Ostracod communities through a cold fluid seepage during the Late Jurassic: the Sahune site (Drôme, France)

2025  47  17 geodiversitas Geodiversitas est une revue en flux continu publiée par les Publications scientifiques du Muséum, Paris Geodiversitas is a fast track journal published by the Museum Science Press, Paris Les Publications scientifiques du Muséum publient aussi / The Museum Science Press also publish: Adansonia, Zoosystema, Anthropozoologica, European Journal of Taxonomy, Naturae, Cryptogamie sous-sections Algologie, Bryologie, Mycologie, Comptes Rendus Palevol Diffusion – Publications scientifiques Muséum national d’Histoire naturelle CP 41 – 57 rue Cuvier F-75231 Paris cedex 05 (France) Tél. : 33 (0)1 40 79 48 05 / Fax : 33 (0)1 40 79 38 40 [email protected] / http://sciencepress.mnhn.fr © Publications scientifiques du Muséum national d’Histoire naturelle, Paris, 2025 ISSN (imprimé / print) : 1280-9659/ ISSN (électronique / electronic) : 1638-9395 Directeur De la publication / Publication director : Gilles Bloch, Président du Muséum national d’Histoire naturelle réDacteur en chef / editor-in-chief : Didier Merle réDacteur associé / associate editor: Sylvain Charbonnier assistant De réDaction / assistant editor : Emmanuel Côtez ([email protected]) Mise en page / Page layout : Emmanuel Côtez coMité scientifique / scientific board : Christine Argot (Muséum national d’Histoire naturelle, Paris) Beatrix Azanza (Museo Nacional de Ciencias Naturales, Madrid) Raymond L. Bernor (Howard University, Washington DC) Henning Blom (Uppsala University) Gaël Clément (Muséum national d’Histoire naturelle, Paris) Ted Daeschler (Academy of Natural Sciences, Philadelphie) Cédric Del Rio (Muséum national d’Histoire naturelle) Gregory D. Edgecombe (The Natural History Museum, Londres) Ursula Göhlich (Natural History Museum Vienna) Jin Meng (American Museum of Natural History, New York) Brigitte Meyer-Berthaud (CIRAD, Montpellier) Zhu Min (Chinese Academy of Sciences, Pékin) Isabelle Rouget (Muséum national d’Histoire naturelle, Paris) Sevket Sen (Muséum national d’Histoire naturelle, Paris, retraité) Stanislav Štamberg (Museum of Eastern Bohemia, Hradec Králové) Paul Taylor (The Natural History Museum, Londres, retraité) couverture / cover : Réalisée à partir des Figures de l’article/Made from the Figures of the article. Geodiversitas est indexé dans / Geodiversitas is indexed in: – Science Citation Index Expanded (SciSearch®) – ISI Alerting Services® – Current Contents® / Physical, Chemical, and Earth Sciences® – Scopus® Geodiversitas est distribué en version électronique par / Geodiversitas is distributed electronically by: – BioOne® (http://www.bioone.org) Les articles ainsi que les nouveautés nomenclaturales publiés dans Geodiversitas sont référencés par / Articles and nomenclatural novelties published in Geodiversitas are referenced by: – ZooBank® (http://zoobank.org) 687 GEODIVERSITAS • 2025 • 47 (17) © Publications scientifiques du Muséum national d’Histoire naturelle, Paris. www.geodiversitas.com KEY WORDS Oxfordian, Ostracoda, south-eastern France Basin, Deep-sea, sequence of fluid seepage, extreme environments. Marie-Béatrice FOREL Sylvain CHARBONNIER Centre de recherche en paléontologie – Paris (UMR 7207, CR2P), CNRS, MNHN, Sorbonne Université, Département Origines et Évolution, Muséum national d’Histoire naturelle, case postale 38, 57 rue Cuvier, F-75231 Paris cedex 05 (France) [email protected] (corresponding author) [email protected] Cristianini Trescastro BERGUE Centro de Estudos Costeiros, Limnológicos e Marinhos – CECLIMAR, Departamento Interdisciplinar, Universidade Federal do Rio Grande do Sul, Avenida Tramandaí, 976, 95625-000 Imbé, RS (Brazil) [email protected] Christian GAILLARD Université Claude Bernard Lyon 1, Lyon (France) [email protected] Submitted on 20 July 2024 | accepted on 11 November 2024 | published on 16 October 2025 Ostracod communities through a cold fluid seepage during the Late Jurassic: the Sahune site (Drôme, France) urn:lsid:zoobank.org:pub:6022CC42-6887-4ED9-86CB-132B7D9A47AF Forel M.