Zootaxa 4466 (1): 205–228 http://www.mapress.com/j/zt/ ISSN 1175-5326 (print edition) Article Copyright © 2018 Magnolia Press ZOOTAXA ISSN 1175-5334 (online edition) https://doi.org/10.11646/zootaxa.4466.1.16 http://zoobank.org/urn:lsid:zoobank.org:pub:1B51A24B-33D0-4AC1-9986-DDE6D15C312F Sponge inventory of the French Mediterranean waters, with an emphasis on cave-dwelling species MARIE GRENIER1,6, CÉSAR RUIZ1, MAIA FOURT1, MATHIEU SANTONJA1,2,3, MAUDE DUBOIS1, MICHELLE KLAUTAU4, JEAN VACELET1, NICOLE BOURY-ESNAULT1,6 & THIERRY PÉREZ1,5,6 1 Institut Méditerranéen de Biodiversité et d’Ecologie marine et continentale. CNRS, Aix Marseille Université, IRD, Avignon Université. Station Marine d’Endoume, Chemin de la Batterie des Lions, 13007 Marseille, France 2 Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Station 2, 1015 Lausanne, Switzerland. 3 Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Site Lausanne, Case postale 96, 1015 Lausanne, Switzerland. 4 Universidade Federal do Rio de Janeiro, Instituto de Biologia, Departamento de Zoologia, Av. Carlos Chagas Filho, 373, 21941-902, Rio de Janeiro, RJ, Brasil 5 Corresponding author. E-mail: thierry.perez@imbe.fr 6 These authors contributed equally Abstract Mediterranean sponges represent about 10 % of the world sponge biodiversity, with these sessile organisms dominating in terms of diversity and biomass in most of the rocky bottoms shaded from light. After 60 years of intensive study of the sponge diversity along the French coast, we present the first comprehensive reference-list for this biogeographic area. A total of 389 sponge species was recorded, of which 222 known in the Marseille region. In this area, special attention was paid to species from underwater caves. Although this particular habitat appeared as one of the richest, a wealth of hidden diversity still requires description. About 37 % of the sponge diversity can be found in underwater caves, most of these species being also distributed in other habitats. However, 23 % of this sponge diversity is cave-exclusive. An easy and rapid assessment method was developed with a selection of 65 representative sponge species, for the monitoring of semidark cave communities. This method, based on data acquisition with photoquadrats and their processing using a DataBase built with ACCESS, was deployed in 13 studied sites. Altogether, this study represents a useful contribution for marine environment managers who might refer to this French reference list and apply the rapid and easy assessment method in the framework of several European Directives and international Conventions. Key words: Porifera, inventory, rapid assessment method, Mediterranean Sea Introduction The Mediterranean Sea is a “miniature ocean” considered as a marine biodiversity hotspot, characterized by an increasing gradient from east to west, and which harbors in average 10% of the world marine species diversity (Fredj et al. 1992; Bianchi & Morri 2000; Coll et al. 2010). Many laboratories, universities and research institutes located in this geographical area started several decades ago to dedicate a great part of their resources to study this sea and its ecosystems. Our current estimation of the Mediterranean sponge diversity might be biased by the fact that the western Mediterranean and the Adriatic basin have been more explored and studied by sponge scientists when compared to the eastern Mediterranean basin and even other parts of the world (Gerovasileiou & Voultsiadou 2012; Van Soest et al. 2012). Indeed, the current knowledge of the Mediterranean biodiversity is the result of a long historical process of knowledge acquisition by pioneer naturalists of the 18th and 19th centuries (Table 1) that remained mostly focused on the western Mediterranean and the Adriatic basin (Coll et al. 2010). In the second part of the 20th century, the most active schools of sponge specialists were long restricted to very few NW Mediterranean countries such as France, Italy and Spain, although an increasing number of new taxonomists arose Accepted by N. de Voogd: 8 Aug. 2018; published: 31 Aug. 2018 205 in several other countries over the last three decades (Cárdenas et al. 2012). Concurrently, studies on sponges in their ecosystems have benefited from the popularization of SCUBA diving and the development of new technologies, such as underwater Remote Operated Vehicles (ROV). These tools allowed access to the least accessible habitats that hide reservoirs of diversity (Van Soest et al. 2012). Nowadays, around 9000 valid marine and freshwater species are listed in the World Porifera Database (Van Soest et al. 2018), and the Mediterranean Sea contains about 10 % of this diversity. TABLE 1. Number of sponge species described during the 18th and 19th centuries in the Mediterranean Sea. Authors Year of description Number of species Peter Simon Pallas (1741–1811) 1766 28 Jean-Louis Marie Poiret (1755–1834) 1789 1 Giuseppe Olivi (1769–1795) 1792 4 Eugenius Johann Christoph Esper (1742–1812) 1794–1797 31 Antoine Risso (1777–1826) 1826 2 Giovanni Domenico Nardo (1802–1877) 1833–1847 9 Eduard Oscar Schmidt (1823–1886) 1862–1868 250 Ernst Haeckel (1834–1919) 1870–1872 250 Franz Eilhard Schulze (1840–1921) 1877–1880 22 Sponges are powerful active filter feeders, components of short food-web chains, able to feed on a wide range of microscopic particles and to recycle organic materials of various origins (e.g. Topçu et al. 2010). They are thus considered as keystone organisms of bentho-pelagic coupling, especially in ecosystems where they dominate in terms of diversity and biomass. This is especially the case on rocky bottom communities, such as coralligenous environments, deep-sea systems and submarine caves (Gerovasileiou & Voultsiadou 2012). Underwater caves are unique and vulnerable ecosystems, nowadays protected by the European Habitat Directive 92/43 EEC because of their low resilience facing environmental disturbances (Gunn et al. 2000; Parravicini et al. 2010a; UNEP-MAPRAC/SPA 2015). Similar to deep inaccessible environments, these cavities are characterized by a particular environmental context. Because they present low light conditions and a high degree of confinement, which can result in a severe oligotrophy, they can be considered as enclaves of the deep-sea environment in the coastal zone (Harmelin et al. 1985; Gerovasileiou & Voultsiadou 2012). At the entrance, underwater caves are usually inhabited by a rich sessile fauna often dominated by sponges of various growth forms, easy to sample and thus quite well known. At the opposite, the sponge community of the less accessible darkest zones is mainly composed of tiny crusts, which are much difficult to sample and, consequently, remain widely unknown. Emile Topsent was the first to dedicate a great effort to study the sponge diversity of the French Mediterranean Sea (Topsent 1892; 1893; 1894; 1896; 1900; 1925; 1928; 1934a; 1936; Topsent & Olivier 1943), then followed by Jean Vacelet and Nicole Boury-Esnault (Vacelet 1959; 1969; Boury-Esnault 1971a, b). With the spread of SCUBAdiving during the same period, a semi-dark cave community was described for the first time in the world (Laborel & Vacelet 1958). With their collaborators, they described a high number of Mediterranean species, including some “sponge oddities” coming from caves, such as the carnivorous sponge Lycopodina hypogea (Vacelet & BouryEsnault 1995; 1996). Nevertheless, a complete inventory of the French Mediterranean sponge fauna has never been published. Moreover, although sponges were used as bioindicators in a good number of studies (e.g. Pérez 2001) and are also well-known to be affected by disease outbreaks related to climate events for instance (Lejeusne et al. 2010), no long-term diversity assessment was implemented to detect the potential effect of the global change on sponge communities. The aim of this work is to provide baselines for further studies that would intend to assess changes on the Mediterranean sponge diversity. We present a reference list of the current knowledge on French Mediterranean sponge diversity, with special attention to marine cave communities, where we implemented a long-term monitoring strategy. 