Sharks, rays and chimaeras of the Seine and Unicorn seamounts (NE Atlantic Ocean)

Background Seamounts are underwater mountains which typically rise rather steeply at least several hundred meters above the deep-sea floor. These geological features interrupt water flow and hence may induce changes in the circulation of different water masses, in turn causing different physical and biological effects. For this reason, seamounts are biodiversity hotspots, housing a wide number of species, as is with the case of the Seine and Unicorn seamounts, which are a part of the Madeira-Tore seamount chain located between Portugal mainland, southwestern Europe and Madeira archipelago (NE Atlantic). Methods Fisheries independent surveys allowed the collection of Chondrichthyes specimens from the Seine and Unicorn seamounts. Individuals were caught over the course of two research cruises, first in 2004 and later in 2017, with species distribution ranging from the summit down to 2500 m of depth. Results Fifteen species belonging to 7 different taxonomical families were collected in the two surveyed areas. Two species were recorded for the first time and added to the checklist of the Seine seamount (Centrophorus granulosus and Somniosus rostratus), and three species for the Unicorn seamount (C. granulosus, Centroscymnus coelolepis and Centroselachus crepidater). Distribution and frequency of occurrence for the collected species were evaluated in relation to depth. Conclusions This work is a valuable contribution to the knowledge of seamount-associated fish fauna. Moreover, the checklist of sharks, rays and chimaeras was updated for the Seine and Unicorn seamounts, summing up 20 species.

Clownfish hosting anemones (Anthozoa, Actiniaria) of the Red Sea: new associations and distributions, historical misidentifications, and morphological variability

Background The Red Sea contains thousands of kilometers of fringing reef systems inhabited by clownfish and sea anemones, yet there is no consensus regarding the diversity of host anemone species that inhabit this region. We sought to clarify a historical record and recent literature sources that disagree on the diversity of host anemone species in the Red Sea, which contains one endemic anemonefish, Amphiprion bicinctus Rüppell 1830. Results We conducted 73 surveys spanning ~ 1600 km of coastline from the northern Saudi Arabian Red Sea to the Gulf of Aden and encountered seven species of host anemones, six of which hosted A. bicinctus. We revise the list of symbionts for A. bicinctus to include Stichodactyla haddoni (Saville-Kent, 1893) and Stichodactyla mertensii Brandt, 1835 which were both observed in multiple regions. We describe Red Sea phenotypic variability in Heteractis crispa (Hemprich & Ehrenberg in Ehrenberg, 1834) and Heteractis aurora (Quoy & Gaimard, 1833), which may indicate that these species hybridize in this region. We did not encounter Stichodactyla gigantea (Forsskål, 1775), although the Red Sea is the type locality for this species. Further, a thorough review of peer-reviewed literature, occurrence records, and misidentified basis of record reports dating back to the early twentieth century indicate that it is unlikely that S. gigantea occurs in the Red Sea. Conclusions In sum, we present a new guide for the host anemones of the Red Sea, revise the host specificity of A. bicinctus, and question whether S. gigantea occurs in the central and western Indian Ocean.

Larvae of the blue crab Callinectes sapidus Rathbun, 1896 (Decapoda: Brachyura: Portunidae) in the Balearic Archipelago (NW Mediterranean Sea)

The invasive blue crab Callinectes sapidus has been frequently recorded during the last years along the NW Mediterranean Sea, leading to established populations. Two megalopae of C. sapidus were found during two different oceanographic surveys in open waters of the Balearic Archipelago, in July 2005 and October 2011, previous to the first reference of adult specimens documented in the Balearic sub-basin. The analyzed environmental conditions of the sampling periods allowed us to hypothesize the likely introduction pathways, namely by maritime transport and surface currents. Furthermore, the recorded megalopae seem to enlarge the life history of C. sapidus in regard to its native area, where spawning peaks occur in late July and early August.

New record of the red prickly sea star Paulia horrida (Gray, 1840), Asterodiscididae, in the north of Chile

We report the capture of a single specimen of the species Paulia horrida Gray, 1840, off the coast of Arica, in the Arica and Parinacota Region, Northern Chile. This finding extends the currently known distributional range of the species by 2,434 km towards the south, since the southernmost known area for this species corresponds to Punta Sal, Peru. We discuss the importance of finding this relatively unknown species in Chile and the need to continue sampling to confirm the continuous distributional range of the species between the south of Peru and the north of Chile.