-B., Charbonnier S., Bergue C. T. & Gaillard C. 2025. — Ostracod communities through a cold fluid seepage during the Late Jurassic: the Sahune site (Drôme, France). Geodiversitas 47 (17): 687-703. https://doi.org/10.5252/ geodiversitas2025v47a17. http://geodiversitas.com/47/17 ABSTRACT The oldest known ostracods from a chemosynthetic community at a cold seep were recently described from an authigenic carbonate lens enclosed within the Upper Jurassic (middle Oxfordian) Terres Noires Formation at Sahune in the south-eastern France Basin. Here we extend the observations to the entire sequence of fluid seepage at Sahune and compare them to those from marls deposited laterally. We report that ostracods are much more abundant throughout the authigenic deposits than within the enclosing marls. The composition of the assemblages is fairly stable over the period of emission of seep-type fluids, likely pointing to their relatively stable chemical composition. Communities are largely dominated by representatives of Pontocyprididae (e.g., Pontocyprella Mandelstam in Ljubimova, 1955), which seems to be a deep-sea feature within the south-eastern France Basin at least from the Oxfordian to the Early Cretaceous. We suggest that the observed abundance of ostracods within seep deposits, and particularly of pontocypridids, may be related to cold seep fluids and associated complex ecosystems. This complete analysis shows the persistent low diversity and distinct taxonomic composition of Sahune communities compared to contemporaneous plat- 688 GEODIVERSITAS • 2025 • 47 (17) Forel M.-B. et al. INTRODUCTION Ostracods (Crustacea Brünnich, 1772, Ostracoda Latreille, 1802) inhabit all types of water bodies, including environments from hydrothermal vents, cold hydrocarbon seeps, and wood falls (e.g., Maddocks& Steineck 1987; Steineck et al. 1990; Kornicker 1991; Van Harten 1993; Maddocks 2005; Kornicker& Harrison-Nelson 2006; Karanovic& Brandão 2015; Tanaka& Yasuhara 2016). However, ostracods from modern chemosynthetic communities associated with cold seeps have only been seldom reported, namely from Black Sea (Schornikov& Syrtlanova 2008), Gulf of Mexico (Degen et al. 2012; Machain-Castillo et al. 2014), Marmara Sea (Ritt et al. 2010), Svalbard margin (Yasuhara et al. 2018), Pelotas Basin (Maia et al. 2022), São Paulo Plateau and Rio Grande Rise offshore Brazil (Bergue et al. 2023). Fundamental questions remain regarding the structure of their taxonomic diversity, their ecological role in these communities and their adaptations to extreme conditions. The evolutionary history of cold seep ostracods is also largely unknown as fossil counterparts have mainly been documented from few Cenozoic deposits, namely from the Eocene-Oligocene of United States (Yamaguchi et al. 2016), the Miocene of Italy (Russo et al. 2012) and the Quaternary of Ireland (Coles et al. 1996) and Svalbard, Norway (Chu et al. 2023). Their oldest occurrence in such environments was recently reported in the Late Jurassic, middle Oxfordian, by the description of the entire community (ostracods, radiolarians, benthic and planktonic foraminifers, echinoids, crinoids, comatulids) of a seep-related limestone at the base of the Sahune site in south-eastern France Basin (Forel et al. 2024). Here we extend these preliminary observations to the entire sedimentary sequence affected by fluid seepage at Sahune, composed of four successive seep-related limestone masses hereafter termed pseudobioherms, and marls MOTS CLÉS Oxfordien, Ostracoda, bassin du sud-est de la France, milieu marin profond, séquence de suintements de fluides, environnements extrêmes. form