Magdalena Błażewicz

Diversity and distribution of peracarid crustaceans (Malacostraca) from the abyss adjacent to the Kuril-Kamchatka Trench

During the KuramBio expedition in 2012, macrobenthos samples were collected with an epibenthic sledge from 12 sites on the abyssal plain of the Northwest Pacific Basin adjacent to the Kuril-Kamchatka Trench (KKT) and on the western slope of the KKT, at depths between 4830 and 5780xa0m. In terms of the peracarid fauna, the NW Pacific abyss was found to be one of the richest and densely populated deep-sea regions of the World Ocean. With 482 species, 168 genera, 61 families and 5 orders, the superorder Peracarida was found to be the most diverse and one of the most abundant macrobenthic taxa in the collection. Of the taxa found, 3 genera and 386 (80%) species were apparently new to science, 30 genera and the family Dendrotionidae (Isopoda) being recorded for the first time in the NW Pacific. The peracarid fauna composition at the abyssal depths of the KKT region was typical of the open, non-isolated abyssal plain. The Isopoda proved the most diverse and abundant peracarid order (245 species, 61.3% of the individuals), followed by the Amphipoda (79 species, 19.6%), Tanaidacea (77 species, 9.1%), the Cumacea (70 species, 9.7%), and the Mysida (11 species, 0.23%). The highest peracarid abundance (up to 1047 ind./1000xa0m2) was recorded on the western slope of the trench, abundances at the abyssal plain being lower (125–639 ind./1000xa0m2). The peracarid distribution in the area studied was affected by a complex of various factors, the food availability reflected in the Particular Organic Matter (POM) flux belonging to the most important ones. Specifically, increases in the peracarid abundance and species richness corresponded in most cases with a high sediment organic carbon content or the high surface productivity level in the area. As indicated by the sediment composition, the food input to the deep-sea system apparently differed between the sites sampled. On the trench slope, accumulation of organic debris, transported down the slope from shallower regions, played an apparently major role. The abyss in the northern and in the southern parts of the area sampled is influenced by the high surface productivity, resulting from the regional hydrography. The area east of the Middle Kuril Islands is likely influenced by the organic material transported from the Sea of Okhotsk through the Kuril Straits.

New Tanaidacea (Crustacea: Peracarida) from the Gulf of Guinea

Four new species of deep-sea Tanaidacea taken from the Gulf of Guinea as part of the Ghanaian marine environmental monitoring programme in 2012 are described. One of the species, which was classified to the family Anarthruridae, differed substantially from the other members of the family, and was accommodated to the newly erected genus – Olokun n. gen. Each of the three other species belongs to a different family: Parakanthophoreus guineus n. sp. – Akanthophoreidae, Collettea agnesi n. sp. – Colletteidae, and Araphura studens n. sp. – Tanaellidae. A key for genera of Anarthruridae is given.

Low abundance and high species richness: the structure of the soft-bottom isopod fauna of a West Antarctic glacial fjord

Isopods belong to the most speciose groups of the Antarctic benthic fauna, although the knowledge on their diversity and small-scale distribution patterns is still limited. Here we analyze the diversity of the isopod fauna in the Admiralty Bay, a glacial fjord on the King George Island. The basin is located in the region of the Antarctic Peninsula, the fastest warming area of the Southern Ocean. The study provides important baseline data for future research, particularly with respect to temporal fluctuations in benthic fauna, associated with global changes observed in that part of the world. Forty species of isopods representing 19 families were recorded on the soft bottom of the Admiralty Bay. The analyses were based on 99 quantitative samples collected, within the 20–502-m depth range, with a 0.1xa0m2 van Veen grab. The materials for the analyses were obtained in the austral summer seasons of 1984/1985 and 1985/1986. The data revealed a high number of isopod species occurring at a low abundance, the mean abundance amounting to 4.8xa0±xa08.6 ind./0.1xa0m2. Most of the species occurred at low abundances, 25% of the species being represented by singletons. Caecognathia polaris, the most abundant species, showed the mean abundance of merely 1.2xa0±xa04.2 ind./0.1xa0m2. Species richness, diversity and abundance of the isopod fauna were much higher in the central basin of the Admiralty Bay than in the Ezcurra Inlet, an area affected by a strong disturbance of glacial origin.

A new genus of Tanaidacea (Peracarida, Typhlotanaidae) from the Atlantic slope

Two new species of deep-sea Tanaidacea (Aremus islandica n. sp. and A. brasilica n. sp.) were collected in the SW and N Atlantic during the scientific cruises organized within the HABITATS and IceAGE (Icelandic Animals Genetic and Ecology) initiatives in 2009 and 2011, respectively. Both species fit well to the current definition of Typhlotanaidae, but differ from the other members of the family by the striking feature of absence of the pleopods (one pair of pinnate setae on each pleonite ventrally), therefore they were accommodated to the newly erected genus – Aremus n. gen.; the new genus lacks the prickly tubercles on the carpus of pereopods 4–6, although it has three distinct serrated spines that makes it similar to four typhlotanaid genera, namely: Meromonakantha, Paratyphlotanais, Hamatipeda and Obesutanais. However, the morphology of the body does not correspond to the typical Meromonakantha neither to short body of Obesutanais. Furthermore Paratyphlotanais and Hamatipeda differ from the new genus on the spines form, in which the first one has long serrated spines and the second has hook-like spines. Both new species can be distinguished by (1) length of the ventrodistal seta on cheliped carpus, (2) length of dorsodistal seta on carpus of pereopods 1–3 and (3) length of the uropodal endopod. The systematics of the typhlotanaids without prickly tubercles on the pereopods 4–6 is briefly discussed.

