jmpaleo 0262-821X 2041-4978 Geological Society of London 10.1144/0262-821X11-020 Micropalaeontological Notebook Cypridea Bosquet, 1852 (Ostracoda) in the Early Albian of Tunisia Micropalaeontological Notebook K. Trabelsi et al. TRABELSI K. 1 2 * COLIN J.-P. 3 4 TOUIR J. 1 SOUSSI M. 2 Faculté des Sciences de Sfax, Université de Sfax, Sfax, Tunisia Faculté des Sciences de Tunis, Université de Tunis El Manar, UR/99/10-04, CP 2092, Tunis, Tunisia Universidade de Lisboa, Faculdade de Ciências, Centro de Geologia, Campo Grande, C-6, 3∘ 1749-016 Lisboa, Portugal 3 Impasse des Biroulayres, 33610 Cestas, France Corresponding author (e-mail: trabkhalfss@yahoo.fr) 09 2011 30 2 187 188 28 06 2011 29 06 2011 © 2011 The Micropalaeontological Society 2011 INTRODUCTION

Cypridea gr. laevigata (Dunker, 1946), sample K6, Early Albian, Jebel Kebar. 1, carapace, right lateral view, specimen J. Keb. 0001 (L = 1.0 mm). 2, carapace, right lateral view, specimen J. Keb. 0002 (L = 1.1 mm).

The sub-cosmopolitan limnic ostracod genus Cypridea Bosquet, 1852 (sensu Horne & Colin, 2005) is known from the Lower Tithonian (Martín-Closas et al., 2008) to the Aptian, with a maximum development during the Berriasian to Barremian (Horne, 1995), in Europe, Africa, the Middle East, North and South America. In the Far East (China, Mongolia) and Alaska it ranges up to the Cretaceous–Tertiary boundary (Brouwers & De Deckker, 1993; Khand, 2000). In North Africa (Tunisia), the youngest occurrences of this genus were, until now, in the Late Aptian (Abdeljaouad, unpubl. data and Ben Youssef, unpubl. data in Bismuth, 1984). In Tunisia, the genus Cypridea is known in pre-Aptian sediments in the ‘Wealdien-Neocomian’ as documented by Glintzboeckel & Magné (1959).

Except for the Far East, the presence of Cypridea in post-Aptian sediments is very rare. It has been documented in the Albian of the Bear River Formation of Wyoming, USA (Peck, 1951), the Albian-Cenomanian Loia ‘stage’ (Lualaba Series) of the central Congo Democratic Republic (Grékoff, 1957, 1960; Colin, 1994), the Early Albian-Aptian of the Doba-Doseo basins in Chad and the Muglad basin in Sudan (Colin & Dépêche, 1997) and the Albian-Cenomanian of the Termit basin in Niger (J.-P.C. unpubl. data).

Recent field work in central Tunisia (Jebel Kebar) yielded samples of limestone containing the genus Cypridea in two sections in the lower part of the Kebar Formation (Trabelsi et al., 2010). A very rich and diversified charophyte assemblage with Sphaerochara verticillata (Peck, 1937) Peck, 1957, Atopochara trivolvis trivolvis Peck, 1968, Clavator harrisii zavialensis (Grambast-Fessard, 1980) emend. Martín-Closas, 1996 and Sphaerochara verticillata. kebariensis Trabelsi, 2010, clearly assigned an Early Albian age to the horizon containing Cypridea.

Ostracods were extracted from the hard limestone by chemical processing (acetic acid and copper sulphate as described in Trabelsi et al., 2010), which explains the preservation state of the specimens recovered. In addition to Cypridea, the ostracod assemblage (Trabelsi et al., work in progress) contains the Timiriaseviinae Vecticypris cf. polita (Grékoff, 1957) and two species of Darwinulidae, clearly indicating a true lacustrine environment.

The species of Cypridea identified is rather large (1.0–1.1 mm), smooth, possess a small rostrum and a rather long and deep alveolus, and has a normal overlap (RV<LV). These characters suggest strong morphological affinities with the Berriasian to Aptian species of the Cypridea laevigata (Dunker, 1846)/Cypridea setina (Anderson, 1939) lineage sensu Schudack & Schudack (2009). The youngest known well dated species of this lineage is Cypridea cf. laevigata leonardi Anderson, 1967, reported and illustrated by Cabral (1998) from the Early Aptian of Algarve, southern Portugal.

