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قراءة كتاب The Baculum in the Chipmunks of Western North America
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625
- 5. Shaft thin; shaft less than .20 mm. in diameter at widest point.
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- 6. Ridges on either side of keel enlarged, partially obscuring lateral view of keel; height of keel 1/10 of length of tip.
- Eutamias sonomae, p. 619
- 6′. Ridges on either side of tip not enlarged, not partially obscuring lateral view of keel; height of keel at least 1/7 of length of tip.
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- 7. Base not widened or dorsoventrally thickened.
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- 8. Shaft more than 4.5 mm. in length; tip 16 per cent of length of shaft; shaft strongly incised on dorsal side of base
- Eutamias merriami, p. 621
- 8′. Shaft less than 4.4 mm. in length; tip more than 25 per cent of length of shaft; shaft not incised on dorsal side of base.
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- 9. Height of keel 1/7 of length of tip; angle formed by tip and shaft distinct
- Eutamias alpinus, p. 616
- 9′. Height of keel at least 1/5 of length of tip; angle formed by tip and shaft poorly defined.
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- 10. Height of keel 1/3 of length of tip; angle formed by tip and shaft 140°
- Eutamias dorsalis, p. 620
- 10′. Height of keel 1/5 of length of tip; angle formed by tip and shaft 130° or less.
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- 11. Tip more than 29 per cent of length of shaft.
- Eutamias amoenus, p. 619
- 11′. Tip less than 28 per cent of length of shaft.
- Eutamias minimus, p. 617
- 7′. Base widened and dorsoventrally thickened.
- Eutamias townsendii, p. 618
- 5′. Shaft thick; shaft more than .25 mm. in diameter at widest point.
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- 12. Length of shaft less than 3.00 mm.; length of tip less than 1.10 mm.
- Eutamias quadrivittatus hopiensis, p. 622
- 12′. Length of shaft more than 3.10 mm.; length of tip more than 1.15 mm.
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- 13. Tip less than 28 per cent of length of shaft.
- Eutamias quadrimaculatus, p. 624
- 13′. Tip more than 29 per cent of length of shaft.
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- 14. Angle formed by tip and shaft more than 140°; ridges on either side of tip indistinct.
- Eutamias cinereicollis, p. 624
- 14′. Angle formed by tip and shaft less than 135°; ridges on either side of tip distinct.
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- 15. Shaft less than 3.65 mm. in length, and .55 mm. or less in diameter at widest point.
- Eutamias quadrivittatus quadrivittatus, p. 621
- 15′. Shaft usually more than 3.65 mm. in length, but when shorter, diameter is .60 mm. or more at widest point.
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- 16. Diameter of shaft at widest point less than .58 mm.; tip less than 35 per cent of length of shaft.
- Eutamias ruficaudus ruficaudus, p. 622
- 16′. Diameter of shaft at widest point more than .65 mm.; tip more than 40 per cent of length of shaft.
- Eutamias ruficaudus simulans, p. 623
Accounts by Species
Figure 1
Pelage silky; tail bright orange beneath; markings relatively obscure; size small; skull broad, flattened, and large in proportion to body.
Baculum: Shaft thin; keel low, 1/7 of length of tip; tip 39 per cent of length of shaft; angle formed by tip and shaft 135°; distal 1/3 of shaft slightly compressed laterally; base slightly wider than shaft; shaft short, 2.17 mm.
Differs from E. speciosus, E. panamintinus, E. umbrinus, E. palmeri, and E. bulleri, in base not markedly widened, and shaft thinner; from E. quadrivittatus, E. ruficaudus, E. cinereicollis, and E. quadrimaculatus, in shaft thinner, baculum shorter; from E. townsendii, in base not dorsoventrally thickened, base not so widened; from E. sonomae, in ridges on either side of tip not enlarged, base not dorsoventrally thickened; from E. amoenus, E. minimus, and E. dorsalis, in keel lower, angle formed by tip and shaft more distinct; from E. merriami, in baculum markedly shorter, base not incised dorsally.
Specimen examined: One from Big Cottonwood Meadows, S of Mount Whitney, 10,000 ft., Inyo Co., California (CN).
Figure 2
Coloration varying from light to dark depending on subspecies; size small to medium; rostrum short and stout.
Baculum: Shaft thin; keel low, 1/5 of length of tip; tip 18 to 28 per cent of length of shaft; angle formed by tip and shaft 125°; distal 1/2 of shaft slightly compressed laterally; shaft short to long, 2.44 to 4.35 mm.
Differs from E. speciosus, E. panamintinus, E. umbrinus, E. palmeri, and E. bulleri, in shaft thinner, base not markedly widened; from E. quadrivittatus, E. ruficaudus, E. cinereicollis, and E. quadrimaculatus, in shaft thinner, tip shorter; from E. amoenus, in tip less than 28 per cent of length of shaft; from E. dorsalis, in angle formed by tip and shaft smaller; from E. townsendii, in tip less than 28 per cent of length of shaft, angle formed by tip and shaft 125° instead of 130°; from E. sonomae, in ridges on either side of tip less well-developed, keel higher; from E. merriami, in shaft shorter (less than 4.40 mm.), base not incised, tip proportionally longer.
For comparison with E. alpinus see the account of that species.
In most places where E. minimus and E. amoenus occur together they can be distinguished without recourse to the baculum, but at Banff and Canmore in western Alberta, recourse to the baculum is almost necessary. There, as elsewhere, they can be distinguished readily by the shape of the bacula.
Specimens examined: 72.
Eutamias minimus borealis: Alberta: Canmore, 1 (BS).
E. m. cacodemus: South Dakota: Shannon Co.: Quinn's Draw, Cheyenne River, 1 (NM); 14 mi. N and 5 mi. W Rockyford, 3,200 ft., 1.
E. m. confinis: Wyoming: Big Horn Co.: 17 mi. E and 3 mi. S Shell, 9,000 ft., 1; 9 mi. E and 9 mi. N Tensleep, 8,200 ft., 1. Washakie Co.: 9 mi. E and 4 mi. N Tensleep, 7,000 ft., 1.
E. m. consobrinus: Montana: Madison Co.: 26 mi. NW West Yellowstone, 6,100 ft., 1. Wyoming: Sublette Co.: 5 mi. E and 9 mi. N Pinedale, 9,100 ft., 2. Uinta Co.: 10 mi. S and 1 mi. W Robertson, 8,700 ft., 1; 13 mi. S and 2 mi. E Robertson, 9,200 ft., 2. Utah: Uintah Co.: Paradise Park, 21 mi. W and 15 mi. N Vernal, 10,050 ft., 8. Colorado: Jackson Co.: 9-1/2 mi. W and 2 mi. N Walden, 8,400 ft., 1.
E. m. jacksoni: Michigan: Menominee Co.: 7 mi. E Stephenson, 4 (MM). Wisconsin: Juneau Co.: Camp Douglas, 1 (NM).
E. m. minimus: