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The Bay of Marseille (North-western Mediterranean Sea, France) is bordered by an over urbanised coastline and faces high anthropogenic pressure. We studied the spatiotemporal concentration of microplastics (MP) in surface waters and sediments during spring and autumn 2020 and 2021, at seven stations in the Bay. The locations are representative of contrasted environments regarding hydrodynamics and proximity with the urbanized areas. Microplastics were extracted and counted with an improved, ecological protocol from 27 surface water samples and 16 sediments samples. We observed MP contamination with an average concentration of 5.83± 1.97 MP.m-3 in surface water and of 865±63 MP.kg dry sediment -1 in sediments. Water concentration ranged from 0.47 ± 0.09 MP.m-3 to 72.66±18.16 MP.m-3 and sediment concentration ranged from 405±106 MP.kg dry sediment -1 to 1490±127 MP.kg dry sediment-1. The characterization of MP in water and sediment demonstrate the dominance of 1mm size elements, belonging mostly to fibre type. Concentrations in water and sediments do not exhibit any spatial trend. Likewise, seasonal and interannual temporal variation is absent, except in spring 2020 with an abnormal high water microplastic concentration (in average 22.47±8.85 MP.m-3). We suggest that accumulation and transport of MP are mainly linked to meteorologic and hydrodynamic features of the Bay of Marseille (i.e., precipitations, wind regimes, intrusion of the Northern Current and Rhône's plume, west swell). The hydrodynamical model MARS3D-RHOMA-ECO-3M was used to test the influence of these forcing on the MP concentration during the study period. While the Northern Current and the precipitations (and therefore runoff) seem to have no influence on the MP distribution, our study shows the influence of the north wind regime to favour MP dispersion outside the Bay and the influence of the Rhône plume's intrusion into the Bay and the south-east wind regime to promote MP accumulation. Also see: https://micro2022.sciencesconf.org/427359/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

Présentation de congrès; Palaeoceanographic studies often rely on microfossil species abundance changes, with little consideration for traits like size that could also relate to environmental changes. We hypothesize that whole-assemblage and/or species-specific planktonic foraminiferal test size could be good predictors of environmental variables, and we test this using a tropical Indian Ocean core-top dataset. We use an automated imaging and sorting system (MiSo) and a convolutional neural network model (CNN) to identify species, analyze morphology, and quantify fragmentation using machine learning techniques. A total of 311380 images were acquired at an average of 3797 images per sample. Machine model accuracy is confirmed by comparison with human classifiers (98% accuracy achieved). Data for 32 environmental parameters are extracted from modern databases and, through Exploratory Factor Analysis and regression models, we investigate the potential of using planktonic foraminiferal size to reconstruct oceanographic parameters. The size frequency distribution of most planktonic foraminifera species is unimodal and larger species show polymodal distributions. Within our tropical dataset, we find that intraspecies size response to environmental parameters is species-specific with carbonate ion concentration, temperature, and salinity identified as primary drivers. At the assemblage level, our analyses suggest that internal biogenic processes (primary) and temperature (secondary) are key drivers of morphometric changes in planktonic foraminifera. Our assessment of the potential to utilize assemblage size in reconstructing sea surface temperature in the tropical Indian Ocean showed that the reconstructed SST of the test MD90-0963 downcore site, relatively followed the delta O18 signals from previous works for the same site.

