Systematics of Lutetian larger foraminifera and magneto- biostratigraphy from the South Pyrenean Basin (Sierras Exteriores, Spain)

DOI: 10.1344/GeologicaActa2021.19.7  R. Silva-Casal, J. Serra-Kiel, A. Rodríguez-Pintó, E.L. Pueyo, M. Aurell, A. Payros, 2021 CC BY-SA R . S i l v a C a s a l e t a l . G e o l o g i c a A c t a , 1 9 . 7 , 1 6 4 , I X V I I ( 2 0 2 1 ) D O I : 1 0 . 1 3 4 4 / G e o l o g i c a A c t a 2 0 2 1 . 1 9 . 7 Systematics of Lutetian larger foraminifera, South Pyrenean Basin


INTRODUCTION
Larger foraminifera are a widely distributed polyphyletic group of marine benthic organisms. These taxa are the result of a stepwise evolutionary trend towards highly adapted k-strategist organisms in stable ecological conditions (Hallock, 1985). Indeed, the variety of morphological adaptations in the shallow marine symbiont-bearing larger foraminifera is related to the specific energy levels, water depths and substrate types of the carbonate shelves where they throve (Hottinger, 1983). The facies specificity of larger foraminifera determines their usefulness in facies analysis and palaeoenvironmental reconstructions. However, this may be disadvantageous for biostratigraphic purposes.
The facies dependence of single taxa is avoided in larger foraminifera biostratigraphy (Shallow Benthic Zones (SBZ), Serra-Kiel et al., 1998) through the usage of Oppelzones, characterized by an assemblage of selected taxa. The lower parts of these zones are largely marked by the first appearances of certain taxa, whereas their upper parts are marked by last appearances (Pignatti and Papazzoni, 2017). The quality of SBZs, thus, relies on the accuracy of correlations from stratigraphic sections where different sedimentary environments are represented. As pointed out by Serra-Kiel in Mochales et al. (2012), Costa et al. (2013) and Rodríguez-Pintó et al. (2012a, b), magnetostratigraphy has extensively been used for this purpose, also providing chronostratigraphic calibration to the SBZs. At a regional scale, the lithostratigraphic correlation of distinct sections, located in different positions of the carbonate shelf, can also improve the reliability of the biostratigraphic dataset.
The study of larger foraminifera biostratigraphy in the Pyrenean area has been of great importance for the definition of SBZ biozones (Canudo et al., 1988;Hottinger, 1960;Samsó et al., 1994;Schaub, 1981;Serra-Kiel, 1984;Tosquella, 1995). The Lutetian biozones (SBZ13 to SBZ16) of Serra-Kiel et al. (1998) are mostly based on data from this area. The magnetostratigraphic recalibration of this Lutetian biozones by Rodríguez-Pintó et al. (2012a) was also performed in the South-Pyrenean area (Guara Formation), focusing on Isuela and Gabardiella sections. However, the available data obtained by previous authors from the Guara Formation (Fm.) (Canudo et al., 1988;Rodríguez-Pintó et al., 2012a;Samsó et al., 1994) shows the need for further studies of its larger foraminiferal content. Recently, Silva-Casal (2017) and Silva-Casal et al. (2019) studied the lithostratigraphy, biostratigraphy and magnetostratigraphy of the Eocene shallow marine limestone units (Boltaña, Guara and Arguis formations) of the westernmost sector of the Sierras Exteriores in the Southern Pyrenees (west of Isuela section), and a correlation with the outcrops of the Sierra de Guara further to the east was proposed. Based on these earlier studies, the work presented herein comprises an extensive biostratigraphic dataset obtained from 11 sections of the Sierras Exteriores (Fig. 1), which were correlated by lithostratigraphic and magnetostratigraphic means. Thus, we provide a magnetostragraphically correlated and calibrated regional study of the Lutetian biozones (SBZ13-SBZ16) of the Guara Formation, including some data for the Bartonian Arguis Fm. (SBZ 17) and the upper Ypresian Boltaña Fm. (SBZ 11).