206 · Zootaxa 4466 (1) © 2018 Magnolia Press GRENIER ET AL. Materials and methods Compilation of bibliographic data. The sponge inventory was achieved by compiling species lists from the oldest to the most recent species reports or descriptions of the French Mediterranean area (e.g. Schmidt 1868; Topsent 1892; 1893; 1894; 1896; 1900; 1925; 1928; 1934a; 1934b; 1936; Topsent & Olivier 1943; Vacelet 1959; Lévi 1960; Vacelet 1960; 1961; 1969; 1976; Laubier 1966; Vidal 1967; Pouliquen 1969; 1972; Boury-Esnault 1971a; 1971b; Griessinger 1971; Vacelet & Boury-Esnault 1982; Pulitzer-Finali 1983; Harmelin et al. 2003; BouryEsnault et al. 2015; Fourt et al. 2017). Cross-referencing these data with those available in the World Porifera Database, which actually gathers all published species records world-wide, allowed us to revise and/or update the information provided on species distribution in the Mediterranean Sea (see Van Soest et al. 2018). We considered sponges occurring up to 900 m between the Spanish (42°26’6”N/3°10’35”E) and Italian borders (43°47’33N/ 7°31’48”E), and all around Corsica as well. We used the most recent Sponge Systematics (Morrow & Cárdenas 2015) and thus taxonomic updates were made when needed. All species records were distributed among the most common types of marine habitats (summarized as underwater caves, deep-sea bottoms, lagoons, mesophotic bottoms, shallow water rocky bottoms, and shallow water soft bottoms, according to the above mentioned sources and our personal observations. Species from underwater caves were highlighted in order to sort the cave-exclusive species from the more generalist ones, and to feed the World Register of marine Cave Species (Gerovasileiou et al. 2018). Rapid assessment method applied to sponge community of semi-dark underwater caves. Thirteen submarine caves were studied off the Marseille-Provence region (Fig. 1; Table 2). The sampling depth ranged between 5 m and 25 m depending on the site. All selected sites are located within the National Park of the Calanques and in the Marine Reserve of Côte Bleue. TABLE 2. Studied submarine caves distributed according to 4 geographical zones and 4 depth ranges. Sampling sites Coordinates Zones Depth range (m) Nb. of quadrats Grotte de Méjean 43° 19.7’ N, 5° 13.2’ E Côte Bleue 15–20 26 Grotte du Chinois 43° 20.2’ N, 5° 15.4’ E Côte Bleue 10–15 43 Grotte de La Vesse 43° 20.5’ N, 5° 15.8’ E Côte Bleue 10–15 30 Grotte de l’Anse des Cuivres 43° 16.8’ N, 5° 21.0’ E Marseille 5–10 28 Grotte à Corail 43° 12.6’ N, 5° 19.9’ E Riou Archipelago 15–20 40 Grotte de Jarre 43° 11.8’ N, 5° 21.9’ E Riou Archipelago 15–20 41 Grotte à Pérès 43° 11.2’ N, 5° 23.5’ E Riou Archipelago 15–20 40 Tunnel de Moyades 43° 10.6’ N, 5° 22.4’ E Riou Archipelago 20–25 40 Grotte de l’Impérial de Terre 43° 10.4’ N, 5° 23.6’ E Riou Archipelago 20–25 27 Calanque sombre 43° 12.8’ N, 5° 24.1’ E Calanques 5–10 48 Grotte du Figuier 43° 12.4’ N, 5° 26.3’ E Calanques 15–20 50 Grotte des Trémies 43° 12.6’ N, 5° 31.7’ E Calanques 10–15 35 Grotte des 3PP 43° 9.8’ N, 5° 36.0’ E Calanques 15–20 51 Sponge species commonly found in semi-dark cave communities were selected for the implementation of a Rapid Assessment Method (RAM). These species were also chosen according to several criteria: 1) easiness for identification with reasonable confidence based on in situ pictures; 2) sensitivity to climate change; 3) bio-indicator for marine environment health. This selection of species was used to design an illustrated brochure, that can be printed on waterproof paper, in order to help putative users of the RAM to make easy identifications while SCUBA-diving (Supplementary Information). A total of 61 sponges commonly found in semi-dark underwater caves was selected, a reference list that includes 4 Calcarea, 6 Homoscleromorpha, and 51 Demospongiae (Table 3). In this part of the study, Hexadella crypta and Hexadella pruvoti were considered as a single species complex due to the difficulty in distinguishing them without molecular analysis. These 61 sponges are illustrated in four SPONGE INVENTORY OF THE FRENCH MEDITERRANEAN WATERS Zootaxa 4466 (1) © 2018 Magnolia Press · 207 plates to aid field identification (Supplementary Information). Each sponge illustration was completed with a brief description of its external traits such as growth form, consistency, colors, and size range. Sponge consistency is an essential piece of information in order to distinguish species that can be mistaken in the field. This is especially the case for some polychromatic species, for example, Oscarella tuberculata (considered cartilaginous) and O. lobularis (considered soft and fragile) (Boury-Esnault et al. 1992). This is also the case for certain growth-forms of Spongia spp., which can be easily mistaken with Scalarispongia or Ircinia spp., a definite diagnostic trait being how easy to tear they are, from very easy for species of the Thorectidae family to nearly impossible for the Ircinidae family, Spongiidae consistency being just in between (Vacelet 1959). Some species were included in the underwater brochure because of their value as bioindicators. This is the case of the excavating species Cliona celata and C. viridis, which proliferate and present much more massive growth forms in disturbed environments (Carballo et al. 1996). This is also the case of Agelas oroides, Aplysina cavernicola, Scalarispongia scalaris, Haliclona fulva, Hippospongia communis, Ircinia dendroides, I. oros, I. variabilis, Petrosia ficiformis, and Spongia officinalis, which have been shown to be sensitive to climate extreme events (Pérez et al. 2000; Garrabou et al. 2009). FIGURE 1. Location of the 13 cave sites of the Marseille Region where the sponge survey was implemented. The sampling was carried out using a non-destructive method. Photoquadrats were performed using a digital underwater camera having a 28 mm lens (Canon Series G for instance) and equipped with at least one strobe. An average of 40 photoquadrats (21 x 28 cm, 588 cm²) were performed on the vertical walls of each submarine cave entrances in order to remain located in the core of the semi-dark community and avoid sampling in transition zones. Thus, the number of photoquadrats varied with the cave geomorphology; for instance, from the narrowest places we were able to take only 26 photoquadrats (Table 2). In each site, photoquadrats were randomly deployed around a fixed mark in order to allow further temporal surveys. 