International audience; L’UMR CEREGE (OSU Institut Pythéas) développe des recherches concernant la paléoclimatologie et la paléocéanographie, la géodynamique et les fluides associés, la dynamique des sols, l’eau et les déchets, la morphogénèse et les risques naturels, la planétologie et la géophysique de surface, l’évolution des sols tropicaux, et les ressources en eau. A ce titre nous accumulons une multitude d’échantillons géologiques d’origines, tailles et compositions différentes (carottages marins et lacustres, roches, météorites, eaux …) qui sont répartis sur plusieurs sites, stockés à des températures différentes et dans des contenants différents (20 ans d’échantillonnage de 150 chercheurs). Une curation des stocks s'est imposée et a donné lieu à un inventaire constituant une première base de données dite "brute". Avec l'objectif d'une gestion efficace des données, constituant un enjeu crucial pour la recherche scientifique, il a été nécessaire de construire, stocker, organiser, tracer, pérenniser, rationaliser et valoriser les données en structurant l’information sous forme relationnelle. Pour ce faire, il est commode d'utiliser un système de gestion de base de données (SGBD). Le système d'information Collec-Science développé par l’INRAe de Bordeaux répond aux besoins du CEREGE en offrant non seulement une grande flexibilité des métadonnées mais aussi l'affiliation précise des échantillons et sous-échantillons. Cette application WEB, déjà déployée et utilisée dans notre laboratoire, permet une grande autonomie des chercheurs. Cet outil, parce que développé dans une logique scientifique, permet la gestion de stock dans toute la complexité des collections scientifiques. Son usage s’étendra aux autres unités de l’OSU Pythéas volontaires. De nombreux laboratoires en France (CEFE, EPOC ...) organisés en groupe de travail national l’utilisent. Dans le contexte actuel des données FAIR, nous développons cette base en intelligence avec la Cybercarothèque Nationale pour les carottages. Nous sommes en demande de supports tel que la Cybercarothèque Nationale pour les différents types d’échantillons (coraux, roches, fossiles..). Développer les relations entre bases et portails est un enjeu pour la visibilité nationale et internationale

International audience

International audience; Les lacs alpins sont particulièrement sensibles aux variations climatiques et environnementales (Cartier et al., 2015) : l'étude des archives sédimentaires lacustres permet de reconstituer l'évolution du lac et de son bassin versant. Une carotte sédimentaire a été prélevée au lac du Lauzet (situé à 890 m d'altitude), dans les Alpes de Haute-Provence, à proximité du Parc National des Écrins. Une étude quantitative et qualitative a été réalisée sur les assemblages de diatomées actuelles, dans le lac, et fossiles, sur les 256 premiers centimètres de la partie supérieure de la carotte. Cette étude a été associée à une analyse de données XRF, 14C et 210Pb. L'étude desdiatomées a permis de reconstituer qualitativement l'hydrochimie (habitat, pH, statut trophique) du lac, et l'ajout de données XRF et d'un modèle âge-profondeur, a aidé à mettre en évidence l'impact de l'Homme sur le lac et son bassin versant. Trois périodes d'évolution distinctes du lac ont été révélées: une ré-installation de l'activité biologique dans le lac (1705-1769 AD), une période soumise à une pression anthropique maximale (1769-1952 AD) et enfin une période de dégradation puis amélioration des paramètres écologiques du lac, soumis à l'impact de l'Homme (1952-2019 AD)

Cyclocostis rolfii Paill��s gen et sp. nov. Figs 1 ���40 Etymology This species is named in honor of Rolf Klee for his dedicated career on Stephanodiscaceae. Type material Holotype Slide PC0608731 and sediment PC0608728 deposited at the Laboratoire de Cryptogamie, Mus��um national d���histoire naturelle (MNHN) Paris, France. Specimen on slide PC0608731 (Fig. 4) represents the holotype designated here. Isotype Slide ZU 11/30 and sediment R1284 deposited at the Friedrich Hustedt Diatom Center in Bremerhaven, Germany. Type locality GUATEMALA ��� Department of Pet��n, Lake Pet��n-Itz��; 16��15���50��� N, 89��15���00��� W; lacustrine sediment in core PI-06; sample GLAD9 - PET06-6B-10H1 - 98��� 99 cm (27.83 m below lake floor) consisting of light gray carbonated sediment; core collected in February 2006. Description Light microscopy (Figs 1���24) In girdle view, cells quadrangular, displaying strongly undulated valve faces (Fig. 1). In valve view, frustules circular, 7���22 ��m in diameter (Figs 2���24). Marginal area (outer �� of valve) concentrically undulated and consisting of an external ring of small bright ��chambers�� transforming into strong radiating costae ��� 10 to 12 striae in 10 ��m. The central �� of valve surface strongly tangentially undulated, forming