The occurrence of mobulid rays at St Helena Island, Cardno seamount and Bonaparte seamount in the South Atlantic and its significance for conservation

Data from 369 sightings of mobulid rays from St Helena Island, Cardno and Bonaparte seamounts in the South Atlantic are summarised. 50 % (183) of sightings were observed from a boat, 48 % (176) of sightings were encountered in water, of which 95 % (168) were whilst actively scuba diving. 2 % (10) of mobulid ray sightings were observed from land. Sightings data indicate that the Chilean devil ray Mobula tarapacana (Philippi, 1892) is a frequent visitor to St Helena and is present all year. We document the first photographic evidence of the presence of oceanic manta, Mobula birostris (Walbaum, 1792) at St Helena. Two solitary individuals were photographed off the north coast of St Helena in June 2018. These sightings confirm previous unverified reports on the species occurrence and extend the known distribution range of M. birostris in the open South Atlantic Ocean to 16°S.

First faunistic results on Valencia (Cresques) Seamount, with some ecological considerations

The living and dead fauna of Valencia Seamount, a deep promontory in the middle of the Balearic Basin which summit is at ca. 1100 m depth, is described by first time based in a rock dredge perfomed in a sedimentary area of the summit Mount. Surface-feeder polychaetes (the Paraonidae Levinsenia gracilis and Terebellidae as dominant), and taxodont bivalves (Ledella messanensis and Yoldiella ovulum) were the main species of benthos. We found alive remains of the bamboo coral Isidella elongata, a vulnerable, habitat-forming species in the deep Mediterranean. Benthos density was low (0.6 organisms/2 dm3 mud). Thanatocoenosis evidenced a rather moderate diversity of benthic bivalves (11 species) and gastropods (9 species) also dominated by surface deposit feeders. Fish (identified/quantified from sedimented otoliths) showed diversified and abundant mesopelagic fauna, mainly Myctophidae. More interestingly, we highlighted among benthopelagic fish the occurrence of recruits of Merluccius merluccius, Micromesistius poutassou, or Hymenocephalus italicus, all species that live in the neighboring slopes of the Iberian Peninsula and the Balearic Islands at quite shallower depths (at 100-700 m) than their distribution in the Valencia Seamount summit (1102–1130 m) based on the deposited otoliths found. Some ecological aspects were discussed and the necessity to consider the deep Valencia Seamount as a potential area that should be under protection.

Geographical range expansion of Nitzschia volvendirostrata Ashworth, Dąbek & Witkowski, 2016 (Bacillariophyta: Bacillariaceae) based on morphological and molecular analysis

In diatoms the use of molecular tools to corroborate traditional (morphological) identification offers a new perspective in the field of biogeography. This manuscript reports the first record of the raphid pennate diatom Nitzschia volvendirostrata along the coast of Mexico, which in turn represents an expansion of the geographic range along the American continent. The cells were isolated from benthic samples taken from Balandra lagoon, La Paz, Baja California Sur, Mexico and cultured as a monoclonal culture. Morphology and morphometry of the diatom obtained from light and electron microscopy reveal that they correspond to the original description of N. volvendirostrata and also its chloroplast sequences, rbcL and psbC, showed 98.7 to 100 % similarity and a close phylogenetic relationship with N. volvendirostrata. The reported places for this taxon show that it has a tropical-temperate biogeographical affinity.

A new range-extending record of the invasive sea squirt S. clava in the north of Scotland

A new record of an individual of the invasive sea squirt, Styela clava, is reported from Scapa Flow in Orkney, Scotland. This represents a 1.54° latitudinal extension (168 km) from the previous northern-most record in UK waters. Diver surveys of hard substrates in the immediate area, part of local biosecurity protocols, did not find any additional individuals. Possible transport vectors, likelihood of an established reproductively active population, and implications to local biodiversity are discussed.

Fishes of Lakshadweep archipelago: new records, review and a revised checklist

Extensive studies on fish diversity in Lakshadweep waters began with Jones and Kumaran’s in 1964. Reports after these authors were sparse and sporadic until the turn of this century. Although recent reports have increased the tally, targeted studies are lacking, and there is a possibility of listing more species for this region. Studies on the diversity and abundance of fishes are due, given the atoll system undergoing rapid changes: structural decline due to several bleaching related coral mortality events, changes in the seagrass meadows, and the increase in fishing reef-associated species. These circumstances call for a revised checklist of fishes for this region, for the latest dates back to 1991. Thus, we present an inventory of ichthyofauna of Lakshadweep atolls based on published literature and incorporating 15 new species records identified through a rapid survey. The new species records for this region are presented here with the diagnostics of these species. The checklist shows 856 species of 432 genera, 43 orders, and 144 families known from these islands, including 16 freshwater forms. 49.3% of the contribution is from 14 fish families having > 15 species each, while the remainder 131 families contributed 52.5%, which have < 15 species. About 154 species belonging to 12 families are known to contribute to the commercial fisheries of these islands. The new records reported in this work for this region are found in the Maldives, and Sri Lanka proves the zoogeographical affinity of these two regions with the Lakshadweep archipelago.