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Vol. 69, pp. 169-176 December 31, 1956 
PROCEEDINGS 
OF THE 
BIOLOGICAL SOCIETY OF WASHINGTON 
THE STATUS, CORRECT NAME, AND GEOGRAPHIC 
RANGE OF THE BOREAL CHORUS FROG 
By Philip W. Smith 
Illinois Natural History Survey, Tlrhana 
In the late 1940 's my wife and I found it necessary to re- 
view the relationships of two races of Pseudacris nigrita (he 
Conte) in the Mississippi Valley in order to allocate properly 
the populations of chorus frogs occurring in Illinois. In the 
course of our investigation, we realized that considerable re- 
vision of the distributional and morphological concepts of the 
subspecies septentrionalis would be required if it were to be 
recognized. Consideration of its status was avoided in our 
study (Smith and Smith, 1952), inasmuch as we were not 
directly concerned with it in Illinois. The boreal chorus frog 
was included in a key to the subspecies of P. nigrita, how- 
ever, and its range was vaguely stated as including high ele- 
vations in the Rocky Mountains. Although some information 
regarding the status of the northern race was accumulated 
during our study of triseriata and feriarum, we withheld these 
data in the belief that a monographic treatment of Pseudacris 
was forthcoming by Dr. Charles F. Walker, the foremost stu- 
dent of the genus. Dr. Walker now informs me (pers. comm.) 
that he has no immediate plans to publish on western chorus 
frogs, and at the urging of friends I am offering the following 
notes on the race currently referred to as P. n. septentrionnlis. 
Acknowledgments. I am indebted to Dr. Hobart M. Smith, wbo was 
my major professor at the time much of the data presented herein was 
assembled, and to Drs. H. K. Gloyd, S. A. Minton, and Eoger Conant for 
helpful suggestions and criticisms. I am indebted to Mr. Benjamin 
Shreve for supplying measurements on cotypes deposited at the Museum 
of Comparative Zoology and to the following museum of&cials for their 
kindness in lending specimens for study: C. M. Bogert, W. J. Brecken- 
ridge, G. C. Carl, D. M. Cochran, E. A. Edgren, D. F. Hoffmeister, E. B. 
S. Logier, J. E. Moore, A. I. Ortenburger, K. P. Schmidt, A. Loveridge, 
F. A. Shannon, E. H. Taylor, and C. F. Walker. 
26— Proo. Biol. Soc. Wash., Vol. 69, 1956 (169) 
170 Proceedings of the Biological Society of Washington 
The sources of material examined are cited by the following abbrevia- 
tions : 
AMNH American Museum of Natural History. 
BC Provincial Museum of British Columbia. 
CNHM Qiicago Natural History Museum. 
FAS Dr. Fred A. Shannon. 
INHS Illinois Natural History Survey. 
KU University of Kansas Museum of Natural History. 
MCZ Museum of Comparative Zoology at Harvard. 
OU University of Oklahoma Museum of Zoology. 
KAE Dr. Eichard A. Edgren. 
EOM Koyal Ontario Museum of Zoology and Paleontology. 
UA University of Alberta Museum. 
UIMNH University of Illinois Museum of Natural History. 
UM University of Minnesota Museum of Natural History. 
UMMZ University of Michigan Museum of Zoology. 
USNM United States National Museum. 
Historical Besume. Boulenger (1882) described ChoropMlus septen- 
trionalis from specimens taken at Great Bear Lake, Northvrest Territory, 
Canada, on the basis of the unusually short legs of the northern frogs. 
Cope (1889), without explanation, placed the name in the synonymy of 
ChoropMlus triseriatus (Wied). Dickerson (1906), on the authority of 
Dr. Stejneger, resurrected septentrionalis as a subspecifie name for the 
Canadian race of ChoropMlus nigritus (Le Conte). Stejneger (Stejneger 
and Barbour, 1917), however, elevated Boulenger 's name to specific 
status, and Wright and Wright (1933) again reduced it to subspecifie 
rank. Since that time septentrionalis has been generally recognized, but 
its geographic and morphological limits have been but vaguely defined 
in the herpetological literature. The southern limit of its range has been 
defined, apparently for purposes of administrative facility, as approxi- 
mately the International Boundary separating Canada and western 
United States. Its diagnostic characters, when given at all, have usually 
had indefinite reference to short leg length. Schmidt (1938), who 
pointed out a correlation between latitude and leg length of frogs, 
alluded to septentrionalis as ' ' doubtfully distinct. ' ' 
The status of the ioreal chorus frog. The northern race of P. nigrita 
is exceedingly similar to triseriata; and, if their slight differences could 
be demonstrated to be opposite extremes of a regular leg-length cline, 
relegation of septentrionalis to the synonymy of triseriata would be the 
most desirable solution. The evidence available suggests, however, that 
the two forms are different biological populations, despite the similarity 
and the wide overlap of diagnostic characters. If the boreal subspecies 
is taxonomically separable from triseriata, its geographic range must be 
regarded as including northern Minnesota, North Dakota, and all of the 
Eocky Mountain states (except parts of Arizona and New Mexico) as 
well as central Canada. The revised concept of its range encompasses 
the type locality of a nominal, but identical, "species" with an earlier 
name, Hyloaes maculatus, which accordingly becomes the correct name 
for the boreal chorus frog. 
Smith — Range of the Boreal Chorus Frog 171 
Pseudacris nigrita maculata (Agassiz) 
Hylodes maculatus Agassiz, Lake Superior . . ., 1850, p. 378, pi. 6, figs. 
1-3 (north shore of Lake Superior; revised to vicinity of Sault Ste. 
Marie by Schmidt, 1953). 
ChoropMlus septentrionalis Boulenger, Cat. Batr. Sal. Brit. Mus., 1882, 
p. 335, pi. 23, fig. 1 (Great Bear Lake, Northwest Territory, 
Canada). 
ChoropMlus nigritus septentrionalis, Diekerson, 1906, p. 157. 
Pseudacris septentrionalis, Stejneger & Barbour, 1917, p. 31. 
Pseudacris nigrita septentrionalis, Wright & Wright, 1933, pp. 92-93. 
Eyla canadensis Noble, Amer. Mus. Nov., no. 70, 1923, p. 5 (substitute 
name for septentrionalis which is preoccupied in Eyla). 
Eediagnosis. — A northern race of Pseudacris nigrita, allied and very 
close to P. n. triseriata from which it differs by the proportionately 
shorter tibia, femur, and foot; relatively shorter and narrower head; 
proportionately heavier body; and by the higher frequency of specimens 
with a spotted or mottled pattern. 
Table 1. — Comparison of diagnostic proportional characters of P. n. 
maculata and P. n. triseriata. 
maculata triseriata* 
Number of specimens 343 
Tibia length/body length ratios. 
Mean ± 1 S. E 39.3 ± .15 42.6 ±: .10 
1 Standard Deviation 
Number of specimens.. 
Head length/body length ratios.. 
Mean ± 1 S. E. 
1 Standard Deviation 
Number of specimens 
Head width/body length ratios... 
Mean ±: 1 S. E. 
1 Standard Deviation 
43 
430 
32-46 
37-49 
39.3 ± 
.15 
42.6 ±: 
2.84 
2.09 
57 
24-34 
25-35 
29.3 ± 
.26 
30.0 
1.97 
54 
23-32 
25-34 
27.4 ± 
.28 
29.0 
2.10 
*Data from Smith and Smith, 1952. 
Types. — Two cotypes, MCZ 38. The two cotypes have tibia/body ratios 
of 38.5 and 41.6, head length/body length ratios of 30.7 and 29.1, and 
head width/body length ratios of 23.1 and 25.0. Tibia/body ratios for 
four near topotypes (AMNH 5127 and three specimens reported by 
Jacobs, 1950) range from 31.2 to 41.7, averaging 38.5. 
