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.
Recent tanaidacean material collected from Antarctic waters, primarily during the ANDEEP expeditions of 2002 and 2005, includes a number of new taxa attributable to the families Nototanaidae and Typhlotanaidae sensu Sieg. Analysis of this material has exposed a problem with the recent contention of the two families, and has revealed consistent morphological trends which support the distinction of these two families. In the present paper, examination of both museum specimens and newly-collected material, has allowed a re-analysis based on a series of detailed morphological observations, resulting in a new definition of the families Typhlotanaidae Sieg, 1984 with the establishment of five new genera (Hamatipeda n. gen., Larsenotanais n. gen., Pulcherella n. gen., Torquella n. gen., Typhlamia n. gen.), a the description of thirteen new species, the redescription of fifteen species, and the construction of keys for the determination of typhlotanaid genera and of the species of three newly-erected genera.
In the Southern Ocean, that is areas south of the Polar Front, long-term oceanographic cooling, geographic separation, development of isolating current and wind systems, tectonic drift and fluctuation of ice sheets amongst others have resulted in a highly endemic benthic fauna,\ud which is generally adapted to the long-lasting, relatively stable environmental conditions. The Southern Ocean benthic ecosystem has been subject to minimal direct anthropogenic impact (compared to elsewhere) and thus presents unique opportunities to study biodiversity and its\ud responses to environmental change. Since the beginning of the century, research under the Census of Marine Life and International Polar Year initiatives, as well as Scientific Committee of Antarctic Research biology programmes, have considerably advanced our understanding of the Southern Ocean benthos. In this paper, we evaluate recent progress in Southern Ocean benthic research and identify priorities for future research. Intense efforts to sample and describe the benthic fauna, coupled with coordination of information in global databases, have greatly enhanced\ud understanding of the biodiversity and biogeography of the region. Some habitats, such as chemosynthetic systems, have been sampled for the first time, while application of new technologies and methods are yielding new insights into ecosystem structure and function. These advances have\ud also highlighted important research gaps, notably the likely consequences of climate change. In a time of potentially pivotal environmental change, one of the greatest challenges is to balance conservation with increasing demands on the Southern Ocean’s natural resources and services. In\ud this context, the characterization of Southern Ocean biodiversity is an urgent priority requiring timely and accurate species identifications, application of standardized sampling and reporting procedures, as well as cooperation between disciplines and nations
Abstract:The global zoogeographic distribution of the most widespread peracarid species occurring in three or more ocean basins below 2000 m is analysed. Basing on the published data we investigated 45 peracarid species, which have a most widespread distribution and most likely are cosmopolitan. Thirty−three species have a wide distribution in the Northern Hemisphere. Most species occur in the North Atlantic, however, 16 of these species occur also in the North Pacific, a more limited number of species occurs in the South Atlantic or South Pacific The Southern Ocean displays some special zoogeographic features and 22 widespread species occur there below 2000 m, including highly eurybathic ones. In total, 11 of the analysed species occur in all oceans. Eucopia australis (Lophogastrida), Munneury− cope murrayi (Isopoda) and Eurythenes gryllus (Amphipoda) are the species with the wid− est distributions. Other peracarids occurring in all oceans are: the isopods Paramunnopsis oceanica and Eurycope sarsi, the mysid Caesaromysis hispida the lophogastrid Eucopia unguiculata, the amphipod Mesopleustes abyssorum and the tanaids Exspina typica, Para− narthura insignis and Pseudotanais nordenskioldi. No cumacean species has been reported with an ocean−wide distribution but Campylaspis glabra occurs in the Atlantic, Indian and Pacific oceans. Among plenty of rare species in each order there are only few species with wide distribution records. There is evidence from molecular genetic studies that some of the widespread peracarids represent several cryptic species, however, some, e.g. Eucopia aus− tralis, seem to be truly cosmopolitan species. Geography of sampling is biasing our view of biogeography. The history and quality of taxonomic work as well as the reliability of geo− graphic records (quality control of large databases) limits our investigations of widespread or cosmopolitan species as much as the limited knowledge of variation within most species causes difficulties in defining morpho−species with certainty.
Błażewicz-Paszkowycz, M. and Bamber, R.N. 2012. The Shallow-water Tanaidacea (Arthropoda: Malacostraca: Peracarida) of the Bass Strait, Victoria, Australia (other than the Tanaidae). Memoirs of Museum Victoria 69: 1-235.All of the shallow-water tanaidacean taxa (except for species of the family Tanaidae) from material collected between 1964 and 1999 within the Bass Strait, Victoria, Australia, have been analyzed. The material had been collected predominantly by staff from the Museum Victoria, Melbourne. The species treated here are those occurring at depths <200 m; substrata were predominantly sands. A total of 65 species in 43 genera is discussed, of which 44 species, five genera and one subgenus are described as new, although two of the species are not named owing to inadequacy of the material. Only nine of the species are known from elsewhere in Australia, and none from outside Australia. In addition, after examination of more material of its type-(and only) species, the genus Annexos is synonymized with Apseudes, as is Xanthapseudes; Apseudes tuski is moved to Apseudopsis; subgenera of Bunakenia are rejected; the "tribes" Parapseudini and Pakistanapseudini are raised to Subfamily rank; Magniaculeus is synonymized with Saltipedis; intraspecific variation in Kalliapseudes obtusifrons is discussed; the genera of the Pagurapseudinae are resolved, and Pagurapseudes abrucei is transferred to Macrolabrum; the first male for the genus Bathytanais is described; the validity of the genus Araphuroides is discussed, and A. io is returned to Araphura; Protanaissus makrotrichos, P. alvesi and P. floridensis are moved to new genera; the family Tanaopsidae is erected to accommodate the genus Tanaopsis (at least).
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