Perognathus flavescens, Merriam, 1889

Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Heteromyidae, Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona: Lynx Edicions, pp. 170-233 : 206-207

23.

Plains Pocket Mouse

Perognathus flavescens

French: Souris-a-abajoues flavescente / German: Plains-Seidentaschenmaus / Spanish: Raton de abazones de llanura

Other common names: Apache Pocket Mouse (apache, caryi, melanotis)

Taxonomy. Perognathus flavescens Merriam, 1889 ,

Kennedy, Cherry Co., Nebraska, USA.

Based on detailed sequencing of nDNA and mtDNA genes, P. flavescens is a member of the fasciatus species group ofsilky pocket mice along with P. fasciatus . The FN = 48 karyotype differs from that of P. fasciatus in that the Xand Y-chromosomes are both biarmed. In 1978, D. F. Williams included P. apache under P.flavescens based on morphological analysis and revised the distribution of the subspecies apache, caryi, and melanotis. In their 2011 analysis of evolutionary diversification in this species group (based on mtDNA and amplified fragment length polymorphisms), S. A. Neiswenter and B. R. Riddle revealed three distinct lineages within P. flavescens that may represent morphologically cryptic species: a basal clade (“apache North”) on the northern Colorado Plateau north of the San Juan River in Utah, which is estimated to have diverged from the other two clades 3-6 million years ago; an “apache South” clade of the southern Colorado Plateau and northern Chihuahuan Desert; and the main flavescens clade of the Great Plains and Llano Estacado. The “apache North” clade is further divided into subclades north and south of the Colorado River, and the “apache South” clade is further divided into subclades east and west of the Continental Divide. They found evidence for possible nDNA introgression between apache and flavescens at one purported zone of hybridization but concluded that it is likely to be geographically limited and uncommon. They proposed that the two groups are maintaining their genetic distinction (i.e. acting as full species) but suggested that further studies were needed to fully describe nature and extent of contact zones. Neiswenter and Riddle also suggested that because morphology tends to follow basic ecogeographical rules, leading to convergence among distinct lineages, it might not be the appropriate basis for identifying species diversity in Perognathus . Genetic clades delineated by Neiswenter and Riddle correspond with subspecies distributions of the Apache Pocket Mouse as they were delineated prior to Williams’s revision based on morphology: the “apache North” clades corresponds to the previous distribution of caryi, and “apache South” with apache. Neither the subspecies melanotis, either as previously restricted to the type locality of Casas Grande in Chihuahua or as more broadly distributed as indicated by Williams, nor the subspecies relictus, which Williams restricted to the San Luis Valley of southern Colorado, were sampled by Neiswenter and Riddle. Williams indicated that specimens of melanotis differ only in pelage color from those of southern New Mexico and south-eastern Arizona, whereas the disjunct isolate relictus differs in skull proportions from populations in New Mexico. It appears that there may be at least two additional, morphologically cryptic species within P.flavescens : the “Apache Pocket Mouse” on the Colorado Plateau south of the San Juan River and a new species in the Colorado Plateau north of the San Juan River. Status of P. flavescens in the northern Chihuahuan Desert is unclear. Extant populations are known along both sides of the Rio Grande south to El Paso,Texas, and adjacent Zaragoza, Chihuahua. Extant but disjunct and isolated populations are known from in and around gypsum sand dunes of White Sands National Monument of southern New Mexico, Samalayuca Dune Fields (Medanos de Samalayuca) of north-eastern Chihuahua, and Casas Grandes in northwestern Chihuahua. All are located within a more continuous distribution of P. flavus . The supposed continuous distribution across southern New Mexico and into southeastern Arizona is based on three records, all of which are in areas where P. flavus is common. The record from the edge of the Willcox Playa (remnant of Pleistocene Lake Cochise) in Arizona was collected in 1931, and no specimens have been found in the vicinity since, despite repeated efforts. Similarly, the record from Deming, New Mexico, was collected in 1889, and no specimens have been found since. Finally, the record from northern Hidalgo County in south-western New Mexico is based on morphological identification of three specimens from one locality. In 2003, of seven specimens of P. flavus collected ¢.20 km south-west ofthat locality, six were clearly of P. flavus but one appeared significantly larger based on external measurements and had a smaller post-auricular spot (i.e. similar to P. flavescens ). All seven specimens possessed mitochondrial sequences of P. flavus . Eight subspecies are recognized.

