Journal of Foraminiferal Research, v. 47, no. 1, p. 93–100, January 2017
SPIROBOLIVINA PAPILLOSA AND SPIROBOLIVINA RETORTA, TWO NEW FORAMINIFERAL MORPHOSPECIES FROM THE BIZERTE LAGOON (TUNISIA) MARIA VIRG´INIA ALVES MARTINS1,2 , NOUREDDINE ZAABOUB3 , MONIA EL BOUR3 , MICHAEL A. KAMINSKI4 AND FABRIZIO FRONTALINI5,* nated wall with calcareous cement. Spirobolivina spp. have been found in Lower Cretaceous to Recent sediments in America, Antarctica, and in the Pacific and Atlantic Oceans ´ (Bermudez & Fuenmayor, 1966; Scheibnerov´a, 1974, 1978; McCulloch, 1977; Sliter, 1977). Despite their global distribution, representatives of this genus are seldom abundant, so its ecology and paleoecology are almost unknown. Modern species include, for example, S. minuta McCulloch, 1977, S. propinqua McCulloch, 1977, and S. antarctica McCulloch, 1977. Bolivinopsis has been recorded mostly from the Upper Jurassic to Pliocene from Europe, North, Central and South America, Russia, Japan, as well as the Atlantic, Indian and Pacific Oceans (e.g., Parr, 1938; Morozova, 1939; Cushman & Stainforth, 1947; Uchio, 1953; Said & Kenawy, 1956; Asano & Murata, 1958; LeRoy, 1964; Krasheninnikov, 1973; Boltovskoy, 1978; Gibson, 1983; Hemleben & Troester, 1984; Govindan & Bhandari, 1988; Kaminski & Lazarus, 2009). Like Spirobolivina, the paleoecology of this genus is also poorly understood. Bolivinopsis praelonga (Schwager, 1866), for example, has been recorded from lower bathyal to lower abyssal fossil strata in the Indian Ocean, Tasman Sea and Chatham Rise (Boltovskoy, 1978; Boersma, 1985; Nomura, 1991; Rai & Srinivasan, 2000; Singh et al., 2014) and was found to live as a deep infaunal species in modern sedimentary environments from the Sulu Sea and South China Sea (Rathburn et al., 1996). Bolivinopsis hiratai Uchio, 1953 was found in Upper Pliocene strata of Japan (Uchio, 1953).
ABSTRACT
Two species, Spirobolivina papillosa n. sp. and Spirobolivina retorta n. sp., are described from the Bizerte Lagoon (Tunisia), a Mediterranean transitional ecosystem. Two additional species, S. curta (Cushman, 1933) and S. minuta McCulloch, 1977, are also recorded from this lagoon. The identification and documentation of the new species are followed by a comparison with all the species belonging to the genus Spirobolivina and with selected species assigned to the genera Bolivinopsis and Spiroplectoides. Spirobolivina spp. are uncommon in Mediterranean modern environments and their ecology and paleoecology are poorly understood. INTRODUCTION This study describes two new species of Spirobolivina found living in surface sediments of the Bizerte Lagoon, Tunisia. Two additional Spirobolivina species were also recorded from this lagoon and described. The genus Spirobolivina was proposed by Hofker (1956) to include species with elongated, flattened tests and a finely perforated calcareous wall. Early chambers of specimens belonging to this genus are planispirally coiled, followed later by biserial arrangement of chambers marked by a change of 90◦ in the axis of coiling. The tests have a loop-shaped aperture with Bolivina-like tooth-plates in all chambers, sutures that are strongly oblique, and a calcareous wall with distinct pores. According to Hofker (1955), the type species of Spirobolivina is represented by Spirobolivina pulchella (Cushman & Stainforth, 1947), originally named Bolivinopsis pulchella Cushman & Stainforth, 1947. Hofker (1955) also included Bolivinopsis (Spiroplectoides) scanica Brotzen 1948 in this genus. Unlike Spirobolivina, Bolivinopsis Yakovlev, 1891 (Type species: Bolivinopsis capitata Yakovlev, 1891), regarded as a junior synonym of Spiroplecta rosula Ehrenberg, 1854 by Kaminski & Lazarus (2009), has a finely agglutinated wall. The morphological characteristics of Spirobolivina are similar to Bolivinopsis, which has, however, a fine aggluti-
STUDY AREA The Bizerte Lagoon is a Mediterranean coastal transitional environment located in north Tunisia (37◦ 8 –37◦ 14 N 9◦ 46 –9◦ 56 E; Fig. 1A). It has a surface area of 130 km2 and a mean depth of 8 m. Seawater enters through the Bizerte Channel (6 km long). This lagoon also receives fresh waters from several surrounding rivers (20 Mm3/yr) and from Ichkeul Lake, through the Tinja River (5 km long; FertounaBellakhal et al., 2014). There is intense human activity around the lagoon including naval and commercial shipping, as well as increasing industrial and urban development that affect its environmental quality (Zaaboub et al., 2015). Water circulation in the Bizerte Lagoon, deduced from observations and numerical simulations (Harzallah, 2003; B´ejaoui et al., 2008), has revealed that tidal currents are very intense in the Bizerte Channel, but weaker in the lagoon itself (Harzallah, 2003). This implies moderate mixing of water from the lagoon and the sea, and a long residence time of water in the lagoon (Harzallah, 2003). Thus, most of the lagoon exhibits a muddy-silty to muddy facies, with the fine fraction representing up to 98% of the total grain-size fraction (Ben Garali et al., 2008). According to Martins et al. (2015, 2016), total organic-matter content
1 Universidade do Estado do Rio de Janeiro UERJ, Faculdade de Geologia, Depto. de Paleontologia e Estratigrafia., Av. S˜ao Francisco Xavier, 524, sala 2020A, Maracan˜a. 20550–013 Rio de Janeiro, RJ, Brasil 2 GeoBioTec, Departamento de Geociˆ encias, Universidade de Aveiro, 3810–193 Aveiro, Portugal 3 Institut National des Sciences et Technologies de la Mer, 1934–2025 ˆ Tunisia Salammbo, 4 Geosciences Department, College of Petroleum Engineering and Geosciences, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia 5 Universit` a degli Studi di Urbino “Carlo Bo”, Dipartimento di Scienze Pure e Applicate (DiSPeA), Campus Scientifico Enrico Mattei, Localit`a Crocicchia, 61029 Urbino, Italy * Correspondence author. E-mail:
[email protected]
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MARTINS AND OTHERS
FIGURE 1. A Study site in Tunisia, N Africa, and B with sampling locations (triangles) in the Bizerte Lagoon. Gray dotted lines represent the direction of movement of the main currents within the lagoon (based on Harzallah, 2003; B´ejaoui, 2009).
is relatively high, with values ranging from 2.5–5.6%, which can reduce dissolved oxygen, as indicated by the presence of pyrite in surface sediments (
