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International audience; Tout le monde s’accorde à dire qu’une planète en bonne santé est une condition nécessaire au bien-être de l’humanité. Mais quels sont les moyens d’action mis à disposition de nos sociétés pour s’engager dans cette nécessaire transition écologique ? Comment changer nos comportements et agir au mieux pour le vivant… et donc aussi pour nous ? Quatre chercheurs, tous écologues, portent ici leur regard sur les relations qu’entretiennent l’homme, la société et l’environnement. Éclairants, enrichissants et facilement accessibles, leurs propos nous offrent ainsi de nouvelles perspectives et nous invitent à repenser nos pratiques tout en nous offrant un beau voyage à la découverte de leurs univers de recherche.

Glandiceps talaboti (Marion, 1876) (Fig. 7): a deep-sea worm with affinities to echinoderms and chordates (Hemichordata, Enteropneusta, Spengelidae) In July–October of 1875, Antoine-Fortuné Marion had undertaken a dredging inventory of the deep-sea bottom to the south-east of the Bay of Marseille, to complete his previous studies of the littoral zone (Marion 1873). These dredging efforts were realized thanks to the financial support of a group of his friends (Talabot, Benet, Renouard, Meilhac, Mazel, Gallas and Martin). Among the most interesting discoveries he made was a new enteropneust species from yellowish sticky mud at 350 m depth in the area then called “Plateau Marsilli”. First Enteropneusta from Provence at this time, it was shortly described by Marion in 1876 as Balanoglossus talaboti, to honour one of his friends and sponsors. Later, he gave a very complete description of the species, pink-coloured, cylindrical and composed of a short anterior and conical proboscis, a collar where the mouth opens, and a trunk (Marion, 1885, 1886). Marion could observe the animal alive, crawling on the sediment surface of an aquarium for several weeks and noticed the emission of thick mucus with iodine smell when the animal was disturbed. Later, Spengel (1893) studied the enteropneusts of the Bay of Naples and subdivided the genus Balanoglossus in four genera, assigning Marion’s species to the genus Glandiceps, even becoming its type-species. The Enteropneusta, although not speciesrich, are part of the Hemichordata and as such have a major evolutionary interest due to their close relationships with both Echinodermata and Chordata. Glandiceps talaboti is a Mediterranean endemic species. It was later collected in bathyal mud of the Cassidaigne and Lacaze-Duthiers canyons (DPR096 cruise, see photo, Zibrowius personal communication), possibly along Egyptian coasts near Alexandria, and also recently off Turkey (Çevik & Erguden 2005)., Published as part of Boury-Esnault, Nicole, Bellan, Gerard, Bellan-Santini, Denise, Boudouresque, Charles-Francois, Chevaldonné, Pierre, Dias, Alrick, Faget, Daniel, Harmelin, Jean-Georges, Harmelin-Vivien, Mireille, Lejeusne, Christophe, Perez, Thierry, Vacelet, Jean & Verlaque, Marc, 2023, The Station Marine d'Endoume, Marseille: 150 years of natural history, pp. 213-252 in Zootaxa 5249 (2) on page 235, DOI: 10.11646/zootaxa.5249.2.3, http://zenodo.org/record/7687250, {"references":["Marion, A. F. (1876) Dragages profonds au large de Marseille (Juillet-Octobre 1875). Note preliminaire. Revue des Sciences Naturelles, 4 (4), 469 - 477.","Marion, A. F. (1873) Recherches sur les animaux inferieurs du golfe de Marseille. Annales des Sciences Naturelles, 5 (17), 1 - 23.","Marion, A. F. (1885) Sur deux especes de Balanoglossus. Comptes Rendus de l'Institut, 101, 1289 - 1291.","Marion, A. F. (1886) Etudes zoologiques sur deux especes d'Enteropneustes (Balanoglossus hacksi & Balanoglossus talaboti). Archives de Zoologie Experimentale & Generale, 4, 305 - 326.","Spengel, J. W. (1893) Die Enteropneusten des Golfes von Neapel. In: Fauna und Flora des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. Herausgegeben von der Zoologischen Station zu Neapel, Berlin, 756 pp. https: // doi. org / 10.5962 / bhl. title. 11517","Cevik, C. & Erguden, D. (2005) First record for two species [Balanoglossus clavigerus delle Chiaje, 1829, Glandiceps talaboti (Marion, 1876)] of the Phylum Hemichordata on the coast of Turkey. Turkish Journal of Zoology, 29, 141 - 145."]}

