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We had previously revised the systematics of four species of Macrobrachium Spence Bate, 1868 from the Pacific coast of Mexico, including the Baja California Peninsula (BCP): M. americanum Spence Bate, 1868 , M. digueti (Bouvier, 1895), M. hobbsi Nates & Villalobos in Villalobos Hiriart & Nates Rodríguez, 1990 , and M. occidentale Holthuis, 1950. Genetic analyses of the mitochondrial markers 16S ribosomal RNA (16S) and cytochrome oxidase I (COI) of individuals of these morphological species from BCP have shown that, even facing the Gulf of California (Sea of Cortés) as an apparent marine ecological barrier, they are conspecific to their respective genetic lineages (species) found from the Pacific slope of mainland Mexico. We discuss the systematics of the fifth species of Macrobrachium from the Mexican Pacific slope, M. tenellum (Smith, 1871) to test the hypothesis that individuals of the putative M. tenellum from BCP belong to the same species from the Pacific slope of mainland Mexico. We revised the morphological characters of taxonomic importance using material obtained in the field and voucher material deposited in Mexican scientific collections, and performed molecular genetic analyses with newly generated fragments of the mitochondrial markers 16S and COI. We conclude, as in our previous studies on Macrobrachium species of the region, that the examined specimens of the putative M. tenellum from BCP belong to the same species found on the Pacific slope of mainland Mexico, and that oceanic dispersal is responsible for the distribution of the species of Macrobrachium in the peninsula rather than by vicariant events. [ABSTRACT FROM AUTHOR]

The amphidromous species of Macrobrachium Spence Bate, 1868 occurring on the Mexican Pacific slope (M. americanum Spence Bate, 1868, M. digueti (Bouvier, 1895), M. hobbsi Nates & Villalobos in Villalobos Hiriart & Nates Rodríguez, 1990, M. occidentale Holthuis, 1950 (Holthuis, 1950b), and M. tenellum (Smith, 1871)) show a disjunct distribution, with the abscence of records along about 2000 km of the coastal margins in the northern Gulf of California. Recent morphological and genetic studies using the mitochondrial genes 16S rRNA (16S) and cytochrome oxidase I (COI) show that individuals of the putative M. digueti , M. hobbsi , and M. occidentale from the Baja California Peninsula are conspecific to their respective taxonomic entities found along the Pacific slope of mainland Mexico. We review the systematics of M. americanum from the Mexican Pacific slope and found that individuals of putative M. americanum from the Baja California Peninsula belong to the same lineage of individuals from the Pacific slope of mainland Mexico based on newly generated fragments of the mitochondrial genes 16S (491 bp) and COI (548 bp). We present a systematic account for M. americanum , including a taxonomic treatment of the studied populations with a report of their genetic identity and phylogenetic relationships. [ABSTRACT FROM AUTHOR]

The varied physiography and climate of the Mexican territory have produced a large mosaic of inland aquatic ecosystems. However, zooplankton ecology has been studied mainly from the water bodies of Central (Trans Mexican Volcanic Belt), eastern (the Yucatán Peninsula), and southern Mexico. In contrast, the zooplankton from the Mesa Central water bodies has been insufficiently investigated. After a long history of zooplankton taxonomic studies, the first contributions to the zooplankton ecology dated to the 1990 s, rapidly increasing afterward. Most ecological information arises from field investigations and experiments under laboratory conditions, lacking mesocosms and whole-lake experiments. In the same way, the studies have been carried out in lentic, natural, and artificial water bodies, primarily eutrophic. Differently, the zooplankton ecology of lotic ecosystems is largely unknown. Here we summarized the progress made in the study of the zooplankton ecology of Mexican inland waters, revealing the most important research topics developed so far. [ABSTRACT FROM AUTHOR]

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