and deep-water communities. For instance, the Cytheroidea Procytherura? praecoquum Forel in Forel, Charbonnier, Gale, Tribovillard, Martinez-Soares, Bergue, Gradstein& Gaillard, 2024 seems to have been adapted and endemic to the active centre of fluid emission, being absent from lateral marly sediments. Well-preserved specimens display morphological characters that were not visible at the time of species description, including fossae arrangement and distribution pattern of normal pores, which are described as a first step toward the clarification of the phylogeny and adaptation of Cytheroidea endemic to cold seeps. Within the limits of the preservation of the material, the valves of this species may display genuine pore clusters and more material may lead to the conclusion that it should be re-attributed to an environment-specific new genus. RÉSUMÉ Communautés d’ostracodes au cours de suintements de fluides au Jurassique supérieur : le site de Sahune (Drôme, France). Les ostracodes les plus anciens connus d’une communauté chimiosynthétique associée à des suintements froids ont été récemment décrits à partir d’une lentille de carbonate authigène contenue dans la Formation des Terres Noires du Jurassique supérieur (Oxfordien moyen) à Sahune dans le bassin sud-est de la France. Nous étendons ici les observations à l’ensemble de la séquence de suintement de fluides à Sahune et les comparons à celles des marnes déposées latéralement. Nous rapportons que les ostracodes sont beaucoup plus abondants dans les dépôts authigènes que dans les marnes encaissantes. La composition des associations est assez stable pendant la période d’émission de fluides, ce qui indique probablement leur composition chimique relativement stable. Les communautés sont largement dominées par des représentants des Pontocyprididae (ex., Pontocyprella Mandelstam in Ljubimova, 1955), ce qui semble être une caractéristique des eaux profondes du bassin du sud-est de la France, au moins de l’Oxfordien au Crétacé inférieur. Nous suggérons que l’abondance observée d’ostracodes dans les dépôts de suintement, et en particulier des pontocyprides, pourrait plutôt être liée aux fluides de suintements froids et aux complexes écosystèmes associés. Cette analyse complète montre la faible diversité et la composition taxinomique distincte des communautés de Sahune par rapport aux communautés contemporaines des plates-formes et d’eaux profondes. Par exemple, le Cytheroidea Procytherura? praecoquum Forel in Forel, Charbonnier, Gale, Tribovillard, Martinez-Soares, Bergue, Gradstein& Gaillard, 2024 semble avoir été adapté et endémique au centre actif d’émission de fluide, étant absent des sédiments marneux latéraux. Des spécimens bien conservés présentent des caractères morphologiques qui n’étaient pas visibles au moment de la description de l’espèce, notamment la disposition des fossae et la distribution des pores normaux, qui sont décrits comme une première étape vers la clarification de la phylogénie et l’adaptation des Cytheroidea endémiques aux suintements froids. Dans les limites de la préservation du matériel, les valves de cette espèce pourraient posséder de véritables agrégats de pores et davantage de matériel pourrait conduire à la conclusion qu’elle devrait être réattribuée à un nouveau genre, spécifique à ces environnements. 