GEOLOGICAL AND STRATIGRAPHIC SETTING
The Pyrenean chain is a double vergence orogen formed by the antiformal stacking of basement thrust sheets during the Santonian to Miocene N-S convergence of the Iberian and European plates (Muñoz, 1992). In middle Eocene times, this orogen developed foreland basins on both North-Pyrenean and South-Pyrenean sides, with a turbiditic succession deposited in the proximal foredeep, flanked by a shallow marine carbonate ramp in the more distal margin of the South Pyrenean Basin (Garcés et al., 2020;Plaziat, 1981).
The Sierras Exteriores are located in the South Pyrenean western zone (Jaca-Pamplona basin) and include syntectonic materials involved in the Pyrenean orogeny ( Barnolas and Pujalte, 2004). They represent the emergence of the South Pyrenean sole thrust in the southwestern part of the chain. Variable along-strike shortening estimates of this basal thrust range between 35 to 10km (Millán et al., 1996) allowing for the exposure of Lutetian platform rocks in the hangingwall block that rides over the 4000m thick Oligocene molasse of the Ebro foreland basin (Oliva-Urcia et al., 2019). The middle Eocene limestones exposed in the Sierras Exteriores were deposited in the distal, shallow marine margin of the South Pyrenean foreland basin (Fig. 1).
The stratigraphic record of the Sierras Exteriores is represented by Triassic to Neogene materials SBZ recalibration; middle Eocene; southern Pyrenees; Paleogene biostratigraphy. KEYWORDS Magnetostratigraphic calibration of described taxa is provided, along with an update of the SBZ calibration to the Geological Time Scale (Gradstein et al., 2012). (Puigdefàbregas and Souquet, 1986). Overlying a very condensed and incomplete Mesozoic succession, the Upper Cretaceous-Paleogene transition is represented by continental deposits, which are part of the Tremp Fm. (Mey et al., 1968). The Eocene limestone succession has been divided into the following lithostratigraphic formations: The Boltaña Formation (Barnolas et al., 1991), lying unconformably on top of the Tremp Formation, represents the beginning of the shallow marine carbonate sedimentation associated with the evolution of the foreland basin. In the study area this unit only occurs in the Gabardiella section (eastern part of the study area). There, the Boltaña Formation is characterized by a 30m thick alternation of limestones and marls. The limestones contain abundant porcellaneous foraminifera (Alveolina, Idalina) and conical agglutinated forms (Coskinolina). In the study area, this unit has been attributed to the late Ypresian (Cuisian) SBZ11 (Rodríguez-Pintó et al., 2012a) and correlated to magnetic polarity Chron C22r (Rodríguez-Pintó et al., 2017). The thicker Ara River section in the east, at the core of the Boltaña anticline spans from the upper part of chron C24n to chron C22r (Mochales et al., 2012).
The Guara Fm. (Puigdefàbregas, 1975) characterizes the Lutetian succession of the Sierras Exteriores. It consists of shallow marine carbonates lying unconformably on the top of the Boltaña Fm. in the Gabardiella section and on the top of the Tremp Fm. further to the west. The lowermost deposits of the Guara Fm. are also highly diachronous, becoming younger westwards. The Guara Fm. spans from chron C22n to C18r, from SBZ 11 (middle Cuisian) to SBZ 16 (late Lutetian) (Rodríguez-Pintó et al., 2012a, 2013aSilva-Casal, 2017;Silva-Casal et al., 2019).
The Guara Fm. was divided into three non-formal lithostratigraphic units, Lower, Middle and Upper Guara units (Rodríguez-Pintó et al., 2012a;Samsó et al., 1992Samsó et al., , 1994. In this work we regard these units as members of the Guara Fm. (see also Silva-Casal et al., 2019). The Isuela The Arguis Fm. records a major change in the sedimentation in the Jaca-Pamplona basin. The dominant carbonate ramp sedimentation was replaced by a marly sedimentation, in a deeper, outer ramp environment with higher siliciclastic imput. The Arguis Fm. is mainly composed of blue marls interbedded with limestones and marly limestones (Millán et al., 1994;Morsilli et al., 2012). The classic Arguis section spans from chron C18r to C16r, just below the diachronic deltaic Belsué-Atarés Fm., as deduced by paleomagnetic studies (Hogan and Burbank, 1996;Kodama et al., 2010;Pueyo et al., 2002;Rodríguez-Pintó et al., 2019). However, in the westernmost sector of the Sierras Exteriores, the marls of the lowermost part of the Arguis Fm. grade laterally to a limestone dominated succession, included in the Santo Domingo Limestone Mb. (Silva-Casal, 2017).
-The Santo Domingo Mb. (Silva-Casal, 2017;Silva-Casal et al., 2019) was formally defined by its lithological differences with the underlying Guara Fm. and its lateral transition to the marls of the lower part of the Arguis Fm. The base of the Santo Domingo Mb. is defined by an erosive surface, related to the drowning unconformity that defines the top of the Upper Guara Mb.
In this study the Santo Domingo Mb. has been logged in the Murillo de Gállego, San Felices, La Osqueta, and Campo Fenero sections (Figs. 8;10;11;12). This unit is characterized by a conspicuous glauconitic level at its base, which is considered a regional datum and allows lithostratigraphic correlation between sections (Silva-Casal, 2017, Silva-Casal et al., 2019. The Santo Domingo Mb. is also characterized by a shallow carbonate ramp facies association of outer and middle ramp facies with predominance of bryozoans, orthophragminids (Discocyclina, Asterocyclina) and red algae, and Systematics of Lutetian larger foraminifera, South Pyrenean Basin 7 acervulinids and echinoids-rich inner ramp facies. Nummulites and Alveolina-rich facies are absent in this unit, but dispersed specimens of these species do occur.

MATERIALS AND METHODS
This work is based on 11 stratigraphic sections (Fig. 1) systematically and evenly sampled from the base to the top for biostratigraphic purposes. This sampling resulted in the description of 359 samples. The samples were studied in thin sections and polished slabs, except those collected to extract loose, separate specimens of nummulitids and alveolinids. These samples were disaggregated in a water, oxygen peroxide and Na 2 CO 3 solution and then sieved through mesh apertures of 1.0, 0.5 and 0.2mm. The material studied is housed in three different repositories (Appendix I). The samples from the Isuela and Gabardiella sections (also named Arguis and Lúsera) are housed in the repository of the Instituto Geológico Minero de España (IGME). Some samples are included in the Serra-Kiel collection, provisionally housed in the Department of Earth and Ocean Dynamics, University of Barcelona (UB), and will be definitively deposited in the Museu de Ciències Naturals de Barcelona. Finally, the rest of the samples, including the new species (MPZ 2019/1681-1683and MPZ 2020, are housed in the Natural Science Museum of the University of Zaragoza (Canudo, 2018).

STRATIGRAPHY
The biostratigraphic information obtained in this work is partly based on the revision of published material, i.e. the Isuela and Gabardiella sections (Rodríguez-Pintó et al., 2012a) and Santa Marina section (Rodríguez-Pintó et al., 2012b). The rest of the information comes from 8 new sections located at the western area of the Sierras Exteriores ( Fig. 1):

