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Chaetodipus nelsoni occurs on rocky substrates across the Mexican Altiplano. We investigated phylogeographic diversity within the species using morphologic, karyotypic, and molecular data. Data from nuclear (AFLP) and mitochondrial DNA support three distinct genetic groups with minimal substructuring coincident with biogeographic barriers previously identified in the Chihuahuan Desert and drainage basins of the Altiplano. We examined the morphological and karyotypic data in light of the molecular data. The results support recognition of three species within the currently accepted widespread C. nelsoni : 1) C. nelsoni restricted to a distribution centered on the El Salado River Basin; 2) elevation of C. n. collis to species, with two subspecies: one centered on Trans-Pecos Texas, the other on the Mapimí Basin (new subspecies); and 3) recognition of a new species, C. durangae , centered on the Nazas Basin and upper Río Mezquital drainage. [ABSTRACT FROM AUTHOR]

Once encompassing as many as 9 species of pocket gophers spread across most of the Mexican Altiplano, the genus Pappogeomys is now restricted to a single species, P. bulleri, occupying the mountains, tablelands, and coastal plains near the western end of the Trans-Mexican Volcanic Belt in west-central Mexico. Herein, we review the taxonomic history of Pappogeomys and examine relationships among populations of P. bulleri from throughout the geographic range of the species based on analyses of nonpreferentially stained karyotypes and mitochondrial and nuclear sequence data. Results of these analyses are concordant and reveal 3 major clades of P. bulleri that are separated by major physiographic features of the region, including the Sierra Madre del Sur and drainages of the Río Grande de Santiago, Río Ameca, Río Ayuquila, and Río Armería. We reduce the number of subspecies of P. bulleri from 9 to 5 valid forms and provide a revised synonymy of the species. [ABSTRACT FROM AUTHOR]

The Southern Coahuila Filter-Barrier (SCFB) effectively subdivides the mammalian fauna of the Mesa del Norte, the northern and most extensive section of the Mexican Altiplano. Pocket gophers of the genus Cratogeomys north and south of this filter-barrier have been informally recognized as 2 distinct species, C. castanops and C. goldmani, respectively. Support for species recognition derives from early morphological comparisons and recent chromosomal and ectoparasite studies. Contradictory conclusions based on the only comprehensive morphometric study have prevented formal recognition of C. goldmani. A morphometric reevaluation based on ratiotransformed data reveals that the previous analysis was unduly biased by size, an ecophenotypically plastic character. When this factor is removed, morphometric variation is fully concordant with chromosomal diploid number and sequence data of mitochondrial and nuclear DNA. We provide synonymies and descriptions for C. goldmani apart from C. castanops, and revise the number of subspecies from a total of 26 to 2 subspecies in each species. The SCFB is most effective in its central portion (Desierto Mayán), and least effective in its western portion (Río Nazas), which should be geographically broadened to include the neighboring Río Aguanaval. [ABSTRACT FROM AUTHOR]

A study of chromosomal variation in the Mexican pocket gopher Cratogeomys merriami revealed differences in diploid number that correspond to 3 major genetic and morphological clades within the species. Each of these 3 clades is diagnosable based on multiple characters, including chromosomal diploid number, quantitative and qualitative morphological characters, and mitochondrial DNA. Accordingly, we restrict the name C. merriami (Thomas) to include only pocket gophers of this genus from the states of México, México D.F., northern Morelos, and west-central Puebla. We resurrect the species name C. fulvescens Merriam to represent members of this genus from southern Tlaxcala, east-central Puebla, and parts of west-central Veracruz. Finally, we resurrect the species name C. perotensis Merriam to represent members of this genus from southern Hidalgo, northern Tlaxcala, north-central Puebla, and parts of west-central Veracruz. Based on the observation that differences in diploid number usually signal reproductive isolation between populations of pocket gophers, we hypothesize that C. merriami, C. fulvescens, and C. perotensis are reproductively incompatible. We provide synonymies and descriptions for these 3 species, along with a key to the C. castanops species group to which these species belong. [ABSTRACT FROM AUTHOR]

The genus Cratogeomys, particularly members of the Cratogeomys gymnurus species group, account for much of the high species diversity of pocket gophers in the Trans-Mexican Volcanic Belt. Recent molecular studies of this species group have shown strong discordance between genetically defined clades and current species taxonomy. Accordingly, we investigated relationships among the 5 species in the C. gymnurus species group using mitochondrial and nuclear DNA, chromosomes, and morphological characters. Although quantitative morphometrics provided little discrimination among species or clades within this group, the molecular data sets were consistent in identifying 5 allopatric clades, none of which corresponded to any of the 5 currently recognized species. Four of these 5 genetically defined clades lack clear diagnosability, and so are grouped into the single polytypic species, C. fumosus. The fifth clade is diagnosable based on multiple characters, including nuclear genotype, chromosomal diploid number, parasite fauna, and qualitative morphological characters. Accordingly, we resurrect Merriam's (1895) species planiceps to represent members of this clade, which occurs in the Volcán de Toluca and Valle de Bravo regions of central Mexico. Based on the observation that differences in diploid number usually signal reproductive isolation between populations of pocket gophers, we hypothesize that C. fumosus and C. planiceps are reproductively incompatible. We provide synonymies and descriptions for these 2 species, along with a key to this species group, which is now called the C fumosus species group. [ABSTRACT FROM AUTHOR]