Paracheilinus hemitaeniatus Randall & Harmelin-Vivien, 1977 (Fig. 10): the half-banded flasherwrasse of mesophotic habitats off Madagascar Paracheilinus hemitaeniatus is a rare brightly colored fish species sampled for the first time in 1972, at 45 m depth on the outer slope of the barrier-reef off Toliara, SW Madagascar. Created in 1961 as a branch of the SME, the marine station of Toliara (Tuléar) hosted many scientists who studied the coral reef communities and described a number of new species of marine organisms, contributing largely to improve our knowledge on coral reef diversity. The half-banded flasherwrasse is known only from the south-west of the Indian Ocean, Madagascar and Comoro Islands, where this elusive and beautiful species remains a ‘holy grail’ for photographers. It belongs to the Labridae, a highly diversified fish family, where sexual dimorphism is so pronounced that males, females and juveniles have often been described as separate species by early ichthyologists! Such color dimorphism is viewed as an adaptation to sexual selection and life in coral reefs, where it is more conspicuous than in other environments. Labrids play an important role in the trophic functioning of coral reefs due to their high abundance and diverse feeding behaviors, from small zooplanktivores, crustacean and mollusk feeders to large-sized piscivores. P. hemitaeniatus is a small (, Published as part of Boury-Esnault, Nicole, Bellan, Gerard, Bellan-Santini, Denise, Boudouresque, Charles-Francois, Chevaldonné, Pierre, Dias, Alrick, Faget, Daniel, Harmelin, Jean-Georges, Harmelin-Vivien, Mireille, Lejeusne, Christophe, Perez, Thierry, Vacelet, Jean & Verlaque, Marc, 2023, The Station Marine d'Endoume, Marseille: 150 years of natural history, pp. 213-252 in Zootaxa 5249 (2) on page 238, DOI: 10.11646/zootaxa.5249.2.3, http://zenodo.org/record/7687250, {"references":["Randall, J. E. & Harmelin-Vivien, M. (1977) A review of the labrid fishes of the genus Paracheilinus with description of two new species from the Western Indian Ocean. Bulletin du Museum National d'Histoire Naturelle, Paris, 436 (Zoologie, 306), 329 - 342."]}

Hemimysis speluncola Ledoyer, 1963 (Fig. 8): an unexpected model for Mediterranean climate change and evolutionary ecology Being among the first SME researchers to use SCUBA, in 1958 Laborel &Vacelet (1958) reported of surprisingly dense swarms of a small red mysid (Crustacea: Mysida) in the darkest reaches of a small underwater marine cave of the Bay of Marseille at Niolon. Closely resembling the well-known Atlantic species Hemimysis lamornae (Couch 1856), it was later recognized that such swarms were common in dark caves of the Marseille area, and that some of them were made of a new species, Hemimysis speluncola Ledoyer, 1963. For twenty years (1966–1986), the new species then became a model for behavioural ecology and ecophysiology, as it was found relatively easy to maintain in aquarium (e.g. Macquart-Moulin & Patriti 1966; Gaudy et al. 1980; Bourdillon & Castelbon 1983; Passelaigue & Bourdillon 1986). Among other things, H. speluncola displayed original horizontal circadian migrations in and out of caves to feed, in a way similar to the vertical migrations of deep-sea zooplankton. Suddenly, in the late 1990s, concomitant with the first marine heat wave and invertebrate mass mortalities recorded in the NW Mediterranean, Chevaldonné & Lejeusne (2003) provided evidence that, in most of its known geographic range, H. speluncola had vanished, gradually being replaced by the more thermophilic Hemimysis margalefi Alcaraz, Riera & Gili, 1986. This was the first documented Mediterranean warming-induced species shift and it triggered a series of studies on the Hemimysis species (many of which cryptic) present in the Atlantic-Mediterranean area, to investigate their molecular phylogeography and evolutionary history. Today, cave-dwelling Hemimysis, including the nowendangered H. speluncola, have become a model to study the effect of natural habitat fragmentation on population connectivity (Lejeusne & Chevaldonné 2006; Rastorgueff et al. 2014)., Published as part of Boury-Esnault, Nicole, Bellan, Gerard, Bellan-Santini, Denise, Boudouresque, Charles-Francois, Chevaldonné, Pierre, Dias, Alrick, Faget, Daniel, Harmelin, Jean-Georges, Harmelin-Vivien, Mireille, Lejeusne, Christophe, Perez, Thierry, Vacelet, Jean & Verlaque, Marc, 2023, The Station Marine d'Endoume, Marseille: 150 years of natural history, pp. 213-252 in