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In this report, we analyse the benthic hydroids collected on the Vema and Valdivia seamounts during a survey conducted in 2015 in the SEAFO Convention Area, focused on mapping and analysing the occurrence and abundance of benthopelagic fish and vulnerable marine ecosystem (VMEs) indicators on selected Southeast Atlantic seamounts. A total of 27 hydroid species were identified, of which 22 belong to Leptothecata and only five to Anthoathecata. Monostaechoides gen. nov. was erected within the family Halopterididae to accommodate Plumularia providentiae Jarvis, 1922, and a new species, Monotheca bergstadi sp. nov., is also described. Campanularia africana is recorded for the first time from the Atlantic Ocean, and the Northeast Atlantic species Amphinema biscayana, Stegopoma giganteum and Clytia gigantea are also recorded from the South Atlantic. Three species were identified to the genus level only, due to the absence of their gonosomes. None of the reported species are endemic, and the hydroid community is clearly dominated by species with a wide geographical distribution in the three major oceans. Only Monotheca bergstadi sp. nov. presently has its distribution restricted to the Vema Seamount and the South African coast.

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Multidisciplinary surveys conducted on-board RV Dr Fridtjof Nansen in the northwest Africa region during November 2011 and June 2012 allowed exploration for the first time of seasonal variations in diversity and structure of decapod communities inhabiting the changing hydrological scenario of the shelf and upper slope off Mauritania (20–750 m depth). Decapods were gathered with a commercial bottom trawl at 95 stations, 39 of which were visited in both surveys. In addition, 249 oceanographic profiles and 95 sediment samples were collected. Shelf and slope assemblages, respectively characterized by the dominance of benthic (63 species) and swimming decapods (37 species), were segregated at 100–150 m depth, coinciding with the shelf-break and the hydrological frontier separating the surface mixed layer from the deeper water masses. The assemblages showed a certain stability in their structure but significant seasonal differences in their composition. Abundance and biomass, and in particular specific richness, were strongly correlated with depth in the case of swimming decapods, which were clearly dominant during the warm season, especially in the southern zone. The most significant seasonal variations were mainly due to the Penaeidae family and its associated species, Parapenaeus longirostris (Lucas, 1846). The latitudinal decreasing trend in upwelling permanence and productivity toward the south, responding to the strength and displacement of trade winds along the Mauritanian coast, which are observable at the surface and sea-bottom, were the main reason explaining the seasonal variations observed in the distribution patterns and assemblages structure of Mauritania decapods.

Brittle stars constitute a common and highly diverse component of epibenthic communities, and they can form dense aggregations on the seabed of all oceans worldwide. Nevertheless, there is limited information on the diversity and distribution of these echinoderms in Northwest Africa. Between 2004 and 2012, 10 multidisciplinary Spanish and Norwegian surveys were conducted off Northwest Africa—between the Strait of Gibraltar and Sierra Leone border—from a depth of 19 to 1888 m. During these surveys, we sampled 1298 stations, and about one million individuals and 124 kg of brittle stars were collected from 502 stations. Forty-two species belonging to eight ophiuroid families considered as suspension feeders were collected from 296 stations and represented 93.4% of the total abundance and 75% of the total ophiuroid-specific richness. Ophiacanthidae was the richest and most abundant family, with 15 species and estimated densities up to almost 4 × 10⁵ by 0.1 square kilometre. The other families found abundantly were Amphiuridae, Ophiotrichidae and Ophiactidae, represented by six, five and four species each, respectively. Ophiotrichidae, Ophiacanthidae and Gorgonocephalidae presented the largest biomass among the suspension-feeder families (35.5%, 33.8% and 28.2%, respectively), and Ophiotrichidae is a well-represented family along the Northwest African coast. The most remarkable concentrations and highest diversity values were detected on the upper slope (depth, 400–600 m) off Western Sahara. Between 24°N and 22°N, we collected huge concentrations of Ophiacantha abyssicola and up to six species per station. This area has permanent and intense upwelling conditions and is out of the minimum oxygen zone. We also noted significant densities and richness at Cape Ghir and Cape Blanc, where important filaments of nutrient-rich waters occur, and at Guinea-Bissau, which is affected by nutrient river inputs. The multivariate analysis clearly separated the brittle stars into two main assemblages, across latitudinal and bathymetrical gradients: northern latitude (Morocco and Northern Sahara) from the area south of 24°N and from the continental shelf–upper slope to the deep slope., Sí

