The distribution of Leurognathus, a southern Appalachian genus of salamanders

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NATURAL
HISTORY SURVEY

FIELDIANA * ZOOLOGY

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Published by

CHICAGO NATURAL HISTORY MUSEUM
Volume 31 OCTOBER 6, 1947* No. 20

THE DISTRIBUTION OF LEUROGNATHUS

A Southern Appalachian Genus of Salamanders

CLIFFORD H. POPE

CURATOR, DIVISION OF REPTILES
AND

NELSON G. HAIRSTON

NORTHWESTERN UNIVERSITY
INTRODUCTION

The speciation of the southern Appalachian Plethodontidae
presents many interesting zoogeographic problems. This speciation
is evidently correlated with long isolation on these ancient, deeply
eroded highlands. Nowhere else are the results of salamander
evolution so plentiful. The over-all picture is extremely complex
and can hardly be understood until the component parts have been
studied individually and intensively. The genus Leurognathus,
with its two forms, is one of these parts well suited for intensive
investigation because of its relative simplicity. Moreover, its range
is confined to the region and its derivation from Desmognathus
certain.

It is but recently that sufficient locality records of this rare
genus have warranted a comprehensive study. Discoveries of the
last few years convince us that the approximate total distribution
is now known.

DISTRIBUTION

The first specimen of the genus Leurognathus was collected on
Roan Mountain, Carter County, Tennessee, by Rhoads in 1895,
but was listed as Desmognathus nigra (= D. quadramaculatus) .
Rhoads should not be severely censured for this mistake because
similar ones are still being made. These mistakes emphasize the
striking superficial similarity between species of the two genera.
Only the most experienced and painstaking workers can recognize
Leurognathus without difficulty.

No. 607 155 THE UBRASY Or THE

OCT 241947

NATURAL UNIVERSITY OF ILLINOIS

HISTORY SURVEY
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156 FIELDIANA: ZOOLOGY, VOLUME 31

This genus was not described until 1899, when Moore erected it
on the basis of three specimens collected by him in Avery County,
North Carolina, on the southern flank of Grandfather Mountain, at
an altitude of 3,500 feet. 'No further material was reported until
1917. In that year Dunn collected a larva at Pineola, Avery County,
which led to recognition of Rhoads' Roan Mountain specimen, and
one from Blowing Rock, Watauga County, overlooked by Moore
himself. These facts were brought out in two papers by Dunn and
one by Fowler and Dunn, all published in 1917. The range of the
genus was greatly extended by the next specimen collected. This
was reported by Dunn in 1924 from Jones Cove, Haywood County,
North Carolina.

With the exception of five topotypes collected by Bishop and
reported by him in 1924 and a series of 28 from the region of the type
locality (Boone Fork, Watauga County) collected and reported in
1924 by Pope, no further material was found until 1927. The mono-
typic status of the genus was changed in 1928 by Pope, who described
the series he collected in 1927 at and near Davis Gap, Haywood
County, North Carolina, as Leurognathus marmorata intermedia.
Later in the same year Bishop reported a salamander from Frying
Pan Mountain, also in Haywood County, as L. marmorata. This
individual has subsequently (Bishop, 1943) been referred to inter-
media; Dunn's Haywood County marmorata long ago met the same
fate (Pope, 1928).

Only a few distributional records of the genus remain to be
enumerated. In 1937 Bailey extended the range of marmorata to
the following North Carolina localities: Montreat, Buncombe
County; Ramsaytown, Yancey County; two localities near Linville
Falls, one in McDowell County and one in Burke County. King
in 1944 reported intermedia from these three places in the Great
Smoky Mountains: Abrams Creek and Cades Cove, Blount County,
Tennessee, and Smokemont, Swain County, North Carolina. He
believed these to be the first Tennessee records of the genus, evidently
because of the confusion resulting from the straddling of the North
Carolina-Tennessee line by Roan Mountain, where Rhoads obtained
the first specimen.

