Late Triassic (Tuvalian – Carnian, Tropites subbullatus/Anatropites spinosus zones) ostracods from Monte Gambanera (Castel di Iudica, Central-Eastern Sicily, Italy)

– Ostracod associations coming from the Upper Triassic ( Tropites subbullatus/Anatropites spinosus zones of the Tuvalian substage) clays and sandstones of the Mufara Formation outcropping along the west side of Monte Gambanera (Castel di Iudica, central-eastern Sicily) have been analysed for the ﬁ rst time. The specimens are relatively abundant, silici ﬁ ed, well preserved and often preserved as complete carapaces. Over 200 specimens have been determined. They belong to the families Healdiidae, Bairdiidae, Bythocyprididae, Acratiidae, Cytheruridae, Limnocytheridae, Candonidae, Cavellinidae, Polycopidae and Thaumatocyprididae. Thirty-seven species are identi ﬁ ed of which nine species are new: Hungarella forelae n.sp., Hungarella siciliiensis n.sp., Bairdia andrecrasquini n.sp., Bairdia gambaneraensis n.sp., Ptychobairdia : ostracodes / systématique / Trias supérieur / Néo-Téthys / Sicile centre est / Mont Gambanera / Formation Mufara


Introduction
This is the second contribution on the LateTriassic ostracod fauna of the Mufara Formation outcropping in central eastern Sicily. Previously the ostracod fauna of the Tropites dilleri zone of the Tuvalian substage outcropping at Monte Scalpello has been analysed . Now, a sedimentary level which is stratigraphically higher than the previous one and referable to the Tropites subbullatus/ Anatropites spinosus zones of the Tuvalian substage, has been identified at the western side of the Monte Gambanera, nine kilometres south of Monte Scalpello (Fig. 1). The samples provided a rich and mostly well-preserved ostracod fauna.

Geological setting and studied samples
Monte Gambanera is a modest relief located in central eastern Sicily (F 269 III NE of the Carta d'Italia alla scala 1:25 000) to the southeast of the town of Castel di Iudica (EN), about 40 kilometres west of Catania (Fig. 1). Structurally Monte Gambanera is part of the "Monte Judica Units" (Lentini et al., 1987) and is inserted along the northern margin of the Gela Foredeep, in the geodynamic context of the southern end of the Maghrebian-Sicilian Southern Apennine nappes (Lentini et al., 1987;Grasso, 2001 inter alias).
In the Monte Gambanera area, the outcropping sediments are assigned to the Neo-Tethyan Mesozoic-Cenozoic complex which belongs to the so-called Imerese Succession (Lentini et al., 1987;Montanari, 1987;inter alias) or Imerese-Sicano Succession (Carrillat and Martini, 2009;Di Paolo et al., 2012). The Imerese Basin, where these sedimentary successions were deposited, was delimited by the Panormide Carbonate Platform to the west and the Trapanese Carbonate Platform to the east and south (Catalano and D'Argenio, 1982;Montanari, 1987;Speranza and Minelli, 2014). In this basin, therefore, occurs a transitional facies between the Panormide and Trapanese shelf facies, on the one hand, and a deep marine facies of the Neo-Tethys, on the other. The sedimentary succession of Monte Gambanera (Fig. 2) starts with the "Carnian Flysch" (Auct.) or the Mufara Formation (Schmidt di Friedberg and Trovò, 1962). This unit, outcropping in the southern slopes of the mount, mainly consists of dark grey pelites, which locally contain rare ammonites, with rare interbeds of fossiliferous calcarenites and fibrous calcite with Halobia spp. imprints. The Mufara Fm. has been analysed since the beginning of the nineteenth century by Calcara (1840Calcara ( , 1845, Nelli (1899a, b) and subsequently by Gemmellaro (1904), Scalia (1907aScalia ( , b, 1909Scalia ( , 1910Scalia ( -1914, Maugeri Patanè (1934) and Lentini (1974). These latter authors attributed these sediments to the Carnian (Late Triassic).
Stratigraphically, the Mufara Fm. outcropping at Monte Scalpello, can be referred to the Tropites dilleri zone of the Tuvalian substage  due to the presence of Trachyceratidae (?Neoprotrachyceras, Trachysagenites, Pamphagosirenites) and Tropitidae. A foraminifera, conodont and palynomorph biostratigraphical analysis, allowed to attribute the levels of the Mufara Fm. outcropping at Monte Gambanera to the Tropites subbullatus/Anatropites spinosus zones of the Tuvalian substage ( Fig. 3) (Carrillat, 2001;Carrillat and Martini, 2009). In this stratigraphic horizon, cropping out near masseria Balconere at the west side of Mount Gambanera, two levels consisting of slightly silty clays have been sampled (Fig. 1). As they are stratigraphicaly very close and the number of specimens is quite low, we consider here the ostracod assemblages of both samples in all. They represent the ostracod association of the present study.