Most of the Southeast Atlantic Ocean is abyssal, and global bathymetries suggest that only ~3.2% of the areas beyond national jurisdiction (ABNJ; also known as the high seas, as defined in the United Nations Convention on the Law of the Sea [UNCLOS]) are shallower than 2 500 m. This study mapped bathymetry and characterised substrates in selected seamount summit areas, including several that have been or may become fishing areas. The southernmost location, the Schmitt-Ott Seamount, has exposed volcanic bedrock with surrounding flats covered by thin biogenic sediments and/or coral rubble that appears ancient. At Wüst, Vema, Valdivia and Ewing seamounts the basaltic base appears to be overlain by coral caps and other coral substrates (sheets, rubble). Adjacent summit plains have biogenic sediments of varying thickness. Vema has a flat, roughly circular summit, Sí

Four multidisciplinary oceanographic surveys were conducted in November and December from 2007 to 2010, along the Mauritanian coast (NW Africa). A total of 10,514 brachyuran crabs belonging to 33 species were captured in 316 hauls at depths between 79 and 1867 m. The most specious family was Inachidae represented by nine species; the remaining 24 species belonged to 16 other brachyuran families. Monodaeus cristulatus is reported for the first time since its original description. Seven other species, Ethusa rugulosa, Pseudomyra mbizi, Inachus grallator, Macropodia gilsoni, Macropodia hesperiae, Solenolambrus noordendei and Spinolambrus notialis extend their range of distribution northwards and, together with Goneplax barnardi, are reported here for the first time in Mauritanian waters. New data about depth ranges are reported for Acanthocarpus brevispinis, Ethusa rugulosa, Inachus aguiarii, Inachus grallator, Inachus nanus, Macropodia macrocheles, Solenolambrus noordendei, Spinolambrus notialis, Liocarcinus corrugatus and Monodaeus cristulatus. New data relating to the spawning period for most of the species are also included, as are some biogeographic and bathymetric considerations about brachyurans studied in the area., Sí

This paper deals with species of the deep-water marine lobsters and lithodids collected on soft and rocky bottoms during the four Spanish Maurit surveys from 2007 to 2010 in Mauritanian waters, at depths between 80 and 2000 m. The collection is represented by eight species included in the infraorders Astacidea, Achelata, and Polychelida, and by five species of the family Lithodidae. The true lobster Nephropsis atlantica, the blind lobster Stereomastis nana, and the king crab Paralomis cristulata are reported for the first time in Mauritanian waters, while the presence of the slipper lobster Scyllarus subarctus is confirmed in the area. New data on the bathymetric distribution of P. cristulata and Lithodes ferox are also included, Sí

Ophiuroidea constitutes the largest class of the phylum Echinodermata. It includes families with suspension-feeder behaviour that can be found in dense aggregations in all oceans worldwide. Ophiothrix maculata was known as a rare suspension-feeder brittle star, with only four records in the Eastern Central Atlantic dating from almost 100 years ago. During the ten multidisciplinary Spanish and Norwegian surveys carried out from 2004 to 2012 off Northwest Africa, between the Gibraltar Strait and the Sierra Leone border from 19 to 1888 m depth, we sampled 1298 stations. We gathered about one million individuals and 124 kg of brittle stars at 501 of the stations. Eight hundred and thirty-two specimens of Ophiothrix maculata were collected at six localities on the continental slope off Mauritania, Western Sahara and Guinea Bissau, at depths between 155 and 594 m. The Guinea Bissau samples represent the southernmost current record for the species. Even though Ophiothrix maculata has been previously recorded only in isolation, we discovered dense concentrations on the Mauritanian slope on the Wolof's Seamount (580 individuals) and off the Western Sahara, in a Lophelia pertusa reef (202 individuals). In this paper, we describe these findings and discuss the association of this species to hard-bottom habitats and high primary production areas, outside of the oxygen minimum zone (OMZ). We also analyse what other factors may explain the patchy distribution of O. maculata on the Northwest African slope, Sí