Santa Marina section
The Santa Marina section (Rodríguez-Pintó et al., 2012b) (Fig. 2) was measured in the Cañada Zerrada   (Rodríguez-Pintó et al., 2012b). Unfortunately, the occurrence of a widespread reverse remagnetization component in the most part of the profile (Rodríguez-Pintó et al., 2013b) precluded achieving a reliable dating and the magnetostratigraphic data is not been considered here.
The base of the section consist of marine sandy limestones of the Boltaña Fm., Cuisian in age. The overlying rocks are represented by the following stratigraphic units: -Lower Guara Mb., represented by a 230m thick alternation of marls and limestones, locally with cross stratification and bioturbation.
-Middle Guara Mb., represented by 370m of limestones. The occurrence of Nummulites boussaci and Nummulites beneharnensis in the middle part of this unit characterizes SBZ 14 (middle Lutetian 1). The occurrence of Nummulites crassus and Nummulites tavertetensis in the upper part characterizes SBZ 15 (middle Lutetian 2).
-Upper Guara Mb., bounded at the base by and unconformity and represented by 15-20m of limestones. The occurrence of Nummulites deshayesi characterizes SBZ 16 (late Lutetian).
The lowermost part of the section is composed of 75m of red marls and lacustrine limestones of continental facies of the Tremp Fm. The overlying rocks consist of the following stratigraphic units: -Boltaña Fm., consists of 30m of limestones and marls. The presence of Coskinolina cf. perpera, Alveolina decastroi and Alveolina cremae characterizes SBZ 11 (middle Cuisian). The Chron C22 was identified in this unit ( Fig. 3) (Rodríguez-Pintó et al., 2017).
-Middle Guara Mb., is represented by 435m of limestones with frequent cross-bedding and bioturbation. The ocurrence of Alveolina munieri characterizes SBZ 14 (middle Lutetian 1). The presence of A. aff. fragilis in the upper part of this unit, together with the correlation with Isuela section, suggests SBZ 15 (middle Lutetian 2). The lower part of this unit correlates to Chron C20r (Rodríguez-Pintó et al., 2017).
-Upper Guara Mb., a 60m thick succession of limestones with some levels of siltstones. Despite the absence of larger foraminifera biomarkers, the correlation with the nearby Isuela section (Fig. 4) suggests SBZ 16 (late Lutetian).

Isuela section
The Isuela section (Fig. 4) is exposed along the old road between the localities of Nueno and Arguis, in the Isuela river gorge, on the western flank of the Pico del Águila anticline. Coordinates UTM (ETRS89): Base: 30T 712081 4685921, Top: 30T 712125 4686840).
The base of the section consists of a 50m thick succession of sandstones, conglomerates and lacustrine limestones of the Tremp Fm.
The overlying rocks are represented by the following stratigraphic units: -Lower Guara Mb., composed of 95m of sandstones, conglomerates and limestones. The presence of Alveolina obtusa, A. stipes and Assilina spira abrardi characterizes SBZ 13 (early Lutetian). Chron C21 is identified in the lower part of the unit, whereas its upper part correlates to chron C20r (Rodríguez-Pintó et al., 2012a).
-Middle Guara Mb. 285m thick unit mainly composed of limestones and thin intervals of marls, siltstones, marly limestones, dolomites and dolosiltites. The presence of Alveolina munieri, Nummulites aspermontis, N. beneharnensis and N. praediscorbinus characterized SBZ 14 (middle Lutetian 1). The presence of N. beaumonti in the uppermost part of this unit indicates SBZ 15 (middle Lutetian 2). This unit spans the time interval from the latter part of Chron C20r to the early C19r (Rodríguez-Pintó et al., 2012a).  Systematics of Lutetian larger foraminifera, South Pyrenean Basin 10 -Upper Guara Mb. is represented by an 88m thick alternation of limestones and marly limestones. The presence of N. aff. deshayesi and N. aff. bullatus in the lower part of this unit indicates SBZ 15 (middle Lutetian 2), and N. deshayesi in the middle part indicates SBZ 16 (late Lutetian). Chron C19n and the base of C18r were identified in the upper part of this unit (Rodríguez-Pintó et al., 2012a, 2019.

Sierra Caballera section
Located in the Sierra Caballera, close to Bentué de Rasal village, the Sierra Caballera composite section is made of two subsections. The lower part was measured along an unpaved road to the south of the -Middle Guara Mb. is a 127m thick unit mainly composed of limestones, but thick intervals are covered. The presence of N. beaumonti in the upper part of this unit indicates SBZ 15 (middle Lutetian 2). SBZ 14 (middle Lutetian 1) biostratigraphic markers were not found.
-Upper Guara Mb. is a unit is mainly composed of limestones, with a minimum thickness of 55m, as its upper part could not be measured because the boundary with the Arguis Fm. is covered. . The presence of N. crassus and N. aff. deshayesi in the lower part of this unit indicates SBZ 15 (middle Lutetian 2) and the presence of N. aturicus and N. deshayesi in the middle and upper part indicates SBZ 16 (late Lutetian). The following stratigraphic units have been recognized ( Fig. 6):

La Foz de Escalete section
-Middle Guara Mb., 84m thick succesion composed of sandstones at the base, followed by limestones with thin intervals of marls, sandstones, marly limestones and limestones. The presence of N. crassus and N. aff. deshayesi indicates SBZ 15 (middle Lutetian 2). Chron C20 and the lower part of C19r were identified in this unit (Silva-Casal, 2017).
-Upper Guara Mb. is composed here of 178m thick limestones. The presence of N. crassus and N. aff. deshayesi in the lower part of this unit indicates SBZ 15 (middle Lutetian 2), and N. deshayesi in upper part indicates SBZ 16 (late Lutetian). Chron C19r was identified in the lower part and C19n in the upper part (Silva-Casal, 2017).
-Arguis Fm. is represented in this section by a 1000m thick marly succession including intervals of marly limestones and sandstones (Millán et al., 1994). The lowermost Arguis Fm. consists of an alternation of marls and siltstones. The upper part of Chron C19n and its boundary with Chron C18r were identified in this unit (Silva-Casal, 2017;Silva-Casal et al., 2019).

La Peña section
Located along the road A-132 next to La Peña dam, in the proximity of Santa María de la Peña village (Silva-Casal, 2017 This section is composed of the following stratigraphic units (Fig. 7): -Middle Guara Mb., 87m thick, composed of marls and limestones with cross stratification. The presence of N. crassus and N. aff. deshayesi indicates SBZ 15 (middle Lutetian 2).

Villalangua section
This section is exposed along an unpaved road between the locality of Villalangua and the abandoned village of Salinas Viejo. The top of the section is complemented with data from the nearby Salinas gorge (Silva-Casal, 2017) Coordinates UTM (ETRS89) are: Base 30T 679218 4697917, Top 30T 679236 4697975. Salinas gorge: 30T 680115 4697682.
This section includes the following stratigraphic units ( Fig. 9): -Middle Guara Mb., 20m thick succesion of marls and limestones. Despite the absence of larger foraminifera biostratigrahic markers, lithological correlation with nearby sections allows the attribution of this unit to SBZ 15 (middle Lutetian 2).
-Upper Guara Mb., composed of 57m of cross stratified limestones, laminated limestones and massive limestones. The presence of N. deshayesi at the top of this unit indicates SBZ 16 (late Lutetian).

San Felices section
Located at the Barranco del Villano gorge, to the northeast of San Felices (Agüero) village (Silva-Casal, 2017). The section is divided into two subsections. The upper subsection is located on an unpaved road, whereas the lower part of the section is located at the bottom of the Barranco del Villano gorge with coordinates UTM ( In this section the following stratigraphic units can be observed ( Fig. 10): -Upper Guara Mb., 35m thick, consists of cross stratified limestones. Despite the absence of larger Systematics of Lutetian larger foraminifera, South Pyrenean Basin 12 foraminifera biostratigraphic markers, stratigraphic correlation with other sections allows the attribution of this unit to SBZ 16 (late Lutetian).
-Santo Domingo Mb. 57m thick, is composed of marly limestones with some marly intervals. Despite the absence of larger foraminifera biostratigraphic markers, the correlation to other nearby sections shows that this unit is early Bartonian in age (SBZ 17).
The base of the section is composed of 20m of lacustrine limestones and red lutites of the Tremp Fm.
The overlying Eocene rocks are represented by the following stratigraphic units (Fig. 11): -Upper Guara Mb., 25m thick, is composed of limestones. Despite the absence of larger foraminifera biostratigraphic markers, the stratigraphic correlation with other sections allowed to assign this unit to SBZ 16 (late Lutetian). Chron C19r was found in this unit (Silva-Casal, 2017).
-Santo Domingo Mb. is represented by 45m of marly limestones and marls. Despite the absence of biostratigraphic markers of larger foraminifera the stratigraphic correlation with other sections indicates that the upper part of this unit belongs to the SBZ 17 (early Bartonian). In this unit the chrons C19n and C18r have been identified (Silva-Casal, 2017;Silva-Casal et al., 2019).

Campo Fenero section
This section is located in the Sierra de Santo Domingo range, west to the source of the Arba de Biel river (Silva-Casal, 2017). This section is located along a path from a mountain hut leading to the Campo Fenero with coordinates UTM ( Material. This species has been identified in the Gabardiella section (Fig. 3).
Description. Test porcellaneous with miliolid growth. Dimorphism marked. The microspheric forms display a spherical morphology, the major length for 5 whorls is 1.85mm. The nepionic stage is formed by a small proloculus 0.60µm in diameter followed by one quinqueloculine whorl. The ephebic stage shows a bilocular growth. The basal layer is thin and locally slightly undulate. The megalospheric forms show an elliptical outline in sections perpendicular to the coiling axis. The nepionic stage is formed with a proloculus 120µm in diameter followed by one quinqueloculine stage. The ephebic stage shows a bilocular arrangement of the chambers. The maximum length in axial section is 1.4mm. The basal layer is thin.