689 Ostracod communities through a cold fluid seepage during the Late Jurassic: the Sahune site (Drôme, France) GEODIVERSITAS • 2025 • 47 (17) deposited laterally. The present analysis provides insights into ostracod assemblages over the whole period of seep fluid circulation and spatially when compared with lateral marls. The discovery of well-preserved specimens of Procytherura? praecoquum Forel in Forel, Charbonnier, Gale, Tribovillard, Martinez-Soares, Bergue, Gradstein& Gaillard, 2024 allows the thorough re-description of its morphological features and possible pore-clusters. Because this species may turn out to represent an environment-specific new genus, we here consider its attribution to Procytherura Whatley, 1970 as uncertain. A particular attention is paid to the reticular pattern of its lateral surface, with the aim of laying the foundation for the future understanding the phylogeny of Cytheroidea Baird, 1850 from cold seeps. C 02 07 09 06 04 05 02b 08 P1 P3 P4 P2 1 m AB B Montpellier Internal Alps Jura platform Cévennes platform Nîmes F. Durance F. Propiac F. Cléry F. Die F. Dauphinois basin Provence basin Provence platform Occitan topographic high Digne Gap Marseille Mediterranean Sea Nice 50 km Grenoble Condorcet diapir Propiac diapir Suzette diapir Igneous rocks Beauvoisin area Beauvoisin Sahune Pelvoux-Argentera lineament External Alps fine grained limestone argillaceous limestone marlstone pseudobioherms lateral marls productive samples non-pseudobiohermal limestone 03 01 N fig. 1. — A, Geographical map of France showing Sahune locality in Drôme, south-eastern France Basin (Google Maps, 2023); B, simplified structural map of the south-eastern France Basin with the location of Sahune in the Natural Regional Park of Baronnies provençales (modified from Tribovillard et al. 2013). Circle represents Beauvoisin area; abbreviation: F, fault; C, interpretative scheme of the Sahune sequence (modified from Forel et al. 2024). P1-P4, pseudobioherms; numbers: 01-09, studied samples, labelled 08SAH (collected in 2008, studied in Forel et al. 2024) and 22SAH (sampled in 2022, newly studied here). Samples 22SAH10 to 22SAH13, of which only 22SAH12 produced unidentifiable specimens, were collected from the opposite side of the main sequence, they are not shown on the present sketch. 690 GEODIVERSITAS • 2025 • 47 (17) Forel M.-B. et al. GEOLOGICAL CONTEXT The Sahune site is located within the south-eastern France Basin, the history of which is linked to the opening of the Liguro-Tethyan Ocean during the Jurassic (Lemoine 1985; Fig. 1A). Following the Early to Middle Jurassic (Hettangian to Bathonian), characterized by low subsidence and deposition of shallow-water carbonate platform, the Bathonian to Oxfordian interval (Middle to Late Jurassic) recorded the maximum of subsidence of the deepest, central part of the basin, due to basement faults controlled by the withdrawal of salt in the extensional domain of the margin (Mascle et al. 1988). It led to the deposition of a 2000 to 2500 m thick marly series, the Terres Noires Formation (Bathonian-Oxfordian; Fig. 1B), which encloses fossiliferous calcareous masses contrasting with the surrounding fossil-poor deposits. Their origin was long debated, with hypotheses ranging from sponge bioherms (Artru& Gauthier 1966; Artru 1972) to hydrothermal activity (Bourseau 1977; Macsotay 1980; Lemoine et al. 1982). These limestone bodies, termed pseudobioherms, have finally been related to a context of passive margin with synsedimentary faults affecting the Terres Noires Formation allowing the upward migration of fluids to the sea bottom (Gaillard et al. 1985; Gaillard& Rolin 1986, 1988). This circulation of seep-type fluids locally induced the formation of authigenic limestone and sustained an ecosystem relying on bacterial chemosynthesis. The Sahune site is located in the Drôme department, Auvergne-Rhône-Alpes region (44°24’28.188”N, 5°16’51.96”E; Fig. 1A, B), in the northern part of the south-eastern France Basin. It is exposed on the northern flank of a hill about 1.4km from the Sahune village and 12km north-east from the well-known Beauvoisin site, today considered as a giant pockmark (Gay et al. 2018, 2020). The Sahune sequence was described in Forel et al. (2024): it is composed of four imbricated meter-scale, seep-related pseudobioherms labelled P1 to P4, enclosed within the