Echinoderms are the most important taxa of megabenthic invertebrates on the Mauritanian deep-sea floor, both in density and biomass . The phylum is represented by approximately 82 species, Ophiuroidea and Asteroidea being the most diverse classes (25 and 23 species, respectively), followed by Holothuroidea and Echinoidea (19 and 12 species, respectively). Crinoidea is poorly represented by only three species. Holothuroidea (sea cucumbers) are, undoubtedly, the main component of deep Mauritanian echinoderms, accounting for 85.5% of numerical abundance and 96.0% of biomass. Species belonging to Echinothurioida are dominant among the sea urchins . The most common echinoderm species are Phormosoma placenta , Enypniastes eximia , Psilaster cassiope , Benthothuria funebris, Ophiernus alepidotus , Pseudarchaster gracilis gracilis and Ophiura flagellata . The Mauritanian echinoderm fauna are mostly composed of species with Atlantic distribution (80.5%) and a smaller group of wide distribution species (19.5%). Only three species, two sea stars and one ophiuroid, could be considered as endemic to Macaronesian African waters : Hymenaster roseus , Dyptaster mollis and Ophiothrix maculata . The bathymetric distribution of species and multivariate analysis clearly identify two main assemblages : the first groups the stations located on the deep shelf and upper slope (

During the four Maurit surveys carried out annually from 2007 to 2010, 342 trawl stations were sampled off the Mauritanian coast between 80 and 2000-m depth. Hydroids were captured at 174 stations, totalling 6169 colonies belonging to 63 species and 19 families . Most of the species were Leptothecata and only seven belonged to Anthoathecata . Thirty-two of the 63 species are new records for Mauritania. Plumulariidae showed the highest species richness (8 species), followed by Sertulariidae and Campanulariidae (7 species), Lafoeidae , Haleciidae and Aglopheniidae (6 species). The most abundant were Sertulariidae , followed by Aglaopheniidae, Plumulariidae, Campanulariidae, Halopterididae and Haleciidae . The ability of hydroids to colonize Mauritanian soft bottom s was driven by hydrorhizal modifications for anchoring the colony to the sediment and by epizoism on 11 invertebrate groups. Families whose species developed both strategies and those which were typically epibionts on hydroids were the most frequent and abundant. Most of the species were eurybathic (58 species), with four species recorded only in the coastal realm, 18 exclusively in the deep benthic realm and 41 in both realms. Therefore, overall hydroid diversity was highest in the deep benthic realm . Biogeographical components included two main groups: species with a wide distribution (59%) and species of Atlantic distribution (41%); our results also emphasize the similarity between the Mauritanian hydroid fauna and the Atlantic-Mediterranean region. Only one species, Hydractinia multitentaculata (Millard 1975), has West African distribution. No endemic species were reported.

The waters surrounding the Islamic Republic of Mauritania, located in the Northwest African region, harbour one of the four major upwelling systems and productive areas of the world’s oceans. Along 754 km of the desert coastline, the permanent upwelling phenomena and seasonal shifting of the oceanographic front strongly influence the water mass structures, climate and species distribution in the Mauritanian EEZ. Despite oceanographic and faunistic interest and the threats of demersal deep˗sea fisheries and oil exploration, for the past few decades, marine research in Mauritania was performed to obtain information on the Banc d’Arguin and other coastal ecosystems; only recently, research is being focused on the study of slope habitats. Between 2007 and 2010, the Spanish Oceanographic Institute launched a partnership program with the Mauritanian Institute for Oceanographic Research and Fisheries and the University of Vigo (Spain) to study the resources and ecosystems in Mauritanian deep waters. Four multidisciplinary expeditions were conducted using the Spanish R/V Vizconde de Eza , and geomorphological prospection and oceanographic and biological sampling were performed. Special efforts were made to characterize the Banc d’Arguin canyon systems, the giant coral carbonate mounds barrier and a newly discovered seamount. In this monograph, we tried to compile, in one volume, the main findings of the Maurit surveys and provide a detailed description of the bathymetry, geomorphology and oceanography, and biodiversity and structure of demersal fishes and benthic communities that inhabit the soft˗ and hard˗bottom habitats of the Mauritanian slope.