Remarks.
No formal species have been described within genus Idalina in the Cuisian yet. However, Drobne (1988) documented two forms assigned to Idalina sp. in the Cuisian of Dalmatia (p. 653, figs. 6.5 and 6.6, op. cit.). They differ from the specimens studied in the thickness of the basal layer and the size of the test. The scarcity of available material did not allow us to describe this species as a new species.
Description. The megalospheric forms show an ovoidsubspherical morphology. The proloculus is spherical with a diameter between 150-220µm followed by a flexostyle (Fig.  13F, H, I, U). The nepionic stage is formed of two chambers in triloculine arrangement ( Fig. 13L) or of one first biloculine growth stage followed by one triloculine growth stage (Fig.  13F). The neanic stage displays a biloculine arrangement of the chambers in the remaining whorls ( Fig. 13F, H, I, J, K, L, S). The dimensions of the test vary between 1.7-2mm in axial section and 1.6-2mm in the longitudinal section. The microspheric forms show a subspherical morphology. Dimorphism is little marked. The initial growth is formed of 2-3 cycles pluriloculine in arrangement, showing then 1-2 Systematics of Lutetian larger foraminifera, South Pyrenean Basin 14 cycles with quinqueloculine arrangement, followed by one triloculine cycle. The remaining whorls follow the biloculine mode ( Fig. 13N-P). The diameter of axial section varies between 1.8-2.3mm for 4-5 biloculine chambers. In both generations the basal layer is slightly undulate and does not exceed half of the height of the chamber. The trematophore is supported by strong pillars (Fig. 13Q, R).
Description. The microspheric and megalospheric forms show an ovoid morphology in longitudinal section and a subcircular outline in sections perpendicular to the coiling axis. The maximum diameter observed in megalospheric forms in axial section is 3.5mm. The proloculus is spherical with a diameter around 180µm, followed by five chambers arranged in quinqueloculine mode; the remaining whorls follow the biloculine mode (Fig. 15A). The trematophore is supported by short pillars (Fig. 15J). The basal layer is very thick, smooth and slightly undulate, exceeding half of the height of the chamber.
Remarks. The size of the test and the thickness of the basal layer of this species are greater than those of the species I. berthelini described above. The size of the test and the thickness of the basal layer increase following an evolutionary trend from Idalina sp. (Cuisian) to I. berthelini and I. osquetaensis (Lutetian) (Fig. 14).
Age. The biostratigraphic range of Idalina osquetaensis extends from middle Lutetian 2 (SBZ15) to late Lutetian (SBZ16). The SBZ15 is characterized by the association of this species with Nummulites aff. deshayesi (sample M 2; Fig. 8 Description. The megalospheric forms show an ovoid morphology and a subcircular outline in axial section. The proloculus is spherical with a diameter between 195-260µm, followed by a flexostyle (Fig. 16F, N). The neanic stage is formed of chambers in biloculine arrangement ( Fig.  16G-H, L-O). The axial length measured for 4-5 biloculine chambers varies between 1.5mm and 1.9mm. The basal layer is thick and can reach the same height as the chamberlets (Fig. 16F, G, L-O). The basal layer exhibits the anastomosed passages in irregular distribution (Fig. 16J). The apertural system in polar location is formed of a trematophore with apertures in cribrate distribution and supported by pillars (Fig. 16I, K). The septula reach the ceiling of the chamber subdivided into almost regular chamberlets ( Systematics of Lutetian larger foraminifera, South Pyrenean Basin 18 morphology. The axial section shows a subcircular outline slightly depressed at the junction of the chambers (Fig. 16A, B). The nepionic stage is formed of 2-3 quinqueloculine chambers with quinqueloculine arrangement, followed by the neanic stage composed of chambers in biloculine arrangement (Fig. 16B, O). The maximum diameter in axial section is around 2.75mm. The basal layer increases in thickness from the first to second biloculine chamber and can reach 3 or 4 times the height of the chamberlets and shows sporadically passages as in the megalospheric forms (Fig. 16B, D).
Description. The megalospheric forms show an ovoid morphology. The outline in axial section is elliptical to slightly depressed at the junction of the chambers (Fig. 16P, S-U). The embryonic apparatus is formed of a spherical proloculus with a diameter between 180-300µm, followed by a flexostyle and chambers in biloculine arrangement (Fig. 16R). For 8 biloculine chambers, in axial section, the maximum elliptical diameter varies between 0.90mm and 1.30mm and the minimum between 675µm and 950µm. The trematophore is supported by a short pillar (Fig. 16R). The basal layer is thin and the septula form chamberlets with a regular distribution (Fig. 16R, S). The chamberlets show a rectangular outline in axial section in the internal chambers, while it changes to a subrectangular shape with rounded base and a flat ceiling in the external chambers.
Remarks. This species differs from Fabularia roselli in the smaller size of the test, in displaying axial sections with an elliptical instead of a subcircular outline and in the tighter growth pattern of the chambers.
Age. The biostratigraphic range of Fabularia ovata extends from early Lutetian (SBZ13) to middle Lutetian 2 (SBZ15). The SBZ13 is characterized by the alternation of samples with this species with samples with A. stipes (Fig. 3), indicating early Lutetian (A. stipes Zone). In the material studied, no characteristic species of the SBZ14 (middle Lutetian 2) were found associated with Fabularia ovata. Finally, the SBZ15 is characterized by the alternation of samples with this species with samples containing N. crassus (Fig. 6)  Material. This species occurs in the Gabardiella, Isuela, Sierra Caballera, La Foz de Escalete, La Peña, Murillo and Villalangua sections (Figs. 2-9).
Description. The megalospheric forms show an ovoidsubspherical morphology. The embryonic apparatus is formed of a subspherical proloculus with a diameter between 175-340µm, followed by a flexostyle (Fig. 17M,  P). The neanic stage is composed of chambers in biloculine arrangement. However, some specimens show a nepionic stage formed of chambers in triloculine arrangement following the flexostyle (Fig. 17J). The basal layer is thin without passages inside it. Four biloculine chambers measured in equatorial section were around 2.3mm across, whereas in axial section they measured 1.8mm. In axial section, the septula subdivided the chamber in chamberlets, some septa do not reach the ceiling of the chamber (Fig. 17D, I, M). The apertural system is a trematophore supported by pillars and apertures in cribrate distribution (Fig. 17H). The microspheric forms show a subspherical morphology and maximum diameter of 4.2mm (Fig. 17A).

Remarks.
Only oblique sections were obtained in the material studied. Nonetheless, the basal layer with coarse ribs in irregular distribution and the biloculine growth pattern of the neanic stage justify its attribution to genus Periloculina (Fig. 17T-X). The lack of an axial centered section is the reason why this species is left in open nomenclature.
Description. Microspheric forms not found. The megalospheric forms are of large size, subcylindrical morphology and rounded poles. The axial length ranges from 17.3mm to 23.3mm and the equatorial diameter from 2.9mm to 3.8mm for 16 whorls. The index of elongation varies from 4.6 to 6.6. The proloculus shows a circular outline in axial section and its diameter varies from 420µm to 700µm. The nepionic stage around the proloculus, formed of 4-5 whorls, produces a slight inflexion in axial section. The nepionic stage is formed of one tightly coiled whorl, followed by 10-12 elongated whorls with rounded poles in axial section. The axial elongation decreases in the last 4-5 whorls with truncated or rounded poles. At the polar zone there are abundant supplementary passages in the basal layer. In axial section the chamberlets are very small, tight, and frequent intercalary chamberlets occur in the outer whorls.

