Part 6

General tone of upper parts grayish; cheeks and underparts white, more or less dulled by gray; size large; skull large.

Baculum: Shaft thin; keel low, 2/5 of length of tip; tip 16 per cent of length of shaft; angle formed by tip and shaft 130°; distal 1/10 of shaft slightly compressed laterally; base incised dorsally; shaft markedly long, 4.88 mm.

Differs from E. speciosus, E. panamintinus, E. umbrinus, E. palmeri, and E. bulleri, in base incised dorsally, base not widened, shaft thinner, tip proportionally shorter; from E. quadrivittatus, E. ruficaudus, E. cinereicollis, and E. quadrimaculatus, in base incised dorsally, shaft thinner, tip proportionally much shorter.

For comparisons with E. alpinus, E. minimus, E. townsendii, E. sonomae, E. amoenus, and E. dorsalis, see the accounts of those species.

Specimens examined: One from Mount Piños, Ventura Co., California (LA).

#Eutamias quadrivittatus# (Say)

Figures 8-10

Color bright and tawny; size medium to large; braincase widened.

Baculum of E. q. quadrivittatus: Shaft thick; keel proportionally low, 1/4 of length of tip; tip 30 to 44 per cent of length of shaft; angle formed by tip and shaft 130°; distal 1/3 of shaft slightly compressed laterally; shaft long, 3.17 to 3.62 mm.

Differs from E. q. hopiensis, in baculum larger, angle formed by tip and shaft less distinct; from E. ruficaudus ruficaudus, in shaft and tip proportionally shorter; from E. r. simulans, in keel proportionally lower, shaft usually shorter and narrower; from E. cinereicollis, in shaft shorter, angle formed by tip and shaft larger, ridges on either side of tip more distinct; from E. quadrimaculatus, in tip proportionally shorter, shaft shorter; from E. speciosus, E. panamintinus, E. umbrinus, E. palmeri, and E. bulleri, in base not markedly widened, shaft longer, angle formed by tip and shaft larger.

For comparisons with E. alpinus, E. minimus, E. townsendii, E. sonomae, E. amoenus, E. dorsalis, and E. merriami, see the accounts of those species.

Baculum of E. q. hopiensis: Shaft thick; keel proportionally low, 1/3 of length of tip; tip 34 per cent of length of shaft; angle formed by tip and shaft 130°; distal 1/3 of shaft slightly compressed laterally; shaft short, 2.64 mm. in length.

Differs from E. ruficaudus ruficaudus, E. r. simulans, E. cinereicollis, and E. quadrimaculatus, in being shorter, proportions as in E. q. quadrivittatus; from E. speciosus, E. panamintinus, E. umbrinus, E. palmeri, and E. bulleri, in base not markedly widened, angle formed by tip and shaft larger; from E. alpinus, E. minimus, E. townsendii, E. sonomae, E. amoenus, E. dorsalis, and E. merriami, except for smaller size, as in E. q. quadrivittatus.

Bacula of E. q. hopiensis from northeastern Arizona are like those in typical E. q. quadrivittatus. The specimens from this region, to judge from parts of the animal other than the baculum, are intergrades between E. q. hopiensis and E. q. quadrivittatus. Specimens from near Moab, Grand Co., Utah, are typical E. q. hopiensis and the bacula of these specimens are considerably smaller than those of specimens of typical E. q. quadrivittatus. No bacula are known to me that are structurally intermediate between those of E. q. quadrivittatus and E. q. hopiensis.

Specimens examined: 21.

E. quadrivittatus quadrivittatus: Colorado: Gunnison Co.: Sapinero, 1 (BS). Chaffee Co.: Unspecified, 1 (MM). Saguache Co.: 5 mi. N and 22 mi. W Saguache, 10,000 ft., 1. Fremont Co.: Canon City, 3 (BS). New Mexico: Rio Arriba Co.: Dulce, 1 (BS). Taos Co.: 23 mi. S and 6 mi. E Taos, 8,750 ft., 4. Union Co.: Sierra Grande, 1 (BS). Valencia Co.: Mirror Spring, Mt. Taylor, 3 (MM). Torrance Co.: S end, E slope, Manzano Mountains, 2 (BS).

E. quadrivittatus hopiensis: Utah: Grand Co.: Mouth of Nigger Bill Canyon, E side Colorado River, 4 mi. N Moab Bridge, 4,500 ft., 1 (UU); Moab, 4,500 ft., 1 (UU). Arizona: Apache Co.: Tunicha Mountains, 1 (BS).

#Eutamias ruficaudus# Howell

Figures 11-12

General tone of upper parts dark tawny; size medium; braincase narrowed.

Baculum of E. r. ruficaudus: Shaft thick; keel proportionally low, 1/4 of length of tip; tip 31 to 33 per cent of length of shaft; angle formed by tip and shaft 120°; distal 2/5 of shaft slightly compressed laterally; base slightly widened; shaft long, 4.09 to 4.56 mm.

Differs from E. r. simulans, in keel proportionally lower, tip proportionally shorter, distal 1/5 of shaft less laterally compressed, shaft usually longer; from E. cinereicollis, in angle formed by tip and shaft smaller, shaft shorter, ridges on either side of tip distinct; from E. quadrimaculatus, in tip proportionally longer, shaft usually shorter; from E. speciosus, E. panamintinus, E. umbrinus, E. palmeri, and E. bulleri, in base not markedly widened, shaft longer, angle formed by tip and shaft larger.

For comparisons with E. alpinus, E. minimus, E. townsendii, E. sonomae, E. amoenus, E. dorsalis, E. merriami, and E. quadrivittatus, see the accounts of those species.

Baculum of E. r. simulans: Shaft thick; keel proportionally low, 2/5 of length of tip; tip 40 to 48 per cent of length of shaft; angle formed by tip and shaft 130°; distal 2/5 of shaft laterally compressed; base slightly wider than shaft; shaft medium to long, 3.30 to 4.26 mm.

Differs from E. cinereicollis in, keel proportionally higher, shaft shorter, tip proportionally longer, angle formed by tip and shaft smaller, distal 2/5 of shaft more laterally compressed; from E. quadrimaculatus in, keel proportionally higher, angle formed by tip and shaft larger, tip proportionally longer, distal 2/5 of shaft more laterally compressed, shaft shorter; from E. speciosus, E. panamintinus, E. umbrinus, E. palmeri, and E. bulleri, in base not markedly widened, shaft usually longer.

For comparisons with E. alpinus, E. minimus, E. townsendii, E. sonomae, E. amoenus, E. dorsalis, E. merriami, and E. quadrivittatus, see the accounts of those species.

The differences between the bacula of the subspecies Eutamias ruficaudus ruficaudus and E. r. simulans are comparable to those usually found between species of chipmunks. Consequently, I suspect that E. r. simulans and E. r. ruficaudus are specifically distinct and suggest that a search would be worth while for specimens in the geographic area between the geographic ranges as now known for the two kinds to ascertain whether intergradation (the criterion of subspecies) occurs. I suppose there is no intergradation but in the absence of precise information, I choose not to modify the current taxonomic arrangement of E. r. ruficaudus and E. r. simulans.

Specimens examined: 17.