Terres Noires deposits (Fig. 1C). Another pseudobioherm and a semi-consolidate nodular limestone likely related to an aborted emission of fluid occur laterally. The relation of Sahune pseudobioherms to the circulation of seep fluids was demonstrated by geochemical proxies (Forel et al. 2024). Pseudobioherm P1 at the base of the sequence yielded a rich and diverse community composed of abundant ostracods together with benthic and planktonic foraminifers, radiolarians, crinoids, echinoids and comatulids. The analysis of the P1 community indicates that the fluid seepage occurred at bathyal depth. The occurrence of the irregular echinoid Tithonia oxfordiana Gaillard, Néraudeau & Thierry, 2011 clarified that Sahune site is coeval to the R4 key-bed, which is one of the seven key-beds (R1 to R7) recognized for middle Oxfordian deposits of the south-eastern France Basin and its western margin (Gaillard et al. 1996, 2004). The planktonic foraminiferal assemblage containing Globuligerina oxfordiana (Grigelis, 1958), Globuligerina bathoniana (Pazdrowa, 1969) and ‘Globuligerina’ balakhmatovae (Morozova in Morozova& Moskalenko, 1961) is in line with the Oxfordian age (Forel et al. 2024). MATERIAL AND METHODS Ten samples were collected from the main sequence at Sahune, labelled 22SAH01 to 22SAH09 (Fig. 1C): Five samples from the four pseudobioherms P1 to P4: 22SAH01 (=08SAH01 collected at the same position in 2008 and studied in Forel et al. 2024; P1), 22SAH02 (P2), 22SAH03 (P3), 22SAH04 and 22SAH05 (P4). One sample from marls deposited laterally to P2: 22SAH02b (hereafter noted LM). Four samples from bedded non-pseudobiohermal limestone: 22SAH06 to 22SAH09. Four additional samples were collected from the opposite side of the main sequence, from the nodular pseudobioherm bed (22SAH10), underlying marls (22SAH11), likely aborted emission of fluid (22SAH12) and underlying marls (22SAH13). About 700g of sediment of each of the 14 studied samples were processed by hot acetolysis technique (Bourdon 1962; Lethiers& Crasquin-Soleau 1988) for ostracod extraction. All residues were sieved through a 0.63mm mesh, oven dried, and specimens were picked under a stereomicroscope. Specimens of interest have been gold coated and photographed using the SEM JEOL JCM-600 at the Centre de Recherche en Paléontologie-Paris (CR2P). All ostracod specimens figured here are deposited in the Palaeontology collections of the Muséum national d’Histoire naturelle, Paris (France). Most species reported here, including those that were not found in Forel et al. (2024), are kept in open nomenclature because of their rarity and/or overall poor preservation. Only the five newly found species are illustrated (Fig. 2A-F) as well as specimens of Procytherura? praecoquum that are well-preserved enough to allow an in-depth discussion of their characters (Fig. 2G-W). The complete taxonomic list of all Sahune species is provided in Appendix 1; their distribution and abundance through the seep sequence is summarized in Table 1. RESULTS AND DISCUSSION InsIghts Into Procytherura? Praecoquum Procytherura? praecoquum was described from P1, it is only known from Sahune and was hypothesized as ecologically restricted to seeps (Forel et al. 2024). At the time of its description, only characters of its outer surface were visible, and green UV light permitted the observation of duplicatures and vestibules through slightly translucent valves. Some of the newly obtained specimens are much better preserved and provide further details on the general morphology, surface reticulation, muscle scars and normal pores of Procytherura? praecoquum. The very likely presence of pore clusters through its valves differs from all Procytherura species known so far, and this species may rather represent a new genus, specifically related to peculiar environmental conditions. For this reason, we choose to consider the generic attribution of this species as uncertain, noted here as Procytherura? praecoquum. 