Alveolina decastroi
Description. Microspheric forms not found. The megalospheric forms show an oval morphology with rounded poles. The axial length ranges from 2.0mm to 2.3mm and the equatorial diameter from 1.2mm to 1.3mm for 6 whorls. The index of elongation varies between 1.5-1.8. The proloculus is circular in axial section, with  o l o g i c a A c t a , 1 9 . 7 , 1 -6  a diameter ranging between 190µm and 275µm. The nepionic stage is formed of 2-3 tightly coiled whorls followed by chambers with a moderate elongation in axial section. The chamberlets have a circular outline in the inner whorls and a subrectangular outline in the outer whorls. The equatorial spiral is tightly coiled and the basal layer is thin, except in the outer whorls where it reaches the height of the chamberlets.
Description. Microspheric forms not found. The megalospheric forms show an oval to fusiform morphology with rounded poles in axial section. The axial length is 3mm and the equatorial diameter is 1.9mm for 8 whorls. The index of elongation is 1.6. The proloculus is subcircular in axial section, with a diameter of 375-410µm. The nepionic stage around the proloculus is formed of 3-4 tight whorls, followed by 4-5 slightly elongated whorls in axial section, and rounded poles. The chamberlets have a circular outline in the inner whorls and an oval-subrectangular outline in the outer whorls. The equatorial spiral is tightly coiled and the basal layer is thin.
Age. According to the data available the biostratigraphic range of A. cremae is middle Cuisian (SBZ11). This species occurs in the Boltaña Fm. (sample G 1; Fig. 3 Material. This species is present in the Gabardiella and Isuela sections (Figs. 3; 4).
Description. Microspheric forms not found. The megalospheric forms show a cylindrical morphology with truncated poles. The axial length ranges from 5.5mm to 5.7mm and the equatorial diameter from 1.9mm to 2.1mm for 9-10 whorls. The index of elongation varies between 2.7-2.9. The proloculus shows an elongated outline in axial section, and a diameter ranging between 240-370µm. The nepionic stage is formed of two tightly coiled whorls followed, in axial section, by two elongated whorls with pointed poles and 7-8 whorls with truncated poles. At the polar area, the basal layer shows abundant supplementary passages. The chamberlets have a circular outline in the inner whorls and a subrectangular outline in the in external whorls. The basal layer is thin, except in the external whorl where it can reach the height of the chamberlets.
Age. The biostratigraphic range of A. obtusa is early Lutetian (SBZ13). The stratigraphic record of SBZ13 is characterized by the alternation of samples containing this species with samples containing A. stipes (Fig. 3), indicating early Lutetian (A. stipes Zone). HOTTINGER, 1960Fig. 19H-I 1960 Alveolina Material. This species is present in the Isuela section (Fig. 4).

Alveolina levantina
Description. Microspheric forms not found. Megalospheric forms are fusiform, with pointed or slightly rounded poles. The axial length ranges from 5.6mm to G e o l o g i c a A c t a , 1 9 . 7 , 1 -6 4 , I -X V I I ( 2 0 2 1 ) D O I : 1 0 . 1 3 4 4 / G e o l o g i c a A c t a 2 0 2 1 . 1 9 . 7 Systematics of Lutetian larger foraminifera, South Pyrenean Basin 24 8.2mm and the equatorial diameter from 1.7mm to 2.0mm for 12 whorls. The index of elongation varies from 3.2 to 4. The proloculus is circular or oval in axial section and the diameter varies from 310µm to 580µm. The nepionic stage around the proloculus is formed of 1 or 2 tightly coiled whorls, followed by 9-11 whorls with axial elongation and rounded or slightly pointed poles. The chamberlets have a circular outline in the inner whorls, and are oval or subrectangular in the outer whorls. The equatorial spiral is tightly coiled and the basal layer is thin. Some specimens exhibit intercalary chamberlets and secondary passages in the basal layer at the polar zone (Fig. 19H-I).
Age. This species has different biostratigraphic attributions. According to Hottinger (1960) its age is probably early Lutetian. Hovewer, Hottinger (1974) and Hottinger and Drobne (1988) attributed this species to middle Cuisian-late Cuisian (see fig. 2, op. cit., Hottinger and Drobne (1988)) but in the figures this species appears as a typical species of the early Lutetian (see pl. IV, op. cit., Hottinger and Drobne (1988)). Finally, Serra-Kiel et al. (1998) constrained the age of this species from the middle part of middle Cuisian (middle part SBZ11) to late Cuisian (SBZ12). Summarizing, the biostratigraphic range of this species is from the middle part of middle Cuisian to early Lutetian (middle part SBZ11-SBZ13).
In the samples studied this species is associated with Alveolina stipes and Assilina spira abrardi (sample I 7; Fig. 4 Material. This species is present in the Gabardiella section (Fig. 3).
Description. Microspheric forms not found. Megalospheric forms are of small size, and show an oval to fusiform morphology with rounded or slightly pointed poles in axial section. The axial length ranges from 1.6mm to 2.0mm and the equatorial diameter from 0.6mm to 0.8mm for 8 whorls, with an index of elongation of 2.4-3.3. For 9 whorls the axial length varies between 2.6-3.4mm and the equatorial diameter between 0.7-1.2mm, with an index of elongation of 2.6-3.7. The diameter of the proloculus is small, 75-80µm. The nepionic stage is formed of 4-5 tightly coiled whorls followed by chambers with a moderate elongation in axial section. The chamberlets have a circular outline in the inner whorls and are subrectangular in the outer whorls. The equatorial spiral is tightly coiled and the basal layer is thin.

Alveolina tenuis
Description. Microspheric forms show a cylindrical morphology with rounded poles. At the polar zones there are abundant and large supplementary passages in axial section. The axial length is 10.8mm and the equatorial diameter is 3.3mm for 14-15 whorls. The megalospheric forms show a subcylindrical morphology and rounded poles. The axial length ranges from 9.2mm to 10.3mm and the equatorial diameter from 1.7mm to 1.9mm for 10-11 whorls. The index of elongation varies from 4.7 to 5.4. The proloculus is circular or slightly elongated in axial section and the diameter varies from 320µm to 340µm. The nepionic stage is formed of one tightly coiled whorl, followed by 2-3 whorls with moderate axial elongation and pointed poles. The neanic stage is formed of 7-10 whorls with strong axial elongation and rounded poles. At the polar zone there are abundant supplementary passages in the basal layer. The chamberlets are small, very numerous and, in axial section, show a circular outline in the inner whorls, and an oval to subrectangular outline in the outer whorls. The equatorial spiral is tightly coiled and the basal layer is thin.

Alveolina callosa
Description. Microspheric forms not found. The megalospheric forms show subcylindrical morphology and rounded poles. For 9 whorls the axial length is 7.8mm and the equatorial diameter is 1.7mm. The index of elongation is 4.5. The proloculus shows a circular outline in axial section and the diameter varies from 290µm to 310µm. The nepionic stage is formed of one tightly coiled whorl, followed by 8-9 whorls with axial elongation and pointed poles. At the polar zone there are abundant large supplementary passages in the basal layer. In axial section, the chamberlets show a circular outline in the inner whorls, and an oval to subrectangular outline in the outer whorls. The basal layer can reach the height of the chamberlets in equatorial section.