208 · Zootaxa 4466 (1) © 2018 Magnolia Press GRENIER ET AL. Presence or absence of each species in the photoquadrats was recorded in an Access® 2013 database, along with their illustrations. For each set of photoquadrats, species occurrences were calculated as follows: Species occurrence = number of photos recording a given species / total number of photos per cave. Mean species richness and cumulative species richness were also calculated for each site. The mean species richness represents the average number of representative species per photoquadrat. The cumulative species richness was calculated by adding the number of new species records quadrat after quadrat. At the end of this process, the total number of species in a site is obtained. The shape of the cumulative species richness curve gives an indication of the efficiency of the sampling effort, but also of a certain picture of the overall sponge diversity. For instance, besides the species richness of the sampling site, the number of quadrats requested to reach the asymptote of the curve gives an indication of the diversity of the sponge community: the lower is the number of quadrats, the faster it is to saturate the sampling, and thus the poorer is the diversity of the sponge community. A non-parametric analysis of variance (Kruskal-Wallis test) was performed using the XLSTAT software 2014 to test the “cave” (13 sites) and “four depth ranges” (5–10 m; 10–15 m; 15–20 m; 20–25 m) effects on the sponge diversity. When a significant difference was observed (p-value ≤ 0.05), a post hoc Dunn test was performed with a Bonferroni correction to identify the various statistically significant groups. Results Sponge inventory of the French Mediterranean Sea. A total of 389 sponges distributed among the four classes of Porifera were identified in the French waters of the Mediterranean Sea (Table 3). Only in the Marseille region, 222 species are present. This reference-list is composed of 337 Demospongiae species (87 %), 29 Calcarea (7 %), 18 Homoscleromorpha (5 %) and 5 Hexactinellida (1 %) (Fig. 2). Three subclasses and 20 orders of Demospongiae were inventoried. The subclass Heteroscleromorpha was represented by 15 orders, with the most highly represented being: Poecilosclerida (84 species), Haplosclerida (48 species), and Tetractinellida (44 species) (Fig. 2). The subclass Keratosa was represented by the 2 orders: Dendroceratida (9 species) and Dictyoceratida (19 species). For the subclass Verongimorpha, three orders were represented: Chondrillida (5 species), Chondrosiida (1 species), and Verongiida (7 species). Myceliospongia araneosa was the only Demospongiae species not assigned to any subclass. Among Hexactinellida, five species were grouped in the two separated subclasses and three orders. The subclass Hexasterophora was represented by four species: two of the order Hexactinosida and two of Lyssacinosida. The subclass Amphidiscophora was represented only by one species of the order Amphidiscosida (Fig 2). Within the Homoscleromorpha, 18 species were found, all of a single order with two families: Oscarellidae (7 species) and Plakinidae (11 species). Within the class Calcarea, 29 species distributed within two subclasses and three orders were found. The subclass Calcaronea was composed of 17 species of two orders: Leucosolenida (14 species) and Lithonida (3 species). The subclass Calcinea was composed of 12 species, all of the order Clathrinida (Fig. 2). Species distribution per habitat with emphasis on cave-dwelling sponge diversity. Hard bottoms, which include several types of shallow water benthic habitats, presented 60 % of the regional species richness, while soft bottoms and lagoons were the poorest habitats, with about 6 % of the overall sponge diversity. Among the remote habitats along the Marseille-Provence Region, the underwater caves were the richest habitat, as they harbor 42 % of the regional species richness against 35% for the mesophotic and deep-sea bottoms. The deep sea was found to harbor the highest percentage (46%) of habitat-exclusive species, soft bottom habitats harboring rather ubiquitous species. Among the sponge diversity occurring in underwater caves, only 23 % were cave-exclusive species, this percentage being about the same in mesophotic habitats, but higher on shallow water rocky bottoms (32%) and in coastal lagoon (31%). In underwater caves, the most emblematic representatives were the Calcarea Petrobiona massiliana, several Homoscleromorpha belonging to the genera Oscarella, Plakina and Plakortis, several Demospongiae such as Rhabderemia (three species cave-exclusive and a fourth also found in caves), both Merlia species, several “Lithistid” species, or the incertae sedis Myceliospongia araneosa. The other sponge species found in caves were also present in other benthic ecosystems: 29 % of the cave sponges were also found in the mesophotic zone, 10% in deep-sea habitats and 66% in shallow water rocky habitats. SPONGE INVENTORY OF THE FRENCH MEDITERRANEAN WATERS Zootaxa 4466 (1) © 2018 Magnolia Press · 209 FIGURE 2. Taxonomic distribution of sponge species, and distribution per habitat; For each type of habitat, the grey color indicates the number of the habitat-exclusive species. Not all sponge taxonomic groups were equally represented in underwater cave ecosystems. Among the total number of Demospongiae and Calcarea, about 40 % of the species diversity were observed in cave systems, but there was a significant difference between these two classes when considering their cave-exclusive representatives: about 50 % of the cave-dwelling calcareous species were exclusive to this ecosystem, against only 16 % of the cave-dwelling demosponges. But the greatest proportion of cave-dwelling species was observed in the class Homoscleromorpha. Indeed, among the 18 Mediterranean species currently known, there is only one Oscarella and one Placinolopha that were never found in underwater caves so far. About half of the known Homoscleromorpha are true cave-exclusive species. Among the five Hexactinellida currently known in the French Mediterranean Sea, Oopsacas minuta is the only one that can be found in a cave. Another interesting finding was the pattern of distribution of sponges without skeleton, which all belong to the homoscleromorph family Oscarellidae (Oscarella and Pseudocorticium) and to the demosponges Verongimorpha of the families Halisarcidae, Chondrosiidae, and Ianthellidae. Among the 18 skeleton-less sponge species currently known in the French Mediterranean Sea, there were only four species that were never found in underwater caves, whereas six species were cave-exclusive: Oscarella microlobata, O. viridis, Pseudocorticium jarrei, Thymosiopsis cuticulatus, Hexadella crypta, and Myceliospongia araneosa. Rapid assessment method of semi-dark cave sponge communities. Benthic assemblages of the semi-dark cave zones in the study area were always characterized by a rich sponge fauna (Fig. 3), with some large-sized representatives shaping a true colorful sea-scape, in association with erect bryozoans or cnidarians such as the emblematic red coral Corallium rubrum. There, Spongia officinalis, Agelas oroides, Cymbaxinella spp., Aplysina cavernicola, Haliclona fulva, Oscarella lobularis, and Petrosia ficiformis were among the largest characteristic sponge species, while some Oscarella species covered large surfaces and constituted plurispecific facies. 