691 Ostracod communities through a cold fluid seepage during the Late Jurassic: the Sahune site (Drôme, France) GEODIVERSITAS • 2025 • 47 (17) CarapaCe morphology Two well-preserved carapaces retrieved from P3 provide thorough insights into their free margin, that was not visible with such fine details on the previous specimens. The anterior and posterior margins are bordered by thin bevelled flanges (Fig. 2G, I, O, S). The posterior flange extends ventrally within the oral concavity in front of mid-length, while the anterior one is shorter and does not develop within the oral concavity. The anterior and posterior flanges of both valves are parallel and closely set together into a sort of narrow funnel when the valves are closed (Fig. 2I, S). The surface of the anterior flange appears serrate in lateral view (Fig. 2G, I, S). musCle sCars In the new material as in Forel et al. (2024), no isolated valve was found and most specimens are recrystallized carapaces or steinkerns, precluding the observation of their inner structures. However, the outer surface of the right valve of the two carapaces from P3 displays adductor muscle scars (AMS; Fig. 2G, H, J). The AMS are located close to mid-length and below mid-height, just below the sulcus (Fig. 2G, H). They are composed of four elongate, ovoid individual scars oriented postero-ventrally, tightly packed into an oblique row oriented antero-ventrally (Fig. 2H, J). This pattern is in line with the original description of the AMS of Procytherura provided by Whatley (1970) and emended by Bate& Coleman (1975). However, the heart-shape frontal scar located antero-dorsally to the adductor row of Procytherura is not visible on the outer surface of the Sahune specimens. This may indicate that the associated muscle was weaker than the others and may have left a fainter mark on the outer lateral surface. ornamentatIon The lateral surface of Procytherura? praecoquum is characterized by a large and shallow polygonal, mostly hexagonal reticulation that fades in the antero-median and antero-dorsal areas and turns into fine longitudinal ribs ventrally (Forel et al. 2024). The reticulation of most specimens originally studied was partly eroded, which limited observations. The betterpreserved specimens recovered here allow the description of fossae arrangement and the identification of homologous fossae. As a comparison, the pattern seen on the holotype (see Forel et al. 2024: Fig. 9U) is reproduced as a line drawing in Figure 2T. One carapace from P3 displays a nearly complete reticular pattern, the only missing part corresponding to its broken posterior end (Fig. 2G, I). On its dorsal and median surfaces, fossae are hexagonal (Fig. 2K) and organized in sinuate rows. They turn to sub-rectangular to rectangular ventrally below the AMS where they are organized in elongate, sub-straight rows. Overall, 120 fossae are seen on the lateral and ventral surfaces of the right valve of this carapace (Fig. 2G-I, N). table 1. — Distribution and abundance of ostracod species (upper part) and summary of the observed richness and diversity (lower part) through the five studied communities at Sahune, Drôme, south-eastern France Basin, Oxfordian, Late Jurassic. Abbreviations: P1-P4, pseudobiohermal communities; LM, lateral marl community. In bold, species newly reported in the present work. Family Species P1 P2 LM P3 P4 Polycopidae Polycope pelta Fischer, 1961 15 4 – 3 2 Sigilliidae Cardobairdia cf. argoviensis Oertli, 1959 15 1 – 1 1 Bairdiidae ‘Bairdia’? sp. 1 15 – 2 1 1 Bairdiidae ‘Bairdia’ cf. major Donze, 1964 8 1 – 2 2 Bairdiidae Isobythocypris? sp. 1 5 1 1 1 – Bairdiidae Isobythocypris? sp. 2 1 – – – 1 Paracyprididae Paracypris cf. acuta (Cornuel, 1848) 1 – – – – Paracyprididae