Description.
Microspheric forms not found. The megalospheric forms show a fusiform to subcylindrical morphology, slightly inflated around the first whorls in axial section, and rounded or slightly truncated poles. For 10 whorls the axial length ranges from 12mm to 14.6mm and the equatorial diameter from 1.6mm to 2mm. The index of elongation varies from 6.0 to 8.6. The proloculus shows a circular or slightly elongated outline in axial section and a diameter of 390 µm to 500µm. The nepionic stage is formed of one tightly coiled whorl. The neanic stage is formed of whorls with axial elongation and abundant supplementary passages in the basal layer at the polar zones. The equatorial spiral is tightly coiled and the basal layer is thin. The chamberlets exhibit a circular axial section in the inner whorls whereas they are oval to subrectangular in the external whorls.

Description.
Megalospheric forms show a cylindrical morphology and rounded poles. For 12 whorls the axial length is 8mm and the equatorial diameter is 2.36mm. The index of elongation is 6.7. The proloculus shows a circular outline in axial section and a diameter of 300-570µm. The nepionic stage is formed of one tightly coiled whorl around the proloculus, followed by whorls with axial elongation. There are abundant supplementary passages located at the polar zone and intercalated chamberlets in the more external whorls. The thickness of the basal layer increases progressively from the proloculus towards the outside of the test in the equatorial section. The chamberlets exhibit a circular axial section in the inner whorls and an oval to subrectangular axial section in the external whorls.
Description. Microspheric forms not found. Megalospheric forms show a fusiform to subcylindrical morphology with frequents irregularities in the surface and rounded poles. The axial length at the 8 th , 10 th and 12 th whorls measures 3.9-7.2mm, 5.0-7.4mm and 6.8-8.8mm respectively, and the equatorial diameter 0.77-1.22mm, 1.0-1.36mm and 1.3-1.7mm respectively. The index of elongation varies from 4.5 to 6.8. The proloculus displays circular or elongated axial outline and a length of 220-470µm. The nepionic stage is formed of one tightly coiled whorl followed by chambers with axial elongation. The basal layer is thin in equatorial section, and in axial section its thickness increases gradually from the 2 nd whorl to the external whorls. There are rare chamberlets intercalated in the external whorls and frequent supplementary passages at the polar area.
Age. Dizer (1965) found this species associated with Nummulites aturicus joly and leymerie, 1848 (Karasivri, Haymana Basin, Turkey, p. 278 op. cit.), indicating a late Lutetian age. On the other hand, Hottinger (1960,1974) considered A. fusiformis to be "Biarritzian" in age, and Sirel and Acar (2008) Bartonian, unfortunately these data was not supported by other larger foraminifera, such as Nummulites. In the material studied the association of A. fusiformis with A. munieri (samples I 20; see Description. Microspheric forms not found. Megalospheric forms show a cylindrical morphology with rounded poles. The axial length ranges from 8mm to 10.4mm and the equatorial diameter from 1mm to 1.5mm for 9-10 whorls. The index of elongation varies between 5.3 and 7.2. The proloculus shows an elongated outline in axial section with a diameter between 400-420µm. The equatorial section is very tightly coiled. The basal layer is thin in equatorial section and its thickness increases in axial section.

Remarks.
A. aff. fragilis is considered here to be ancestor of A. fragilis because of the smaller dimensions of the test and proloculus.

Remarks.
Small shell, with a maximum length of 0.9mm. The first 17-18 chambers display a planispiral arrangement, followed by an uniserial pattern. The uniserial length for 5 chambers is 0.4-0.6mm. Proloculus small, 20µm in diameter.
Age. This species has not biostratigraphical significance. It is found in the Guara Formation, where it is abundant in facies attributed to seagrass environments rich in porcellanous foraminifera (Silva-Casal, 2017).
Description. The specimen shows a nepionic stage formed of chambers in planispiral-involute arrangement with the apertures located at the base of the chambers. The neanic stage dispalys uncoiled growth and dendritine aperture. The septa are inclined and slightly arcuate.
Description. The test of the megalospheric forms is planispiral-involute, with an equatorial diameter of about 0.9-1.0mm for 5 whorls with 50 chambers. The nepionic stage is formed of a spherical proloculus with a diameter of ca. 130µm and a flexostyle. The chambers with inclined septula present low ridges at the base (Fig. 21D, F).
Systematics of Lutetian larger foraminifera, South Pyrenean Basin 29 Remarks. The specimens studied are smaller than the specimens identified as P. glynnjonesi (type species) by Hottinger (2007) and Serra-Kiel et al. (2016).
Description. Small test of discoidal, flattened morphology and annular-cyclic growth. The diameter of the shell for 17-19 annuli is around 3mm. Embryonic apparatus large, with a maximum diameter of 475µm, measured in axial section, and 200µm in height. Juvenarium (nepionic stage) formed of 2-3 annuli. In axial section, this species shows an endoskeleton simpler than the endoskeleton of other species of this genus.
Description. The megalospheric forms show a highconical morphology. The wall is thick and the texture pseudokeriothecal. The nepionic stage is formed of protoconch and deuteroconch in eccentric location, followed by 7-10 chambers with high-trochospiral arrangement (Fig. 22F). The neanic stage is formed of 5-7 chambers in uniserial arrangement ( Fig. 22N-O). The endoskeleton is formed of pillars beginning in the 3 rd -4 th nepionic chamber. At the apex of the cone the diameter ranges 330-375µm, with a maximum diameter of 1.5-2.0mm. The axial length is 2.0-2.3mm and the axial plane cuts 4-5 pillars. The pillars are discontinuous from one chamber to the next (Fig. 22J). The chamber sutures are slightly depressed. The apertural face is slightly convex, and the apertures show a cribrate distribution (Fig. 22I, Q).
Age. The biostratigraphic range of Coskinolina roberti extends from early Lutetian (SBZ13) to late Lutetian (SBZ16). The SBZ13 is characterized by its association with Alveolina stipes (sample G 21; Fig. 3), indicating early Lutetian (A. stipes Zone). The SBZ14 is characterized by the association of C. roberti with A. munieri (samples G 24,I 16,I 17,I 20 and I 21;Figs. 3;4), indicating middle Lutetian 1 (A. munieri Zone). In the sections studied, the SBZ15 is characterized by the alternation of samples with Coskinolina roberti with samples with Nummulites crassus (Fig. 5; 7). The SBZ16 is characterized by the stratigraphic location of C. roberti in samples overlying samples with N. aturicus and N. deshayesi (Fig. 5 fig. 1-6 Material. This species is present in the Gabardiella section (Fig. 3).
Description. The test is bilamellar with coarse pores and low-trochospiral growth. The dorsal side is convex and smooth; the ventral side is slightly convex and displays an umbo with beads (Fig. 23C). The lamination is composed of a thicker and perforate outer layer and a thin inner layer. Between both layers there is a marked dark median layer. The proloculus is spherical with a diameter of 80-100µm (Fig. 23A, E). The equatorial diameter is 0.77mm with 21 chambers and the longitudinal diameter is 0.52mm.