an S shape in large specimens (Figs 7���8). The central area with radial anastomosing striae of unequal length, some extending deep in the central zone to a central bright punctum. Marginal and central areas not distinctively structured. In small specimens, strong transversal undulation is attenuated and radiating striae are converging to a central ring. Scanning electron microscopy (Figs 25 ���40) Valves strongly undulated externally (Figs 25���26). Cingulum present, consisting of an open valvocopula and several copulae (Figs 27���28). Valve surface is irregular with sprinkled granules and prominent embossed ribs. The marginal striated area is circumferentially undulated with numerous granules; the mantle is gently sloping (Fig. 27). Striae consisting of 3���4 rows of finely aligned areolae alternating with reduced hyaline interstriae bearing near the valve margin big rounded openings corresponding to the external openings of marginal fultoportulae (Figs 27���28). The central area displays a steep tangential undulation (Fig. 29). If the junction between the valve face and the mantle is steeply marked vertically both on the elevated and depressed sides (Fig. 30), horizontally, from the elevated to depressed parts, the incline is smooth and gradual. On the internal side of the marginal area, striae become single rows of large rounded to oblong areolae that progressively become smaller and arranged to some extent into a stellate pattern (Fig. 31). Where ribs are fusing, external areolae are bigger and occluded by volae. Broken specimen displays a simple valve structure: a basal siliceous layer composed of anastomosing ribs starting from a central hollow and continuing to the valve rim where intercostal spaces are covered by a finely perforated silica layer (Fig. 32). Internally, there is no central lamina inside the valve (Fig. 33). Costae are strongly silicified and elevated, extending from the valve rim to the valve center and fusing into a thick silicified hollow (Figs 34���35). The alveolar structure could be classified as complex as the alveolus bears in its middle a recessed / sunken costa that carries the marginal fultoportula (mfp) (Fig. 36). As such, mfp are located on every second striae and are composed of one tube and three satellite pores (Figs 37���38). The ring of mfp and rm stands just beneath marginal lamina. One single rimoportula (rm) positioned on a recessed costa consisting of a short tube with a tangential slit that is always diametrally opposed to the raised side (Fig. 39). One single valve face fultoportula (vffp) ��� composed of one tube and three satellite pores ��� is always diametrically opposed to the rimoportula (Fig. 39). It appears eccentric since positioned on the raised part (Fig. 40). The external opening of the vffp is difficult to observe as it is positioned on the external slope of the raised central part (see in Fig. 26). Time range 23���28 ka, abruptly absent after, considered extinct. Remarks Cyclocostis rolfii gen et sp. nov. belongs unequivocally to the family Stephanodiscaceae (Glezer & Makarova 1986). In LM, it resembles Discostella woltereckii (Hust.) Houk & Klee in Klee & Houk (1996). However, SEM observations reveal a completely different structure in C. rolfii gen et sp. nov., particularly in the position of mfp and rm on costae, ruling out its belonging to the genus Discostella. With alternating and unequal striation pattern on the valve face, C. rolfii gen et sp. nov. also resembles Cyclotella stoermeri Khursevich & Kociolek in Kociolek & Khursevich (2013) in LM. Even though they share the absence of a central area, unequal striation, reduced alveoli and position of mfp and rm on recessed costae, C. rolfii gen et sp. nov. differs by the absence of centripetal roofing (central lamina) and thus the alveoli have no distinct border at the valve center side. The unequal striation visible in LM in C. rolfii gen et sp. nov. only corresponds to the way ribs are arranged internally: elevated, strongly silicified, anastomosing and joining in a central hollow. These thick radial ribs are the external characteristic features of the genus Stephanocostis Genkal & Kuzmina represented by S. chantaica Genkal & Kuzmina. However, these structures are internal in C. rolfii gen et sp. nov., whereas they are external in S. chantaica whose internal structure is flat with fine areolae forming �� radial rows of starlike criba. The strongly tangentially undulated valve is a character shared by Cyclotella and Pliocaenicus Round & H��k., the latter genera being included into Lindavia by Nakov et al. (2015). The position and structure of mfp are also a common character. But unlike in some Cyclotella or Pliocaenicus, no domed criba are observed internally in Cyclocostis gen. nov. As the position of the rm within the ring of mfp in C. rolfii