This proves geological longevity extending over more than 50 million years and characterizes the corresponding species, respectively the genus Halimeda, as living fossils. The results also prove the early origin of the basal clades of the genus Halimeda, defined from morphological and molecular data of extant species. Origin of the extant Sections Rhipsalis, Micronesicae, Halimeda and of an opuntoid basal clade is assumed to be prior to the Late Thanetian, either in the late Cretaceous or in the earliest Paleocene, following the end-Cretaceous extinctions. Separation of the opuntoid basal clade into the lineages of the pres- ent-day sections Pseudoopuntia and Opuntia was achieved before Mid Ypresian and further differentiation of the clades during the Ypresian and Lutetian, much earlier than hitherto postulated. Presumed timing of the origin of the basal clades of Halimeda and delayed first occurrences in southern Morocco invoke speciations of the recognized extant taxa outside of the peculiar Atlantic-bound Moroccan epeiric sea somewhere on the wide shelfs of the southern Tethys. Neogene vicariance events influencing the evolution of Halimeda are shortly discussed. Concerning the fossil record, they seem to be of minor importance except for the Holocene outburst of Recent taxa, which might be a sampling or preservational artifact. Halimeda-rich facies at the southern rim of the central High Atlas is comparable to modern Halimeda meadows and banks of the Great Barrier Reef. This concerns the almost total absence of other algae, minor lateral changes in the composition of the Halimeda flora, high diversity with analogous percentage of composition patterns, which show few dominant and common taxa, and quite a lot rare to very rare taxa. In both cases, psammophytic and lithophytic species co-occur, demonstrating sufficiently coarse-grained, immo- bile substrates. Both Halimeda floras flourish due to upwelling of cold, nutrient-rich waters. INTRODUCTION subtropical (Hillis-Colinvaux 1980, see also Hillis 2001), and Halimeda is one of the most common green alga in modern Halimeda tuna (Ellis and Solander 1786) Lamouroux 1812 ex- tropical marine environments. Thirty-four species, arranged in tends to the temperate zone of the Mediterranean (compare five morphological groups (Sections) are recognized in tradi- Fornos et al. 1972). The alga has considerable extension into the tional taxonomy. Gene sequencing (Hillis et al. 1998; Kooistra deep sublittoral (e. g. Goreau and Goreau 1973; Blair and Norris et al. 1999, revisions in Kooistra et al. 2002 and Verbruggen 1988; Littler and Littler 2000a). Recently, Bandeira-Pedrosa et and Kooistra 2004) proved good correlation with several mor- al. (2004) recorded Halimeda from depth of more than 160m off phological characters in spite of some phenotypical similar but Brazil. It is famous for its extensive contribution to carbonate para- or polyphyletic entities. The ecological and sediment- production through decay into algal gravel and micritic aragon- ological constraints of the genus are well studied (e. g. ite needles (first noted by Chapman and Mawson 1906, and, Hillis-Colinvaux 1980) and were already highlighted in the among many others Ginsburg 1956; Neumann and Land 1975; classical textbooks of Milliman (1974) and Wray (1977). Al- Enos 1977; Drew and Abel 1985, 1988a; Macintyre and Reid though Halimeda is essentially a dweller of tropical environ- 1995). Discovery of extensive Halimeda bioherms (Davies and ments, Halimeda cuneata Hering (in Krauss 1846) is mostly Marshall 1985; Roberts et al. 1987, 1988; Hine et al. 1988; Mar- micropaleontology, vol. 53, nos. 1-2, pp. 1-72, text-figures 1-9, plates 1-28, tables 1-8, appendix 1, 2007 1 O. N. Dragastan and H.-G. Herbig: Halimeda from the Paleogene of Morocco – Taxonomy, phylogeny and paleoenvironment shall and Davies 1988) prove its important potential to form hy- thallus segments and conical utricles), and around the Creta- drocarbon reservoirs. However, fossil Halimeda bioherms have ceous-Paleogene transition (H. opuntia lineage – taxa with been described only from the Messinian (Late Miocene) of extremely variable, laterally compressed thallus segments and southeastern Spain (Braga et al. 1996) and southern Italy differentiated utricle morphology). (Bosellini et al. 2002). Morphological and molecular cladistic analyses of Recent Halimeda soltanensis Poncet 1989 from the Late Permian has Halimeda identified three major basal clades (Hillis et al. 1998; been considered to be the oldest true Halimeda (Poncet 1989), Kooistra et al. 1999) Opuntia + Micronesica, Rhipsalis, and but Bucur (1994) did not exclude homeomorphism of another Halimeda, i. e. the major modern sections of the genus. The taxon. Subsequent taxa from the late Triassic (Flügel 1975, clades were modified by subsequent studies (Kooistra et al. 1988; Kemper et al. 1976; Dragastan et al. 2000) are now as- 2002; Verbruggen and Kooistra 2004), but the major clades signed to H. cylindracea Decaisne 1842 (Dragastan et al. 2002). Rhipsalis, Halimeda, and an opuntoid clade (Opuntia + Having originated from Paleozoic ancestors grouped in the Pseudoopuntia clades) are still recognized; the small clade family Protohalimedaceae, “Boueina” (late Triassic to early Micronesicae was newly assembled from its earlier representa- Cretaceous), “Arabicodium” (mid Jurassic to Paleogene) and tives H. micronesica, H. fragilis and the hitherto morphologi- “Halimeda” (early Cretaceous to Recent) all belong to the mod- cally isolated deeper-water species H. cryptica.Twobasal ern genus Halimeda (Dragastan et al. 2002). Halimeda, resp. its clades apparently match the phylogenetic lineages postulated by synonyms are commonly recorded in Cretaceous shallow-water Dragastan et al. (2002) from the paleontological record. The H. carbonates of the Tethyan realm and abound throughout the Ce- cylindracea lineage, the most ancient lineage, and the next an- nozoic (Flügel 1988 cum lit.; Dragastan et al. 2002, 2003). Al- cient H. incrassata lineage both plot into basal clade/extant sec- though Halimeda has been extensively used as an indicator of tion Rhipsalis. The somewhat younger H. opuntia lineage tropical climate and mostly lagoonal and reefal to peri-reefal