Perognathus alticola, Rhoads, 1894

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 : 208-209

26.

White-eared Pocket Mouse

Perognathus alticola

French: Souris-a-abajoues alticole / German: Weil 3ohrSeidentaschenmaus / Spanish: Raton de abazones de orejas blancas

Other common names: Tehachapi Pocket Mouse (inexpectatus)

Taxonomy. Perognathus alticola Rhoads, 1894 ,

Squirrel Inn, near Little Bear Valley, 5,500 ft, San Bernardino Mountains, San Bernardino Co., California, USA.

Despite contradictory published statements, the correct species name is alticola , not alticolus (the original spelling), to be in accordance with grammatical requirements of Latin, based on the opinion of the Nomenclature Committee of the American Society of Mammalogists. Based on detailed sequencing of nDNA and mtDNA genes, P. alticola is a member of the parvus species group of silky pocket mice, along with P. mollipilosus and P. parvus , and is sister-taxon to P. mollipilosus. It may represent a smaller, disjunct, and isolated subspecies of P. mollipilosus: it lacks notable differentiation in nDNA and mtDNA genes that have been studied, and while it has a different FN compared to the neighboring P. mollipilosus xanthonotus (74 vs. 76, respectively), it has the same fundamental number as Pm. clarus (in Utah) within the variable FN of P. mollipilosus (70-76), and is only slightly different morphologically from that geographically adjacent species. Two subspecies recognized.

Subspecies and Distribution.

P.a.alticolaRhoads,1894—SWUSA(SanBernardinoMts,SWCalifornia),butmaybeextinct.

P. a. inexpectatus Huey, 1926 — SW USA (Tehachapi Mts, SW California ).

Descriptive notes. Head—body mean 78 mm (males) and 73 mm (females), tail mean 86 mm (males) and 77 mm (females), ear mean 6 mm, hindfoot mean 22 mm (males) and 21 mm (females); weight 16-24 g. Male White-eared Pocket Mice are significantly larger than females. Pelage 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. Unlike most other silky pocket mice, the White-eared Pocket Mouse has lobed antitragus of ear pinna, and tail is slightly crested for distal one-third (with dark hairs). The White-eared Pocket Mouse is medium-sized to large-sized for the genus but smaller than its close relatives, the Great Basin Pocket Mouse (PF. mollipilosus) and the Columbia Plateau Pocket Mouse ( P. parvus ). Hairs on inner surface of ear pinna are white or yellowish. Dorsal pelage is yellowish brown and heavily blackish lined, dorsal hairs are plumbeous at their bases for 75% of their length, lateral line usually is faintly expressed, and under parts are white. Tail is the same length or slightly longer than head-body length and bicolored. Chromosomal complement has 2n = 54 and FN = 74. The subspecies inexpectatus is larger than the subspecies alticola and similar in size to P. mollipilosus xanthonotus. It seems most reasonable that the Great Basin Pocket Mouse extends south-east along slopes of the Sierra Nevada , with continuous populations connecting P. m. olivaceous and P. m. xanthonotus, a small geographical discontinuity (65 km) to inexpectatus, then a larger gap between that subspecies and disjunct,likely extinct, alticola . Compared with the nearby San Joaquin Pocket Mouse ( P. inornatus ) and the Little Pocket Mouse ( P. longimembris ), the White-eared Pocket Mouse is distinguished by its lobed antitragus and longer, darker hairs forming crest on distal part oftail.

Habitat. Arid shrub and forest communities. The White-eared Pocket Mouse is the rarest of the silky pocket mice and occurs as isolated, relictual populations in a few scattered localities in the Transverse (1067-1829 m elevation) and San Bernardino (1646-1768 m) ranges along the western edge of the Mojave Desert. The two subspecies are separated by the intervening San Gabriel Mountains. In the San Bernardino Mountains, the White-eared Pocket Mouse is (or was) restricted to arid ponderosa pine ( Pinus ponderosa, Pinaceae ) communities in the vicinity of Little Bear Valley and Strawberry Peak. In the Tehachapi Mountains,it is found in arid shrub-steppe communities from Tehachapi Pass to Mount Pinos, and Elizabeth and Quail Lakes. Specific habitats are dry open floors of ponderosa pine forest in bracken ferns (Pteridium aquilinum), grassy flats among scattered ponderosa pines and Jeffrey pines ( Pinus jeffreyi), and Joshua tree ( Yucca brevifolia, Asparagaceae ) and pinyon—juniper woodland. At lower elevations, it occurs in chaparral and coastal sage and rangeland habitat of mostly introduced grasses. Much ofits limited distribution is used as cattle range that supports a variety of introduced grasses. It has been found in heavily disturbed habitat (e.g. fallow grain fields dominated by Russian thistle, Salsola , Amaranthaceae ).

Food and Feeding. There is no information available for this species.

Breeding. There is no information available for this species.

Activity patterns. The White-eared Pocket Mouse is nocturnal and terrestrial, and it likely enters torpor for long periods in winter.

Movements, Home range and Social organization. There is no information available for this species.

Status and Conservation. Classified as Endangered on The IUCN Red List. No specimens of the subspecies alticola have been collected since 1934, and it may be extinct. The other subspecies (inexpectatus) has been verified since 1978 at three localities, and it may be present at several other historical sites.

Bibliography. Aquino & Neiswenter (2014), Best (1993a, 1994b), Jones (1993), Linzey & NatureServe (Hammerson) (2008i), Riddle et al. (2014), Williams (1978a, 1999a), 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.a.alticolaRhoads,1894—SWUSA(SanBernardinoMts,SWCalifornia),butmaybeextinct. P. a. inexpectatus Huey, 1926 — SW USA (Tehachapi Mts, SW California ).