This chapter describes the main features of the giant mounds structure running parallel to the shelf break along the Mauritanian slope between the Senegalese border and Cape Timiris. At over 580 km long, it is the world’s largest identified cold-water coral mounds barrier and, in our opinion, conforms to a single province, the Mauritanian Province . The Maurit series of Spanish-Mauritanian oceanographic surveys collected multibeam echosounder data, performed 16 conductivity-temperature-depth (CTD) profiles and 13 rock dredge samplings , which led to the mapping of the reef complex , oceanographic characterization of water masses and faunistic studies. The reef framework is mostly composed of dead coral, mainly Lophelia pertusa , with a minor fraction of Madrepora oculata . Associated fauna mainly consists of Acesta excavata and other bivalve and prosobranch molluscs, soaked in abundant, fine compacted mud . At least 150 macrobenthic species of 27 high-range taxa inhabit this reef. The coral surface is either almost devoid of sessile fauna or poorly colonized by small encrusting epifaunal species. We only found fragments of living L. pertusa in the four southernmost stations. The multivariate analysis clearly groups some areas where corals and other suspension-feeders exhibit the highest diversity. Despite their small size, the 17 taxa of suspension-feeders represent 75% of abundance and biomass . Surprisingly, despite the unfavourable history of climatic change episodes, current environmental conditions, deterioration and overall faunistic poverty of the mounds, Lophelia specimens still survive in some areas , sheltering communities of apparently similar structure to those on well-developed cold-water coral reefs in Northern Atlantic latitudes.

A total of 16,036 cephalopods belonging to 48 species were caught on the Mauritanian continental shelf and slope, between 80 and 2000 m depth, in November–December of 2007–2010 during the joint Spanish-Mauritanian surveys . Samples were collected using a commercial bottom trawl . Ommastrephidae was the most abundant family (71.1%) in number and weight. Neritic and benthic species of Loliginidae , Octopodidae and Sepiidae represented 7.3, 6.2 and 5.3% of the total number, respectively. A checklist of 132 Mauritanian species is shown. The geographical and bathymetric distribution of species sampled in the area is discussed. Eight species, Mastigoteuthis flammea , Cycloteuthis akimushkin i, Muusoctopus fuscus , M. janarii, Bathypolypus arctic us, B. biardii, B. valdiviae and Graneledone verrucosa are recorded for the first time in Mauritanian waters. This is the first time that M. fuscus is cited in Atlantic waters and that B. valdiviae is observed in the northern hemisphere. Two main cephalopods assemblages , Shelf and Slope, were identified in the zone. Both are largely dominated by ommastrephid species which could constitute an important resource not currently exploited in the area. This work provides the first data on benthic octopods species that inhabit the deep waters of Northwest Africa.

The composition and structure of megabenthic communities of bathyal soft-bottoms off Mauritania were analysed, based on data and material collected at 291 trawling stations accomplished during the four Maurit surveys carried out in November–December of 2007–2010. A total of 551,281 specimens with a corresponding wet weight of 2.2 tons were recorded and more than 700 species of benthic invertebrates belonging to 37 high-range taxa were identified. The best-represented group in terms of specific richness was Decapoda with 118 species, followed by Polychaeta , Porifera and Hydrozoa (74–63 species). In terms of biomass , Holothuroidea clearly dominates the megabenthic communities representing the 83% of the total, while in numerical abundance the dominance was shared by Decapoda (39%) and Holothuroidea (34%). The distribution of megabenthos showed latitudinal patterns along the Mauritanian coast, with a decreasing trend southwards for specific richness , Shannon and Pielou indexes , but with a reverse figure for abundance and biomass that reached their maximum values in the southern area. The bathymetric distribution showed a decreasing trend with depth only for Shannon and Pielou but species richness, abundance and biomass reached their highest values in deep waters. Multivariate analysis identified four megabenthic assemblages structured by depth. The giant coral mounds barrier together with the minimum oxygen values obtained at the same depths seems to perform the main faunistic discontinuity separating the shelf and upper slope assemblages from those located at middle and lower slope .