Twenty kilograms of sediments were collected from each of the two stratigraphic levels. Sediments were routinely washed, dried in oven and sieved. Then, ostracod specimens were picked out from the 63 mm fraction. The ostracod specimens were examined and measured under a stereomicroscope, then photographed under an LMU Tescan Vega II SEM. The material is housed in the Palaeontological Museum of the University of Catania. The repository number of the specimens are given in the systematic descriptions and/or in plate explanations. Over 200 specimens have been picked out from the two samples. The specimens are silicified, quite well preserved and often consist of complete carapaces.   dorsal border; ADB: antero-dorsal border. We follow here the general classification of Moore (1961) and Horne et al. (2002).
A great confusion exists in the systematics of Late Permian -Triassic Healdiidae genera Hungarella -Ogmoconcha -Ogmoconchella. Some authors consider Hungarella Méhes (1911) (which has no type material -Gerry and Kozur (1973); but the Hungarian original material in under revision by E. Tóth, pers. com.) and Ogmoconcha Triebel (1941) as synonyms (Moore, 1961;Anderson, 1964). Shaver (in Moore 1961),  and Kristan-Tollmann (1971, 1977a don't agree with this synonymy. In fact, the two genera are close but the valves are strongly dissymmetric in shape in Hungarella. The third genus, Ogmoconchella was introduced by Gründel (1964) and emended by Michelsen (1975) mainly due to the presence of a spine at PVB. In a recent revision, Forel and Crasquin (submitted) considered that until the relationship of Ogmoconcha and Hungarella is clarified, Hungarella should only been used for Triassic species to avoid artificially rooting Ogmoconcha down to the Triassic. Morphologically, the left and right valves of Hungarella are asymmetrical contrary to those of Ogmoconcha (Kristan- Tollmann, 1977a, b;Lord, 1982) Diagnosis. A species of Hungarella with triangular shape carapace, a posteroventral spine at RV, delicate flattening in blade shape at anterior border of RV.
Description. Massive carapace with a symmetric triangular shape; quite symmetric relative to H max; shape of left and right valves similar ; LV is significantly larger than RV and radius of curvature of PB smaller than anterior one; LV overlaps RV all around the carapace with minimum at PVB; maximum of H located in front of or at mid L; maximum of L at mid H or a little below; VB quite straight; presence of a very fine flattening all around the AB of RV in blade shape; small spine more or less distinct at PVB of RV; dorsal view biconvex with valves almost symmetric in shape and W max at or just behind mid L; surface seems to be smooth.
Remarks. The present specimens are close to Ogmoconchella felsooersensis (Kozur, 1970) from the early Anisian of Hungary (Kozur, 1970, Monostori, 1995 and Romania (Sebe et al., 2013). In a previous paper  two of the present specimens were attributed to this O. felsooerensis. Based on the new material this determination was revised and they are attributed to Hungarella forelae. Here the carapace is more triangular with a smaller radius of curvature of PB; the blade at AB is also more expressed here. The specimens described by Forel et al. (2019b;Plate 4, particularly fig. E, K) as Hungarella gommerii Forel, 2019 from the Carnian of Sichuan (South China) are very close to our specimens. However, the Sichuan specimens are smaller (biggest one ≈ L = 600 mm, H = 400 mm) and show a smaller radius of curvature at both extremities. The largest specimen of H. forelae (Fig. 4) presents some morphological variability: overlap less important, at RV: the blade is located only at the ventral part of AB and occurrence of a small spine at the upper part of it, at LV: anteroventral blade seems to be also present. We consider that these morphological variations could be the expression of ontogenic variations but some doubt remains.   Paratype. One complete carapace, collection number PMC O 78 P 13/10/2019, Plate 1C.
Diagnosis. A species of Hungarella with triangular shape carapace, two posteroventral spines at RV, flattening in blade shape plus a spine at anterior border of RV, spine at AB of LV.
Description. Massive stocky carapace with a symmetric triangular shape; quite symmetric relative to H max; general shape of valves similar, but LVis significantly larger than RVand radius of curvature of PB smaller than anterior one; LVoverlaps RVall around the carapace with minimum at PVB; maximum of H located at mid L or in front of mid L; maximum of L at mid H or a little below mid H; VB quite straight; presence of a very fine flattening at AB of RV in blade shape and a spine located near the maximum of convexity of AB; two more or less distinct spines at PVB of RV; one spine at AB of LV; dorsal view biconvex with valves almost symmetric in shape and W max at or just behind mid L; surface seems to be smooth.
