Cratogeomys merriami
Creators: name: Don E. Wilson
name: Thomas E. Lacher, Jr
name: Russell A. Mittermeier
Publisher: name: Lynx Edicions
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Rodentia
Geomyidae
Cratogeomys
Cratogeomys merriami

description: 38.
Merriam’s Pocket Gopher
Cratogeomys merriami
French: Gaufre de Merriam / German: Merriam-Taschenratte / Spanish: Tuza de Merriam
Taxonomy. Geomys merriami Thomas, 1893,
“S. Mexico.” Restricted by C. H. Merriam in 1895 to “probably the Valley of Mexico.”
Cratogeomys was regarded as a subgenus of Pappogeomys by R. J. Russell in 1968 but was returned to generic status by R. L. Honeycutt and S. L. Willams in 1982. Prior to systematic revision of C. merriami by M. S. Hafner and colleagues in 2005, C. fulvescens and C. perotensis were considered subspecies of C. merriami. Molecular studies show C. merriami to be closely related to C. fulvescens and C. perotensis, and these three species together with C. goldmani and C. castanops comprise the C. castanops species group. J. L. Patton in 2005 recognized six subspecies of C. merriami, but M. S. Hafner and colleagues in 2005 found no subspecies-level differentiation. Monotypic.
Distribution. Mexican endemic, patchily distributed in the S part of the Valley of Mexico (Sierra de Las Cruces, Sierra de Ajusco, Popocatéptl and Iztaccthutl Mts, and from Lerma at the E Toluca Valley E into W Puebla).
Descriptive notes. Head-body 230-285 mm (males) and 200-255 mm (females), tail 90-125 mm (males) and 80-120 mm (females); weight 580-700 g (males) and 450-670 g (females). Male Merriam’s Pocket Gophers are usually larger than females, but sexual dimorphism is not as pronounced as it is in many other geomyid species. Merriam’s Pocket Gopheris large for the genus. It has a fusiform body shape typical of all pocket gophers, and it possesses fur-lined cheek pouches that open external to the mouth. Dorsal coloris highly variable, from dull chestnut-brown to slate black. Ventral color is similar to dorsal color but paler. Anterior surface of each upper incisor has a single medial groove slightly displaced to the inner side of the tooth. Chromosomal complement has 2n = 36 and FN = 68.
Habitat. Wide variety of habitats, most characterized by arid conditions, sandy soils, and xeric-adapted vegetation. In parts ofits distribution, Merriam’s Pocket Gopher can be found in oak, pine, and fir woodlands and grassy mountain meadows, and it is known from near timberline on volcanic peaks east of Mexico City. It is known from elevations of 1800-4000 m.
Food and Feeding. There is no specific information available for this species, but all pocket gophers that have been studied eat predominately underground roots and tubers and a limited amount of surface vegetation. Merriam’s Pocket Gopher readily invades cultivated fields and is considered an agricultural pest wherever it comes in contact with humans. As in all other pocket gophers, the burrow system is a series of shallow feeding tunnels radiating spoke-like from a deeper, central network that contains one or more nest chambers and several smaller chambers for storage of food or fecal pellets. Burrow systems of Merriam’s Pocket Gopher can encompass 400 m* of surface area.
Breeding. Captures of pregnant female Merriam’s Pocket Gophers suggest that they breed throughout the year, with peak reproductive activities in October—March. Females may have multiple litters per year, with litters usually of 1-3 young.
Activity patterns. Merriam’s Pocket Gophers in the Valley of Mexico were active at any hour of the day, with periods of peak activity around dawn and dusk. Digging activity was generally higher in the dry season (especially December—January) and lower at the beginning of the wet season (June). It does not hibernate and is active year-round.
Movements, Home range and Social organization. There is no specific information available for this species, but Merriam’s Pocket Gopheris likely solitary and aggressively territorial. Individuals probably leave their burrow systems only rarely, meaning that their home range is defined by size and extent of their burrow system.
Status and Conservation. Classified as Least Concern on The IUCN Red Last.
Bibliography. Alvarez-Castafieda, Castro-Arellano, Lacher & Vazquez (2008f), Ceballos (2014), Hafner et al. (2005), Honeycutt & Williams (1982), Merriam (1895), Patton (2005b), Russell (1968b), Whisson & Villa-Cornejo (1994).
description: Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Geomyidae, pp. 234-269 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on pages 251-252, DOI: 10.5281/zenodo.6603807