Redescription of Ctenapseudes sapensis (Chilton, 1926) from the Upper Songkhla Lagoon, Thailand (Crustacea: Tanaidacea)

The parapseudid tanaidacean Ctenapseudes sapensis (Chilton, 1926) is minutely redescribed and illustrated. The species is very similar to C. chilkensis, described by the same author based on samples from the brackish Chilka Lake in India (Chilton, 1924). C. sapensis was the only apseudomorph tanaidacean found in Upper Songkhla Lagoon, southern Thailand.This species is dominant in this lagoon, and, at the same time, is a major food source for some catfishes (Osteogeneiosus militaris, Arius truncatus and Arius maculatus)

\u3ci\u3eBrachylicoa lui\u3c/i\u3e, a New Species of Parapseudid Tanaidacean (Crustacea: Peracarida: Apseudomorpha), From the Hawaiian Islands, With a Taxonomic Key

Brachylicoa lui sp. n. is described from the coastal waters of the Hawaiian island of O‘ahu. It is distinguished from the other four nominal members of Brachylicoa by a combination of characters including (1) an incised margin between base of rostrum and carapace, (2) mandible palp article-1 with cluster of 20–25 simple setae, (3) maxillule biarticulate palp ending in eight “cleaning’ setae, (4) maxilliped inner sub-distal margin with two stout spiniform seta, and (5) pereopod-6 with carpus having three plumose setae on mid-dorsal margin. Brachylicoa (=Apseudes) babelmandebensis sensu Guţu is tentatively transferred to the genus Saltipedis Guţu sensu lato. Brachylicoa lui is the only member of the genus known from the mid-Pacific Region and the Northern Hemisphere; the other species of the genus are known from the western Pacific and Indian Ocean in the Southern Hemisphere. A key to separate the four nominal species of Brachylicoa species is presented

INFLUENCE OF NATURAL AND ANTHROPOGENIC DISTURBANCE ON THE SOFT BOTTOM MACROBENTHIC COMMUNITY OF THE CAMPECHE BANK, MEXICO

The structure of macrobenthic communities was investigated in carbonate and transitional carbonate-terrigenous sediments of the Southern Gulf of Mexico (Campeche Bank). The aim was to assess the influence of natural disturbance represented by winter storms and river runoff and the putative influence of oil-related activities using a regional approach. At a scale of > 100 km community composition of benthic macroinfauna was characterised as distinct assemblages within the carbonate and transitional sedimentary provinces controlled by natural disturbance. The carbonate assemblage was numerous and diverse influenced by a heterogeneous substratum. Winter storms had a severe impact with mortality probably resulting from abrasion and passive transport causing low values of number of taxa, abundance, biomass and diversity measurements. Conversely, on the transitional shelf a sequence of disturbance from river runoff and winter storms resulted in a general impoverished community due to fine sedimentation and sediment instability. Immediately after the rainy season, values of biological measures were low, but the severity of disturbance was contingent with depth. At a scale of 10s km within the transitional shelf, the combined effect from natural and anthropogenic disturbance caused extremely low values of biological measures within the so called oil exclusion zone. Despite the lack of adequate controls the effects of oil related activities were identified as severe reductions in macroinfauna densities and biomass resulting in a very simple community. Large spatial variability at this scale masks the temporal variation observed in other areas of the Campeche Bank and the relationship between biological measures and indicators of oil activities (Barium, Nickel and oil-hydrocarbons). Finally the increased variability resulting from the influence of oil activities interrupts the natural gradient of macroinfauna patterns across the shelf.Plymouth Marine Laboratory, Centro de Investigacion y de Estudios Avanzados del IPN unidad Merida, Mexico and Instituto de Ciencias del Mar y Limnologi'a UNAM, Mexic

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