A new species of Palaemon from Cần Giớ District, Vietnam, previously confused with Palaemon sewelli (Kemp, 1925)

A new species of Palaemon is described from Cần Giớ District, Vietnam. This species has previously been reported from Vietnam as a colour morph of Palaemon sewelli (Kemp, 1925), to which it is clearly morphologically very closely related. However, the new species can be separated from P. sewelli through the position of the branchiostegal tooth relative to the branchiostegal groove, the shape of the suborbital lobe, a hirsute carapace and abdomen and the colour pattern of living individuals. The description of this new species brings the number of species of Palaemon known from Vietnam to eleven species

A new species of Palaemon from Cần Giớ District, Vietnam, previously confused with Palaemon sewelli (Kemp, 1925)

A new species of Palaemon is described from Cần Giớ District, Vietnam. This species has previously been reported from Vietnam as a colour morph of Palaemon sewelli (Kemp, 1925), to which it is clearly morphologically very closely related. However, the new species can be separated from P. sewelli through the position of the branchiostegal tooth relative to the branchiostegal groove, the shape of the suborbital lobe, a hirsute carapace and abdomen and the colour pattern of living individuals. The description of this new species brings the number of species of Palaemon known from Vietnam to eleven species

Diet analysis indicates seasonal fluctuation in trophic overlap and separation between a native and an introduced shrimp species (decapoda: palaemonidae) in the tidal River Thames (U.K.)

The diets of Palaemon longirostris and the non-native P. acrodactylus were investigated to explore their competitive interactions. Both species are largely carnivorous with amphipods being the dominant rey. Chironomid larvae were consumed in large numbers by both species in summer. Vacuity coefficients were higher for both species in winter than summer. A high degree of dietary overlap occurs in winter, with less overlap in summer suggesting that the two species compete for food on a seasonal basis, which may be attributed to the absence of chironomid larvae, and generally reduced prey availability, in the winter. If summer prey also become limited then competition for food may increase and P. macrodactylus may then have an adverse effect on P. longirostris. An introduction of P. macrodactylus in the summer, when there is less competition for food, may be more likely to lead to a successful colonisation than one in the winter.</p

Notes on the shrimp genus Palaemon Weber, 1795 (Crustacea, Decapoda, Palaemonidae) and related genera from Taiwan

The shrimp genus Palaemon Weber, 1795 and its related genera in Taiwan are reviewed based on newly collected specimens, whilst older records are critically reviewed. Five genera and 11 species are now known to occur in Taiwan, although there are no recent records for Palaemon modestus (Heller, 1862), which could be nationally extinct. The records of P. debilis Dana, 1852 and Nematopalaemon tenuipes (Henderson, 1893) in Taiwan are confirmed. Three genera, namely Brachycarpus Spence Bate, 1888, Leander Desmarest, 1849 and Leandrites Holthuis, 1950, each with one species are reported for the first time from Taiwan

Notes on the shrimp genus Palaemon Weber, 1795 (Crustacea, Decapoda, Palaemonidae) and related genera from Taiwan

The shrimp genus Palaemon Weber, 1795 and its related genera in Taiwan are reviewed based on newly collected specimens, whilst older records are critically reviewed. Five genera and 11 species are now known to occur in Taiwan, although there are no recent records for Palaemon modestus (Heller, 1862), which could be nationally extinct. The records of P. debilis Dana, 1852 and Nematopalaemon tenuipes (Henderson, 1893) in Taiwan are confirmed. Three genera, namely Brachycarpus Spence Bate, 1888, Leander Desmarest, 1849 and Leandrites Holthuis, 1950, each with one species are reported for the first time from Taiwan

Freshwater transitions and symbioses shaped the evolution and extant diversity of caridean shrimps

Understanding the processes that shaped the strikingly irregular distribution of species richness across the Tree of Life is a major research agenda. Changes in ecology may go some way to explain the often strongly asymmetrical fates of sister clades, and we test this in the caridean shrimps. First appearing in the Lower Jurassic, there are now ~3500 species worldwide. Carideans experienced several independent transitions to freshwater from marine habitats, while many of the marine species have also evolved a symbiotic lifestyle. Here we use diversification rate analyses to test whether these ecological traits promote or inhibit diversity within a phylogenetic framework. We demonstrate that speciation rates are more than twice as high in freshwater clades, whilst symbiotic ecologies are associated with lower speciation rates. These lower rates amongst symbiotic species are of concern given that symbioses often occur in some of the most diverse, delicately balanced and threatened marine ecosystems