In giving the generic range in his handbook (1943) Bishop
includes Caldwell, Henderson, and Haywood counties, North Caro-
lina, in the distribution of marmorata but adds no further details.
We learn from him (letter of June 10, 1947) that the Caldwell County
series in the United States National Museum was taken 9J^ miles

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158 FIELDIANA: ZOOLOGY, VOLUME 31

southwest of Blowing Rock; the Henderson County record is based
on a larva (78 mm. long) from Stony Mountain, which lies about
three miles northwest of Hendersonville and reaches an altitude of
2,843 feet. His listing of marmorata from Haywood County actually
refers to an old record of intermedia from there.

Recent field work by both of us and examination of series of
" Desmognathus" in the Chicago Academy of Sciences1 and Chicago
Natural History Museum have brought to light important new
material. In the summer of 1946 the range of intermedia was
extended to extreme northeastern Georgia, when Whitney Pope
secured a large specimen near Mountain City, Rabun County.
Another was caught on Standing Indian, a mountain about twenty
miles to the northwest but in North Carolina. These are now
C.N.H.M. 47771 and 47772, respectively. Examination of the
Museum series referred to above revealed seventeen Great Smoky
Mountains specimens of intermedia masquerading as species of
Desmognathus; all came from the immediate vicinity of Greenbrier
Cove, Sevier County, Tennessee. Hairston collected marmorata
at Duncan Cove Creek in western McDowell County, North
Carolina, near the Yancey County boundary.

All of the locality records enumerated above are shown on the
spot map. A study of the map reveals two facts about the two sala-
mander populations hitherto designated as L. m. marmorata and
L. m. intermedia: they are discrete and both are confined to the
mountains. The only physical separation of the two populations is
the valley of the French Broad River. Although this river, which
in our area flows at relatively high elevations (about 2,000 to 1,200
feet), would not seem to be a serious barrier to a mountain stream
salamander, the fact remains that it does divide them. Further-
more, Leurognathus is not the only plethodontid genus in which this
phenomenon occurs: Pseudotriton ruber nitidus and P. r. schenckii
are separated by the same valley. It is also interesting to note that
the range of Plethodon yonahlossee ends with this valley.

The range of Leurognathus is confined to the southern part of the
Blue Ridge Province. In contrast to this correlation with physiog-
raphy, we find no watershed correlation, both forms being found in
Atlantic and Gulf drainages.

We feel that the records on our map approximately delimit the
total range of the genus because (1) to the northeast, extensive col-
lecting by various experienced herpetologists at White Top Moun-

1 We are indebted to Director Howard K. Gloyd for his generous cooperation.

POPE AND HAIRSTON: DISTRIBUTION OF LEUROGNATHUS 159

tain, Virginia, has failed to reveal specimens; (2) to the southwest,
in the region of Copperhill, Tennessee, the vegetation has been
destroyed; (3) elsewhere the natural habitat of the salamanders is
eliminated with the abrupt change in physiography. Further col-
lecting in Transylvania, Henderson, Buncombe, and Madison

6000

5000'

4000'

3000

2000

1000'

intermedia

marmorata

1

FRENCH BROAD RIVER

FIG. 29. Vertical distribution of the species of Leurognathus (approximate
altitudes in feet).

counties (all outlined on the map) will test the validity of the French
Broad Valley as a natural boundary separating the two forms.

ECOLOGY

Little is known of the ecology of Leurognathus. This ignorance
stems partly from the comparative rarity of both forms, and partly
from the fact that most collectors have been interested only in
distribution. All observers are agreed that the genus is purely
aquatic; no specimen has ever been taken elsewhere than in mountain
streams, not even along the banks under rocks such as form typical
hiding places for several species of Desmognathus. .Leurognathus
marmorata has been recorded solely from the larger streams, whereas
intermedia was first collected from a bare trickle (Dunn, 1924), and

160 FIELDIANA: ZOOLOGY, VOLUME 31

later observers have tended to confirm a preference for the smaller
streams. Although this is' an inconsequential difference in itself,
possibly there is a correlation with other more basic ecological
separations; different types of food is one worthy of investigation.

