RESUMO
A new species of pardaliscid amphipod is described and illustrated from a single male specimen collected from bathyal sediments (2125 m depth) in the southern Gulf of Mexico. The new species is morphologically closest to Pardaliscoides fictotelson Barnard, 1966, previously documented from Southern California, at 218 m depth. The new pardaliscid differs from other species in the genus in having antenna 1 with a 10-articulate accessory flagellum; maxilliped palp very long; pereopods 5-7 elongate, slender; basis pereopod 7 expanded; telson with a short U-shaped cleft and pointed lobes; uropods 1-2 outer ramus curved, peduncle flat, longer than rami; uropod 3 rami flat, fleshy-lined, with marginal distal short robust setae. An identification key for all known species in the Pardaliscoides genus is also provided. The new species increase the number of Pardaliscoides species documented to six worldwide.
Assuntos
Anfípodes , Masculino , Animais , Golfo do MéxicoRESUMO
We examine the abundance and species composition variability of benthic infauna from tropical coastal lagoons in relation to environmental factors and organic pollutants. Sediment samples were collected at 40 sites in four lagoons in the northern Yucatan Peninsula. A total of 7985 individuals belonging to 173 species were sampled. While the eastern lagoons were dominated by polychaetes, the western ones were dominated by crustaceans. Overall, polychaetes had the highest abundance (48%), followed by crustaceans (42%). According to canonical correspondence analysis, species attributes were correlated with water salinity, pH and temperature, but also with sediment pentachlorobenzene, trichlorobenzene, and low molecular weight polycyclic aromatic hydrocarbons. Some pollutants exceeded sediment quality guidelines, representing a potential environmental risk to benthic infauna. Together, environmental factors and pollutants explained 52% of the variance in abundance and species composition among sites.
Assuntos
Biodiversidade , Compostos Orgânicos/análise , Água do Mar/química , Poluentes Químicos da Água/análise , Animais , Monitoramento Ambiental , Invertebrados/classificação , Invertebrados/crescimento & desenvolvimento , México , Salinidade , Clima Tropical , Poluição Química da Água/estatística & dados numéricosRESUMO
Black corals (antipatharians) are colonial cnidarians whose branched tree-like skeleton is mostly constituted of chitin fibrils inside a lipoproteic matrix. The skeleton exhibits growth rings formed by chitin layers (micro-lamellae). In order to know the effect of the arrangement microlamellae of chitin of black corals and to improve the understanding of the role of chitin structure in the antipatharian skeleton, the mechanical properties of the skeleton of two black corals, Antipathes caribbeana and Antipathes pennacea, were examined using nanoindentation tests. Measurements of reduced elastic modulus, nanohardness and the viscoelastic behavior were measured with a spheroconical indenter. The results indicate variations in the values of the mechanical properties clearly associated with different structures present in the skeletons, the core being the one that invariably shows the maximum values. The solid multilamellar arrangement of black coral chitin, its viscoelastic behavior, and the anisotropic mechanical response, are relevant factors contributing to the successful adaptation of black coral colonies to shallow as well as to very deep waters.