210 · Zootaxa 4466 (1) © 2018 Magnolia Press GRENIER ET AL. FIGURE 3. Illustrations of sponge diversity in the semi-dark part of the caves with 10 common sponge species; photoquadrats recorded in A) Grotte de la Triperie, B) Grotte du Chinois, 1) Haliclona mucosa, 2) Diplastrella bistellata, 3) Dendroxea lenis, 4) Cymbaxinella damicornis, 5) Agelas oroides, 6) Oscarella tuberculata, 7) Crella pulvinar, 8) Petrosia ficiformis, 9) Ircinia oros, 10) Ircinia variabilis. SPONGE INVENTORY OF THE FRENCH MEDITERRANEAN WATERS Zootaxa 4466 (1) © 2018 Magnolia Press · 211 FIGURE 4. Four species that were taken into account in the sponge survey, although they were not previously selected, because they appeared more frequently than expected in the photoquadrats. A) Haliclona lacazei was always found in the semidark community, whereas the three remaining species were previously supposed to occur mostly in the dark community: B) Pseudocorticium jarrei, C) Myceliospongia araneosa, D) Plakina crypta. B and C are examples of skeletal-less sponges, which are quite abundant in underwater caves. Interestingly, our study revealed that four species, which were not previously selected (and thus not represented in the brochure), could be added to the reference species list. Indeed, they were supposed to be rather rare and usually dwellers of the darkest zones, but they appeared more frequently than expected in the photoquadrats (more than a quadrat and more than a single site). They are the Homoscleromorpha species, Plakina crypta and Pseudocorticium jarrei, and the Demospongiae, Haliclona (Gellius) lacazei and M. araneosa (Fig. 4). On the other hand, among the selected sponges, 17 species were surprisingly never observed in the photoquadrats. This includes Borojevia cerebrum, Clathrina lacunosa, Calyx nicaeensis, Tethya citrina, Axinella vaceleti, Ciocalypta penicillus, Halichondria (Halichondria) genitrix, Axinella polypoides, Crambe tailliezi, Crella (Yvesia) rosea, Cymbaxinella verrucosa, Haliclona (Reniera) mediterranea, Phorbas fictitius, P. topsenti, Tethya, Petrobiona massiliana, and Plakortis simplex. Considering all sampling sites, nine species were recorded in only one site: Corticium candelabrum, found in Grotte à Pérès; Chondrilla nucula and Thymosiopsis conglomerans, found in Grotte du Chinois; Cliona celata, 212 · Zootaxa 4466 (1) © 2018 Magnolia Press GRENIER ET AL. found in Grotte de l’Anse des Cuivres; Crella elegans, found in Grotte à Corail; Haliclona cratera, found in Grotte du Figuier; Haliclona sarai, found in Grotte de Jarre; Hexadella topsenti, found in Grotte de l’Impérial de Terre; and Spongia lamella, found in Calanque sombre. On the other hand, seven species were distributed through all the study sites but with various occurrences. Among these species, Dendroxea lenis was predominant in Grotte de Jarre, Grotte des Trémies, Grotte du Figuier, and Grotte du Chinois (found in 80 % to 95 % of the photoquadrats). Crella pulvinar was predominant in Grotte de l’Impérial de Terre, Grotte de Méjean, Grotte à Pérès, Grotte à Corail and Tunnel de Moyades (found in 70 % to 98 % of the photoquadrats). Dysidea sp. was predominant in Grotte de l’Impérial de Terre and Grotte de l’Anse des Cuivres (found in about 70 % of the photoquadrats). The occurrences of Cymbaxinella damicornis, Diplastrella bistellata, Petrosia ficiformis, and Pleraplysilla spinifera were much more variable, from 10 to 68 %, from 5 to 83 %, from 4 to 78 %, and from 3 to 63 % respectively. This heterogeneous pattern of distribution was even higher with species such as Oscarella tuberculata and Agelas oroides, which were predominant in some sites (Grotte de Méjean, Calanque sombre), but totally absent in others (Grotte de l’Impérial de Terre and Grotte de l’Anse des Cuivres). The cumulative number of species recorded varied between sites and according to depth (Fig. 5), with a minimum of 20 species recorded in Grotte de Méjean, Grotte de l’Anse des Cuivres, and Grotte des Trémies, and a maximum of 31 species recorded in Grotte du Chinois. In between, 25 species were recorded in Grotte des 3PP, Grotte du Figuier, Calanque Sombre, and Grotte de Jarre. The cumulative curve reached a plateau for sites such as Grotte des 3PP, with no new species recorded after the 33rd photoquadrat. This was even clearer for Grotte de Jarre and Grotte de l’Impérial de Terre, where no new species were found after the 23th and the 19th photoquadrat, respectively. On the contrary, the cumulative curve did not reach a plateau in sites such as Grotte du Figuier and Tunnel de Moyades, indicating that a greater sampling effort might reveal higher species richness in these locations. The cumulative curve of Grotte du Chinois, which recorded the highest number of species, reached a plateau after the 40th photoquadrat. Overall, the species richness varied according to the cave site (K = 174.74 ; p-value <0.0001). The sites with the lowest number of species were Grotte de l’Anse des Cuivres (4.32 ± 0.26) and Calanque Sombre (4.50 ± 0.21), while the richest sites were located in the islands of the Riou Archipelago, more specifically Grotte à Pérès (8.48 ± 0.32) and Grotte de Jarre (8.56 ± 0.30) (Fig. 5). There was also an obvious effect of depth (K = 104.62; p-value <0.0001), as caves between 5 and 10 m depth had lower species richness (4.43 ± 0 17) than caves located between 10 and 25 m (7.10 ± 0.10). FIGURE 5. Cumulative richness curves for each surveyed sites and mean species richness; bars indicate standard errors. SPONGE INVENTORY OF THE FRENCH MEDITERRANEAN WATERS Zootaxa 4466 (1) © 2018 Magnolia Press · 213 Hexactinellida TABLE 3. Sponge inventory of the French Mediterranean Sea and their distribution among habitats, C = underwater Caves, D = Deep sea bottoms, L = Lagoon, M = Mesophotic bottoms, R: shallow water Rocky bottoms, S = shallow water soft bottoms; * species used in the cave survey of the Marseille Region. The most recent Sponge Systematics (Morrow and Cárdenas 2015) is used and all given names are accepted by the World Porifera Database, except for two taxa not yet accepted marked with ** that follow the classification proposed by Gazave et al. (2010) and Redmond et al. (2013). Order Family Species Authorship Habitat Amphidiscosida Pheronematidae Pheronema carpenteri (Thomson, 1869) D Hexactinosida Farreidae Farrea bowerbanki D Tretodictyidae Tretodictyum reiswigi Leucopsacidae Oopsacas minuta Boury-Esnault, Vacelet & Chevaldonné, 2017 Boury-Esnault, Vacelet & Chevaldonné, 2017 Topsent, 1927 Rossellidae Sympagella delauzei D Amphoriscidae Leucilla endoumensis Grantiidae Grantia capillosa Boury-Esnault, Vacelet, Reiswig & Chevaldonné, 2015 Borojevic & BouryEsnault, 1986 (Schmidt, 1862) Leucandra aspera (Schmidt, 1862) R Leucandra crambressa Haeckel, 1872 R Leucandra gossei (Bowerbank, 1862) R Ute glabra Schmidt, 1864 R Ute viridis Schmidt, 1868 L Leucosoleniidae Leucosolenia variabilis (Haeckel, 1870) L, R Sycetiidae Sycon ciliatum (Fabricius, 1780) R Sycon elegans (Bowerbank, 1845) R Sycon humboldti Risso, 1827 R Sycon quadrangulatum (Schmidt, 1868) R Sycon raphanus Schmidt, 1862 C, L Sycon sycandra (Lendenfeld, 1895) C Monoplectroninia hispida C Plectroninia