Remarks. Hungarella siciliiensis n.sp. is very close to H. forelae n.sp.. The shapes of the valves are similar. The main differences between the two species is the presence of 2 spines at PVB of RV, presence of a spine at AB of booth valves and the less distinct "blade" at the AB of H. siciliiensis n.sp.. We can't exclude that these differences are due to morphological variability of H. forelae n.sp. (sexual or ontogenic). However, for the time being we have not enough specimens to settle this question. Diagnosis. A species of Bairdia with an elongated carapace, flattened AB and PB, and a ventral ridge along the posterior part of the VB and PB.
Description. Bairdioid carapace, quite elongated (H/ L = 0.44); DB straight at RV and slightly convex at LV; ADB and PDB straight and quite symmetric with respect to DB; AB with large radius of curvature and maximum located above mid-H, AB strongly flattened laterally; VB slightly concave; PB slender and pointed, maximum of curvature located at lower 1/3 of H, strongly flattened laterally; presence of the ventral ridge which begins in posterior part of VB and runs along PB.
Remarks. This species is quite original and differs from all other ones by the specific characters (flattened AB and PB, and a ventral ridge along the posterior part of the VB and PB.). The shape of carapace is comparable to Bairdia sp. 4 sensu Etymology. Refering to the locus typicus Monte Gambanera, Sicily, Italy.
Diagnosis. A species of Bairdia with a very compact carapace, a continuously arched dorsal boarder and flattened and crenulated ventral parts of AB and PB Description. Bairdioid carapace, quite short (H/L = 0.6-0.7), LV overlaps RV all around the carapace with minimum at AB and anterior part of VB; LV: all the dorsal part regularly arched; AB with large radius of curvature with maximum at mid-H, VB almost straight; BP with large radius of curvature with maximum at lower 1/3 of H; PDB arched; RV: DB straight, ADB straight with an angulation of 145°-150°against DB; AB with large radius of curvature; AVB and PVB flattened laterally in its very external part and with very fine crenulation; VB slightly concave; bairdioid beak quite absent; PDB straight with an angle of 125°-130°with DB; Presence of a shoulder on medio-dorsal part of LV; carapace biconvex and quite slender in dorsal view.
Occurrence. Tuvalian -Carnian, Tropites dilleri zone  and Tropites dilleri zone  and Tropites subbullatus/Anatropites spinosus zones, Monte Gambanera, Central-Eastern Sicily, Italy (this study). Remarks. This species of Bairdia is characterized by the BD which is underlined by a blade, and by the reticulation of the carapace. The upper part of PB is quite horizontal and its radius of curvature is small. This could be a new species.
Occurrence. Tuvalian -Carnian, Tropites dilleri zone   Remarks. This species is characterized by its triangular shape, the flattening of the ventral borders and the reticulated surface. The PB has a very small radius of curvature.
Description. Carapace massive, high (H/L = 0.6); surface reticulated; LV: Flattened laterally all around with maximum at DB and PB; BD strongly arched; AB with quite large radius of curvature and maximum at mid H; VB almost straight; BP with a very small curvature; two vertical sulci in dorsal part; LV strongly overlapping RV all around with maximum at BD.
RV: Strongly flattened all around except in ventral part; presence of a sulcus in AD part; BD long; AB with quite small radius of curvature; VB gently concave at its anterior part; BP very slender; DB, ADB, AVB, PVB, PDB straight.
Remarks. Ptychobairdia iudicaensis n.sp. is comparable with P. oberhauseri Kollmann (1960) from the Rhaetian of Austria (Kollmann, 1960) and the Carnian -Norian of Queen Charlotte Island, Canada (Arias and Lord, 2000). The latter species is longer, has a smaller AB and shows a horizontal sulcus. P. iudicaensis n.sp. differs from P. kristanae Kollmann (1960) from the Rhaetian -Early Jurassic of Austria (Kollmann, 1960 and the late Carnian of Sicily  by its reticulated carapace and the RV being clearly smaller than LV. Dimensions. L = 720-1083 mm; H = 480-667 mm (see Fig. 5).
Description. Carapace with massive coarse reticulation, flattened laterally at AB and PB; DB straight at both valves and parallel to VB; ontogenic modifications of DB: at RV with nodules or blade at biggest specimens, at LV development of shoulders at each extremities in largest specimens; AB and PB with small radius of curvature, flattened laterally and covered by a fine reticulation; VB straight to slightly concave, with development of adventral structure; presence of a big node in median part of the carapace.