One of the objectives of the Maurit˗1011 survey was the environmental and faunistic characterization of a small seamount of 200 m in height, discovered during the Maurit˗0911 expedition, on the upper continental slope south of Nouakchott, at 17°08′ 50″N and 16°46′ 38.1″W. It is an isolated conical structure with small ridges, almost parallel to the edge of the continental shelf and not connected to nearby coral mounds barrier. The geomorphology of this submarine elevation, as well as the debris from a hydrothermal vents or cold seeps discovered in the rock dredge samples suggests a diapiric association because no hydrothermal benthic fauna was found. The summit of the seamount was covered with sponges belonging mainly to the family Geodiidae, and ophiuroids belonging to the suspension-feeders family Ophiotrichidae. We also found accompanying fauna comprising about 50 species, mainly consisting of molluscs and decapods. Despite its small size but taking into account the richness of the suspension-feeders community living on it, this Wolof’s Seamount (so called to honour the artisanal fishermen who first discovered it) could be promoted as a marine protected area in the Mauritanian continental margin.

Quantitative data were collected with a 3.5 m beam-trawl gear at 25 stations along five latitudinal transects , covering five bathymetric strata from 100 to 2000 m depth. More than 500 species belonging to 35 epibenthic high-range taxa are present in Mauritanian deep-sea bottom s. Pisces , Decapoda and Polychaeta , represented by 111, 80 and 56 species, respectively, constituted the richest groups, being the first two collected at all stations. Decapoda were dominant in abundance (55.8% of the total), although in biomass they shared their dominance with Actinopterygii and Holothuroidea (29.4, and 26.0%, respectively). Although suspension feeders were represented by 131 species (25.7%), they only accounted for 9% of the abundance and 1% of biomass (small-sized species). Low diversity indices varied widely between localities but showed no latitudinal pattern . Richness and densities decreased with increasing depth, a strongly marked trend in the case of densities, which peaked on the deep shelf and upper slope (150–300 m), while the biomass remain standing showing only minimum values at 500 m depth. Depth seems to be the strongest factor determining the structure and composition of the four main epibenthic assemblages identified on the deep shelf (150 m), upper slope (300–550 m), middle slope (1000 m) and deep slope (1600 m). The two shallowest assemblages were clearly separated from the deeper ones and were typified by different decapods and fish species , while the two deepest assemblages were characterized by echinoderms and fishes.

The composition of megabenthic communities from the Northern Mauritanian canyons was studied using data and material obtained during the four Maurit surveys , accomplished in November–December of 2007–2010. Cartography of the canyons was carried out using a multibeam echosounder and a high resolution seismic system (TOPAS). Oceanographic data were obtained in 29 vertical CTD profiles located in four transects along the canyons. The megabenthos survey was limited to canyon edges and included 11 stations sampled with a rock dredge . Twenty nine canyons and other minor channels , grouped in four large complex systems, were located in the Arguin Province . The canyons, with very steep walls, can reach down to 700 m depth and extend over 8–70 km in length along the slope. The water mass influencing the canyons correspond to the South Atlantic Central Water (SACW). The megabenthos species richness was estimated to be over 206 species, distributed among 29 high˗range taxa . Hydroids , sponges , decapods, bivalves , polychaetes and prosobranchs showed the highest species richness, oscillating from 29 to 15 species. In terms of feeding strategies , suspension-feeders dominated the species richness (63%), abundance (75%) and also biomass (94%). While ophiuroids composed the largest proportion of total abundances (23%), demosponges dominated the biomass (80%). Multivariate analysis identified two megabenthic assemblages mainly segregated by its trophic strategy . The first cluster was defined by strong dominance of suspension˗feeders and higher values of diversity indexes, and included four stations where living corals were collected. The second cluster was dominated by scavengers , carnivorous and detritivorous species, with much lower diversity.

Ramos, Ana ... et al.-- 45 pages, 16 figures, 3 annexes, Human activities in continental margins have progressively increased during the last decades, threatening vulnerablemarine ecosystems in many continental slopes, such as cold-water coral reefs, seamounts and canyons. In order to protect these ecosystems and ensure the sustainable management of resources, countries and organizations should endorse effective policy actions. However, nowadays about only 0.8% of the oceans and 6% of the territorial seas belong to conservation area systems, a lack of protection that is particularly acute in deep-sea waters. The Mauritanian continental margin is the outcome of exceptional marine features, with abrupt canyon systems, sediment slides and a giant carbonate-mounds barrier occurring together. Mauritanian waters have both tropical and subtropical origins, being affected by coastal and offshore upwelling that leads to elevated productivity and abundant fishery resources. Soft-bottom habitats hold high diversity of species, and hard-bottoms sustain assemblages of suspension-feeders and vulnerable species. Nevertheless, despite the recent increase of extractive activities, the location and characterization of those Mauritanian deep-water areas of biological or ecological interest that require protection remain poorly known. The Maurit surveys have offered the opportunity to perform a first approach to the biodiversity and ecosystems in soft and hard bottoms of the Mauritanian outer shelf and slope. This last chapter provides an integrated overview of the demersal and benthic communities inhabiting Mauritanian deep waters and describes areas of particular ecological and/or biological interest that are vulnerable habitats and should be preserved according to international conventions, This work was undertaken within the framework of the EcoAfrik project and it has been partially funded by the MAVA Foundation pour la Nature (MAVA contract 12/87 AO C4/2012)

This publication is the third in a series of accounts on large collections of Plumularioidea McCrady, 1859 (Cnidaria, Hydrozoa, Hydroidolina) obtained during several French expeditions to the Philippines region, Vanuatu, New Caledonia, Fiji, and the Marquesas Islands. Additional material from Mozambique was also examined and is discussed. A total of 17 species, belonging to the families Kirchenpaueriidae Stechow, 1921 (two species) and Plumulariidae McCrady, 1859 (15 species), are scrutinized and illustrated in the present report. Three new species of the genus Plumularia Lamarck, 1816 are described (Plumularia bathyale n. sp., Plumularia contraria n. sp., Plumularia pseudocontraria n. sp.). The name Plumularia milsteinae n. nom., is proposed for Plumularia spiralis Milstein 1976, a permanently invalid junior homonym of Plumularia spiralis Billard, 1911. Polyplumaria kossowskae (Billard, 1911) is recorded for the first time since its original description. Two species of Plumularia are identified ...

One new genus ( Schizoplumularia ) and three new species ( Schizoplumularia vervoorti , S. geniculata and S. elegans ) of plumulariids are recognized and described from large collections of plumularioid hydroids collected in New Caledonia and vicinity during several French expeditions. During taxonomic studies of these hydroids, colonies were compared with type material of Plumularia insignis Allman, 1883 and several other similar species-group taxa. As a result, three of the latter ( P. flabellum Allman, 1883, P. conjuncta Billard, 1913, and P. billardi nom. nov.) are recognized as valid in addition to P. insignis . The binomen P. billardi is a replacement name for P. insignis var. gracilis Billard, 1913. In being elevated to the rank of species in this work, it becomes an invalid junior primary homonym of several others having the same name.

Neopilumnoplax corallicola n. sp. is described from waters off Mauritania on the basis of two specimens collected during the Spanish-Mauritanian survey BMaurit- 0911^ from 488 m over a giant cold-water coral reef running from Cape Timiris to the Senegalese border. The new species is readily separated from its congeners by the shape of the front and anterolateral teeth, the low granulation on the dorsal carapace, and the morphology of the cheliped and ambulatory legs. This is the first record of the family from the Northeastern Atlantic and the second record of the genus in West Africa. A diagnosis of the family Mathildellidae with a key to genus level, as well as dichotomous and tabular keys to the world species of the genus Neopilumnoplax, are included., MAVA (Contract 12087 Coastal West Africa C4/2012), SI

Agís, José Ansín, Vervoort, Willem, Ramil, Fran (2009): Hydroids of the family Halopterididae (Cnidaria, Hydrozoa) collected in the western Pacific by various French expeditions. Zoosystema 31 (1): 33-61, DOI: 10.5252/z2009n1a3, URL: http://www.bioone.org/doi/abs/10.5252/z2009n1a3

The Maurit surveys along the Mauritanian coast revealed the small collection of thalassinideans examined in this work. A total of four species were identified, of which Ezaxius ferachevali n. gen., n. sp. is described and figured here. Calocaris macandreae Bell, 1853 is the most abundant species, while the presence of Calocarides coronatus (Trybom, 1904) is confirmed on the West African coast. Trypaea oblonga n. comb. is proposed for Callianassa oblonga Le LoeuffIntès, 1974 and it has been recaptured for the first time since its original description, with the addition of a female specimen. We also include remarks on the current status of thalassinidean systematics.