Eemarlcs. — The name septentrionalis has been used exclusively, al- 
though infrequently, for 50 years and accordingly would seem a worthy 
candidate for the Official List of Conserved Names. However, there are 
extenuating circumstances in the present case that make strict applica- 
tion of priority the more simple solution. In keeping with a decision of 
the International Commission at Paris, CJwropMlus septentrionalis 
Boulenger, 1882, must be rejected as a secondary junior homonym of 
Eyla septentrionalis Schlegel, 1837 {fide Mittleman, 1950) or Eyla 
septentrionalis Dumeril and Bibron, 1841 (fide Myers, 1950), and 
Pseudacris n. canadensis Noble accepted as the valid name of the boreal 
172 Proceedings of ike Biological Society of Washington 
chorus frog siuce Noble (1923), clearly recognizing the homonymy 
created by his union of Pseudacris and Hyla, expressly proposed cana- 
densis as a substitute name. It is perhaps fortunate that the name 
maculata, which is earlier than either septentrionalis or canadensis, is 
available for the northern race. 
Variation. — The provenance of the material studied lends itself to be- 
ing divided arbitrarily into six samples which may be compared for 
purposes of discerning geographic variation. Sample A, consisting of 
maculata X triseriata intergrades, includes all specimens from northern 
Wisconsin, central and southwestern Minnesota, northwestern Iowa, 
eastern South Dakota, and eastern Nebraska. Sample B, consisting of 
typical viaculata, includes all specimens from Ontario, northern Min- 
nesota, North Dakota, and southern Manitoba; sample C, central and 
northern Manitoba, Alberta, Saskatchewan, British Columbia, and North- 
west Territory; sample D, Idaho, Montana and northern Wyoming; 
sample E, Utah, Colorado, and southern Wyoming; and sample F, con- 
sisting of specimens tentatively referred to triseriata, includes the few 
specimens available from Arizona and New Mexico. 
Table 2. — Geographic variation in six samples of Pseudacris nigrita 
from Canada and western United States. 
Number 
of 
Tibia/body ratios 
1 
Number of 
% specimens 
Sample 
specimens 
Eange 
Mean 
S.D. 
specimens 
striped 
A 
104 
32-46 
40.5 ± .23 
2.4 
93 
95 
B 
172 
32-44 
38.7 ± .22 
2.9 
93 
85 
C 
69 
34-45 
38.5 ± .30 
2.5 
47 
70 
D 
79 
32-46 
39.6 ± .16 
1.5 
68 
44 
E 
62 
36-45 
39.6 ± .24 
1.9 
49 
69 
F 
33 
39-46 
42.8 ± .30 
1.7 
30 
84 
The proportionate leg length in sample A is somewhat greater, pre- 
sumably because of the genetic influence of adjacent populations of 
triseriata, although the mean is actually close to that of maculata rather 
than exactly intermediate between that of triseriata and maculata. 
Samples B and C are aligned in an east to west direction. Although these 
samples are from an area over 1,500 miles in width, relatively little 
variation in tibial length means is apparent. The frequency of distinctly 
striped individuals appears to decrease toward the west, but this sug- 
gested cline may be fortuitous, particularly since distinguishing a 
striped from a mottled pattern is quite subjective in many eases. 
Samples C, D, E, and F are aligned in a north to south direction covering 
a distance of over 2,000 miles. A comparison of the means of C, D, and 
E reveals that the leg length gradient predicted by Schmidt (1938) is 
not apparent, at least intraracially. The somewhat higher means for 
samples D and E are probably fortuitous, although there is a possibility 
that a slight correlation may exist between elevation and proportionate 
leg length. The differences in frequencies of striped individuals in the 
three samples are probably insignificant. 