Zootaxa 5249 (2) on page 235, DOI: 10.11646/zootaxa.5249.2.3, http://zenodo.org/record/7687250, {"references":["Ledoyer, M. (1963) Hemimysis speluncola n. sp. Mysidace nouvelle des grottes sous-marines obscures. Recueil des Travaux de la Station Marine d´Endoume, 30 (45), 77 - 81.","Laborel, J. & Vacelet, J. (1958) Etude des peuplements d'une grotte sous-marine du golfe de Marseille. Bulletin de l'Institut Oceanographique, 1120, 1 - 20.","Macquart-Moulin, C. & Patriti, G. (1966) Remarque sur la biologie d' Hemimysis speluncola, Ledoyer, mysidace sciaphile des grottes sous-marines obscures de la region de Marseille. Recueil des Travaux de la Station Marine d'Endoume, 56, 253 - 258.","Gaudy, R., Guerin, J. P. & Pagano, M. (1980) Ecophysiologie comparee des mysidaces Hemimysis speluncola Ledoyer (cavernicole) et Leptomysis lingvura G. O. Sars (non cavernicole). Respiration et excretion. Journal of Experimental Marine Biology and Ecology, 44, 29 - 46. https: // doi. org / 10.1016 / 0022 - 0981 (80) 90099 - 4","Bourdillon, A. & Castelbon, C. (1983) Influence des variations de temperature sur la geotaxie de deux especes de mysidaces. Journal of Experimental Marine Biology and Ecology, 71, 105 - 117. https: // doi. org / 10.1016 / 0022 - 0981 (93) 90067 - X","Passelaigue, F. & Bourdillon, A. (1986) Distribution and circadian migrations of the cavernicolous mysid Hemimysis speluncola Ledoyer. Stygologia, 2, 112 - 118.","Chevaldonne, P. & Lejeusne, C. (2003) Regional warming-induced species shift in north-west Mediterranean marine caves. Ecology Letters 6 (4), 371 - 379. https: // doi. org / 10.1046 / j. 1461 - 0248.2003.00439. x","Alcaraz, M., Riera, T. & Gili, J. M. (1986) Hemimysis margalefi sp. nov. (Mysidacea) from a submarine cave of Mallorca Island, western Mediterranean. Crustaceana, 50, 199 - 203. https: // doi. org / 10.1163 / 156854086 X 00214","Lejeusne, C. & Chevaldonne, P. (2006) Brooding crustaceans in a highly fragmented habitat: the genetic structure of Mediterranean marine cave-dwelling mysid populations. Molecular Ecology, 15, 4123 - 4140. https: // doi. org / 10.1111 / j. 1365 - 294 X. 2006.03101. x","Rastorgueff, P. - A., Chevaldonne, P., Arslan, D., Verna, C. & Lejeusne, C. (2014) Cryptic habitats and cryptic diversity: unexpected patterns of connectivity and phylogeographical breaks in a Mediterranean endemic marine cave mysid. Molecular Ecology, 23 (11), 2825 - 2843. https: // doi. org / 10.1111 / mec. 12776"]}

Peyssonnelia rosa-marina Boudouresque & Denizot, 1973 (Fig. 9): an unsuspected Mediterranean rose garden It is perhaps one of the most abundant seaweeds in the Mediterranean Sea, since it thrives from the infralittoral to the widely extended and widespread coastal detritic bottoms, in the circalittoral, where it is often dominant. It is also a particularly elegant macrophyte, resembling a calcified rosebud, hence its name, Peyssonnelia rosa-marina. Like many red algae, this seaweed can live in rather low irradiance down to ca. 100 m depth; it is an important producer of carbonate sediment and is furthermore an ecosystem engineer that takes a significant part in the construction of the coralligenous beds so characteristic of the Mediterranean. Yet, it has long been confused with its sister species, Peyssonnelia polymorpha, until the 1970s. It was then very surprising to realize that such an abundant, conspicuous, and well-characterized species, both by its morphology and anatomy, had been overlooked for so long., Published as part of Boury-Esnault, Nicole, Bellan, Gerard, Bellan-Santini, Denise, Boudouresque, Charles-Francois, Chevaldonné, Pierre, Dias, Alrick, Faget, Daniel, Harmelin, Jean-Georges, Harmelin-Vivien, Mireille, Lejeusne, Christophe, Perez, Thierry, Vacelet, Jean & Verlaque, Marc, 2023, The Station Marine d'Endoume, Marseille: 150 years of natural history, pp. 213-252 in Zootaxa 5249 (2) on page 236, DOI: 10.11646/zootaxa.5249.2.3, http://zenodo.org/record/7687250, {"references":["Boudouresque, C. F. & Denizot, M. (1973) Recherches sur le genre Peyssonnelia (Rhodophycees). I. Peyssonnelia rosa-marina sp. nov. et Peyssonnelia bornetii sp. nov. Giornale Botanico Italiano, 107 (1), 17 - 27. https: // doi. org / 10.1016 / 0022 - 0981 (93) 90067 - X"]}

