Molecular data suggest that Heteromys irroratus bulleri should be recognized as a species-level taxon

Recent collecting surveys in the Sierra de Manantlán Biosphere Reserve, Jalisco (México), uncovered the existence of a new population of the Mexican spiny pocket mouse, Heteromys irroratus. Because the subspecies H. i. bulleri and H. i. jaliscensis occur nearby, our objective was to properly determine the taxonomic identity of the novel sample. Also, we evaluate its distinctiveness, both in terms of genetic divergence and phylogenetic placement, relative to other members of H. irroratus. Preliminary, we compared external and cranial measurements of recently collected individuals to those reported for representatives of the subspecies of H. irroratus occurring close by. In addition, we examined levels of genetic differentiation and phylogenetic relationships, based on sequence data of the Cytochrome b, among this population and other members of H. irroratus, including an individual from Sierra de Juanacatlán, Jalisco, the type locality of H. i. bulleri. Phylogenetic relationships were estimated using Maximum Likelihood and Bayesian Inference methods and levels of genetic divergence were assessed employing Kimura-2-parameters genetic distances. Samples from Sierra de Manantlán and Sierra de Juanacatlán were grouped together in a well-supported haplogroup and genetic distances between them were lower than < 1.02 %. Our phylogenetic hypothesis shows that H. i. bulleri represents the sister group to all other samples of H. irroratus but that, genetically, is a very divergent lineage. Distances values between H. i. bulleri to any of the other groups were > 10.05 %. Comparison of external and cranial measurements showed that, in average, individuals from Sierra de Manantlán are larger than those of H. i. jaliscensis, but more similar in size to H. i. bulleri. Our results show that the new population of the Mexican spiny pocket mouse from Sierra de Manantlán belongs to H. i. bulleri. In addition, the phylogenetic separation and the high levels of genetic divergence of H. i. bulleri, relative to other members of H. irroratus, suggest that the first should be recognized as a species-level taxon. Considering the scarce collecting records of H. i. bulleri and the known area of occurrence, that is very restricted, this taxon may warrant special conservation status.

Rediscovery of Heteromys nelsoni in its type locality after over a century

We rediscovered a population of Nelson’s spiny pocket mouse (Heteromys nelsoni; Merriam, 1902) in the type locality of Pinabeto in the Mexican state of Chiapas, 121 years after it was last collected. We describe five topotype specimens according to their morphology and external measurements, and we confirm its identity at the species level in the Basic Local Alignment Search Tool (BLAST) of GenBank. As the population of H. nelsoni in Pinabeto is isolated, it is likely to be susceptible to extinction. There is a need to carry out additional scientific studies of this microendemic species in order to obtain more information regarding its biology, ecology and evolutionary history, and to be able to influence environmental policy to protect and conserve this species, as well as the region’s cloud forests.

Do island populations differ in size and shape compared to mainland counterparts?

Adaptation and evolution of terrestrial vertebrates inhabiting islands have been the topic of many studies, particularly those seeking to identify trends or patterns in body size in mammals, albeit not necessarily in shape, in relation to mainland populations. The spiny pocket mouse, Chaetodipus spinatus, is distributed in the Baja California peninsula and its surrounding islands. Insular populations became isolated ~12,000 due to changes in sea level; these populations’ matrilinear (mitochondrial) DNA shows minor interpopulation variation. We tested the hypothesis that adaptation and evolution in these island populations involve variation in both skull size and skull shape (using geometric morphometrics) relative to mainland populations, rather than only in size as previously assumed. A total of 363 specimens from 15 insular and peninsular populations were used in analysis of the skull length and geometric morphometric analyses. Our findings revealed significant differences related to skull size among population. The skull shape analyses showed two significantly different morphotypes: one for all island specimens and one for all mainland samples. Our analyses support the hypothesis that insular populations may not only vary in size relative to mainland populations, but may also show variations in shape, regardless of differing conditions across islands.

Projected impact of global warming on the distribution of two pocket mouse species with implications on the conservation of Heteromys nelsoni (Rodentia: Heteromyidae)

We explain through potential distributions and changes in altitudinal variation, the possible impacts of climate change in an endangered micro-endemic rodent of Mexico with narrow altitudinal range, Heteromys nelsoni and a rodent with a wide distributional and altitudinal range, Heteromys goldmani. We obtained historical and current records of both Heteromys species. Potential distribution models were generated using Maxent, including altitudes for each species and bioclimatic layers. We determined the Extent of Occurrence and Area of Occupancy for H. nelsoni according to the criteria of the IUCN in order to generate information about its risk status. The altitude is not a variable that determines a shift in the distribution caused by climate change. In contrast, the temperature and precipitation are important for the potential distribution of both Heteromys species. The future changes in climatic conditions will reduce the area of suitable habitat for H. nelsoni and will favor the presence of H. goldmani. The distribution surface is not greater than 33.44 km2 for H. nelsoni. Therefore, is urgent to re-evaluate their conservation status by the IUCN, mainly in its B criterion, and to take specific actions for their conservation. We suggest the creation of a terrestrial protected area.

Phylogeography and taxonomic revision of Nelson’s pocket mouse (Chaetodipus nelsoni)

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.

A New Species of Flea of the Genus Kohlsia Traub, 1950 (Siphonaptera: Ceratophyllidae) from Veracruz, Mexico

A new flea species, Kohlsia misantlensis, is described from the central mountains of Veracruz, Mexico. The hosts of this new species are the Mexican deer mouse Peromyscus mexicanus (Saussure, 1860) (Mammalia: Rodentia:Muridae) and the Mexican spiny pocket mouse Heteromys sp. (Heteromyidae). This flea species is easily recognized by the great development of sternite VIII with a tuft of seven long bristles near the apex. The new species is included in a taxonomic key for the species of genus Kohlsia occurring in Mexico.

Two new genera and two new species of the mite family Neopygmephoridae (Acari: Heterostigmata) associated with small mammals from USA

Two new monotypic genera and two new species of the mite family Neopygmephoridae (Acari: Pygmephoroidea) associated with small mammals are described from USA: Crossdania gen. nov. with the type species Crossdania tubulosa sp. nov. associated with Northern grasshopper mouse, Onychomys leucogaster (Rodentia: Cricetidae) and Great Basin pocket mouse, Perognathus parvus (Rodentia: Heteromyidae), and Theriodania gen. nov. with the type species Theriodania venusta sp. nov. associated with Merriam's kangaroo rat, Dipodomys merriami (Rodentia: Heteromyidae).