gen et sp. nov. differs from Pliocaenicus, it rules out its belonging to this genus. The alveoli of C. rolfii gen et sp. nov. could be classified as complex, because there is a median fultoportula born on a recessed costa. However, structurally they are simple since not partially occluded by central lamina and widely open towards the valve center. The structure of alveoli of C. rolfii gen et sp. nov. rather corresponds to some extent to the marginal chambers defined by Lange & Syvertsen (1989) as ���a marginal space characterized by an opening on the inside of the valve encompassing two or more alveolus openings that is limited by coarse interstriae���. These marginal chambers are present in Cyclostephanos novaezeelandiae (Cleve) Round in Theriot et al. (1987) or C. dubius (Hust.) Round in Theriot et al. (1987). However, the genus Cyclostephanos Round is largely heterogenous in terms of frustule morphology as it includes species with and without alveolar chambers. Except the marginal chambers, C. rolfii gen et sp. nov. shares no other characters with the genus Cyclostephanos. The characteristics of the striae, composed of fine pori on the mantle and becoming uniseriate with large radially arranged areolae towards the center of the valve, as observed in C. rolfii gen et sp. nov., are shared with Paleotertiarius. Even though C. rolfii gen et sp. nov. and Paleotertiarius share characters such as strong ribs and the structure and position of mfp, in Paleotertiarius, flat or concentrically undulated valves, internal domed criba and rimoportula located on the side of a costa inside the alveolus are morphological differences that exclude C. rolfii gen et sp. nov. from belonging to Paleotertiarius., Published as part of Paill��s, Christine, Sylvestre, Florence, Tonetto, Alain, Mazur, Jean-Charles & Conrod, Sandrine, 2020, New fossil genus and new extant species of diatoms (Stephanodiscaceae, Bacillariophyceae) from Pleistocene sediments in the Neotropics (Guatemala, Central America): adaptation to a changing environment?, pp. 1-23 in European Journal of Taxonomy 726 on pages 4-8, DOI: 10.5852/ejt.2020.726.1169, http://zenodo.org/record/4298412, {"references":["Glezer Z. I. & Makarova I. V. 1986. Nouveaux ordres et familles de Diatomees (Bacillariophyta). Botaniceskij zurnal 71 (5): 673 - 676.","Klee R. & Houk V. 1996. Morphology and ultrastructure of Cyclotella woltereckii Hustedt (Bacillariophyceae). Archiv fur Protistenkunde 147: 19 - 27. https: // doi. org / 10.1016 / S 0003 - 9365 (96) 80005 - 4","Kociolek J. P. & Khursevich G. H. 2013. Morphology of some lacustrine centric species from the western United States assigned to the genus Cyclotella (Bacillariophyta), including four described as new. Phytotaxa 127 (1): 81 - 99. https: // doi. org / 10.11646 / phytotaxa. 127.1.11","Nakov T., Guillory W. X., Julius M. L., Theriot E. C. & Alverson A. J. 2015. Towards a phylogenic classification of species belonging to the diatom genus Cyclotella (Baccilariophyceae): transfer of","Theriot E. C., Hakansson H., Kociolek J. P., Round F. E. & Stoermer E. F. 1987. Validation of the centric diatom genus name Cyclostephanos. British Phycological Journal 22: 345 - 347. https: // doi. org / 10.1080 / 00071618700650411"]}

Discostella gabinii Paill��s & Sylvestre sp. nov. Figs 41 ���58 Etymology This taxon is named in honor of deceased Gabin Sylvestre, the courageous 7 years old nephew of F. Sylvestre. Type material Holotype Slide PC0608732 and sediment PC0608730 deposited at the Laboratoire de Cryptogamie, Mus��um national d���histoire naturelle (MNHN) Paris, France. Specimen on slide PC0608732 (Fig. 45) represents the holotype designated here. Isotype Slide ZU 11/31 and sediment R1285 deposited at the Friedrich Hustedt Diatom Center in Bremerhaven, Germany. Other material examined Modern specimens collected from Cenote Juarez and Lake Amatitlan (see Table 1). Type locality GUATEMALA ��� Department of Pet��n, Lake Pet��n-Itz��; 16��15���50��� N, 89��15���00��� W; lacustrine sediment in core PI-06; sample GLAD9 - PET06-6 B-18E1- 35.4��� 36.4 cm (51.53 m below lake floor) consisting of dark gray clayish sediment; core collected in February 2006. Description Light microscopy (Figs 41���50) Cells quadrangular in connective view. Valvar views circular and flat, 8���18 ��m in diameter with a small central area (�� of the valve radius). Central area with 5 to>30 scattered large areolae, the number being independent of valve size (Figs 41���50). When numerous, the scattered areolae give the impression of a colliculate/granular flat center. The marginal area of the valve face has radial striae numbering from 10 to 14 in 10 ��m. The striae are long (�� of the valve radius) and of equal length. On large specimens, marginal striation is crossed circumferentially by a ring (��Schattenlinie�� = ��shadow