Remarks. Ptychobairdia leonardoi n.sp. differs from other species by the specific characters. Margarobairdia zapfei Kristan-Tollmann (1983) from the Anisian of South China (Kristan- Tollmann, 1983) has a similar valve shape but a different ornamentation.
Description. Carapace subrectangular, almost equivalve; BD long and straight, presence of a ridge on each side of hinge; presence of an eye spot; AB with large radius of curvature with maximum located below mid-H, flattened laterally and smooth; VB almost straight; PB with small radius of curvature with maximum around mid H, upper and lower part quite straight; H max at anterior angle; L max at PB; sulcus more or less developed in anterior 1/3 of L; surface reticulated and ornamented with possible pustules and ridges: one lateral, thick, reaching from antero-ventral part of the carapace up to PB, ascending in posterior part; group of ventral ridges, one thick parallel to VB and several (at least three) below.
Remarks. Kerocythere dittainoensis n.sp. could be compared to Kerocythere reticulata Kristan-Tollmann (1972) from early Carnian of the Dolomites (Italy). This species doesn't show the ventral group of ridges but has one ridge at the AD part of the carapace following the AB. The new species is also close to Kerocythere tricostata Forel, 2017 from the middle Carnian of southern Tauride-Anatolide platform (Turkey; Forel et al., 2017). At the present material the lateral ridge is longer, ascends at its posterior part and the surface is reticulated.
Diagnosis. A species of Mockella with a long subrectangular carapace and a well-developed rib all around the carapace.
Description. Carapace sub rectangular, long (H/ L = 0.535); eye spot well developed; AB with maximum of curvature located low between mid-H and lower 1/3 of H; VB straight; PB equivalent to AB in heteromorphs and smaller in tecnomorphs with maximum of curvature located above mid-H; anteromedian sulcus located in front of mid-L; posterior lobe well developed; anterior lobe less distinct; presence of a distinct ridge all around the carapace including BD; presence of additional ridges on lateral surface of the valves: a median ridge which begins at maximum of curvature of AB and precedes on the posterior lobe; this ridge is high and stands out on the surface; a lateral ridge below the lobes parallel to VB; a small ridge in upper part of AB and below the eye spot.
The valve surface is reticulated with 4 small pustules distributed parallel to AB; in dorsal view, the flanks are parallel. Sexual dimorphism present, expressed by the thickness of the posterior part of the carapace in heteromorphs.
Remarks. Mockella barbroae n.sp. is very close to M. muelleri Bunza and Kozur (1971) from the late Carnian of Tyrol, Austria  and the Carnian of Monte Cammarata, Sicily (Cafiero and De Capoa Bonardi, 1982). In the study on the Mufara Formation  we attributed the specimens to the latter species. The very well preserved present material enabled us to review our attribution. At the present specimens the BP is larger, the median ridge ends at the posterior lobe and doesn't reach the BP; an additional ridge is present below the lobes and the flanks are parallel in dorsal view.

Assemblage analysis
The assemblage is composed of 200 specimens belonging to 10 families (plus two undetermined families), 19 genera and 37 species. The 10 determined families present are: Healdiidae, Bairdiidae, Bythocyprididae, Acratiidae, Cytheruridae, Limnocytheridae, Candonidae, Cavellinidae, Polycopidae, Thaumatocyprididae. The relative abundance of the different families expressed by the numbers of genera and species is given in Figure 8.