hindei mediterranea Pouliquen & Vacelet, 1970 Vacelet, 1967 Petrobionidae Petrobiona massiliana * Vacelet & Lévi, 1958 C Clathrinidae Borojevia cerebrum * (Haeckel, 1872) C, R Clathrina clathrus * (Schmidt, 1864) C, R Clathrina coriacea (Montagu, 1814) R Clathrina lacunosa * (Johnston, 1842) C, R Clathrina primordialis (Haeckel, 1872) C Clathrina rubra Sarà, 1958 R Clathrina blanca C, R Ascandra contorta (Miklucho-Maclay, 1868) (Bowerbank, 1866) Ascandra falcata Haeckel, 1872 R Calcarea Lyssacinosida Leucosolenida Lithonida Clathrinida Minchinellidae Homoscleromorpha Leucaltidae Homosclerophorida D C, D ? L C C, R Ascandra minchini Borojevic, 1966 R Leucascidae Ascaltis reticulum (Schmidt, 1862) C, R Leucettidae Leucetta solida (Schmidt, 1862) R Oscarellidae Oscarella balibaloi * Pérez, Ivanisevic, Dubois, Pedel, Thomas, Tokina & Ereskovsky, 2011 Muricy, BouryEsnault, Bézac & Vacelet, 1996 (Schmidt, 1862) C, R Oscarella imperialis Oscarella lobularis * 214 · Zootaxa 4466 (1) © 2018 Magnolia Press R C, R GRENIER ET AL. Oscarella microlobata Muricy, BouryEsnault, Bézac & Vacelet, 1996 (Schmidt, 1868) C C Corticium candelabrum * Muricy, BouryEsnault, Bézac & Vacelet, 1996 Boury-Esnault, Muricy, Gallissian & Vacelet, 1995 Schmidt, 1862 Placinolopha moncharmonti (Sarà, 1960) M Plakina crypta * Muricy, BouryEsnault, Bézac & Vacelet, 1998 Schulze, 1880 C C Plakina monolopha Muricy, BouryEsnault, Bézac & Vacelet, 1998 Muricy, BouryEsnault, Bézac & Vacelet, 1998 Schulze, 1880 Plakina topsenti (Pouliquen, 1972) C Plakina trilopha Schulze, 1880 C, R Plakinastrella copiosa Schulze, 1880 C, R Plakortis aff. simplex * Schulze, 1880 C Agelasidae Agelas oroides * (Schmidt, 1864) C, R Hymerhabdiidae Hymerhabdia oxytrunca Topsent, 1904 D Hymerhabdia typica Topsent, 1892 R Cymbaxinella damicornis ** (Esper, 1794) C, R Cymbaxinella verrucosa ** (Esper, 1794) C, R Prosuberites longispinus Topsent, 1893 C, D, M, R Auletta pedunculata (Topsent, 1896) M, R Axinella babici Vacelet, 1961 M Axinella guiteli Topsent, 1896 R Axinella minuta Lévi, 1967 M Axinella perlucida Topsent, 1896 R Axinella polypoides * Schmidt, 1862 M, R Axinella vaceleti * Pansini, 1984 C, M, R Phakellia hirondellei Topsent, 1892 D Phakellia robusta Bowerbank, 1866 D Phakellia ventilabrum (Linnaeus, 1767) M Halicnemia geniculata Sarà, 1958 C Halicnemia patera Bowerbank, 1864 M, R Ceratopsion minor Pulitzer-Finali, 1983 M Endectyon (Endectyon) lacazei (Topsent, 1892) D, R Endectyon (Endectyon) pilosum (Vacelet, 1961) M, R Eurypon cinctum Sarà, 1960 R Eurypon clavatum (Bowerbank, 1866) C, D, M, R Eurypon coronula (Bowerbank, 1874) M, R Eurypon denisae Vacelet, 1969 D Eurypon lacazei (Topsent, 1891) C, R Oscarella tuberculata * Oscarella viridis Pseudocorticium jarrei * Plakinidae Plakina dilopha Plakina endoumensis Demospongiae Plakina jani * Agelasida Axinellida Axinellidae Heteroxyidae Raspailiidae SPONGE INVENTORY OF THE FRENCH MEDITERRANEAN WATERS C, R C C, R C, R C C, R Zootaxa 4466 (1) © 2018 Magnolia Press · 215 Biemnida Eurypon obtusum Vacelet, 1969 D Raspaciona aculeata * (Johnston, 1842) C, R, S Raspailia gracillima Topsent, 1894 M Raspailia (Raspailia) viminalis Schmidt, 1862 M, R Rhabdeurypon spinosum Vacelet, 1969 D Stelligeridae Stelligera rigida (Montagu, 1814) D, M, R Rhabderemiidae Rhabderemia gallica Van Soest & Hooper, 1993 Topsent, 1896 C C Rhabderemia toxigera Van Soest & Hooper, 1993 Topsent, 1892 Bubaris carcisis Vacelet, 1969 M Bubaris subtyla Pulitzer-Finali, 1983 M Bubaris vermiculata (Bowerbank, 1866) M Monocrepidium vermiculatum Topsent, 1898 C, D Rhabdobaris implicata Pulitzer-Finali, 1983 M Desmanthidae Sulcastrella tenens (Vacelet, 1969) D Dictyonellidae Acanthella acuta * Schmidt, 1862 C, M, R Dictyonella incisa * (Schmidt, 1880) C, M, R Dictyonella marsilii (Topsent, 1893) M, R Dictyonella obtusa (Schmidt, 1862) D, M Dictyonella pelligera (Schmidt, 1864) C, R Tethyspira spinosa (Bowerbank, 1874) M Cliona burtoni Topsent, 1932 R Cliona celata * Grant, 1826 C, L, R Cliona janitrix Topsent, 1932 R Cliona lobata Hancock, 1849 L Cliona schmidtii (Ridley, 1881) R Cliona vermifera Hancock, 1867 C Cliona viridis * (Schmidt, 1862) C, R Pione vastifica (Hancock, 1849) L, M, R Spiroxya heteroclita Topsent, 1896 R Spiroxya levispira (Topsent, 1898) C Spiroxya pruvoti (Topsent, 1900) D Diplastrella bistellata * (Schmidt, 1862) C, D, M Spirastrella cunctatrix * Schmidt, 1868 C, R Desmacella annexa Schmidt, 1870 D, M Desmacella inornata (Bowerbank, 1866) D, M Dragmatella aberrans (Topsent, 1890) D, M Callyspongia septimaniensis Griessinger, 1971 R Callyspongia subcornea (Griessinger, 1971) C Chalinula limbata (Montagu, 1814) L, R Chalinula renieroides Schmidt, 1868 L Cladocroce fibrosa (Topsent, 1890) D Dendroxea adumbrata Corriero, ScaleraLiaci & Pronzato, 1996 (Topsent, 1892) C Rhabderemia spinosa Demospongiae Rhabderemia topsenti Bubarida Clionaida Bubaridae Clionaidae Spirastrellidae Desmacellida Haplosclerida Desmacellidae Callyspongiidae Chalinidae Dendroxea lenis * 216 · Zootaxa 4466 (1) © 2018 Magnolia Press C C, R C, R GRENIER ET AL. Petrosiidae Demospongiae Phloeodictyidae Merliida Hamacanthidae Merliidae Haliclona aperta (Sarà, 1960) C, R Haliclona flavescens (Topsent, 1893) R Haliclona (Gellius) angulata (Bowerbank, 1866) L, M, R Haliclona (Gellius) arnesenae (Arndt, 1927) D Haliclona (Gellius) fibulata (Schmidt, 1862) M, R Haliclona (Gellius) lacazei * (Topsent, 1893) C, D Haliclona (Gellius) laxa (Topsent, 1892) C, R, M Haliclona (Gellius) microsigma (Babic, 1922) R Haliclona (Gellius) uncinata (Topsent, 1892) D Haliclona (Halichoclona) fistulosa (Bowerbank, 1866) R, S Haliclona (Halichoclona) fulva * (Topsent, 1893) C, R Haliclona (Halichoclona) latens (Topsent, 1892) D, R Haliclona (Halichoclona) magna (Vacelet, 1969) C, D, M Haliclona (Halichoclona) parietalis (Topsent, 1893) R Haliclona (Halichoclona) perlucida (Griessinger, 1971) R Haliclona (Haliclona) reptans (Griessinger, 1971) R Haliclona (Haliclona) simulans (Johnston, 1842) L, M, R Haliclona (Haliclona) varia (Sarà, 1958) R Haliclona poecillastroides (Vacelet, 1969) D, M Haliclona (Reniera) aquaeductus (Schmidt, 1862) M, R Haliclona (Reniera) cinerea (Grant, 1826) L, R Haliclona (Reniera) citrina (Topsent, 1892) R Haliclona (Reniera) cratera (Schmidt, 1862) C, R Haliclona (Reniera) griessingeri R Haliclona (Reniera) mediterranea * Van Lent & De Weerdt, 1987 Griessinger, 1971 Haliclona (Reniera) subtilis Griessinger, 1971 C Haliclona (Rhizoniera) rhizophora (Vacelet, 1969) D, M Haliclona (Rhizoniera) sarai C, M, R Haliclona (Soestella) arenata (Pulitzer-Finali, 1969) (Griessinger, 1971) Haliclona (Soestella) implexa (Schmidt, 1868) R Haliclona (Soestella) mamillata (Griessinger, 1971) R Haliclona (Soestella) mucosa * (Griessinger, 1971) C, R Haliclona (Soestella) valliculata (Griessinger, 1971) C, R Haliclona stirpescens (Topsent, 1925) L Reniera porrecta Schmidt, 1868 L Petrosia (Petrosia) ficiformis * (Poiret, 1789) C, M, R Xestospongia plana (Topsent, 1892) M, R Calyx nicaeensis * (Risso, 1826) C, D, M, R Janulum spinispiculum (Carter, 1876) D Oceanapia vacua (Sarà, 1961) C Siphonodictyon cf. labyrinthicum (Hancock, 1849) C, M Hamacantha (Hamacantha) johnsoni (Bowerbank, 1864) D, M Hamacantha (Hamacantha) lundbecki Topsent, 1904 D Hamacantha (Vomurela) falcula (Bowerbank, 1874) D, M