Sample F from central Arizona and northern New Mexico contains 
specimens inseparable, from a practical standpoint, from triseriata of 
Smith — Range of the Boreal Chorus Frog 173 
the tall grass prairie region, and the few specimens at hand are so as- 
signed, pending the availability of additional series from the critical 
areas. The specimens I have examined are: ARIZONA: UMMZ 79156 
(12), 11 mi. S Springerville and UMMZ 99154(2), 17 mi. S Springer- 
ville, Apache Co.; USNM 58082, Flagstaff, UMMZ 79153(2), 23 mi. SW 
Heber, and UMMZ 113848(3), Mormon Lake, Coconino Co.; PAS 1 
spec, 8 mi. NNW Lakeside, Navajo Co.; AMNH 772, Fort Verde, 
Yavapai Co. NJEW MEXICO: UMMZ 79155(2), David Lee Lake, Catron 
Co.; and OU 21642-54, Las Vegas, San Miguel Co. It is hoped that this 
paper will call attention to the problem and that western investigators 
may clarify the status of the southern populations. 
Mange.— ^QQ fig. 1. In Canada P. n. maculata occurs north to the south 
edge of Great Bear Lake and the southern border of Hudson Bay; east 
1 — 
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Fig. 1. Distribution of Pseudacris nigrita in western North America. 
174 Proceedings of the Biological Society of Washington 
to James Bay; and west to Peace Eiver District, B. C. In the United 
States it occurs east to northeastern Minnesota; west to the Oregon 
border ; and south through the Eockies to southern Utah and northern 
New Mexico, south of which it is replaced by a form tentatively regarded 
as a disjunct western population of tri^eriata. Intergradation of macu- 
lata and triseriata occurs in a rather wide belt extending through north- 
ern Wisconsin, central Minnesota, southeastern South Dakota, north- 
western Iowa, and most of Nebraska. 
Localities from which specimens have been examined are plotted on 
fig. 1 by solid symbols; published records, by hollow circles. No attempt 
has been made to locate all published records, but locality records for 
certain areas on the periphery of the range of maeulata have been tran- 
scribed from the following distributional summaries: Logier and Toner, 
1955 (Canada) ; Tanner, 1941 (Idaho) ; Hudson, 1942 (Nebraska) ; and 
Wheeler, 1947 (North Dakota). The distribution of adjacent subspecies 
is indicated on fig. 1 by a cross hatch pattern; the area of integradation 
of maeulata and triseriata is designated by parallel Lines. 
In the interest of saving space, two departures from usual practice in 
citing localities and records have been employed. First, the sources of 
the specimens examined are indicated only by the initials of the mu- 
seums, and the exact specimen numbers of the material have been 
omitted. Second, the localities in the United States are designated only 
by the names of the counties, and the detailed list of precise localities 
has been omitted. 
Locality records for Pseudacris nigrita maeulata (403 specimens ex- 
amined) : ALBERT A: Brewster Creek, SW Banff CNHM, UA; 15 mi. 
NW Chipewyan MCZ; Fort Chipewyan (Logier & Toner, 1955); Ed- 
monton CNHM, MCZ, USNM; 28 mi. N. Edmonton USNM; Ft. Smith 
AMNH, USNM; High Eiver (Logier & Toner, 1955); Eocky Mountain 
House CNHM; Spring Creek CNHM; Slave Eiver, Athabaska USNM; 
20.8 mi. N Waterton UMMZ. BRITISH COLUMBIA: Charlie Lake 
BC; Tupper Creek, Peace Eiver BC; North Pine Eiver (Logier & Toner, 
1955). COLORADO: Archuleta Co. USNM; Boulder Co. USNM; Costilla 
Co. USNM; Delta Co. USNM; Denver Co. USNM; Gunnison Co. OU; 
Jackson Co. MCZ; Lake Co. USNM; Larimer Co. INHS; Mesa Co. 
UIMNH; Mineral Co. MCZ; Moffat Co. USNM; Park Co. USNM; Eio 
Blanco Co. USNM; Eoutt Co. USNM; Washington Co. USNM; Weld 
Co. AMNH. IDAHO: Ada Co. (Tanner, 1941); Canyon Co. (Tanner, 
1941); Cassia Co. (Tanner, 1941); Jefferson Co. UMMZ; Teton Co. 
(Tanner, 1941); Twin Falls Co. (Tanner, 1941). MANITOBA: Bois- 
sevain AMNH, USNM; Delta CNHM; Ft. Garry, 20 mi. N Winnipeg 
AMNH; Gypsumville EOM; Horseshoe Lake EOM; Lake St. Martin 
EOM; Landing Lake near Churchill (Logier & Toner, 1955); Norway 
House USNM; Oxford House USNM; St. Charles, near Winnipeg EOM; 
Selkirk Settlement USNM; Shoal Lake USNM; The Pas EOM, UM; 
Treesbank AMNH; York Factory USNM. MINNESOTA: Becker Co. 
UM; Beltrami Co. UM; Clay Co. UM; Clearwater Co. UM, AMNH, 
CNHM; Cook Co. (Jacobs, 1950); Lake Co. (Jacobs, 1950); Mahnomen 
Co. UM; Marshall Co. UM; Polk Co. UM; Traverse Co. UM. MON- 
TANA: Big Horn Co. USNM; Carter Co. USNM; Custer Co. USNM; 
Dawson Co. USNM; Fallon Co. USNM; Powder Eiver Co. USNM; Eose- 
Smith — Range of the Boreal Chorus Frog 175 
bud Co. USNM; Stillwater Co. USNM; Sweet Grass Co. USNM; Wheat- 
land Co. USNM. NORTH DAKOTA: Billings Co. (Wheeler, 1947); 
Bottineau Co. MGZ; Griggs Co. (Wheeler, 1947); McHenry Co. USNM; 
Nelson Co. (Wheeler, 1947) ; Pembina Co. (Wheeler, 1947) ; Eamsey Co. 
(Wheeler, 1947) ; Eolette Co. UM ; Stutsman Co. UM; Ward Co. USNM. 
NOETEWEST TEERITOEY : Fort Norman (Logier & Toner, 1955); 
Fort Eesolution USNM; Great Bear Lake MCZ. ONTAEIO: Cochrane 
District, Ft. Albany ROM; Patricia District, Ft. Severn EOM; Gold- 
pines, on Lac Seul EOM ; Eainy Eiver District, Emo EOM ; Lake Superi- 
or, north shore AMNH. SASKATCHEWAN: Edenwold EOM; Quill 
Lake CNHM; Saskatoon (Logier & Toner, 1955) ; Waskesiu Lake EOM. 
SOUTH DAKOTA: Harding Co. USNM; Jones Co. AMNH; Stanley Co. 
USNM; Washington Co., Battle Creek Canyon CNHM. UTAH: Emery 
Co. INHS; Salt Lake Co. AMNH; Utah Co. UIMNH, USNM; Wash- 
ington Co. FAS; Weber Co. MCZ. WYOMING: Albany Co. USNM, 
MCZ; Laramie Co. MCZ; Sweetwater Co. AMNH; Teton Co. INHS, 
USNM; Uinta Co. KU, USNM; Yellowstone National Park AMNH, 
MCZ, USNM. 
Locality records for Pseudacris n. maculata X triseriata intergrades 
(125 specimens examined): IOWA: Monana Co. AMNH; Palo Alto Co. 
USNM. MINNESOTA: Anoka Co. UM; Carleton Co. UM; Cass Co. 
