44. Narrow-skulled Pocket Mouse Chaetodipus artus French: Souris-a-abajoues svelte / German: Schmalschddel-Rauhaartaschenmaus / Spanish: Raton de abazones de craneo estrecho Taxonomy. Perognathus artus Osgood, 1900, Batopilas, Chihuahua, Mexico. Based on detailed sequencing of nDNA and mtDNA genes, C. artus is a close relative of C. goldmani, the two are next closely related to C. nelsoni, and all three are part of the continental lineage of the “modern” clade of coarse-haired pocket mice, along with C. intermedius, C. penicillatus, C. eremicus, and C. pernix. Monotypic. Distribution. NW Mexico (Pacific coastal slope of S Sonora and SW Chihuahua to NW Durango, Sinaloa, and N Nayarit). Descriptive notes. Head-body mean 92 mm (males) and 86 mm (females), tail mean 99 mm (males) and 95 mm (females), ear mean 11 mm, hindfoot mean 23 mm; weight 13-27 g. Male Narrow-skulled Pocket Mice are slightly larger than females. It is a coarse-haired pocket mouse and medium-sized for the genus, with crested and tufted tail that is 125% longer than head-body length. Ears are large, rounded, and dark. Pelage is relatively coarse with conspicuous spines on rump. Pelage is brownish, obscured by black hairs along midline and particularly toward rump, with conspicuous bufty lateral stripe and white under parts. Dark colored populations occur in the drainage of the Rio Septentrion, Chihuahua, in foothills of Sierra Madre Occidental, where soil is darker and conditions are more mesic. Chromosomal complement has 2n = 54 and FN = 54. The Narrow-skulled Pocket Mouse is narrowly sympatric with its close relative, Goldman’s Pocket Mouse (C. goldmani), in the northern one-third ofits distribution. Compared with that species, the Narrow-skulled Pocket Mouse is slightly smaller with narrower skull and smaller auditory bullae, has less well-developed rump spines, wider dorsal tail stripe, less hairy tail, darker ears, and darker and more uniform (less grizzled) dorsal pelage. Where the coarse-haired Narrow-skulled Pocket Mouse occurs in the vicinity of the smooth-haired Sinaloan Pocket Mouse (C. pernix), it avoids arid thornscrub on fine, sandy soils to which the Sinaloan Pocket Mouse is restricted. Bailey’s Pocket Mouse (C. baileyi), another species that occursin the general vicinity,is larger, has lighter-colored pelage lacking rump spines, and favors more open areas of pebbly soils that mark transitions from sandy flats to rocky alluvial slopes or “bajadas.” Habitat. Somewhat sandy areas among mesquite (Prosopis, Fabaceae) along low elevations of rivers along the coast of southern Sonora and Sinaloa and progressively more rocky and gravelly river bottoms in more mesic, high-elevation areas supporting a more tropical riparian flora of fully developed, short-tree forests. Distribution of the Narrow-skulled Pocket Mouse becomes increasingly dendritic to the east as it follows rocky, riparian rivers and streams on western slopes of Sierra Madre Occidental. Its close relative, Goldman’s Pocket Mouse, occupies more open, xeric short-tree forest with gravelly and rocky soils, and it is replaced by the Narrow-skulled Pocket Mouse in closed, more mesic short-tree forest and riparian galleries along river and stream beds. Food and Feeding. Diet of the Narrow-skulled Pocket Mouse consists largely of seeds of shrubs, annuals, and grasses, but it also includes smaller amounts of green vegetation and insects. Food items are collected in external, fur-lined cheek pouches and transported back to burrows, where they are stored in burrow caches. It does not need to drink water, subsisting entirely on water from its food and water produced as a byproduct of metabolism. Breeding. There is no information for this species. Activity patterns. The Narrow-skulled Pocket Mouse is nocturnal and terrestrial, and it is active throughout the year. Movements, Home range and Social organization. There is no information is available for this species. Status and Conservation. Classified as Least Concern on The IUCN Red List. Bibliography. Alvarez-Castaneda, Castro-Arellano & Lacher (2008c), Aquino & Neiswenter (2014), Best & Lackey (1992a), Ceballos & Oliva (2005), Patton (1969a), Williams et al. (1993).

Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Heteromyidae, pp. 170-233 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on page 219, DOI: 10.5281/zenodo.6611160