The Baculum In The Chipmunks Of Western North America Part 3

#Eutamias merriami# (J. A. Allen)

Figure 7

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 Pinos, 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 n.i.g.g.e.r 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.

_E. ruficaudus ruficaudus_: Montana: _Flathead Co._: 1 mi. W and 2 mi. S Summit, 5,000 ft., 2. _Ravalli Co._: Big Hole Hill, 6,000 ft., 2; Big Hole Hill, 6,600 ft., 1; Continental Divide, Big Hole Hill, 7,000 ft., 1.

_E. r. simulans_: Idaho: _Bonner Co._: Priest Lake, 1 (BS).

_Kootenai Co._: 13 mi. E and 5 mi. N Coeur d'Alene, 3. _Shoshone Co._: Mullan, 1 (BS). _Clearwater Co._: 25 mi. E and 16 mi. N Pierce, 6.

#Eutamias cinereicollis# (J. A. Allen)

Figure 13

General tone of upper parts dark grayish tawny; size medium to large; skull large; braincase widened.

Baculum: Shaft thick; keel proportionally low, 1/5 of length of tip; tip 34 per cent of length of shaft; angle formed by tip and shaft 145; distal 1/3 of shaft slightly compressed laterally; base slightly widened; shaft long, 4.88 mm.

Differs from _E. quadrimaculatus_, in keel lower, ridges on either side of tip weakly developed, angle formed by tip and shaft larger; from _E.

speciosus_, _E. panamintinus_, _E. umbrinus_, _E. palmeri_, and _E.

bulleri_, in shaft longer, base not markedly widened, angle formed by tip and shaft much larger.

For comparisons with _E. alpinus_, _E. minimus_, _E. townsendii_, _E.

sonomae_, _E. amoenus_, _E. dorsalis_, _E. merriami_, _E.