UM; Chisago Co. UM; Crow Wing Co. UM; Hennepin Co. Isanti 
Co. UM; Jackson Co. UM; Kandiyohi Co. UM; Lae Qui Parle Co. UM; 
Meeker Co. UM; McLeod Co. UM; MiUe Lacs Co. UM; Pine Co. UM; 
Eamsey Co. UM ; Eock Co. UM ; Scott Co. UM ; Wadena Co. UM ; Wash- 
ington Co. UM. NEBEASKA: Boyd Co. (Hudson, 1942); Cherry Co. 
(Hudson, 1942) ; Dakota Co. (Hudson, 1942) ; Holt Co. CNHM, USNM; 
Jefferson Co. USNM; Keya Paha Co. (Hudson, 1942); Lancaster Co. 
(Hudson, 1942); Logan Co. (Hudson, 1942); Merrick Co. USNM; Per- 
kins Co. (Hudson, 1942) ; Sheridan Co. (Hudson, 1942) ; Sherman Co. 
(Hudson, 1942); Wheeler Co. (Hudson, 1942); NEW MEXICO: Colfax 
Co. AMNH. SOUTH DAKOTA: Brookings Co. AMNH; Lyman Co. 
AMNH. WISCONSIN: Ashland Co. CNHM; Bayfield Co. EAE; Bur- 
nett Co. CNHM; Chippewa Co. AMNH; Clark Co. CNHM. 
LITERATURE CITED 
Agassiz, L. 1850. Lake Superior; its physical character, vegetation, and 
animals compared with those of other and similar regions. Gould, 
Kendall, and Lincoln, Boston, x -f- 428 pp. 
Boulenger, G. A. 1882. Catalogue of the batrachia salientia S ecaudata 
in the collection of the British Museum. London, xvi -f- 503 pp. 
Cope, E. D. 1889. The batrachia of North America. Bull. U. S. Nat. 
Mus. 34. 525 pp. 
Dickerson, M. C. 1906. The frog book. Doubleday, Page and Co., New 
York, xvii + 253 pp. 
Hudson, G. E. 1942. The amphibians and reptiles of Nebraska. Nebr. 
Conserv. Bull. 24. 146 pp. 
Jacobs, D. 1950. Pseudacris nigrita triseriata on the north shore of 
Lake Superior. Copeia 1950(2) :154. 
Logier, E. B. S., and G. C. Toner 1955. Check-list of the amphibians 
176 Proceedings of the Biological Society of Washington 
and reptiles of Canada and Alaska. Contrib. Eoyal Ont. Mus. Zool. and 
Paleont. 41. v + 88 pp. 
Mittleman, M. B. 1950. Status of the name Hyla septentrionalis. Herpe- 
tologica 6(2) :24-26. 
Myers, G. S. 1950. The systematic status of Hyla septentrionalis, the 
large tree frog of the Florida Keys, the Bahamas and Cuba. Copeia 
1950(3) :203-214. 
Noble, G. K. 1923. The generic and genetic relations of Pseudacris, the 
swamp tree frog. Amer. Mus. Novit. 70. 6 pp. 
Schmidt, K. P. 1938. A geographic variation gradient in frogs. Zool. 
Series Field Mus. Hist. 20(29) :377-382. 
Series, P. W., and D. M. Smith. 1952. The relationships of the chorus 
frogs, Pseudacris nigrita feriarum and Pseudacris n. triseriata. Amer. 
Midi. Nat. 48(1) : 165-180. 
Stejneger, L., and T. Barbour 1917. A check list of North American 
amphibians and reptiles. Harvard Univ. Press, Cambridge, i + 120 pp. 
Tanner, W. W. 1941. The reptiles and amphibians of Idaho, No. 1. 
Great Basin Nat. 2(2) : 87-97. 
Wheeler, G. C. 1947. The amphibians and reptiles of North Dakota. 
Amer. Midi. Nat. 38(1) : 162-190. 
Wright, A. H., and A. A. Wright 1933. Handbook of frogs and toads. 
Comstock Publ. Co., Ithaca, xi + 231 pp.