The Bairdiidae, the most abundant family in number of species (53%) and genera (37%) (Fig. 8), are present in marine environments ranging from very shallow waters up to deep seas. The morphology of the family changes from massive thick-shelled forms in nearshore environments to elongate thin-shelled forms beyond continental slope (particularly in genus Bairdia). In the same way, the carapaces of Acratiidae lengthen with depth (as example: Acratia goemeryi Kozur (1970) from Early-Smithian-to Late-Carnian-Triassic; see Forel et al., 2017). Here these two families present thick and ornamented shells (Plates 1E-1R and 2A-2L) which testify an open marine environment with moderate energy. The Healdiidae do also show a change of morphology with depth. The specimens with massive shells and small spines are neritic  inhabitants (Plate 1A-1D) of relatively nearshore muddy conditions. In the deep sea, the specimens are thin shelled, elongate with long spines (e.g. Palaeozoic genus Timorhealdia Bless, 1987). In other families, some genera also show different morphological adaptation from neritic to deep sea environments (Healdia, Microcheilinella etc. see synthesis Tab. 1 in Crasquin and Horne). The ratios between these different morphologies have been used to characterize the depth of ate Palaeozoic and Early Mesozoic environments since quite a long time (model of Lethiers and Raymond, 1991). The present assemblage doesn't include any unequivocal deep water taxa such as those discovered recently in the Carnian of Southern Turkey for example  or of Sichuan, South China . Although the number of specimens is very low, the diversity is quite high with 10 determined families (plus 2 undetermined), 17 genera and 37 species. This biodiversity testifies normal marine conditions and absence of environmental stress. The taxon Simeonella brotzenorum  which is characteristic of brackishhypersaline conditions Monostori, 1994) is present but with only 2 carapaces. Quite all the specimens are preserved with the complete carapace. After the death of the specimens, the carapaces tend to open in a few hours (Guernet and Lethiers, 1989). This could suggest a rapid burial in the sediments due to a high sedimentation rate. Similar taphonomic characteristics were also found by Pokorny (1964) and Oertli (1971) for pelitic layer associations deposited in basins with extremely rapid distal sedimentation. We compare the results of the Tropites subbullatus/Anatropites spinosus zones (this study), with the data obtained in levels just below in Tropites dilleri zone   (Fig. 9). Through time, the assemblage became more diversified as recorded by the increasing number of families (8 to 12), genera (14 to 18) and species (23 to 36). The percentage of Bairdiidae decreases in favour of two families being absent before, Cytheruridae and Limnocytheridae which include typical genera of nearshore environments such as Simeonella, Mockella and Kerocythere. We observe also the presence of the brackishhypersaline species Renngartenella sanctaecrusis Kristan-Tolmann, which was suggested by Gerry et al. (1990) to be a stenohaline ostracod.
For Monostori (1994), the dominance of three genera Kerocythere -Renngartenella -Simeonella seems to be a signal of salinity variability. Although these genera are not dominant here, their presence testifies a shallowing of environment from the Tropites dilleri zone to the Tropites subbullatus/Anatropites spinosus zones. The genus Acratia is a typical Palaeozoic form present both in Eifelian (neritic) and Thuringian (deep) mega-assemblages (see synthesis in Crasquin and Horne, 2018). Nevertheless, this genus survived the Permian -Triassic extinction events. In 2013, Crasquin and Forel mentioned the last occurrence of neritic Acratia in the Spathian and of deep marine Acratia in the Anisian (Crasquin-Soleau and Grădinaru, 1996). Since then, some deep marine forms were also found in the Ladinian of Balaton Highland (Monostori and Tóth, 2013), in the Carnian of Turkey  and Slovenia . In 2013, Monostori and Tóth, described Acratia goemeryi from Ladinian neritic sediments of a borehole in Hungary. Three species of Acratia from the Carnian of Karavanke Mountains, Solvenia, are figured in Forel et al. (2019b). The occurrence of Acratia maugerii in the present material confirms that Acratia occurs in neritic environments of the Carnian.

Conclusion
The palaeoecological interpretation of the sedimentary facies of the Mufara Formation is extremely difficult due to the absence of intact outcrops. The original stratification and the sedimentary structures have been completely destroyed because of continuous agricultural processing of the pelitic soils and their very consistency which determines frequent drifts and landslides. In very few and limited locations parallel laminations and sandy levels were observed. The only useful palaeoecologic data are those obtained from the 1 The ostracod assemblage doesn't yield any evidence of deep marine taxa both at Mt. Scalpello  and at Mt. Gambanera. The Mufara Basin, therefore, can be interpreted as a shallow marine basin (Fig. 10) within the deepest and most distal part of a vast continental shelf where the carbonate platforms Panormide, Trapanese, Saccense were located. The deep marine ostracod fauna discovered recently in the Carnian of Southern Turkey  or in the South China (Forel et al., 2019a) suggests a deepening of the Neo-Tethys basin towards the more eastern areas. 2 The Mufara Basin was a site of rapid and intense sedimentation probably linked to rapid bottom currents which, sometimes, displaced and transported (also in vivo) microfaunas from more superficial neighbouring environments. It is pointed out here that the sediments of the Mufara Basin at Monte Gambanera do not show vortex structures which were recognized in the Mufara Basin at Monte Scapello. This suggests, that the sediment environment of the Mufara Formation outcrops at Monte Gambanera ( Fig. 11) was more distal and less turbulent than that of Mt which was effected by strong bottom traction and swirling currents . 3 According to many authors, the Mufara basin is located in a transitional position between the bathyal Neotethys facies to the south and southeast and the carbonate platforms that surround it (Figs. 10 and 11).