Subspecies and Distribution.

P.f.flavescensMerriam,1889—CUSA(WCGreatPlains,SWSouthDakota,andSEWyomingtoEColoradoandSEKansas).

P.f.apacheMerriam,1889—SWUSA(NEArizona,SEUtah).

P.f.caryiGoldman,1918—SWUSA(E&SEUtah,W&SWColorado,NEArizona,andNW&CNewMexico).

P.f.cockrumiHall,1954—SCUSA(CKansastoSCOklahoma).

P.f.copeiRhoads,1894—SCUSA(WOklahoma,WTexas,andENewMexico).

P.f.melanotisOsgood,1900—SWUSAandNMexico(SEArizona,CNewMexico,extremeWTexas,andNChihuahua).

P.f.pernigerOsgood,1904—NCUSA(SENorthDakota,SWMinnesotatoNENebraskaandNWMissouri).

P. f. relictus Goldman, 1938 — SW USA (San Luis Valley, SC Colorado).

Descriptive notes. Head-body mean 71 mm,tail mean 64 mm, ear mean 7 mm, hindfoot mean 19 mm; weight 7-16 g. There is no significant secondary sexual dimorphism. As in other silky pocket mice, pelage of the Plains Pocket Mouse is soft, fine, and full, with no hint of spines orstiff bristles; posterior one-half of sole of hindfoot has sparse covering of short hairs; and tail is short and not tufted. The Plains Pocket Mouse has short, rounded ears without a lobed antitragus, and tail lacks crest or tuft. It is medium-sized for the genus. Usual dorsal pelage ranges from dark ocherous buff, heavily suffused with blackish hairs to pale ocherous lightly mixed with dusky hairs, but it is quite variable: nearly black mice occur on black volcanic sands near Flagstaff, Arizona, and nearly white mice live on the white gypsum sands of the Tularosa Basin, New Mexico. The Plains Pocket Mouse has small buffy post-auricular spot, dark ocherous to pale yellowish lateral line, and white under parts (same color as lateral line in dark-colored races). Tail is shorter than head-body length and moderately bicolored. Chromosomal complement has 2n = 44 and FN = 48 or 50 (melanotis).

Habitat. Sand dunes and stabilized sandy soils with a sparse vegetative cover and occasionally reported from rocky, brushy slopes. Vegetation ranges from sand sage ( Artemisia filifolia, Asteraceae ), yucca ( Yucca , Asparagaceae ), skunkbrush ( Rhus aromatic, Anacardiaceae ), and sunflowers (Helinathus, Asteraceae ) to sage—grass and yucca—grass communities, or even cornfields. Burrows with tiny openings (2-3 cm diameter) are usually found around bases of shrubs or in banks of dry streambeds. Burrows of Plains Pocket Mice are plugged during the day; burrows are simple, usually not extending beyond a few meters and 50 cm in depth, with only a single opening. Nest and cache chambers are simply widened areas of the tunnel.