Hamacantha (Vomerula) papillata Vosmaer, 1885 C, D, M Merlia deficiens Vacelet, 1980 C SPONGE INVENTORY OF THE FRENCH MEDITERRANEAN WATERS C, R R, S Zootaxa 4466 (1) © 2018 Magnolia Press · 217 Poecilosclerida Acarnidae Chondropsidae Cladorhizidae Merlia normani Kirkpatrick, 1908 C Acarnus levii Vacelet, 1960 D Acarnus souriei (Lévi, 1952) R, S Acarnus tortilis Topsent, 1892 C, D Acheliderma lemniscatum Topsent, 1892 R Damiria curvata (Vacelet, 1969) M Iophon hyndmani (Bowerbank, 1858) R Iophon funis Topsent, 1892 R Batzella inops (Topsent, 1891) C, R Psammoclema nicaeense (Pulitzer-Finali & Pronzato, 1980) Sars, 1872 M C, D Forcepia (Leptolabis) brunnea (Vacelet & BouryEsnault, 1996) (Topsent, 1904) Forcepia (Leptolabis) luciensis (Topsent, 1888) C, M, R Lissodendoryx (Anomodoryx) cavernosa (Topsent, 1892) D, M, R Crambe crambe * (Schmidt, 1862) C, L, M, R Crambe tailliezi * C, R Anisocrella hymedesmina Vacelet & BouryEsnault, 1982 Topsent, 1927 Crella (Crella) elegans * (Schmidt, 1862) R Crella (Grayella) pulvinar * (Schmidt, 1868) C, M, R Crella (Pytheas) alba (Vacelet, 1969) D Crella (Pytheas) digitifera Lévi, 1959 M, S Crella (Pytheas) sigmata Topsent, 1925 C, M Crella (Yvesia) rosea * (Topsent, 1892) C, R Esperiopsis strongylophora Vacelet, 1969 D Ulosa stuposa (Esper, 1794) R, S Ulosa tubulata Pulitzer-Finali, 1983 M Hamigera hamigera (Schmidt, 1862) R Hemimycale columella * (Bowerbank, 1874) C, R Hemimycale mediterranea R Hymedesmia (Hymedesmia) baculifera Uriz, Garate & Agell, 2017 (Topsent, 1901) Hymedesmia (Hymedesmia) gracilisigma Topsent, 1928 M Hymedesmia (Hymedesmia) inflata Vacelet, 1969 M Hymedesmia (Hymedesmia) mutabilis (Topsent, 1904) D Hymedesmia (Hymedesmia) pansa Bowerbank, 1882 C, R Hymedesmia (Hymedesmia) peachi Bowerbank, 1882 C, R Hymedesmia (Hymedesmia) plicata Topsent, 1928 D Hymedesmia (Hymedesmia) rissoi Topsent, 1936 R Hymedesmia (Hymedesmia) serrulata Vacelet, 1969 D Hymedesmia (Hymedesmia) versicolor (Topsent, 1893) R Hymedesmia (Stylopus) coriacea (Fristedt, 1885) C, M, R Hymedesmia (Stylopus) nigrescens (Topsent, 1925) R Phorbas dives (Topsent, 1891) M, R Phorbas fibulatus (Topsent, 1893) R Phorbas fictitius * (Bowerbank, 1866) C, R Phorbas tailliezi Vacelet & Pérez, 2008 R Cladorhiza cf. abyssicola Lycopodina hypogea Coelosphaeridae Crambeidae Crellidae Esperiopsidae Hymedesmiidae 218 · Zootaxa 4466 (1) © 2018 Magnolia Press D C, M D C, R GRENIER ET AL. Latrunculiidae Microcionidae Mycalidae Myxillidae Polymastiida Phorbas tenacior * (Topsent, 1925) C, M, R Phorbas topsenti * R Plocamionida ambigua Vacelet & Perez, 2008 (Bowerbank, 1866) Spanioplon armaturum (Bowerbank, 1866) M, R Latrunculia (Biannulata) citharistae Vacelet, 1969 M Latrunculia rugosa (Vacelet, 1969) D Sceptrella insignis (Topsent, 1890) D Antho (Antho) arcitenens (Topsent, 1892) R Antho (Antho) involvens (Schmidt, 1864) C, M, R, S Clathria (Clathria) compressa Schmidt, 1862 C, R Clathria (Clathria) coralloides (Scopoli, 1772) C, R Clathria (Clathria) toxistricta Topsent, 1925 R Clathria (Clathria) toxivaria (Sarà, 1959) C, R Clathria (Microciona) assimilis Topsent, 1925 M, R Clathria (Microciona) cleistochela (Topsent, 1925) C Clathria (Microciona) frogeti (Vacelet, 1969) M Clathria (Microciona) gradalis Topsent, 1925 D, R Clathria (Microciona) spinarcus R Clathria (Microciona) strepsitoxa (Carter & Hope, 1889) (Hope, 1889) Clathria (Microciona) toximajor Topsent, 1925 R Clathria (Microciona) toxitenuis Topsent, 1925 C, R Clathria (Paresperia) anchorata (Carter, 1874) D Clathria (Thalysias) jolicoeuri (Topsent, 1892) C, R Mycale (Aegogropila) contarenii (Lieberkühn, 1859) R Mycale (Aegogropila) retifera Topsent, 1924 R Mycale (Aegogropila) rotalis (Bowerbank, 1874) R Mycale (Aegogropila) syrinx (Schmidt, 1862) M Mycale (Aegogropila) tunicata (Schmidt, 1862) M, R, S Mycale (Carmia) macilenta (Bowerbank, 1866) C, L, R Mycale (Carmia) minima (Waller, 1880) R Mycale (Carmia) subclavata (Bowerbank, 1866) R Mycale (Mycale) massa (Schmidt, 1862) D, M, R Melonanchora emphysema (Schmidt, 1875) D, M Myxilla (Myxilla) iotrochotina (Topsent, 1892) C, R Myxilla (Myxilla) macrosigma Boury-Esnault, 1971 C, R Myxilla (Myxilla) prouhoi (Topsent, 1892) M, R D, M, R C, R Myxilla (Myxilla) rosacea (Lieberkühn, 1859) C, M, R Podospongiidae Podospongia lovenii D, M Tedaniidae Tedania (Tedania) anhelans Barboza du Bocage, 1869 (Vio in Olivi, 1792) Polymastiidae Polymastia boletiformis (Lamarck, 1815) M, S Polymastia harmelini R Polymastia inflata Boury-Esnault & Bézac, 2007 Cabioch, 1968 Polymastia penicillus (Montagu, 1814) M, S Polymastia polytylota Vacelet, 1969 D, M Polymastia sola Pulitzer-Finali, 1983 M Polymastia tissieri (Vacelet, 1961) D SPONGE INVENTORY OF THE FRENCH MEDITERRANEAN WATERS L, M, R M, S Zootaxa 4466 (1) © 2018 Magnolia Press · 219 Pseudotrachya hystrix (Topsent, 1890) D, M Radiella sol Schmidt, 1870 D Weberella verrucosa Vacelet, 1960 M, S Scopalinida Scopalinidae Scopalina lophyropoda * Schmidt, 1862 C, R Suberitida Halichondriidae Amorphinopsis pallescens (Topsent, 1892) R Axinyssa papillosa C Ciocalypta penicillus * (Sarà & Siribelli, 1962) Bowerbank, 1862 Halichondria (Halichondria) genitrix * (Schmidt, 1870) M, R Halichondria (Halichondria) panicea (Pallas, 1766) C, R Hymeniacidon perlevis (Montagu, 1814) L, R Laminospongia subtilis Pulitzer-Finali, 1983 M Spongosorites intricatus (Topsent, 1892) R Topsentia pachastrelloides (Topsent, 1892) M, S Stylocortylidae Stylocordyla pellita (Topsent, 1904) D Suberitidae Aaptos aaptos (Schmidt, 1864) C, M, R Protosuberites denhartogi Van Soest & De Kluijver, 2003 (Topsent, 1900) C, R (Boury-Esnault & Lopes, 1985) (Topsent, 1893) C D Pseudosuberites mollis (Ridley & Dendy, 1886) Topsent, 1925 Pseudosuberites sulphureus (Bowerbank, 1866) L Rhizaxinella elongata D, M, R, S Rhizaxinella pyrifera (Ridley & Dendy, 1886) (Delle Chiaje, 1828) Suberites carnosus (Johnston, 1842) C, D, M, R Suberites domuncula (Olivi, 1792) M, R, S Suberites massa Nardo, 1847 L Suberites syringella (Schmidt, 1868) M Terpios cf. fugax C, R, S Terpios gelatinosus Duchassaing & Michelotti, 1864 (Bowerbank, 1866) Hemiasterellidae Paratimea constellata (Topsent, 1893) C, R Tethyidae Tethya aurantium * (Pallas, 1766) L, R Tethya citrina * Sarà & Melone, 1965 C, M Timea chondrilloides (Topsent, 1904) D Timea crassa (Topsent, 1900) C, L Timea fasciata Topsent, 1934 C, R Timea mixta (Topsent, 1896) R, S Timea simplistellata Pulitzer-Finali, 1983 M Timea stellata (Bowerbank, 1866) M, R Timea tristellata (Topsent, 1892) R Timea unistellata (Topsent, 1892) C, M, R Dercitus (Stoeba) plicatus (Schmidt, 1868) C, M, R, S Holoxea furtiva Topsent, 1892 M, R Jaspis johnstonii (Schmidt, 1862) C, R, M Jaspis inconditus (Topsent, 1892) R Protosuberites ectyoninus Protosuberites ferrerhernandezi Protosuberites rugosus Pseudosuberites hyalinus Tethyida Timeidae Tetractinellida C, R, S Ancorinidae 220 · Zootaxa 4466 (1) © 2018 Magnolia Press D D L, R D, M C, R GRENIER ET AL. Corallistidae Geodiidae Pachastrellidae Stelletta defensa Pulitzer-Finali, 1983 M Stelletta dichoclada Pulitzer-Finali, 1983 M Stelletta dorsigera Schmidt, 1864 M, R, S Stelletta grubii Schmidt, 1862 L, R Stelletta lactea Carter, 1871 C, R Stelletta mediterranea (Topsent, 1893) R Stelletta stellata Topsent, 1893 R Stryphnus mucronatus (Schmidt, 1868) M, R, S