The Rhachotropis species (Fig. 12) of Mid-Atlantic Ridge deep-sea hydrothermal vents: R. flamina, R. licornia, R. pilosa Bellan-Santini, 2006 SME taxonomists also have taken part in the major adventure started with the 1977 discovery of deep-sea chemosynthetic animal communities. In the vicinity of hydrothermal vents of the Mid-Atlantic Ridge, 3 new species of Rhachotropis (Crustacea: Amphipoda: Eusiridae) were collected by sediment traps at 1700–2750 m depth: Rhachotropis flamina Bellan-Santini, 2006, Rhachotropis licornia Bellan-Santini, 2006, and Rhachotropis pilosa Bellan-Santini, 2006. With 63 species (Horton et al. 2021) this genus is found in all oceans with a large bathymetric distribution (0–7160 m) (L̂rz et al. 2018). It is the most common amphipod genus in bathyal and abyssal zones. Morphologically, Rhachotropis have a delicate body with slender pereiopods, long antennae and sometimes dorsal processes. However, some of them display antennae bearing complex and puzzling structures called calceoli (present in R. pilosa and R. licornia) that are believed to be part of sensory organs. Cuplike receptacles, arranged serially on the antennae, would act as non-visual sensory organs, ensuring the perception of sound and vibration stimuli by the amphipods. These likely mechanoreceptors are found in several amphipod species (Hurley 1980, Lincoln & Hurley 1981, Bellan-Santini 2015); some could be involved in the detection of mates, others to detect preys. However, at hydrothermal vents, they could also be a good way to locate active fluid emissions.

Schizoretepora hassi Harmelin, Bitar & Zibrowius, 2007 (Fig. 13): a mysterious bryozoan from the East Schizoretepora hassi is a cheilostomate bryozoan belonging to the Phidoloporidae, i.e. the family of the beautiful reteporid Reteporella grimaldii (Jullien, 1903), the so-called “lace coral” well-known of Mediterranean divers and which has been the first bryozoan in the world to be illustrated in the literature, by Rondelet in 1554. Among the bryozoans described from the material collected during surveys of the Station Marine d’Endoume, S. hassi is not the most spectacular and its features are only but typical of the family. It lives in shaded rocky habitats of the Lebanese littoral zone and has not yet been found anywhere else. What is surprising is that a Mediterranean species living in the shallow coastal zone with large, conspicuous colonies, had not been described before. The question of its status, steno-endemic of the Levantine Basin or Erythraean immigrant introduced in the Mediterranean, remains open. It was dedicated to Dr Hans Hass, Austrian biologist who was both a famous diving icon and a pioneer in scientific diving and underwater photography. In 1948, he also had written a thesis on the Mediterranean reteporids, collected by diving., Published as part of Boury-Esnault, Nicole, Bellan, Gerard, Bellan-Santini, Denise, Boudouresque, Charles-Francois, Chevaldonné, Pierre, Dias, Alrick, Faget, Daniel, Harmelin, Jean-Georges, Harmelin-Vivien, Mireille, Lejeusne, Christophe, Perez, Thierry, Vacelet, Jean & Verlaque, Marc, 2023, The Station Marine d'Endoume, Marseille: 150 years of natural history, pp. 213-252 in Zootaxa 5249 (2) on page 240, DOI: 10.11646/zootaxa.5249.2.3, http://zenodo.org/record/7687250, {"references":["Harmelin, J. - G., Bitar, G. & Zibrowius, H. (2007) Schizoretepora hassi sp. nov. (Bryozoa: Phidoloporidae) from Lebanon (Eastern Mediterranean) and reappraisal of Schizotheca serratimargo (Hincks, 1886). Cahiers de Biologie Marine, 48 (2), 179 - 186.","Jullien, J. & Calvet, L. (1903) Bryozoaires provenant des campagnes de l'Hirondelle (1886 - 1888). Resultats des campagnes scientifiques accomplies sur son yacht par Albert Ier, prince souverain de Monaco, 23, 1 - 188."]}

Boury-Esnault, Nicole, Bellan, Gerard, Bellan-Santini, Denise, Boudouresque, Charles-Francois, Chevaldonné, Pierre, Dias, Alrick, Faget, Daniel, Harmelin, Jean-Georges, Harmelin-Vivien, Mireille, Lejeusne, Christophe, Perez, Thierry, Vacelet, Jean, Verlaque, Marc (2023): The Station Marine d'Endoume, Marseille: 150 years of natural history. Zootaxa 5249 (2): 213-252, DOI: 10.11646/zootaxa.5249.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5249.2.3

Genus Aspiculophora Ruiz et al. 2017 Diagnosis: Plakinidae without spicules, well-developed mesohyl with a collagen layer between ecto- and choanosome, with or without sub-ectosomal cavities. Leuconoid aquiferous system and aphodal choanocyte chambers. High abundance of prokaryotic symbionts.