Paracypris cf. siliqua Jones & Hinde, 1890 2 – – – 3 Paracyprididae Paracypris cf. stripta Ljubimova, 1956 8 1 – 2 2 Paracyprididae Paracypris? sp. 1 2 – 1 – – Paracyprididae Paracypris? sp. 2 1 – – – – Paracyprididae Paracypris? sp. 3 1 1 – – – Pontocyprididae Pontocyprella vescusa Ljubimova, 1956 in Tesakova, 2003 7 – – – – Pontocyprididae Pontocyprella cf. cavata Donze, 1967 1 2 3 – – Pontocyprididae Pontocyprella cf. rara Kaye, 1965a 107 7 6 13 14 Pontocyprididae Pontocyprella sp. 1 1 – – – – Pontocyprididae Pontocyprella sp. 2 7 2 – 2 1 Pontocyprididae Pseudomacrocypris sp. 3 – – – – Pontocyprididae Rectangulocyprella cf. semiquadrata (Kaye, 1965b) 42 2 2 1 9 Cytheruridae Eucytherura sp. 2 – – 3 – Cytheruridae Eucytherura sp. 2 2 – – – – Cytheruridae Cytheropterina sp. 1 – – – – Cytheruridae Pedicythere? sp. 1 – – – – Cytheruridae Procytherura? praecoquum Forel in Forel et al., 2024 75 2 – 4 11 Cytheruridae Tethysia cf. bathonica Sheppard in Brand, 1990 4 – – – – Cytheruridae Tethysia sp. 1 7 – – 2 – Cytherellidae Cytherella sp. 1 – – – – Observed richness and diversity Number of specimens 335 24 15 35 47 Number of species 27 11 6 12 11 Number of genera 14 8 5 10 8 Number of families 7 6 3 6 6 692 GEODIVERSITAS • 2025 • 47 (17) Forel M.-B. et al. J K GHI JKLMN OP Q V S U RT W AB C DE F fig. 2 . — Ostracods from the deposits at Sahune, Drôme, south-eastern France Basin, middle Oxfordian, Late Jurassic: A, Cytheropterina sp., right view of a complete carapace, sample 22SAH01 (MNHN.F.F73027); B, Eucytherura sp. 2, left view of a complete carapace, sample 22SAH01 (MNHN.F.F73028); C, Paracypris cf. acuta (Cornuel, 1848), right view of a complete carapace, sample 22SAH01 (MNHN.F.F73029); D, Paracypris? sp. 3, right view of a complete carapace, sample 22SAH02 (MNHN.F.F73030); E, F, Pontocyprella cf. cavata Donze, 1967; E, right view of a complete carapace, sample 22SAH02 (MNHN.F.F73031); F, right view of a complete carapace, sample 22SAH02 (MNHN.F.F73032); G-W, Procytherura? praecoquum Forel in Forel, Charbonnier, Gale, Tribovillard, Martinez-Soares, Bergue, Gradstein & Gaillard, 2024; G, right view of a complete carapace broken posteriorly, sample 22SAH03 (MNHN.F.F73033); H, sketch of the same specimen showing fossae arrangement and normal pores; I, same specimen in sub-ventral view; J, close-up on AMS; K, close-up on fossae I4 and H3; L, close-up on mural pore conuli associated with muri between fossae H4 and I6; M, close-up on mural pore conuli associated with muri between fossae F7 and E6; N, sketch of the same specimen in sub-ventral showing fossae arrangement and normal pores; O, right view of a complete carapace, sample 22SAH03 (MNHN.F.F73034); P, sketch of the same specimen showing fossae arrangement and normal pores; Q, close-up on mural pore conuli associated with muri between fossae H4 and I6; R, close-up on solar pore conuli associated with fossa M7; S, same specimen in sub-ventral view; T, sketch of the holotype (see Forel et al. 2024: fig. 9U) 693 Ostracod communities through a cold fluid seepage during the Late Jurassic: the Sahune site (Drôme, France) GEODIVERSITAS • 2025 • 47 (17) H1 K2 K3 K4 J2 J3 J4 J5 J6 J7 I3 I4 I5 I6 H2 H3 H4 H5 H6 H7 H8 C2 C3 A2 A3 A4 A5 A6 B1 B2 B3 F11 L1 P4 L2 L3 J8 I7 C4 A7 F10 H1 K3 K4 J3 J4 J5 J6 J7 J8 I2 I3 I4 I5 I6 I7 I8 H2 H3 H4 H5 E5 E8 E9 E10 A3 A4 A5 A6 A7 B1 B2 B3 D6 F6 F7 F8 F9 F10 H1 Q1 Q2 I1 I3 I4 I5 I6 I7 H2 H3 H4 H5 H6 H7 H8 F3 F4 F5 E2 E3 E4 E5 D2 D3 D4 D5 E6 E7 E8 E9 E10 E11 D8 C2 C3 C4 C5 D7 B8 A2 A3 A4 A5 A6 A7 A8 A10 A11 B2 B3 B4 B5 D6 F6 F7 F8 F9 F10 F11 F12 F13 B6 B7 M7 M8 M9 M10 M11 A9 A12 I2 J5 J4 J3 R1 L8 D1 E1 F1 G1 H1 I1 J1 K1 L1 M1 N1 O1 P1 P3 P4 P2 O2 O3 N2 N3 L2 L3 L4 L5 L6 L7 L8 K2 K3 K4 J2 J3 J4 J5 J6 J7 J8 I2 I3 I4 I5 I6 I7 I8 H2 H3 H4 H5 H6 H7 H8 G2 G3 G4 F2 F3 F4 F5 E2 E3 E4 E5 D2 D3 D4 D5 E6 E7 E8 E9 E10 D8 C2 C3 C4 