Thirteen hermit crab species of the families Diogenidae, Paguridae and Parapaguridae were captured in deep waters off Mauritania during Maurit surveys. A new species of the genus Paguristes, Paguristes candelae n. sp., is described. Areopaguristes mauritanicus n. comb. is proposed for Paguristes mauritanicus Bouvier, 1906 and Pseudopaguristes marocanus n. comb. for Paguristes marocanus A. Milne-EdwardsBouvier, 1892; the females of the latter species are reported for the first time. Our data extends the geographical distribution of Pseudopaguristes marocanus southwards and that of Paragiopagurus macroceros northwards. Both species, together with Diogenes pugilator (Roux, 1829), are recorded for the first time in Mauritanian waters. New data about bathymetric ranges are also reported for Pseudopaguristes marocanus n. comb., Areopaguristes mauritanicus n. comb. and Paragiopagurus macroceros.

This paper is the result of the study of a squat lobsters collection obtained along the Mauritanian coast, between 91 and 1867 m depth, during the 'MAURIT' surveys carried out in the period from 2007 to 2010. Eumunida bella de Saint LaurentMacpherson, 1990 (Chirostyloidea) and six species of Munida and Munidopsis (Galatheoidea) are reported in the present work.A new species, Munidopsis anaramosae n. sp. collected off northwestern Banc d'Arguin at 1000-1012 m depth, is described and illustrated. The presence of an eyespine that arises distally from the middle end of the cornea, walking legs merus spinose on dorsal and ventral margins and cheliped merus ventrally unarmed distinguish it from related species. Munida chunii Balss, 1913 is redescribed here and the new records of Munida guineae MiyakeBaba, 1970, M. speciosa von Martens, 1878 and Munidopsis chunii Balss, 1913 extend their geographical distribution northwards, and in the case of the last species, increase its bathymetric range.

The Ponto-Caspian hydroid Cordylophora caspia has been found for the first time in the Tagus estuary. There is only one previous citation for this invasive species in Portuguese waters. The colonies of C. caspia were branched and had healthy gastrozooids and gonophores. The specimens were collected from a saline boundary zone characterized by high fluctuations in salinity (maximum of 15.3 and minimum of 0.2) and high suspended solids loading. Cordylophora caspia is capable of colonizing man-made infrastructures such as industrial facilities and can inhabit both brackish and freshwater environments. These features of C. caspia, together with its resilience when in a dormant stage (menonts), indicate that the monitoring of this invasive species is advisable in the Tagus estuary.

The first record of the non-indigenous Corella eumyota on the Galicia coast (north-west Spain) is reported. One hundred and forty-one specimens of this solitary ascidian were found on soft bottoms at 12 m depth in the inner part of the Ria de Vigo. This is a species from cooler waters of the southern hemisphere and was recorded for the first time in the northern hemisphere in 2002, in France. The specimens have been compared with Antarctic and South American museum samples. Some intraspecific variability was noted.

The Maurit surveys along the Mauritanian coast revealed the small collection of thalassinideans examined in this work. A total of four species were identified, of which Ezaxius ferachevali n. gen., n. sp. is described and figured here. Calocaris macandreae Bell, 1853 is the most abundant species, while the presence of Calocarides coronatus (Trybom, 1904) is confirmed on the West African coast. Trypaea oblonga n. comb. is proposed for Callianassa oblonga Le Loeuff & Intes, 1974 and it has been recaptured for the first time since its original description, with the addition of a female specimen. We also include remarks on the current status of thalassinidean systematics.

Thirteen hermit crab species of the families Diogenidae, Paguridae and Parapaguridae were captured in deep waters off Mauritania during Maurit surveys. A new species of the genus Paguristes, Paguristes candelae n. sp., is described. Areopaguristes mauritanicus n. comb. is proposed for Paguristes mauritanicus Bouvier, 1906 and Pseudopaguristes marocanus n. comb. for Paguristes marocanus A. Milne-Edwards & Bouvier, 1892; the females of the latter species are reported for the first time. Our data extends the geographical distribution of Pseudopaguristes marocanus southwards and that of Paragiopagurus macroceros northwards. Both species, together with Diogenes pugilator (Roux, 1829), are recorded for the first time in Mauritanian waters. New data about bathymetric ranges are also reported for Pseudopaguristes marocanus n. comb., Areopaguristes mauritanicus n. comb. and Paragiopagurus macroceros.