Aspiculortis garifuna sp. nov. Etymology: The genus name Aspiculortis refers to the absence of skeleton and to the genetic proximity of Plakortis. The species name garifuna honors the ethnical and cultural diversity of the Garifuna people, descendants of the first Caribs, Arawak Amerindians and the African people who inhabited the Lesser Antilles. Diagnosis: Thick crust (about 5 mm thick) with irregular form. No spicules, nor fibrous skeleton. The surface is covered by ostia with a series of translucent canals ending in prominent oscula of about 2 mm diameter. One type of vacuolar cell abounds in the ectosome and is also present in the mesohyl. Examined material: Holotype: Muséum National d’Histoire Naturelle de Paris, France MNHN DJV202 Martinique, “Grotte Fer à Cheval” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark section of the cave, date 25/03/2012, sample code: 120325 MT4 b-TP6, collector: T. Pérez. Genbank accession number: MK 949483 Paratype: Muséum National d’Histoire Naturelle de Paris, France MNHN DJV203 Guadeloupe, “Grotte aux Barracudas” (16°27.301’ N, 61°32.253’ W), 19 m depth, on a vertical wall in the semi-dark part of the cave, date 30/05/2015, sample code: 150530GU5-CR6, collector: C. Ruiz. Genbank accession number: MK 949485 Other material examined: Bequia, The Grenadines “Full Moon Cave” (12°59.525’ N, 61°16.731’ W), 10-12 m depth, beneath an overhang, date 19/05/2015, sample code: 150519LG1-CR14, collector: C. Ruiz. Genbank accession number: MK 949484 Martinique, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark section of the cave, date 11/06/2011, sample code: 110613 MT4 -TP3, collector: T. Pérez. Genbank accession number: MK 949482 Martinique, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark part of the cave, date 11/06/2011, sample code: 110613 MT4 -TP8, collector: T. Pérez. Martinique, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark part of the cave, date 15/05/2015, sample code: 150515 MT4 -CR1, collector: C. Ruiz. Martinique, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark part of the cave, date 16/05/2015, sample code: 160515 MT4 -CR9, collector: C. Ruiz. Comparative material examined: Aspiculophora madinina Ruiz, Muricy, Lage, Domingos, Chenesseau & Pérez 2017, Martinique, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark section of the cave, date 16/05/2015, sample code: 160515 MT4 -CR10, collector: C. Ruiz. Plakina nathaliae (Ereskovsky et al. 2014), Saint Martin, “Basses Espagnoles” (18°07.821’N, 63°00.270’W), 15 m depth, beneath an overhang, date 27/05/2015, sample code: 270515SN5-TP01, collector: T. Pérez. Oscarella zoranja Pérez & Ruiz, 2018, Martinique, Rocher du Diamant, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark section of the cave, date 16/05/2015, sample code: 150516 MT4 -CR05, collector: C. Ruiz. Oscarella filipoi Pérez & Ruiz, 2018, Saint Lucie, “Anse Chastenet reef” (13°51.848’ N, 61°04.729’ W), 15 m depth, beneath an overhang, date 22/05/2015, sample code: 150522SL1-CR05, collector: C. Ruiz. Description: External morphology: Aspiculortis garifuna sp. nov. has an encrusting irregular form and a brown color in vivo and after fixation in ethanol. The largest specimen recorded measured 10 cm in diameter. This sponge is quite fragile. The smooth surface is pseudo-criblate, that it is to say covered by numerous ostia diverging soon under the epidermal surface in various inhalant canals. The