General tone of upper parts bright; light and dark elements of color pattern strongly contrasting; outer stripes broad and strikingly conspicuous; size medium; skull moderately broadened; dorsal outline of skull strongly arched in profile; upper incisors short and sharply recurved.
Baculum: Shaft thick; keel of medium height, 1/3 of length of tip; base of keel 1/3 of length of tip; tip 47 to 55 per cent of length of shaft; angle formed by tip and shaft 90°; distal 2/3 of shaft markedly compressed laterally; base markedly wider than shaft; shaft short to medium, 2.11 to 3.17 mm.
Differs from _E. panamintinus_, in base of keel proportionally shorter, angle formed by tip and shaft smaller; from _E. umbrinus_ and _E. palmeri_, in keel higher, angle formed by tip and shaft smaller, distal 2/3 (not 1/2) of shaft markedly laterally compressed, base markedly wider; from _E. bulleri_, in keel smaller, shaft shorter, tip proportionally longer, ridges on either side of tip distinct.
For comparisons with all other species of chipmunks of western North America, see the accounts of those species.
The baculum in _E. speciosus frater_ is approximately the same size as in _E. umbrinus inyoensis_, but differs in shape as described above.
_E. speciosus frater_: California: _Madera Co._: San Joaquin River, near head of N fork, Sierra Nevada Mountains, 2 (BS).
_E. speciosus sequoiensis_: California: _Tulare Co._: Mount Whitney, 1 (BS); Sequoia National Park, 2 (BS).
_E. speciosus callipeplus_: California: _Kern Co._: Mount Pinos, 1 (BS).
Dorsal dark stripes reddish; size small to medium; skull of medium size; braincase flattened.
Baculum: Shaft thick; keel low, 1/3 of length of tip; base of keel 1/2 of length of tip; tip 52 per cent of length of shaft; angle formed by tip and shaft 110°; distal 2/3 of shaft moderately compressed laterally; base markedly widened; shaft short, 2.17 mm.
Differs from _E. umbrinus_ and _E. palmeri_, in distal 2/3 (rather than 1/2) of shaft moderately compressed laterally; from _E. bulleri_, in keel smaller, shaft shorter, ridges on either side of tip distinct.
For comparisons with other species of chipmunks of western North America, see the accounts of those species.