Stryphnus ponderosus (Bowerbank, 1866) M Neophrissospongia endoumensis C Neophrissospongia nolitangere Pisera & Vacelet, 2011 (Schmidt, 1870) Neoschrammeniella bowerbankii (Johnson, 1863) C, D Caminella intuta (Topsent, 1892) C, M Caminus vulcani Schmidt, 1862 C, M, R Erylus corsicus Pulitzer-Finali, 1983 M Erylus deficiens Topsent, 1927 R Erylus discophorus (Schmidt, 1862) C, M, R Erylus expletus Topsent, 1927 C, M Erylus papulifer Pulitzer-Finali, 1983 M Penares euastrum (Schmidt, 1868) C, M, R Penares helleri (Schmidt, 1864) C, M, R Geodia conchilega Schmidt, 1862 C, M, R, S Geodia cydonium (Jameson, 1811) C, L, R Calthropella (Calthropella) pathologica (Schmidt, 1868) C, D Calthropella (Corticellopsis) stelligera (Schmidt, 1868) R Nethea amygdaloides (Carter, 1876) M C Pachastrella monilifera Schmidt, 1868 C, R Samidae Samus anonymus Gray, 1867 R Siphonidiidae Siphonidium ramosum (Schmidt, 1870) D Theneidae Annulastrella verrucolosa (Pulitzer-Finali, 1983) (Bowerbank, 1858) M C, M Thenea muricata D, M Theonellidae Discodermia polymorpha Thoosidae Alectona millari Pisera & Vacelet, 2011 Carter, 1879 Thoosa armata Topsent, 1888 R Thoosa mollis Volz, 1939 C Thrombidae Thrombus abyssi (Carter, 1873) C Vulcanellidae Poecillastra compressa (Bowerbank, 1866) D, M Poecillastra rudiastra Pulitzer-Finali, 1983 M Poecillastra saxicola (Topsent, 1892) R Vulcanella gracilis (Sollas, 1888) D, M C, M Trachycladida Trachycladidae Trachycladus minax (Topsent, 1888) C, D, M, R Dendroceratida Darwinellidae Aplysilla rosea (Barrois, 1876) R Aplysilla sulfurea Schulze, 1878 C, M, R Chelonaplysilla noevus (Carter, 1876) C, M, R Chelonaplysilla psammophila (Topsent, 1928) M Darwinella intermedia Topsent, 1893 R SPONGE INVENTORY OF THE FRENCH MEDITERRANEAN WATERS Zootaxa 4466 (1) © 2018 Magnolia Press · 221 Dictyoceratida Darwinella simplex Topsent, 1892 C, R Darwinella viscosa Boury-Esnault, 1971 R Dendrilla cirsioides Topsent, 1893 R Dictyodendrillidae Spongionella pulchella (Sowerby, 1804) C, M, R Dysideidae Dysidea avara * (Schmidt, 1862) C, M, R Dysidea fragilis (Montagu, 1814) D, M, L, R Dysidea pallescens (Schmidt, 1862) C, R Dysidea tupha (Martens, 1824) M, R Pleraplysilla spinifera * (Schulze, 1879) C, D, M, R Ircinia dendroides * (Schmidt, 1862) C, R Ircinia oros * (Schmidt, 1864) C, R Ircinia variabilis * (Schmidt, 1862) C, R Sarcotragus foetidus Schmidt, 1862 R Sarcotragus spinosulus Schmidt, 1862 C, R Hippospongia communis * (Lamarck, 1814) C, R Spongia (Spongia) lamella * (Schulze, 1879) C, R, M Spongia (Spongia) nitens (Schmidt, 1862) C, R Spongia (Spongia) officinalis * Linnaeus, 1759 C, M, R Spongia (Spongia) virgultosa (Schmidt, 1868) C, M, R Cacospongia mollior Schmidt, 1862 R Fasciospongia cavernosa (Schmidt, 1862) C, R Hyrtios collectrix (Schulze, 1880) M, R Scalarispongia scalaris * (Schmidt, 1862) C, M, R Chondrilla nucula * Schmidt, 1862 R Thymosiopsis conglomerans * Vacelet, Borchiellini, Pérez, Bultel-Poncé, Brouard & Guyot, 2000 Vacelet & Pérez, 1998 Johnston, 1842 C, R C, R Irciniidae Spongiidae Thorectidae Chondrillida Chondrillidae Thymosiopsis cuticulatus * Halisarcidae Halisarca dujardinii Halisarca harmelini C R Chondrosiida Chondrosiidae Chondrosia reniformis * Eresovsky, Lavrov, Boury-Esnault & Vacelet, 2011 Nardo, 1847 Verongiida Aplysinidae Aplysina aerophoba (Nardo, 1833) R Aplysina cavernicola * (Vacelet, 1959) C, M, R Hexadella crypta C Hexadella dedritifera Reveillaud, Allewaert, Pérez, Vacelet, Banaigs & Vanreusel, 2012 Topsent, 1913 Hexadella pruvoti * Topsent, 1896 C, M, D, R Hexadella racovitzai * Topsent, 1896 C, M, R Hexadella topsenti * Reveillaud, Allewaert, Pérez, Vacelet, Banaigs & Vanreusel, 2012 Vacelet & Pérez, 1998 R Ianthellidae Insertae sedis Myceliospongia araneosa * 222 · Zootaxa 4466 (1) © 2018 Magnolia Press C, R M, D C GRENIER ET AL. Discussion A total of 389 species belonging to the four sponge classes were inventoried in the French Mediterranean Sea. The main challenge in compiling this kind of inventory was to ensure that the geographical records reported in the literature were correct. In fact, returning to the original publications allowed us to revise the distribution data presented in the World Porifera Database and add or modify about 70 % of data (Van Soest et al. 2018). In the Western Mediterranean Sea, Italy is known for its school of spongiologists that generated a great knowledge about the world sponge fauna. The first comprehensive Italian checklist was published in 2003 and updated in 2008, after inventories conducted in nine geographical areas within the Western Mediterranean basin, the Ionian Sea, and the Adriatic Sea (Pansini & Longo 2008). The Italian list included 509 species belonging to three classes and 19 different orders. Hence, even if the species diversity was far higher than for the French Mediterranean Sea, this inventory could be further updated by better considering the classes Homoscleromorpha and Calcarea, and by including reports on Hexactinellida. All three classes are indeed well represented in poorly accessible ecosystems (see below) and request specialized taxonomic skills. Despite being numerically smaller than the Italian inventory, the French list represents a reference for the Western Mediterranean basin, as the researchers involved have tried to consider equally the four Porifera classes and most of the orders recognized by the latest classification (Morrow & Cárdenas 2015) from shallow to deep waters, from easily accessible to remote habitats. In the last decade, similar studies were conducted in the Eastern Mediterranean basin (Voultsiadou 2005; Voultsiadou et al. 2016). The Greek sponge list now comprises 215 species, classified into four classes, 24 orders and 65 families. However, Homoscleromorpha and Calcarea have been included only very recently in this inventory, and considering the great maritime territory of this country, there is a great chance that the sponge diversity remains far underestimated (e.g. Lage et al. 2018). Efforts are currently being made in order to improve this knowledge in the Levantine basin, what includes initiatives in several other countries such as Israel (Idan et al. 2018) and Lebanon (Vacelet & Pérez, pers. obs.). However, the lack of taxonomists and a limited investment in basic naturalistic inventories obviously explain that big gaps of knowledge remain in the Mediterranean Sea. The improvement of knowledge will come from the exploration of poorly accessible habitats, which contain a significant reservoir of hidden species diversity such as submarine caves (e.g. Russ & Rützler 1959; Sarà 1968; 1976; Uriz et al. 1992; Bussotti et al. 2006; Gerovasileiou & Voultsiadou 2012), mesophotic and deep sea habitats (e.g. Uriz & Rosell 1990; Bertolino et al. 2015). In underwater caves, the main limitation relies in the time and experience required for the sampling of many little crusts located in the darkest sectors, which might include a high rate of cave-exclusive species. The 3PP cave is an emblematic example of such habitats, which markedly impacted the sponge world after reports of various biological novelties such as the first carnivorous sponge and shallow populations of a poorly known Hexactinellida (Boury-Esnault & Vacelet 1994; Vacelet et al. 1994; Vacelet & Boury-Esnault 1995; 1996; Boury-Esnault