line��) close to the valve center (Figs 48���50). Scanning electron microscopy (Figs 51���58) Valves flat to barely concave externally with gently sloping mantle. Central area covered with several scattered punctae separated by knots (colliculate) bearing papillae (Figs 51���52). Radiating striae starting on the mantle as crescents of three to five rows of fine areolae (60���70 areolae/ 10 ��m), merging into two rows near the central area and ending with a single large pore (Figs 53���54). The central area is thus bordered by a ring of large areolae. On the valve face, striae are depressed, whereas they are smooth on the mantle. Near the valve margin, every third to fifth striae, pores just below the crescent of fine areolae mark the external openings of marginal fultoportulae (Fig. 54). Interstriae are narrow, domed and granular on the valve face, whereas smooth on the mantle. The mantle is unornamented except for the large round openings of marginal fultoportulae and few papillae. The external opening of the rimoportula was not observed, although it should be positioned at the same level since it is within the ring of marginal fultoportulae. Interior views of the valve show a flat to slightly concave but smooth central area with none or single areola (Figs 55���56). The internal lamina spread from the valve center to �� of the valve radius. The alveoli are thus medium sized, oblong and of unequal length, those bearing marginal fultoportulae being longer (Fig. 56). Marginal fultoportulae with two laterally positioned satellite pores surrounding a short tubulus are located at the distal extremity of every third to fourth alveoli (Fig. 57). One nearly sessile rimoportula with vertically orientated lips located between two costae at the edge of an alveolus and within the ring of marginal fultoportulae (Fig. 58). Girdle bands present, an open valvocopula with two copulae (Fig. 56); a row of fine pores is noted on the interior of the girdle band (Fig. 58). Time range Present since at least 84 ka in the geological record, present in Lake Amatitlan and Cenote Juarez (20��48���09.6��� N, 87��27���23.8��� W) in March 2008. Remarks With marginal fultoportulae and rimoportula being located between costae on the marginal side of the alveolus, Discostella gabinii sp. nov. belongs undoubtedly to the genus Discostella. Amongst the 15 species of Discostella described so far (Kociolek et al. 2018), D. gabinii sp. nov. showed some resemblance to D. areolata (Hust.) Houk & Klee. However, in LM they look somewhat different, the unique holotype of D. areolata having coarser striation (6���9 striae in 10 ��m) and a large colliculate central area (Houk et al. 2010: table 330, figs 1���7). A reexamination of the original material of D. areolata from Hustedt by Tagliaventi & Cavinaci (2002) provided unambiguous SEM images of external views but only ambiguous internal views since D. areolata was rare and mixed with D. stelligera (Cleve & Grunow) Houk & Klee var. robusta (Hust.) Houk & Klee in the original material. The central area of D. areolata is concave or convex, smooth or consisting of alternating impressions and protrusions of various size with small punctae being mainly located in the depressions. Sometimes domed radiating striae resembling a poorly defined rosette are present in the central area. In D. gabinii sp. nov., the central area is always flat, indeed colliculate but with large punctae inserted in the depressions. Moreover, in D. areolata, striae are depressed and costae elevated on their entire length, whereas in D. gabinii sp. nov., this feature is restricted to the valve face, the mantle being smooth. Internally, two types of central area could be attributed to D. areolata: smooth with no central fultoportula or smooth with a punctum. These variations are also visible in D. gabinii sp. nov. Despite uncertainties related to the species described as D. areolata, D. stelligera var. robusta and D. stelligera var. hyalina (Hust.) Houk & Klee, the structure of marginal costae and the position of marginal fultoportulae and rimoportula are quite different compared to that of D. gabinii sp. nov. Marginal costae can be forked or not. Furthermore, marginal fultoportulae (composed of one tube and two satellite pores placed horizontally) and rimoportula (vertically orientated slit) are inserted within the alveolar chamber. Another somewhat similar species is D. elentarii (Alfinito & Tagliaventi) Houk & Klee with flat valves, although it has a large central area with radiate rows of granules and scattered punctae, coarsely striated (9���10 striae in 10��m) and reduced marginal area, and a marginal row of small spinae. Internally, it has similar smooth central area (sometimes with a faint stellate pattern) and similar structure and position of mfp and rm. The only difference is