Magdalena Błażewicz-Paszkowycz

Diversity of Tanaidacea (Crustacea: Peracarida) in the World's Oceans - How Far Have We Come?

Tanaidaceans are small peracarid crustaceans which occur in all marine habitats, over the full range of depths, and rarely into fresh waters. Yet they have no obligate dispersive phase in their life-cycle. Populations are thus inevitably isolated, and allopatric speciation and high regional diversity are inevitable; cosmopolitan distributions are considered to be unlikely or non-existent. Options for passive dispersion are discussed. Tanaidaceans appear to have first evolved in shallow waters, the region of greatest diversification of the Apseudomorpha and some tanaidomorph families, while in deeper waters the apseudomorphs have subsequently evolved two or three distinct phyletic lines. The Neotanaidomorpha has evolved separately and diversified globally in deep waters, and the Tanaidomorpha has undergone the greatest evolution, diversification and adaptation, to the point where some of the deep-water taxa are recolonizing shallow waters. Analysis of their geographic distribution shows some level of regional isolation, but suffers from inclusion of polyphyletic taxa and a general lack of data, particularly for deep waters. It is concluded that the diversity of the tanaidomorphs in deeper waters and in certain ocean regions remains to be discovered; that the smaller taxa are largely understudied; and that numerous cryptic species remain to be distinguished. Thus the number of species currently recognized is likely to be an order of magnitude too low, and globally the Tanaidacea potentially rival the Amphipoda and Isopoda in diversity.

Diatoms as food source indicator for some Antarctic Cumacea and Tanaidacea (Crustacea)

The gut contents of three species of cumaceans: Eudorella splendida, Vaunthompsonia inermis and Campylaspis maculata, and three species of tanaids: Nototanais antarcticus, N. dimorphus and Peraeospinosus pushkini from the shelf of Admiralty Bay and two cumaceans: Diastylis mawsoni and Ekleptostylis debroyeri from the deeper Antarctic shelf were studied. With the exception of Campylaspis maculata, which is a predator or scavenger, and Ekleptostylis debroyeri, whose gut was filled with mud only, detritus was an important diet component of all the species studied. On the basis of qualitative and quantitative components of diatom taxa it can be concluded that the food of Diastylis mawsoni comes from the pelagial, whereas the food of the other peracarids is of benthic origin. Species inhabiting the shallowest waters consume almost exclusively epipelic food, whilst those living below the euphotic zone feed mostly on particles sedimented from the pelagial; taxa occurring at intermediate depths feed on pelagic matter, but also of epiphytic and of epipelic origin.

Macrozoobenthos of two Antarctic glacial coves: a comparison with non-disturbed bottom areas

There are only few studies on shallow Antarctic benthic communities associated with habitats affected by intense mineral sedimentation inflow. The analysis of macrofaunal communities associated with two shallow, isolated glacial coves was performed in Admiralty Bay (King George Island) and compared with non-disturbed sites. Multivariate analyses (hierarchical classification, nMDS) clearly separated glacial cove communities (two assemblages) from the sites situated outside both basins (two assemblages). The community influenced by the streamflow of glacial discharge of meltwater situated in the area with sandy–clay–silt sediments had a very low species richness, diversity and abundance. It was dominated by eurytopic, motile deposit feeding polychaetes such as Mesospiomoorei, Tharyxcincinnatus and Leitoscoloploskerguelensis as well as the bivalve Yoldiaeightsi. The second glacial community of the area located at a grater distance from the outlet of the stream was characterized by sandy–clay–silt and clay–silt deposits and showed also a low diversity and species richness. The most abundant here were peracarid crustaceans, with the dominant opportunistic feeder Cheirimedonfemoratus. Community from the non-disturbed area with silty–clay–sand, and silty–sand sediments had higher species richness and diversity. The assemblage of fauna from the sandy bottom has values of those two indexes similar to those found in the disturbed areas.

Tanaidacea (Crustacea, Malacostraca) of two polar fjords: Kongsfjorden (Arctic) and Admiralty Bay (Antarctic)

The tanaidacean faunas of two polar fjords, Kongsfjorden (Arctic) and Admiralty Bay (Antarctic), were compared. The results show that Tanaidacea in the southern fjord are more diversified than those in the northern one. This difference is especially evident in species richness (12 species vs 3 species, respectively), but is not too significant in terms of diversity. In both polar fjords, the highest densities of tanaids were noted in sites where mud was swept off by the water current or eroded off steep bottom expoing coarser mineral particles used for tube building. The distribution of tanaids is suggested to be based on the joint action of inter alia factors such as the quality of bottom sediments, sedimentation ratio, accessibility of food, predation pressure, behaviour and heterogeneity of habitats.

