Palaemon

Abstract: Life-history traits were studied in one marine and four fresh-water shrimps from tropical regions of western South America: Palaemon northropi, P. pandaliformis, Macrobrachium acanthurus, and M. olfersi (Palaemonidae). Occasional data are given for Macrobrachium carcinus and an atyid shrimp, Potimirim potimirim. Size was measured as total body length (TBL), carapace length (CL), and telson length (TL), weight as dry weight (W), and realized fecundity as number of eggs per female. Size and W of eggs were determined in an early stage of development. Relationships between measurements of size, weight, and fecundity are described with regression equations. Significant species- and sex-specific variation was found in the slopes of the allometric TBL-W relationship. In the 2 species of Palaemon, females grew to a larger size than males; they showed also a steeper W increase with increasing TBL. Opposite patterns were observed in M. acanthurus and M. olfersii, suggesting different traits on the generic level. The minimum sexable size (minimum size of males with appendix masculina) was unrelated to the species-specific maximum size. Size at the onset of female maturity (minimum size with eggs) was larger in M. acanthurus than in the other species (29 versus 20-22 mm); W at the onset of female maturity increased with the maximum size of a species. Regressions of egg number on TBL indicated the highest overall level as well as the strongest size-dependence of fecundity in M. olfersii; these parameters were lowest in P. pandaliformis. The reproductive output (RO:W of egg mass in relation to female body W) was lowest in the only marine species studies here, P. northropi (14.4 versus 18.6-21.7%). With the possible exception of the RO, the life-history traits of these tropical shrimps appear unrelated to the climatic origin or habitat of a species.

Abstract: A detailed illustrated key to the identi¢cation of the European species of the genera Palaemon and Palaemonetes is provided.This key has been elaborated taking into account recent changes in the species composition of both genera for European waters, such as the invalidity of Palaemon garciacidi, which is a synonym of P. longirostris, and the presence of an introduced species, Palaemon macrodactylus that has been recently recorded at diierent localities along the Atlantic coast. The key is based on external morphological characters to facilitate its use by non-specialists. Data on the coloration, habitat and distribution of all species are also given.

Abstract: The palaemonid shrimp genus Palaemon Weber 1795 is currently represented by 87 species worldwide, of which 36 species inhabit freshwater environments. In this study, we describe a new species of the genus, P. septemtrionalis, primarily based on material collected from rivers in Miyagi Prefecture, Tohoku District, northeastern Japan. The present new species is morphologically and genetically close to Palaemon paucidens De Haan, 1841, but it is morphologically distinguishable from the latter by the chela of the pereopod 2 being longer than the carpus (versus shorter than the carpus in P. paucidens) and the possession of a low, laminar convexity on the flexor margin of the pereopod 3 dactylus just proximal to the base of the unguis (such a laminar structure is absent in P. paucidens). Comparison of partial sequences of the mitochondrial 16S rRNA gene supports the recognition of the new species. Examination of museum collections and a BLAST search on GenBank revealed that the geographical range of the new species includes the Sea of Japan side ranging from Hokkaido to Hyogo Prefecture and the Pacific side ranging from Aomori to Miyagi Prefecture. An identification key to the 13 Japanese species of the genus is presented.

Abstract: The taxonomy of the palaemonid freshwater prawns of Myanmar is reviewed and 19 species are recorded. These belong to three genera, with 17 species of Macrobrachium, one species of Palaemonetes and one species of Leptocarpus. The identities of Palaemon spinipes birmanicus Schenkel, 1902, and Palaemon naso Kemp, 1918, are clarified with both recognised as distinct taxa. The taxonomy of several poorly known species of Macrobrachium,viz. M. villosimanus (Tiwari, 1949), M. peguense (Tiwari, 1952), M. hendersoni (De Man, 1906) and M. platyrostrum (Tiwari, 1952) is revised and discussed. Five species are reported from Myanmar for the first time, viz. Macrobrachium lamarrei (H. Milne-Edwards, 1837), M. dayanum (Henderson, 1893), M. lanchesteri (De Man, 1911), M. nipponense (De Haan, 1894), and Palaemonetes sinensis (Sollaud, 1911). One new species, Macrobrachium lanatum, which is closely allied to M. scabriculum (Heller, 1862) and M. dolichodactylus (Hilgendorf, 1879), is described and figured.