Illustrated specimens are deposited in the collections of the Paleontology and Sedimentology Survey of the National Office of Mines of Tunisia, Tunis (Collection Trabelsi 2011, n° SPSONM Trab., J. Keb. 0001-0002).

 ACKNOWLEGEMENTS

The authors wish to thank Dr B. Sames (Vienna) for his judicious comments and Dr D.J. Horne (London) for his review. The SEM photos were taken by M. Sghaïer (ETAP, Tunis). This study was financed by project UR/99/10-04 (Sciences Faculty of Tunis).

 REFERENCES Bismuth H. 1984. Les ostracodes de Tunisie: recensement bibliographique. Bulletin des Centres de Recherche Exploration-Production Elf-Aquitaine, 8: 425–534. Brouwers E.M. De Deckker P. 1993. Late Maastrichtian and Danian ostracode faunas from Northern Alaska: reconstructions of environment and paleogeography. Palaios, 8:140–154. Cabral C. 1998. Paléobiogéographie de ostracodes aptiens du Portugal. In: Crasquin-Soleau S. Braccini E. Lethiers F. (Eds), What about Ostracoda! Bulletin du Centre de Recherches Elf-Exploration Production, Mémoire, 20: 290–303. Colin J.-P. 1994. Mesozoic-Cenozoic lacustrine sediments in the Zaire Interior Basin. In: Kelts K. Gierlowski-Kordesch E. (Eds), The Geologic Record of Lake Basins. Cambridge University Press, Cambridge, 31–36. Colin J.-P. Dépêche F. 1997. Faunes d'ostracodes lacustres des bassins intra-cratoniques d'âge albo-aptien en Afrique de l'Ouest (Cameroun, Tchad) et au Brésil: considérations d'ordre paléoécologique et paléobiogéographique. Africa Geoscience Review, 4: 431–450. Glintzboeckel C. Magné J. 1959. Répartition des microfaunes à plancton et à ostracodes dans le Crétacé supérieur de la Tunisie et de l'est algérien. Revue de Micropaléontologie, 2: 57–67. Grékoff N. 1957. Ostracodes du Bassin du Congo. I. Jurassique supérieur et Crétacé inférieur du Nord du Bassin. Annales du Musée Royal du Congo Belge, Science Géologique, 19: 1–97. Grékoff N. 1960. Ostracodes du Bassin du Congo. II. Crétacé. Annales du Musée Royal du Congo Belge, Science Géologique, 35: 1–70. Horne D.J. 1995. A revised ostracod biostratigraphy for the Purbeck-Wealden of England. Cretaceous Research, 16: 639–663. Horne D.J. Colin J.-P. 2005. The affinities of the ostracod genus Cypridea Bosquet, 1852, and its allies, with consideration of implications for the phylogeny of nonmarine Cypridoidea ostracods. Revue de Micropaléontologie, 48: 25–35. Khand Y. 2000. The origins of modern nonmarine ostracod faunas: evidence from the Late Cretaceous and Early Palaeogene of Mongolia. Hydrobiologia, 419: 119–124. Martín-Closas C. Colin J.-P. Billon-Bruyat J.-P. El-Albani A. Mazin J.-M. Schnyder J. 2008. Palaeobiogeography of genus Latochara (fossil Charophyta) in the Upper Jurassic of Southern Europe. New data from Île d'Oléron (France). Geologia Croatica, 31: 177–184. Peck R.E. 1951. Nonmarine ostracodes – the subfamily Cyprideinae in the Rocky Mountain area. Journal of Paleontology, 25: 307–320. Schudack U. Schudack M.E. 2009. On the taxonomy of the species Cypridea setina Anderson, 1939 and Cypridea laevigata Dunker, 1846 (Crustacea: Ostracoda) from the Early Cretaceous of Europe – a special note on systematical inconsistencies. Berliner Paläobiologische Abhandlungen, 10: 311–320. Trabelsi K. Touir J. Soulié-Märsche I. Martín-Closas C. Soussi M. Colin J.-P. 2010. Découverte de charophytes de l'Albien dans la Formation Kebar (Tunisie centrale): implications paléoécologiques et paléobiogéographiques. Annales de Paléontologie, 96: 117–130.

Scientific Editing by Alan Lord.