Small-scale species richness of the Great Barrier Reef tanaidaceans—results of the CReefs compared with worldwide diversity of coral reef tanaidaceans

The Great Barrier Reef (GBR) is considered to be one of the most important marine biodiversity hotspots on Earth. At the same time, knowledge on the smallest inhabitants of this habitat is extremely scarce, which is particularly apparent with respect to small peracarid crustaceans of the order Tanaidacea. Prior to this study, as few as 20 tanaidacean species had been reported from Australian coral reefs, this study yielding 56 species new to science. Our analysis of a high number of qualitative samples collected at two GBR sites (Heron and Lizard Islands) from a depth range of 0 to about 30xa0m in the framework of the Census of Coral Reef Ecosystem program (one of the Census of Marine Life-related projects) almost doubled the total number of coral reef-associated tanaidacean species known worldwide. Altogether, 60 species (distributed among 7622 individuals) were identified, 46 and 41 species being recorded on Heron and Lizard Islands, respectively. The tanaidaceans were dominated by members of the families Leptocheliidae (8 species and more than half of all specimens at both sites) and Metapseudidae (11 species, 6 and 3% of individuals, respectively). The most speciose genera were Pseudoapseudomorpha (4 species), Paradoxapseudes, Parapseudes, Pugiodactylus, and Zeuxo (3 species each). Most species were rare, their frequency of occurrence in samples not exceeding 15%. The species accumulation curves did not reach the asymptote.

Sinelobus stromatoliticus sp. nov. (Peracarida: Tanaidacea) found within extant peritidal stromatolites

Living coastal stromatolites, layered structures formed by the microbially mediated precipitation of calcium carbonate, are scarce because of grazing and burrowing disruption by metazoans, amongst other reasons. This paper describes Sinelobus stromatoliticus sp. nov., a tanaidacean living within laminated stromatolites along the South African coastline. S. stromatoliticus is the sixth geographically isolated species now recognised within what was once considered to be a single globally cosmopolitan species, S. stanfordixa0Richardson, 1901. A revised, sex-specific dichotomous key to all the species currently recognised within this genus is provided. Sinelobus stromatoliticus is a prominent and abundant metazoan within the living stromatolite habitats, yet despite being a burrowing and grazing species, stromatolite layering is not hampered by its presence. Future work should determine the relationship between other populations (cf. S. stanfordi) in South Africa (previously identified as Tanais philetaerus Stebbing, 1904) and those of the stromatolite-dwelling S. stromatoliticus. However, given South Africa’s clear biogeographic zonation in other taxa, it is unlikely that this genus that features no pelagic larval stage would be morphologically similar across biogeographic regions.

New species of Anarthruridae (Tanaidacea: Crustacea)of the western Australian slope

In the collection of Tanaidacea from the continental slope of Western Australia made during the two scientific cruises of the FRV Southern Surveyor (2005 and 2007)xa0and organised under the aegis of the Commonwealth Scientific and Industrial Research Organisation (CSIRO), five new species of the family Anarthruridae were identified. To accommodate the new species, three new genera Abrotanais n. gen., Macilenta n. gen. and Waki n. gen. arexa0erected. The new species, in contrast to all the other members of the Anarthruridae, have an unusually elongatedxa0bodies thatxa0are 18 to 50 times longer than broad.

A tip of the iceberg—Pseudotanaidae (Tanaidacea) diversity in the North Atlantic

During two IceAGE expeditions, a large collection of Tanaidacea was gathered from the shelf down to the slope (213−2750xa0m) in six areas off Iceland—the Irminger Basin, the Iceland Basin, the Norwegian Sea, the Denmark Strait, the Iceland-Faroe Ridge, and the Norwegian Channel. In this collection, members of the family Pseudotanaidae were most numerous component. We examined 40 samples collected with different gears (e.g., EBS, VVG. GKG), in which 323 pseudotanaid individuals were counted and covered a total depth from 213.9 to 2746.4xa0m. Morphological identification of the material has revealed the presence of five species: Akanthinotanais cf. longipes, Mystriocentrus biho sp. n. Pseudotanais misericorde sp. n., P. svavarssoni sp. n., and P. sigrunis sp. n. The description of the four new species has been presented in the paper and a rank of the subgenus Akanthinotanais is elevated to a genus rank. A large group of morphologically almost identical specimens, similar with P. svavarssoni sp. n. from a wide depth range and from various areas off Iceland was discriminated to species by applying morphometric methods; one distinct species (P. svavarssoni sp. n.) and complex of presumably cryptic species the species was discovered. Based on current data and literature records, similarity among fauna of Pseudotanaidae was assessed with applying Bray–Curtis formula. As results, potential zoogeographic regions in the North Atlantic have been distinguished.

A new genus of family Akanthophoreidae and new species of genus Parakanthophoreus Larsen & Araújo-Silva, 2014 (Crustacea: Tanaidacea: Tanaidomorpha) from the North Atlantic

Based on tanaidacean material collected primarily during the IceAGE cruises in the North Atlantic, three new species from the family Akanthophoreidae are described; one is classified in the genus Parakanthophoreus, and the other two represent a new genus—Brixia n. gen. The main characters that distinguish Brixia n. gen. from other akanthophoreids is the lack of fully developed pleopods in adult females and a seven-articled antenna. The diagnosis of the family Akanthophoreidae is amended. Cheliped ornamentation of Parakanthophoreus catharina n. sp. is illustrated using SEM pictures.