C5 D7 B8 sulcus A1 A2 A3 A4 A5 A6 A7 A8 A10 A11 A9 B1 B2 B3 B4 B5 D6 F6 F7 F8 F9 F10 F11 F12 F13 B6 B7 C1 M2 M4 M7 M8 M9 M10 M11 M5 M6 M3 A12 H1 L5 L7 L8 J5 J8 I4 I5 I6 I7 I8 H2 H3 H4 H5 H6 H7 H8 F3 F4 F5 E3 E4 E9 E10 F6 F7 F8 F9 F10 F11 F12 M7 M8 M6 I1 J2 I2 I3 E2 E5 D3 D4 D5 E6 C5 D7 B8 D6 B6 B7 M3 V T N H P showing fossae arrangement; U, right view of a complete carapace, sample 22SAH02 (MNHN.F.F73035); V, sketch of the same specimen showing fossae arrangement and normal pores; W, close-up on solar pore conuli associated with fossa A5 and mural pore conuli associated with muri between fossae A7 and B3. 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Journal of Micropalaeontology 37: 139-148. https://doi. org/10.5194/jm-37-139-2018 Submitted on 20 July 2024; accepted on 11 November 2024; published on 16 October 2025. 703 Ostracod communities through a cold fluid seepage during the Late Jurassic: the Sahune site (Drôme, France) GEODIVERSITAS • 2025 • 47 (17) Class OSTRACODA Latreille, 1806 Subclass MYODOCOPA Müller, 1894 Order HALOCYPRIDA Dana, 1853 Suborder CLADOCOPINA Sars, 1866 Superfamily POLYCOPOIDEA Sars, 1866 Family POLYCOPIDAE Sars, 1866 Genus Polycope Sars, 1866 Polycope pelta Fischer, 1961 (P1, P2, P3, P4; n=24) Subclass PODOCOPA Müller, 1894 Order PODOCOPIDA Sars, 1866 Suborder SIGILLIOCOPINA Martens, 1992 Superfamily SIGILLIOIDEA Mandelstam, 1960 Family SIGILLIIDAE Mandelstam, 1960 Genus Cardobairdia van den Bold, 1960 emend. McKenzie, 1967 Cardobairdia cf. argoviensis Oertli, 1959 (P1–P4; n=18) Suborder BAIRDIOCOPINA Gründel, 1967 Superfamily BAIRDIOIDEA Sars, 1888 Family BAIRDIIDAE Sars, 1865 Genus ‘Bairdia’ M’Coy, 1844 ‘Bairdia’? sp. 1 (P1, P3, P4, LM; n=19) ‘Bairdia’ cf. major Donze, 1964 (P1-P4; n=13) Genus Isobythocypris Apostolescu, 1959 Isobythocypris? sp. 1 (P1-P3, LM; n=8) Isobythocypris? sp. 2 (P1, P4; n=2) Suborder CYPRIDOCOPINA Jones, 1901 Superfamily CYPRIDOIDEA Baird, 1845 Family PARACYPRIDIDAE Sars, 1923 Genus Paracypris Sars, 1866 Paracypris cf. acuta (Cornuel, 1848) (P1; n=1) Paracypris cf. siliqua Jones & Hinde, 1890 (P1, P4; n=5) Paracypris cf. stripta Ljubimova, 1956 (P1– P4; n=13) Paracypris? sp. 1 (P1, LM; n=3) Paracypris? sp. 2 (P1; n=1) Paracypris? sp. 3 (P1, P2; n=2) Superfamily PONTOCYPRIDOIDEA Müller, 1894 Family PONTOCYPRIDIDAE Müller, 1894 Genus Pontocyprella Mandelstam in Ljubimova, 1955 Pontocyprella vescusa Ljubimova, 1956 in Tesakova, 2003 (P1; n=7) Pontocyprella cf. cavata Donze, 1967 (P1, P2, LM; n=6) Pontocyprella cf. rara Kaye, 1965a (P1–P4, LM; n=147) Pontocyprella sp. 1 (P1; n=1) Pontocyprella sp. 2 (P1–P4; n=12) Genus Pseudomacrocypris Michelsen, 1975 Pseudomacrocypris sp. (P1; n=3) Genus Rectangulocyprella Wilkinson, 1990 Rectangulocyprella cf. semiquadrata (Kaye, 1965b) (P1–P4, LM; n=56) Suborder CYTHEROCOPINA Baird, 1850 Superfamily CYTHEROIDEA Baird, 1850 Family CYTHERURIDAE Müller, 1894 Genus Eucytherura Müller, 1894 emend. Horne & Lord (2024) Eucytherura sp. (P1, P3; n=5) Eucytherura sp. 2 (P1; n=2) Genus Cytheropterina Mandelstam, 1956 Cytheropterina sp. (P1; n=1) Genus Pedicythere Eager, 1965 Pedicythere? sp. (P1; n=1) Genus Procytherura Whatley, 1970 emend. Bate & Coleman, 1975 Procytherura? praecoquum Forel in Forel et al., 2024 (P1–P4; n=92) Genus Tethysia Donze, 1975 Tethysia cf. bathonica Sheppard in Brand, 1990 (P1; n=4) Tethysia sp. 1 (P1, P3; n=9) Order PLATYCOPIDA Sars, 1866 Suborder PLATYCOPINA Sars, 1866 Superfamily CYTHERELLOIDEA Sars, 1866 Family CYTHERELLIDAE Sars, 1866 Genus Cytherella Jones, 1849 Cytherella sp. (P1; n=1) appenDix 1 . — Taxonomic list of all ostracod species identified at Sahune, Drôme, south-eastern France Basin, Oxfordian, Late Jurassic, including sample numbers and abundance. In bold, species newly reported in the present work; all other species were already reported in Forel et al. (2024) from P1 only.