sponge surface also presents a series of larger translucent exhalant canals ending in prominent oscula of about 2 mm in diameter. This dense network can appear contracted in some specimens (Figure 2 A-B). Internal Anatomy: No spicule nor fibrous skeleton. The ectosome is 40-60 µm thick (Figure 2 C-D). The aquiferous system is leuconoid. Inhalant canals are 10-15 µm wide, running perpendicular to the surface. Choanocyte chambers (15-33 µm in diameter) are diplodal, spherical to ovoid (Figure 2E). The proportion between mesohyl and choanocyte chambers is greater than 1. Cytology: Choanocytes are cylindrical, 5 µm wide and 7 µm high. Their nucleus is spherical (2 µm diameter) in apical position, their cytoplasm usually contains osmiophilic inclusions and vacuoles of about 2-3 µm in diameter that often harbor phagocytized bacteria (Figure 3A). The exo- and endopinacocytes are flagellated and flattened (12- 19 µm long; 3-4 µm wide) with several vacuoles and osmiophilic inclusions. The external surfaces of the exo- and endopinacocytes are covered with a double-layer of 0.5 µm thick glycocalyx (Figure 3B). One type of vacuolar cell is found in abundance in the ectosome, and to a lesser extent in the mesohyl. This irregular shaped-cell, 10 x 20 µm in dimension, harbors 2-4 translucent vacuoles which are 3 to 8 µm in diameter (Figure 3C) and which often contain dense or loose heterogeneous material (Figure 3D). No archaeocyte was observed. There is a high abundance of prokaryotic symbionts in the mesohyl, with at least five dominant morphotypes randomly distributed throughout the mesohyl (Figure 3E). The first morphotype is an ovoid cell 2 - 4 µm long, 2.5 – 3 µm wide with a clear cytoplasm. The second morphotype has the same ovoid shape and size but has a denser cytoplasm. The third morphotype is an irregular cell shape which is 2 – 4 µm long and about 1 – 2.5 µm wide. The fourth morphotype is bean-shaped, 2.5 - 3 µm long and about 0.5 wide. The fifth morphotype is circular with a diameter of about 0.5 µm. Ecology: This new sponge has been collected in the Caribbean islands (Lesser Antilles) of Guadeloupe, Martinique and Bequia. In all sites, this sponge inhabits vertical walls and ceilings of dark marine caves, located at depths between 10 and 25 m, in syntopy with several other Homoscleromorpha species. No sign of predation was observed. Serpulidae worms live in close association and are often observed living among the new sponge species (Figure 2B). Taxonomic remarks: Aspiculortis garifuna gen. nov. sp. nov. has an encrusting form, as do most of the cave-dwelling Homoscleromorpha. It clearly belongs to a well-supported clade gathering Plakortis species, but its pseudo-criblate surface is unique, and thus has never been observed in Plakortis. The lack of cytological description of Caribbean Plakortis did not allow any comparison with the cells content of the new sponge. The absence of skeleton and this original pseudo-criblate surface justify the creation of a new genus. The new sponge also clearly differs from the other skeleton-less Plakinidae by its external morphology and internal organization, particularly the proportion between mesohyl and choanocyte chambers and the low abundance of symbiotic microorganisms in the thinly encrusting Plakina nathaliae, and the thick collagen layer found in the ectosome of the massive Aspiculophora madinina, as well as its aphodal choanocyte chambers.