et al. 1999). After these discoveries, a species inventory was initiated 20 years ago by the scientists of the Marine Station of Endoume. Nonetheless, confronted by a great number of other novelties or original body plans (e.g. Vacelet & Pérez 1998; Vacelet et al. 2000), this inventory, likely to be in the most original shallow water habitat of the Western basin, has never been completed. In greater depths, the main limitation of a better knowledge relies in the ability to sample using a ROV, but when it is possible it allows the description of large new species, which can physiognomically mark the seascape (Boury-Esnault et al. 2017). The cave survey implemented in the Marseille region was based on a selection of 65 common species of the semi-dark community, usually found in the entrance of submarine caves. Previous studies focused on ‘indicator’ sponges in this type of habitat. In 2000, Corriero et al. analyzed the distribution of 55 species within an Italian submarine cave, and among these indicators, only 17 sponges are in common with our species selection. Indeed, this study considered a greater number of species found in the dark community, and applied a combination of photographic surveys and of an exhaustive sampling followed by accurate determinations in laboratory. In 2016, Gerovasileiou and Voultsiadou studied the sponge species composition of two submarine caves in the northern Aegean Sea, Greece. Among the 50 identified species, 24 are in common with our selection, but in this study as well, underwater pictures were accompanied by some sampling for taxonomy. In average, we used about the same number of indicators, as we wanted to focus on easily identifiable species, requiring only a gross determination key, which can be used underwater. This selection can assist in the conduction of surveys through photography or simply visual census along transects or in quadrats. SPONGE INVENTORY OF THE FRENCH MEDITERRANEAN WATERS Zootaxa 4466 (1) © 2018 Magnolia Press · 223 The application of our simplified assessment method revealed some clear patterns of sponge species diversity among the study sites. For instance, Grotte d’Endoume and Calanque Sombre appeared significantly different from the others, as they are the shallowest cave sites and the most highly influenced by human activities. Grotte d’Endoume is located within an urban area while Calanque Sombre is close to the sewage outlet of Marseille city. Our assessment method also highlighted the dominance of certain species in the studied caves. For example, Oscarella tuberculata, Dendroxea lenis, Agelas oroides, Crella pulvinar and Dysidea sp. are very well represented in all study sites, although they do not dominate the sampling surfaces. In other cases, massive sponges such as Aplysina cavernicola and Spongia officinalis can dominate the assemblage, although these species do not present the same ubiquitous distribution as the previous examples. These results confirm the rather high heterogeneity of underwater cave communities previously pointed out in other region of the Mediterreanean Sea (e.g. Bussotti et al. 2006; Gerovasileiou & Voultsiadou 2016). Differences in terms of species diversity were also revealed by comparing accumulation curves obtained from our study sites. In some cases, they showed that the sampling effort should be intensified, as some curves did not reach a plateau. Our protocol does not limit the sampling effort, which is actually much more constrained by the extent of the semi-dark part and the geomorphology of each submarine cave. For example, only 26 underwater pictures were taken in Grotte de Méjean due to the narrowness of the semidark sector. An increase in the number of photoquadrats would also cover dark zones, dominated by a totally different community. Nevertheless, we suggest that the highest sampling effort should be attempted where possible. For instance, if like Martí et al. (2004) we had used only 20 photoquadrats, the species richness recorded in our study sites would have been underestimated. Such a limitation would have resulted in a loss of six species recorded in Grotte du Chinois, eight species each in Grotte du Figuier and Grotte des 3PP and nine species in Tunnel de Moyades. The sampling strategy adopted, taking into account each single cave configuration, allowed us to draw a baseline providing a rather good picture of the sponge diversity of the semi-dark cave community. It could be further optimized by sampling the various types of substrates found in cave entrances (soft bottom, silted rocky surface, ceiling etc.), which would allow to better use our species selection. Some species, like Ciocalypta penicillus and Halichondria genitrix, grow on sandy bottoms in the entrances. Some species were not recorded in our study, because they are quite rare in the Marseille Region: Calyx nicaeensis, Axinella vaceleti, Tethya aurantium or T. citrina. However, other absences are more difficult to explain because these species can be observed in the area, but their spatial micro-distribution did not allow to sample them. This is the case for Petrobiona massiliana, Axinella polypoides and Haliclona mediterranea, for example. To overcome this problem, additional photographic surveys by visual census using the illustrated underwater plates could be implemented. Finally, even if not complete, our assessment method highlighted significant differences between cave sites, including unexpected records of “dark cave-dwellers“, such as the species Plakina crypta, Myceliospongia araneosa, Thymosiopsis conglomerans and T. cuticulatus, within the semi-dark zones. The main purpose of this part of the study was to provide environmental managers with both solid baselines on Mediterranean sponge diversity and a rapid assessment method to monitor potential change in biodiversity through time. Of course, much more sophisticated assessment methods, not only based on the occurrence of selected taxa, could be proposed. The treatment of photoquadrats could include evaluation of taxa percentage cover, which would allow the calculation of other diversity indexes (Corriero et al. 2000; Gerovasileiou & Voultsiadou 2016). Such a treatment would require a sub-sampling within each photoquadrat, and thus a longer post-processing time, which would be less compatible with the challenges of an easy and rapid assessment method for marine environment managers who must combine many other technical, administrative and scientific tasks. Furthermore, by comparing a more complex approach (estimation of each taxa coverage) with a simple approach (the one used in this study), Parravicini et al. (2010b) showed very similar results, demonstrating the suitability of a simple approach in order to achieve a scientific objective. In shallow waters, such as coral reefs or mangroves, these density estimations are usually accompanied by sponge’s volume measurement (Wulff 2012). These approaches allow a better understanding of community dynamics, diversity changes and also demographic structures further to a major disturbance. Future survey methods could also involve taking a number of photos in order to make threedimensional (3D) representations of benthic communities and automatic comparative analyses of these 3D reconstructions. 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