that, internally, in D. elantarii costae are broadening toward the valve margin with a punctum in the middle giving the impression of forked costae. After reexamination of D. elantarii by Knapp et al. (2006), it appears that the correct striae density is 8���14 and that each collared marginal fultoportula and the single rimoportula are surrounded by satellite pores covered by a cribum. Although we did not use a field emission variable pressure SEM, such structures are absent in D. gabinii sp. nov. Interestingly, it is the only morphological feature used to differentiate D. elantarii from D. stelligera in SEM (Knapp et al. 2006). The presence of pores in the girdle band is also a subtle character shared by D. elentarii and D. gabinii sp. nov. that requires further investigation. Despite morphological similarities with D. areolata and D. elentarii, D. gabinii sp. nov. possesses distinctive characteristics that are sufficient to define a new species. Stelligeroid species of Cyclotella have been transferred to the genus Discostella on the basis of the unique position of strutted and labiate processes (Houk et al. 2010). However, difficulties arise because these species are often heterovalvate and size and morphological variations exist. As reported by Tagliaventi & Cavinaci (2002), Alfinito & Tagliaventi (2002) and Knapp et al. (2006), only minute distinctive features allow one to differentiate D. areolata, D. stelligera, D. stelligera var. robusta, D. stelligera var hyalina and D. elantarii. This latter species is endemic to New Zealand and coexists with D. stelligera in two lakes. Knapp et al. (2006 ) suggest that considering the difficulty in differentiating them, they could be sibling species and D. elantarii may descend from D. stelligera. Stratigraphic diatom succession The base of the section (84 ka) is characterized by an assemblage dominated (58���90%) by Aulacoseira granulata (Ehrenb.) Simonsen and A. ambigua (Grunow) Simonsen (Fig. 59). Cyclotella meneghiniana and Discostella stelligera occurred punctually (Aulacoseira dominated assemblage persists up to 70 ka then greatly recedes (D. stelligera, C. meneghiniana, Discostella gabinii sp. nov. and Cyclotella caspia Grunow. At 45 ka, Cyclotella petenensis takes over the assemblage (73���97%) then declines abruptly at 31.5 ka. Prior to the collapse of C. petenensis, Discostella gabinii sp. nov. returned with fluctuating percentages for about 5 ka. Then, Cyclocostis rolfii gen et sp. nov. emerges at 26.9 ka, develops with fluctuating abundances with Nitzschia amphibioides Hust., Mastogloia smithii Thwaites, M. elliptica (C.Agardh) Cleve and Navicula seminuloides Hust. At 22.2 ka, Cyclocostis rolfii gen et sp. nov. disappears definitely while Cyclotella petenensis reoccurs. At first, C. petenensis coexists with Discostella gabinii sp. nov. (10���60%) then it takes over when D. gabinii sp. nov. declines. The dominant C. petenensis persists until 16.1 ka and does not reoccur thereafter in the sequence. Ecology and associated diatom flora In the modern dataset (P��rez et al. 2013), Discostella gabinii sp. nov. was initially identified as ��� Cyclotella sp22 ��� (code CP22) and another species was identified as ��� Discostella aff. pseudostelligera ��� (CYAP). When analyzing the fossil flora and diagnosing D. gabinii sp. nov., we re-examined modern samples and observed that the two species were similar. ��� Discostella aff. pseudostelligera ��� and ��� Cyclotella sp22 ��� were therefore combined together under the name Discostella gabinii sp. nov. Conductivity, which is related to the precipitation gradient and marine influence on the Yucatan Peninsula, is the main variable that structures diatom, ostracod and cladoceran communities (P��rez et al. 2013). Discostella gabinii sp. nov. occurs in 11 water bodies of the Yucatan Peninsula (Table 1). In the Guatemalan highlands, its maximum occurrence (13%) was in Lake Amatitlan, a hypereutrophic alkaline lake spreading over 15.2 km 2 at 1200 m a.s.l. altitude. Water was calcium-bicarbonate rich, warm (22.6��C), with electrical conductivity of 630 ��S/cm and high dissolved oxygen content (17.8 mg /L). Subdominant species were Aulacoseira granulata, Cyclotella meneghiniana and Nitzschia pseudofonticola Hust. In Cenotes Juarez, D. gabinii sp. nov. reached 4.8% in an assemblage dominated by Achnanthidium exiguum (Grunow) Czarn. and A. lineare W.Sm. Water was warm (27.9��C) and alkaline with relatively high dissolved oxygen content (8.7 mg /L). Conductivity was 643 ��S/cm. Water analyses determined Ca 2+ (68.3 mg /L) and Mg 2+ (23 mg /L) as the dominant cations and HCO 3 - (292.7 mg /L) as important anion. Overall, D. gabinii sp. nov. seems to tolerate varying conductivities but is most abundant in alkaline, low conductivities (600���650 ��S/cm) and calcium-bicarbonated waters. Cyclotella