Oscarella minka sp. nov. Etymology: From the Quechuan mink’a (minga), this species name honors the pre-Columbian tradition of communal work for social purposes. Diagnosis: Thin crust less than 3 mm thick. Smooth surface. Ectosome 25 to 50 µm thick, well-developed mesohyl. Two types of vacuolar cells, leuconoid aquiferous system with diplodal choanocyte chambers. High abundance of prokaryotic symbionts in the mesohyl. Examined material: Holotype: Muséum National d’Histoire Naturelle de Paris, France MNHN DJV206 La Martinique, “Grotte Fer à Cheval” (14°27.882’ N, 61°01.162 W), 19 m depth, on a vertical wall in the semi-dark part of the cave, date 25/03/2012, sample code: 120325 MT4 b-TP8, collector: T. Pérez. Genbank accession number: MK 949481 Paratype: Muséum National d’Histoire Naturelle de Paris, France MNHN DJV207 Bequia, The Grenadines, “Full Moon Cave” (12°59.525’ N, 61°16.731’ W), 10-12 m depth, beneath an overhang, date 19/05/2015, sample code: 150519LG1-CR9, collector: C. Ruiz. Genbank accession number: MK 949480 Other material examined: Martinique, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark part of the cave, date 13/06/2011, sample code: 110613 MT4 -TP4, collector: T. Pérez. GenBank accession number: MK 949478 Martinique, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark part of the cave, date 15/05/2015, sample code: 150515 MT4 - CR2, collector: C. Ruiz. Genbank accession number: MK 949479 Martinique, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark part of the cave, date 13/06/2011, sample code: 110613 MT4 -TP6, collector: T. Pérez. Martinique, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark part of the cave, date 16/05/2015, sample code: 150516 MT4 -CR11, collector: C. Ruiz. Martinique, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark part of the cave, date 16/05/2015, sample code: 150516 MT4 -CR16, collector: C. Ruiz. Martinique, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark part of the cave, date 16/05/2015, sample code: 150516 MT4 -CR17, collector: C. Ruiz. Bequia, The Grenadines, “Full Moon Cave” (12°59.525’ N, 61°16.731’ W), 10-12 m depth, beneath an overhang, date 28/04/2015, sample code: 150428LG1-AE55, collector: A. Ereskovsky. Bequia, The Grenadines, “Full Moon Cave” (12°59.525’ N, 61°16.731’ W), 10-12 m depth, beneath an overhang, date 19/05/2015, sample code: 150519LG1-TP5, collector: T. Pérez. Guadeloupe, “Grotte Cathédrale” (16°27.740’ N, 61°31.837’ W), 18 m depth, on a vertical wall in the dark part of the cave, date 29/05/2015, sample code: 150529GU3-TP2, collector: T. Pérez. Guadeloupe, “Grotte aux Barracudas” (16°27.301’ N, 61°32.253’ W), 19 m depth, beneath an overhang, date 30/05/2015, sample code: 150530GU5-CR4, collector: C. Ruiz. Guadeloupe, “Grotte aux Barracudas” (16°27.301’ N, 61°32.253’ W), 19 m depth, beneath an overhang, date 30/05/2015, sample code: 150530GU5-CR10, collector: C. Ruiz. Comparative material examined: Oscarella filipoi, Martinique, Anse d’Arlet, Grande Anse, Pointe Burgos - Grotte Couleur (14°2.787’N, 61°5.351’W), 10 m depth, on a vertical wall in semi-dark conditions, date 11/06/2011, sample code: 110611 MT3 -TP05, collector: T. Pérez. Oscarella zoranja, “ Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark part of the cave, date 13/06/2011, sample code: 110613 MT4 -TP1, collector: T. Pérez

Genus Oscarella Vosmaer, 1884 Diagnosis: Homosclerophorida without skeleton, with a variable development of the ectosome with a collagen layer between ecto- and choanosome. The aquiferous system has a sylleibid-like or leuconoid organization, with spherical to ovoid eurypilous or diplodal choanocyte chambers arranged around large exhalants canals (Muricy & Díaz 2002). Mitochondrial genomes that have been sequenced so far encode a gene absent in other animal mitochondrial genomes: tatC (Ereskovsky et al. 2017).

Aspiculophora papillata sp. nov. Etymology: the species name refers to the papillate surface of this Plakinidae, papilla = nipple in Latin. Diagnosis: encrusting Aspiculophora with papillate surface. Collagen layer ( Examined material: Holotype: Muséum National d’Histoire Naturelle de Paris, France MNHN DJV204 Bequia, The Grenadines, “Full Moon Cave” (12°59.525’ N, 61°16.731’ W), 10-12 m depth, beneath an overhang, date 19/05/2015, sample code: 150519LG1-CR13, collector: C. Ruiz. Genbank accession number: MK 949486 Paratype: Muséum National d’Histoire Naturelle de Paris, France MNHN DJV205 Guadeloupe, “Grotte Cathédrale” (16°27.740’ N, 61°31.837’ W), 18 m depth, on a vertical wall in the dark part of the cave, date 29/05/2015, sample code: 150529GU3-CR1, collector: C. Ruiz. Other material examined: Martinique, “Grotte Zeb” (14°27.832’N, 61°01.065’W), 19 m depth, on a vertical wall in the semi-dark part