Another inordinate fondness†: diversity of the tanaidacean fauna of Australia, with description of three new taxa

The shallow-water tanaidacean fauna of the Bass Strait has been the subject of recent intensive studies. The present paper extends this work into the deeper waters of the region, describing two new species and one new genus. The new species of the genus Paradoxapseudes has a combination of three maxillule palp setae, no plumose setae on the basis of pereopod 1 nor proximal serration on the antennal peduncle. The second species represents a new genus of the family Anarthruridae, having six marginal setae on the third maxilliped palp article and spines on the merus and carpus of the anterior pereopods. The high diversity of Tanaidacea in Australian waters is discussed. In particular, we conclude that Australian coasts suffer a diversity of immigration routes, have sufficient marine longevity, and afford such a diversity of available niches to have allowed multiple colonization and subsequent allopatric speciation of Tanaidacea. http://www.zoobank.org/urn:lsid:zoobank.org:pub:EE309A5A-E06D-416F-95BD-4C8D0D2BEB97

Skin-digging tanaids: the unusual parasitic behaviour of Exspina typica in Antarctic waters and worldwide deep basins

Abstract The order Tanaidacea includes over 1000 species which are mainly free-living or tube-dwelling detritivores. Exspina typica Lang, 1968 represents an exception to these common life styles, having being found in the intestine and body cavity of deep sea holothuroids. The 2008 New Zealand ‘IPY-CAML Cruise’ held in the Ross Sea collected several deepwater holothuroids that were observed to carry specimens of E. typica inside their coelomic cavity. A clear interpretation of this association was hence possible. Even if E. typica shows slight adaptations to a parasitic life style, the tanaids were found to actively ‘dig’ into the hosts skin, grasping tissue with their claws and producing tunnels in the body wall. It is therefore possible to clearly define this association, which is here reported from the Antarctic for the first time, as parasitism.

Tanaidacea of the Amundsen and Scotia seas: an unexplored diversity

Abstract The Scotia Arc and Amundsen Sea are contrasting regions within West Antarctica. The Scotia Sea shelf is well studied and central to the origin and diversity of the Southern Ocean benthic fauna, whilst the shelf of Amundsen Sea is one of the least studied shelf areas in the world; a ‘white spot’ on the map of benthic research. Here we report on the tanaidaceans collected using an epibenthic sledge on two expeditions, BIOPEARL 1 and 2, of the RRS James Clark Ross in 2006 and 2008, respectively. This study represents the first analysis of the tanaidacean fauna of those two basins. Thirty-seven species were found in the Amundsen Sea from 500–1500 m depth and 51 species were found at depths ranging from 200–1600 m in the Scotia Sea. In the Scotia Sea, many species were unique to each of the study sites which may be evidence of allopatric speciation episodes. Site specificity was especially evident for Typhlotanais and Pseudotanais. Only three species were common to both basins. Around 90% of the species were previously undescribed. Our findings increase the number of the tanaidaceans known in the Southern Ocean by 50%.

Distributional records of Ross Sea (Antarctica) Tanaidacea from museum samples stored in the collections of the Italian National Antarctic Museum (MNA) and the New Zealand National Institute of Water and Atmospheric Research (NIWA)

Abstract Here we present distributional records for Tanaidacea specimens collected during several Antarctic expeditions to the Ross Sea: the Italian PNRA expeditions (“V”, 1989/1990; “XI”, 1995/1996; “XIV”, 1998/1999; “XIX”, 2003/2004; “XXV”, 2009/2010) and the New Zealand historical (New Zealand Oceanographic Institute, NZOI, 1958-1961) and recent (“TAN0402 BIOROSS” voyage, 2004 and “TAN0802 IPY-CAML Oceans Survey 20/20” voyage, 2008) expeditions. Tanaidaceans were obtained from bottom samples collected at depths ranging from 16 to 3543 m by using a variety of sampling gears. On the whole, this contribution reports distributional data for a total of 2953 individuals belonging to 33 genera and 50 species. All vouchers are permanently stored in the Italian National Antarctic Museum collection (MNA), Section of Genoa (Italy) and at the National Institute of Water and Atmospheric Research (NIWA Invertebrate Collection), Wellington (New Zealand).

Revision of the genus Peraeospinosus Sieg, 1986 (Crustacea: Peracarida: Tanaidacea)

Ten species, four new to science, five formerly belonging to genus Typhlotanais, and Peraeospinosus pushkini (Tzareva, 1982) are congeneric species, based on the following set of characters: a row of setae is present on the dorsal margin of the cheliped carpus, the distal seta of pereopods 4–5 exceeds the bifurcated unguis, large prickly tubercles on pereopods 4–6 surrounded by well‐calcified spines, the pleopods semi‐elliptical, and the rami of the uropod subequal in length. The new definition of the genus is proposed together with a key for identification of the females. The present‐day distribution of the genus does not in itself indicate geographical origin, although the possibility of a deep‐water origin cannot be excluded. It is assumed that phylogenetically young, blind Peraeospinosus could have colonized Antarctic free niches and then radiated.

First record of Tanaidacea (Crustacea) from a deep-sea coral reef in the Gulf of Guinea

Four undescribed species of Tanaidacea were discovered during a baseline monitoring program conducted off the coast of Ghana. The specimens came from a deep-water reef largely composed of the ahermatypic coral, Lophelia pertusa. The tanaidacean material was collected during November 2012 onboard the RV Dr Fridtjof Nansen using a van Veen grab in depths of between 375 and 386 m. Three of the new species described herein are tanaidomorphans belonging to the genera Bathyleptochelia (Leptocheliidae), Pseudotanais (Pseudotanaidae) and Cryptocopoides (Cryptocopidae). The fourth species, an apseudomorphan, belongs to Calozodion (Metapseudidae), a genus hitherto known only from shallow waters (<200 m). This report constitutes the first records of tanaidaceans from a deep-sea Lophelia reef.