large-toothed shrew

With an estimated range around 6,400 to 12,000 km², S. macrodon is endemic to Mexico and occupies mossy banks, moist cloud forest, and dense oak forests, where it may live under rocks or logs, beside streams, and in weedy vegetation. Mexican large-toothed shrews inhabit pine-oak, coniferous, and tropical forest growing inside the Trans-Mexican Volcanic Belt (TVB) within the southernmost Sierra Nevada.{{cite journal|last=Amori|first=Giovanni|author2=Chiozza, Federica |author3=Rondinini, Carlo |author4= Luiselli, Luca |title=Worldwide conservation hotspots for Soricomorpha focusing on endemic island taxa: an analysis at two taxonomic levels|journal=Endangered Species Research|year=2011|volume=15|issue=2|pages=143–149|doi=10.3354/esr00377|doi-access=free}} This natural landmark is found inside the Gulf of Mexico, and is a recognized hotspot for diversity, endemicity, and geographic transition of living biology - it boasts more than 75% of the sporadic distribution of S. macrodon.{{cite journal|last=Gámez|first=Niza|author2=Escalante, Tania |author3=Rodrígues, Gerardo |author4=Linaje, Miguel |author5= Morrone, Juán J. |journal=Revista Mexicana de Biodiversidad|year=2007|volume=83|pages=258–272}}

This particular species is entirely terrestrial; coincident species include: Megadontomis cryophilus, Peromyscus aztecus, and Peromyscus furvus.{{cite journal|last=Rogers|first=Duke|author2=Skoy, James |journal=Mammalian Species|year=2010|volume=43|issue=888|pages=209–215|doi=10.1644/888.1|title=Peromyscus furvus (Rodentia: Cricetidae)|doi-access=free}} S. macrodon shares extensive trails with Lepus callotis, and Microtus oaxacensis, as well as mountainous territory – at altitudes of 4200 meters - along with fellow shrews S. veraepacis, S. saussurei, and S. trowbridgii.{{cite journal|last=Escalante|first=Tania|author2=Rodríguez, Gerardo |author3=Morrone, Juán J. |title=The diversification of Nearctic mammals in the Mexican transition zone|year=2004|volume=83|pages=327–339}} Species are micro endemic to the neotropics of Veracruz, Oaxaca, and Puebla in southern Mexico.{{cite journal|last=Escalante|first=Tania|author2=Rodríguez, Gerardo |author3=Gámez, Niza |author4=León-Paniagua, Livia |author5=Barrera, Omar |author6= Sánchez-Cordero, Victor |title=Biogeografía y conservación de los mamíferos|year=2007|pages=485–502}}

Uninhibited destruction of local forests continues to shrink its narrow habitat. In 2005, civilian development had rendered 84% of the shrew’s original range unsuitable. “Biological Conservation” records that only 15.95% of S. macrodon habitat remained ecologically intact after deforestation; less than 25% of their potential distributions endured.

In farmland, shrews are likely to be affected by pesticides either through secondary contamination by the food chain or by direct exposure. Destruction of habitat boundaries, including markers such as forest limits and grass lines, diminish S. macrodon survival rates within small and sparse distribution. As a result, even small natural disasters or human interferences – such as mining operations, livestock ranching, wood-harvesting, or forest fires – could exterminate the entire population.{{cite book|last=Mares|first=Michael A.|title=Latin American Mammalogy|year=1991|publisher=University of Oklahoma Press|location=Norman, Oklahoma|pages=178}} Unfortunately, the Mexican large-toothed shrew is very poorly known, even in its native country. In summary, agriculture and urbanization pose major extinction threats to Sorex macrodon.{{cite journal|last=Sánchez-Cordero|first=Victor|author2=Illoldi-Rangel, P. |author3=Linaje, Miguel |author4=Sarkar, Sahotra |author5= Peterson, A. Townsend |title=Deforestation and extant distributions of Mexican endemic mammals|journal=Biological Conservation|year=2005|volume=126|issue=4|pages=465–473 |doi=10.1016/j.biocon.2005.06.022}}

It is mainly insectivorous, and feeds on small arthropods, arachnids, and some plant material.{{cite journal|last=Cervantes|first=Fernando A.|author2=Castro-Campillo, Alondra |author3=Ramírez-Pulido, José |title=Mamíferos terrestres nativos de México|journal=Anales Institucionales de Biología en la Universidad Nacional|year=1994|volume=65|issue=1|pages=177–190}}

The Mexican large-toothed shrew is rather large with a total length of 11.8 cm or more and a hind foot of 1.5 cm. Its pelage is a comparatively light (to other shrews in the family) mixed russet and black, with chamois colored ventral parts. The skull of S. macrodon is large and heavy with bulky teeth and reinforced margins of the anterior nostrils.{{cite journal|last=Merriam|first=C. Hart|title=Synopsis of the American shrews of the genus Sorex|journal=North American Fauna|year=1895|volume=10|pages=57–125|doi=10.3996/nafa.10.0003|doi-access=free}}

S. macrodon is part of the Beringean clade, one of two major clades in North America, and shows an early divergence from other North American species. S. macrodon has a cytochrome b gene sequence of 1081 base pairs, about the median range of its relatives. The Mexican large-toothed shrew is inferred to have diverged from others in its clade during the late Miocene.{{cite journal|last=Esteva|first=Martha|author2=Cervantes, Fernando A. |author3=brant, Sara V. |author4= Cook, Joseph A. |title=Molecular phylogeny of long-tailed shrews (genus Sorex) from México and Guatemala|journal=Zootaxa|volume=2615|year=2010|issue=2615|pages=47–65|doi=10.11646/zootaxa.2615.1.3|doi-access=free}}

{{Reflist}}

{{Soricomorpha|S2.}}

{{Taxonbar|from=Q1768840}}

Category:Sorex

Category:Endemic mammals of Mexico

Category:Fauna of the Trans-Mexican Volcanic Belt

Category:Mammals described in 1895

Category:Taxonomy articles created by Polbot

Category:Fauna of the Sierra Madre de Oaxaca