petenensis, although considered to be fossil at the time of description (Paill��s et al. 2018), was identified as C. meneghiniana (CYMG) in the modern dataset mainly due to the fact that specimens were small in size, tangentially undulated with petenensis was present in low percentages (C. petenensis reached 17.8% (Table 1). Of all water bodies investigated, Lake Yalahau had the highest diatom species richness. In this lake, water is shallow, warm (28.8��C) and alkaline (pH 8.9) with a high dissolved oxygen content (8.7 mg /L). Electrical conductivity is high 2350 ��S/cm. Water was magnesium (136.8 mg /L) and bicarbonate (707.4 mg /L) rich. Its diatom population was composed of 33% of C. meneghiniana accompanied by Brachysira australofollis Lange-Bert. & Gerd Moser, B. neoexilis Lange-Bert., Encyonema densistriata Novelo, Tavera & Ibarra and Fragilaria famelica (K��tz.) Lange-Bert. In coastal Lake Progreso where C. petenensis represents 4% of the flora, water conductivity was 2040 ��S/cm. In the modern samples, it appears that C. petenensis seems to favor waters with conductivities close to 2000 ��S/cm., Published as part of Paill��s, Christine, Sylvestre, Florence, Tonetto, Alain, Mazur, Jean-Charles & Conrod, Sandrine, 2020, New fossil genus and new extant species of diatoms (Stephanodiscaceae, Bacillariophyceae) from Pleistocene sediments in the Neotropics (Guatemala, Central America): adaptation to a changing environment?, pp. 1-23 in European Journal of Taxonomy 726 on pages 10-15, DOI: 10.5852/ejt.2020.726.1169, http://zenodo.org/record/4298412, {"references":["Kociolek J. P., Balasubramanian K., Blanco S., Coste M., Ector L., Liu Y., Kulikovskiy M., Lundholm N., Ludwig T., Potapova M., Rimet F., Sabbe K., Sala S., Sar E., Taylor J., Van de Vijver B., Wetzel C. E., Williams D. M., Witkowski A. & Witkowski J. 2018. DiatomBase. Discostella Houk & Klee, 2004. Available from http: // www. diatombase. org / aphia. php? p = taxdetails & id = 465545 [Accessed 19 Mar. 2020].","Houk V., Klee R. & Tanaka H. 2010. Atlas of freshwater centric diatoms with a brief key and descriptions. Part III. Stephanodiscaceae A, Cyclotella, Tertiarius, Discostella. Fottea 10 (supplement): 1 - 498.","Knapp J. M., Furey P. C. & Lowe R. L. 2006. A comparison of the morphology and ultrastructure of the diatoms (Bacillaryophyceae) Discostella stelligera and D. elentarii from two lakes in Fiorland, New Zealand. New Zealand Journal of Marine and Freshwater Research 40: 429 - 438. https: // doi. org / 10.1080 / 00288330.2006.9517433","Alfinito S. & Tagliaventi N. 2002. Morphology and taxonomy of Cyclotella elentarii spec. nova a newly described centric diatom from a New Zealand lake. Algological studies 105: 29 - 38. https: // doi. org / 10.1127 / algol _ stud / 105 / 2002 / 29","Perez L., Lorenschat J., Massaferro J., Pailles C., Sylvestre F., Hollwedel W., Brandorff G. - O., Brenner M., Islebe G., del Socorro Lozano M., Scharf B. & Schwalb A. 2013. Bioindicators of climate and trophic status in aquatic ecosystems of the northern Neotropics. Revista de Biologia Tropical 61 (2): 603 - 644. https: // doi. org / 10.15517 / rbt. v 61 i 2.11164","Pailles C., Sylvestre F., Escobar J., Tonetto A., Rustig S. & Mazur J. C. 2018. Cyclotella petenensis and Cyclotella cassandrae, two new fossil diatoms from Pleistocene sediments of Lake Peten-Itza, Guatemala, Central America. Phytotaxa 351 (4): 247 - 263. https: // doi. org / 10.11646 / phytotaxa. 351.4.1"]}

Genus Cyclocostis Paillès gen. nov. Type species Cyclocostis rolfii Paillès gen et sp. nov. (see below). Diagnosis A new morphotypic genus of Stephanodiscaceae. Cells solitary, circular in valve view. Marginal and central areas coarsely striated with branching striae merging in the middle of the valve into a central punctum. Central area strongly tangentially undulated, focus clear only on half the central area. Submarginal alveoli finely punctuated, transforming into radiating rows of large irregular areolae in the central area. Internally, alveoli delineated by thick elevated costae reaching the valve center to form a subcircular silica ring. Alveoli widely open with a median recessed costa bearing marginal fultoportulae. Central lamina absent. Single rimoportula within a ring of marginal fultoportulae reduced to a rounded tube tangentially orientated and born on a recessed costa. On the mantle, outer expressions of marginal fultoportulae and rimoportula consisting of simple rounded openings without projections. One single valve face fultoportula consisting of a central tube surrounded by three satellite pores that opens externally into a round opening on the raised part. Cingulum present consisting of an open valvocopula and several copulae. Etymology The genus name refers to the circular morphology of the valve and marked radiating costae.