Food and Feeding. Diet of the Plains Pocket Mouse consists largely of seeds of shrubs, annuals, and grasses, but it also includes smaller amounts of green vegetation and insects. Seeds are usually smaller, abundant seeds of herbaceous plants, but they may include larger seeds of pinyon pine ( Pinus edulis, Pinaceae ), juniper ( Juniperus , Cupressaceae ), and oak ( Quercus , Fagaceae ). Corn becomes a large part of the diet when the Plains Pocket Mouse lives along or in cornfields. Food items are collected in external, fur-lined cheek pouches and transported back to burrows, where they are stored in burrow caches. One burrow contained cached seeds with caloric content sufficient to last for 35 days. The Plains Pocket Mouse readily climbs stems of sedges and other plants to collect seeds. Like all small silky pocket mice, it tends to husk seeds or separate seeds from seed-heads before stuffing them in its cheek pouches. It does not need to drink water, subsisting entirely on water from its food and water produced as a byproduct of metabolism.

Breeding. Plains Pocket Mice breed in April-August, probably with a mid-summer lull in reproductive activity. It appears that females usually have a single litter of 4-5 young/year (range 2-7), although they are capable of having 2-3 litters in favorable years. Gestation is 25-26 days. Females born early in the year often breed at 10-12 weeks old. Population turnoveris high, with most individuals living 1-2 years.

Activity patterns. The Plains Pocket Mouse is nocturnal and terrestrial, and it likely enters torpor for long periods in winter. In Minnesota, individuals become active as early as March, and males may emerge before females. Individuals are inactive aboveground from late autumn to early spring, awaking periodically from torpor to feed on seed caches.

Movements, Home range and Social organization. Estimates of home range sizes of the Plains Pocket Mouse are 0-02-0-05 ha. Longest reported movement in 24 hours was 47 m.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Aquino & Neiswenter (2014), Linzey, Timm, Alvarez-Castaneda, Castro-Arellano & Lacher (2008e), Monk & Jones (1996), Neiswenter & Riddle (2011), Williams (1978a, 1978b, 1999b), Williams et al. (1993).

Figures

1. Salvin’s Spiny Pocket Mouse (Heteromys salvini), 2. Panamanian Spiny Pocket Mouse (Heteromys adspersus), 3. Mexican Spiny Pocket Mouse (Heteromys irroratus), 4. Jaliscan Spiny Pocket Mouse (Heteromys spectabilis), 5. Painted Spiny Pocket Mouse (Heteromys pictus), 6. Nelson's Spiny Pocket Mouse (Heteromys nelsoni), 7. Trinidad Spiny Pocket Mouse (Heteromys anomalus), 8. Overlook Spiny Pocket Mouse (Heteromys catopterius), 9. Paraguana Spiny Pocket Mouse (Heteromys oasicus), 10. Southern Spiny Pocket Mouse (Heteromys australis), 11. Ecuadorean Spiny Pocket Mouse (Heteromys teleus), 12. Gaumer’s Spiny Pocket Mouse (Heteromys gaumeri), 13. Desmarest’s Spiny Pocket Mouse (Heteromys desmarestianus), 14. Goldman’s Spiny Pocket Mouse (Heteromys goldmani), 15. Cloud-dwelling Spiny Pocket Mouse (Heteromys nubicolens), 16. Mountain Spiny Pocket Mouse (Heteromys oresterus)

Subspecies and Distribution. P.f.flavescensMerriam,1889—CUSA(WCGreatPlains,SWSouthDakota,andSEWyomingtoEColoradoandSEKansas). P.f.apacheMerriam,1889—SWUSA(NEArizona,SEUtah). P.f.caryiGoldman,1918—SWUSA(E&SEUtah,W&SWColorado,NEArizona,andNW&CNewMexico). P.f.cockrumiHall,1954—SCUSA(CKansastoSCOklahoma). P.f.copeiRhoads,1894—SCUSA(WOklahoma,WTexas,andENewMexico). P.f.melanotisOsgood,1900—SWUSAandNMexico(SEArizona,CNewMexico,extremeWTexas,andNChihuahua). P.f.pernigerOsgood,1904—NCUSA(SENorthDakota,SWMinnesotatoNENebraskaandNWMissouri). P. f. relictus Goldman, 1938 — SW USA (San Luis Valley, SC Colorado).