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The freshwater genus Palaemon is widely distributed in north-eastern Mexico, where six species have been recognized. Of special interest is the area of the Cuatro Cienegas Valley (CCV) and the Salado and Bravo Rivers basins in central and northern Coahuila, where interconnections, ancient and contemporary, have created a mosaic of populations of species belonging to Palaemon that cannot unequivocally be assigned to one species. We seek to encompass the species determination in a phylogenetic framework by reconstructing phylogenetic relationships of the aforementioned populations and 4 of the species occurring in Mexico. We collected information of three genetic fragments (COl, 12S, and H3) and performed maximum likelihood and Bayesian inference phylogenetic analyses. Also, through the analysis of a partial sequence of the cytochrome oxidase subunit I gene (COI) from individuals coming from 22 populations, we explored phylogeographic patterns from the three basins. Relaxed molecular clock were carried out focused on dating the cladogenesis of all species, while mismatch and Bayesian Skyline Plots analyses were used to test for possible demographic changes in populations from CCV. Gene-separated and concatenated phylogenetic analyses supported the monophyly of the species described from Mexico, but did not show their inclusion in one monophyletic clade, rather depicting a structure congruent with multiple invasions to freshwater. Dating analysis provided long-term temporal framework for cladogenesis. Three different lineages were found in the CCV, confirming the high diversity of this region. One of them is identified with P. sutkussi, and two are possible new species to science. Haplotype analyses provided insight from recent population processes and are congruent with a scenario where despite keeping signatures of past cladogenesis, more recent genetic structure reveals surprisingly higher connectivity between basins associated to the Bravo river system and CCV. [ABSTRACT FROM AUTHOR]

Palaemonid shrimps form a large and diversified group distributed primarily in marine waters. Within the family Palaemonidae the subfamily Palaemoninae is composed of 26 genera and more than 370 species inhabiting marine and fresh waters in epigean and hypogean habitats. One of the relevant questions that have emerged in relation to the subfamily is how the invasion to freshwater has occurred in Mexico, where six freshwater genera belonging to the Palaemoninae (Creaseria, Cryphiops, Macrobrachium, Palaemonetes, Neopalaemon and Troglomexicanus), are present. The purpose of this study was to explore the relationships among these freshwater lineages through a phylogenetic analysis based on partial sequences of the 16S mitochondrial gene to elucidate if these genera are closely related and derived from a common ancestor or if each lineage has invaded the freshwater habitat independently. The analysis included species representing monotypic and diversified genera, from epigean and hypogean habitats and with complete and abbreviated larval development. The results suggest that the invasion of freshwater occurred on four different occasions and that the different lineages originated before the invasions of freshwater occurred. [ABSTRACT FROM AUTHOR]

New records are provided for four species of caridean shrimp (Alpheidae and Palaemonidae) from Sonora, Sinaloa, and Oaxaca, along the west coast of Mexico. Alpheus tenuis Kim & Abele, 1988 extends its northern range to Puerto Peñasco, Sonora. Alpheus martini Kim & Abele, 1988 is recorded for the first time outside of Panama (Alcatraz Island, Sonora). Pontonia simplex Holthuis, 1951 is recorded from Teacapan, Sinaloa, in the pen shell Atrina maura (Sowerby, 1835), which constitutes a new host record; additionally, its live colour pattern is described. The range of Pontonia margarita Smith, 1869 is extended along the Mexican coast south to Oaxaca. [ABSTRACT FROM AUTHOR]

In the Papaloapan River two freshwater prawns with abbreviated development have been recorded: Macrobrachium villalobosi (a stygobitic species) and Macrobrachium totonacum (an epigeal species). In this paper we describe four new species from this genus, and the distribution of these six species along the river basin. M. oaxacae nov. sp. occurs in the River La Junta, and together with M. cosolapaense nov. sp. is geographically close to the stygobitic species and M. totonacum, but differs from these in the following aspects: pigmentation, the number of rostral spines, and the relative proportions of the articles of the second pereiopod, of appendix masculina and appendix interna, and the number of spines on the appendix masculina. Macrobrachium mazatecum nov. sp. lives in two streams in Veracruz: the first close to Tierra Blanca Veracruz and the second on the Zapotal Veracruz near Mpio. Lerdo de Tejada. This species was also recorded in two springs near Valle Nacional Oaxaca, and differs from M. oaxacae nov. sp. and M. cosolapaense nov. sp. in the number of rostral spines, and the relative proportions on the articles of second pereiopod, of appendix masculina and appendix interna, and of the spines on the appendix masculina. Finally, Macrobrachium jacatepecense nov. sp. occurs only in a spring near Jacatepec, Oaxaca. This species differs from the other species in the relative proportions of the articles of the second pereiopod: however, it is very close to Macrobrachium oaxacae nov. sp. in the number of rostral spines, but based on the geographical distribution of both species and other features, it is clearly a different species. In this Papaloapan River basin, the distribution of this complex of species is very limited, because the various populations live in very restricted areas associated with springs or small streams, and without direct interconnections. All these new species are comparable with the epigeal Macrobrachium species in the southeast of Mexico that have abbreviated larval development. [ABSTRACT FROM AUTHOR]

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Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)