Genus Cyclocostis Paill��s gen. nov. Type species Cyclocostis rolfii Paill��s gen et sp. nov. (see below). Diagnosis A new morphotypic genus of Stephanodiscaceae. Cells solitary, circular in valve view. Marginal and central areas coarsely striated with branching striae merging in the middle of the valve into a central punctum. Central area strongly tangentially undulated, focus clear only on half the central area. Submarginal alveoli finely punctuated, transforming into radiating rows of large irregular areolae in the central area. Internally, alveoli delineated by thick elevated costae reaching the valve center to form a subcircular silica ring. Alveoli widely open with a median recessed costa bearing marginal fultoportulae. Central lamina absent. Single rimoportula within a ring of marginal fultoportulae reduced to a rounded tube tangentially orientated and born on a recessed costa. On the mantle, outer expressions of marginal fultoportulae and rimoportula consisting of simple rounded openings without projections. One single valve face fultoportula consisting of a central tube surrounded by three satellite pores that opens externally into a round opening on the raised part. Cingulum present consisting of an open valvocopula and several copulae. Etymology The genus name refers to the circular morphology of the valve and marked radiating costae., Published as part of Paill��s, Christine, Sylvestre, Florence, Tonetto, Alain, Mazur, Jean-Charles & Conrod, Sandrine, 2020, New fossil genus and new extant species of diatoms (Stephanodiscaceae, Bacillariophyceae) from Pleistocene sediments in the Neotropics (Guatemala, Central America): adaptation to a changing environment?, pp. 1-23 in European Journal of Taxonomy 726 on page 4, DOI: 10.5852/ejt.2020.726.1169, http://zenodo.org/record/4298412

International audience; Phytophthora spp. secrete proteins called elicitins in vitro that can specifically induce hypersensitive response and systemic acquired resistance in tobacco. In Phytophthora parasitica, the causal agent of black shank, most isolates virulent on tobacco are unable to produce elicitins in vitro. Recently, however, a few elicitin-producing P. parasitica strains virulent on tobacco have been isolated. We investigated the potential diversity of elicitin genes in P. parasitica isolates belonging to different genotypes and with various virulence levels toward tobacco as well as elicitin expression pattern in vitro and in planta. Although elicitins are encoded by a multigene family, parAl is the main elicitin gene expressed. This gene is highly conserved among isolates, regardless of the elicitin production and virulence levels toward tobacco. Moreover, we show that elicitin-producing P. parasitica isolates virulent on tobacco down regulate parAl expression during compatible interactions, whichever host plant is tested. Conversely, one elicitin-producing P. parasitica isolate that is pathogenic on tomato and avirulent on tobacco still expresses parAl in the compatible interaction. Therefore, some P. parasitica isolates may evade tobacco recognition by down regulating parA1 in planta. The in planta down regulation of parA1 may constitute a suitable mechanism for P. parasitica to infect tobacco without deleterious consequences for the pathogen.

The enteric nervous system (ENS) is a complex network of diverse molecularly defined classes of neurons embedded in the gastrointestinal wall and responsible for controlling the major functions of the gut. As in the central nervous system, the vast array of ENS neurons is interconnected by chemical synapses. Despite several studies reporting the expression of ionotropic glutamate receptors in the ENS, their roles in the gut remain elusive. Here, by using an array of immunohistochemistry, molecular profiling and functional assays, we uncover a new role for d-serine (d-Ser) and non-conventional GluN1-GluN3 N-methyl d-aspartate receptors (NMDARs) in regulating ENS functions. We demonstrate that d-Ser is produced by serine racemase (SR) expressed in enteric neurons. By using both in situ patch clamp recording and calcium imaging, we show that d-Ser alone acts as an excitatory neurotransmitter in the ENS independently of the conventional GluN1-GluN2 NMDARs. Instead, d-Ser directly gates the non-conventional GluN1-GluN3 NMDARs in enteric neurons from both mouse and guinea-pig. Pharmacological inhibition or potentiation of GluN1-GluN3 NMDARs had opposite effects on mouse colonic motor activities, while genetically driven loss of SR impairs gut transit and fluid content of pellet output. Our results demonstrate the existence of native GluN1-GluN3 NMDARs in enteric neurons and open new perspectives on the exploration of excitatory d-Ser receptors in gut function and diseases., Competing Interests: Conflicts of interest The authors disclose no conflicts.