Superfamily
Description. Test of high-conical morphology. Nepionic stage composed of proloculus and two chambers in low-trochospiral arrangement. Neanic stage formed of chambers in high-trochospiral arrangement. The diameter of the proloculus varies between 145µm and 160µm. The lateral wall shows coarse pores and an exoskeleton formed of folds of the inner layer (Fig. 23I). The peripheral sections show a pseudo-polygonal network formed of folds of the inner layer over the outer lamella of the chamber lateral wall (Fig. 23I). Apertures in interiomarginal location (Fig.  23G). The septum backwards to umbiliculus overlaps the previous septum forming a massive accumulation of folia.
Age. The biostratigraphic range of Fabiania cassis extends from early Lutetian (SBZ13) to late Lutetian (SBZ16). The stratigraphic record of SBZ13 is characterized by its association with Alveolina stipes (sample I 7; Fig. 4), indicating early Lutetian (A. stipes Zone). SBZ14 is characterized by the association of F. cassis with A. munieri (samples G 24, G 34, G 35 and G 36; Fig. 3), and SBZ15 is characterized by its association with Nummulites crassus (samples SC 38 and P 21; Figs. 5; 7), indicating middle Lutetian 2 (N. sordensis-N. crassus Zone). Finally, SBZ16 is characterized by the occurrence of F. cassis overlying samples with N. aturicus Description. Trochospiral test with flattened umbilical side and concave dorsal side. Smooth dorsal side with marked pores. Length in axial section is around 1.5mm, and length in section perpendicular to the coiling axis is 1.4mm for 12-14 chambers. Small proloculus with a diameter of ca. 120µm (Fig. 24C).

Description.
Test with trochospiral growth. Thick lateral wall with coarse pores. Flat or slightly convex ventral side and concave dorsal side. In axial section, the diameter for three whorls is ca. 2mm and the length of the section perpendicular to the coiling axis is about 1.7mm for 10 chambers. Septum inclined backwards in dorsal side (Fig.  24D). The diameter of the proloculus is ca. 150µm (Fig.  24.E). Foramen located in interiomarginal position.
Age. According to Hottinger (2014) the biostratigraphic range of this species is SBZ13 (early Lutetian). Here, the biostratigraphic range of this species is SBZ13-SBZ14.
Description. Shell with trochospiral growth. Flat umbilical side and conical dorsal side. Slightly depressed sutures in subequatorial section (Fig. 24H, L). In axial section, the diameter for three whorls is around 2.3mm and the length of the section perpendicular to the coiling axis is around 2.4mm for 18-20 chambers. Proloculus about 190µm in diameter.
Age. Romero (2001) found this species in Bartonian rocks from the Igualada Basin (Spain). In the material studied this species is located in samples intercalated with Alveolina munieri (A. munieri Zone), indicating middle Lutetian 1 or SBZ14 (Fig. 3) Material. This species occurs in the Isuela section (Fig. 4).
Description. Test with low-trochospiral growth. The first whorls show a conical morphology and are followed by whorls with enlarged morphology. The sutures between chambers are depressed. Thick wall with marked pores and beads (Fig. 24Q). The length in longitudinal section is 1.85mm and in sections perpendicular to the coiling axis is 1.3mm.
Remarks. This species was formely considered to be a red algae. Later, Perrin (1987, 1994 and Bassi (2003) showed that its morphostructure was rather the morphostructure of an acervulinid foraminifera. As pointed out by the later author "each layer of the test consists of an expanse chamber subdivided into small, chamberlets connected by tubular passages". Unfortunately, the embryonic apparatus could not be observed, leading to a less well-defined taxonomic attribution.
Age. This species has been interpreted to be living attached to the substrate, especially in seagrass and reef environments of the inner shelf (Silva-Casal, 2017;Tomás et al., 2016). It has not biostratigraphic significance since it ranges from early Paleogene (Plaziat and Perrin, 1992;Perrin, 1994) to late Lutetian.
Remarks. Brugnatti and Ungaro (1987) described this species following morphological and structural criteria. In axial section the chambers show an arcuate outline with stolons located at the base of the chambers (Fig. 24E-F). According to these authors the concave morphology of the shell indicates an epiphytic habitat and suggests attachement to the substrate. This species was probably abundant in seagrass and reef environments of the inner shelf (Silva-Casal, 2017;Tomassetti et al., 2016). Its biostratigraphic significance is moderate since it occurs throughout the Lutetian.  fig. 17 1975 Sphaerogypsina globula (Reuss). Colom, p. 241; pl. 28, fig. 1 Material. This species occurs in the Gabardiella, Sierra Caballera, La Foz de Escalete, La Peña and Villalangua and Campo Fenero sections (Figs. 3;(5)(6)(7)(8)12).

GENUS
Remarks. Test spherical. Chambers distributed in the sphere and subdivided in chamberlets with chessboard pattern (sensu Hottinger, 2006). The ceilings of the chamberlets are flat or slightly concave (Fig. 25I) and its wall shows coarse pores. The apertures are located at the base of the lateral wall and connect the chamberlets of adjacent chambers.