of the cave, dates 15 and 16/05/2015, sample codes: 150515 MT4 -CR3, 150515 MT4 - CR6, 160515 MT4 -CR14, collector: C. Ruiz. Bequia, The Grenadines “Full Moon Cave” (12°59.525’ N, 61°16.731’ W), 10-12 m depth, beneath an overhang, date 19/05/2015, sample codes: 150519LG1-CR10, 150519LG1-CR13, 150519LG1-TP11, collectors: C. Ruiz & T. Pérez Comparative material examined: Aspiculophora madinina MNHN DJV 180, Rocher du Diamant “Grotte Zeb”, Martinique (14°26.5´N, 61°03.083´W), 12 m depth, date 13/06/2011, sample code: 110613 MT4 -TP11 collector: T. Pérez, Aspiculophora madinina, “ Grotte Amédien”, Guadeloupe (16°30.033’ N, 061°28.774’ W), 12 m depth, date 30/05/2015, sample code: 150530-GU6-TP07, collector: T. Pérez. Plakina nathaliae MNHN DJV 179, Rocher du Diamant “Grotte Zeb”, La Martinique (14°26.5´N, 61°03.083´W), 17 m depth, date 13/06/2011, sample code: 110613 MT4 -TP2, collector: T. Pérez. Description: External morphology: Aspiculophora papillata sp. nov. is a thinly encrusting irregular sponge which is quite hard to collect because of its fragile consistency. Collected specimens measured up to 10 cm wide and 1 mm thick. The sponge has a papillate surface and its color varies from yellow to light brown in vivo, whereas it is light brown in ethanol. Papillae are cylindrical, up to 3 mm high and about 1 mm in diameter. The top of the papillae is often larger with an umbrella-like form of 2-3 mm in diameter. Oscula of about 1 mm in diameter are sometimes visible in the top of the papillae (Figure 4A, B). Internal Anatomy: No spicule or fibrous skeleton. A collagen lager Cytology: Choanocytes are cylindrical, 5 µm wide and 8 µm high. Their nuclei are spherical, about 2 µm in diameter and are located in apical position. Their cytoplasm usually contains osmiophilic inclusions of about 0.1 µm in diameter in basal position (Figure 5A, B). Apopylar cells have a trapezoid shape (Figure 5A). Exo- and endopinacocytes are flat and flagellated (5-15 µm long; 1-2 µm wide) with a nucleus of about 2.5 µm in diameter (Figure 5C). One type of abundant vacuolar cell was found randomly distributed in the mesohyl. This cell has an ovoid to spherical shape, is 12-20 µm in diameter, and generally harbors one to five vacuoles occupying most of the volume of the cytoplasm. Some heterogeneous to filamentous materials can be seen inside the vacuoles, and microorganisms can be found in their cytoplasm (see arrow in Figure 5C). No archaeocyte was observed. The new species can be considered as an HMA sponge. At least four prokaryotic morphotypes seem to be dominant in the mesohyl (Figure 5D). The first morphotype is peanut-shaped, 2.5 µm long 0.5 µm wide, with a dense cytoplasm and a double membrane. The second morphotype is of similar size, is cylindrical in shape and has a translucent external membrane. The third morphotype has an irregular shape and is 2-4 µm long and 1 µm wide. The fourth morphotype is bean-shaped with a dense membrane and translucent cytoplasm. Ecology: The new sponge species was found in the Caribbean islands of Guadeloupe, Martinique and Bequia (Lesser Antilles). It lives in sympatry (and sometimes in syntopy) with A. madinina, on walls and ceilings of dark marine caves, where it is always found between 10 and 20 m depth. No sign of predation was observed, but the new species usually lives in close association with other sponges and invertebrates such as Serpulidae and Sabellidae worms (Figure 4A). Taxonomic remarks: Aspiculophora papillata sp. nov. is a skeleton-less Plakinidae like A. madinina. The new species mainly differs by its external morphology, the papillate surface being a trait observed for the first time among Homoscleromorpha. In contrast with A madinina, no dark exudate was recorded in contact with alcohol for A. papillata. The collagen layer between the exopinacoderm and the ectosome region in A. papillata sp. nov. is very thin in comparison with A. madinina. Another difference between these species is the presence of sub-ectosomal cavities in A. papillata sp. nov. that do not exist in A. madinina. Both species share the leuconoid aquiferous system with aphodal choanocyte chambers, only one type of vacuolar cell which is mostly concentrated in the ectosome and similar microbial compositions.

Aspiculortis gen. nov. Diagnosis: Plakinidae without spicules. Smooth pseudo-criblate surface covered by numerous ostia diverging soon under the epidermal surface in various inhalant canals. A network of superficial translucent much larger exhalant canals leading to prominent oscula. Well-developed mesohyl with several layers of vacuolar cells in the ectosome. No sub-ectosomal cavities. Leuconoid aquiferous system with diplodal choanocyte chambers. High abundance of prokaryotic symbionts in the mesohyl.