The shape of the secondary sexual characters is, traditionally, used to discriminate the marine shrimps at the species level. However, the qualitative evaluation of structures that are morphologically variable in the taxonomy of species can favor misunderstandings and misidentifications. These possibilities of taxonomic inaccuracies are especially alarming when there is a need to evaluate the invasion of introduced species. The present study used geometric morphometric analyses to identify differences in the cephalothorax shape that would help discriminate the native and non-native species of Litopenaeus of the South American coast. The comparative morphology analysis was conducted using the right profile of adult males' cephalothorax of L. schmitti, captured in the natural environment, and L. vannamei captured in the natural environment or grown in shrimp farms. In intraspecific evaluation, it was not possible to distinguish the specimens of L. vannamei that were grown in shrimp farms from those acclimated to the natural environment. However, significant interspecific differences in shape were found in the shape of this body structure. Additionally, the base position of the first rostral spine to the tip of the hepatic spine is indicated as a characteristic that can be used to distinguish these two species by eye in the field.
Potimirim potimirim (Müller, 1881), a species of coastal freshwater shrimp, is recorded for the first time from the state of Rio Grande do Norte, northeastern of Brazil, where it was collected in a small tributary of the Potengi River. This record extends the distribution of this species about 220 km north along Brazilian coast. New records, such as this, reinforce the need for greater research efforts in the northeastern freshwater ecosystems of Brazil to provide better understand the region’s biodiversity and establish better parameters for conservation actions.
This study constitutes the most comprehensive effort ever done to assess the faunal diversity of the Macrobrachium genus within two ecoregions that encompass part of the northeastern Brazil: the Northeastern Caatinga & Coastal Drainages, and the São Francisco (Lower-middle and Lower portions). Through sampling in several of their hydrographic basins, bibliographic research, and consulting scientific collections, our results reveal the occurrence of five species along these ecoregions: Macrobrachium acanthurus, M. amazonicum, M. carcinus, M. jelskii and M. olfersii. We also provide the first record of these species for several river basins in both ecoregions. Additionally, we confirm the occurrence of M. carcinus from Rio Grande do Norte State and provide updated distribution maps for each species in the studied area. This carcinofauna survey may form the basis for future evaluations of eventual anthropic impacts on biological diversity resulting from projects being implemented in these regions, which involve the São Francisco interbasin water transfer.
We present the first record of Ambidexter symmetricus Manning & Chace, 1971 for the state of Rio Grande do Norte, northeastern Brazil, filling a distribution gap of this species in the country. We confirm the preference of this species for seagrass meadows in the Curimataú river estuary. Lastly, a brief overview and an updated distribution map for the records of this species on the Brazilian coast are provided.
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