Furthermore, intermedia would seem to be the more tolerant of
variations in altitude, both high and low (see fig. 29); until now,
marmorata has been reported only from altitudes between 3,000
and 4,000 feet, whereas intermedia has been found from 1,700 (King,
1944) to 5,400 feet (Bishop, 1928). The upward distribution of
marmorata may well be limited by the small creeks at higher eleva-
tions, a factor that would not affect intermedia. However, it is
difficult to account for its absence from apparently acceptable
streams at lower elevations than those reported. The single low-
altitude record (1,900 feet) of marmorata given herein might be a
specimen washed down in the severe flood that occurred four months
earlier. An important limiting factor could be the preference of
herpetologists for the higher elevations, particularly on Grand-
father Mountain, where the road is placed conveniently at 4,000
feet, and high-altitude desiderata, such as Plethodon welleri, tempt
the collector to ascend the mountain rather than to go down its
more precipitous slope below. Perhaps a more thorough search
along the foot of the Blue Ridge escarpment would bring more low-
altitude specimens to light, just as similar collecting on the west
face of the Smokies has recently revealed the presence of intermedia.

The breeding habits of L. marmorata are much like those of
Desmognathus quadramaculatus (Pope, 1924), and L. intermedia
probably will prove to have similar ones.

TAXONOMY

The nineteen specimens of intermedia that inspired this paper
have been discussed in a preceding section. Their characters are
listed in the table. All fall within the recorded size range. Six of the
nineteen have vomerine teeth, and this character is not correlated
with sex; both sexes thus show a lower incidence than in the type
series, a difference that is not significant. The dorsal pattern proves
to be surprisingly diagnostic, 74 per cent showing the two rows of
light spots. Those without spots are immaculate brown above.
No indication of the zigzag design of marmorata is evident.

In the twenty years since the description of intermedia no inter-
grades have been reported. For this reason we are raising this form
to specific rank. Those who do not regard intergradation as an

POPE AND HAIRSTON: DISTRIBUTION OF LEUROGNATHUS 161

CHARACTERS OF Leurognathus intermedia

C.N.H.M. 47771 from Mountain City, Georgia; C.N.H.M. 47772 from Stand-
ing Indian Mountain, North Carolina; others from Greenbrier, Tennessee.

The costal grooves include one in the axilla and two in the groin; the inter-
costal spaces are counted between the tips of the adpressed toes.

Specimen no.

C.A.S.
C.N.H
C.N.H
C.A.S.
C.N.H
C.A.S.
C.N.H
C.A.S.
C.N.H
C.A.S.
C.A.S.
C.A.S.
C.A.S.
C.A.S.
C.N.H
C.A.S.
C.N.H
C.N.H
C.A.S.

1126

.M. 48102...
.M. 48105...

1143

M. 48101...,

1145

.M. 47771...

1089

.M. 47772...

1128

1129

1125

1141

1140

.M. 48106...

609

,M. 48104...
.M. 48103...
9263..

Sex

.cP
G?

Total

length

(in mm.)

95

90

73

68

57

50

111

?

105
103
102

90

88

85

83

82

77

75

65

Snout to

vent length

(in mm.)

50
47
40
38
32
31
62
57
56
55
55
47
48
45
45
44
42
40
34

Vomerine
teeth
R L

1 1

0 0

00
00
00

1 2
00
00
23
00
00
20
00
00
00
10
00
00
11

Costal
grooves

14

14
14
14
14
14
14
13
14
15
13
14
14
14
14
14
14
14
13

Inter-
costal Rows dorsal
spaces white spots

2

2

0

2 (dim)

2

2 (dim)

2

0

2 (dim)

2

2

0

2

0

2 (dim)

Tail only

0

2 (dim)

2 (dim)

essential criterion of subspecific status will no doubt continue to
regard intermedia as a subspecies, a position to which we do not
seriously object.

DISCUSSION

Desmognathus quadramaculatus, obviously the closest living
relative of Leurognathus, has been assumed to be its direct ancestor
by Dunn, Noble, and others. Ecologically, Leurognathus is a com-
pletely aquatic extrapolation of D. quadramaculatus. This fact is
borne out by morphological characters: flattened skull, lack of
vomerine teeth, more lateral location of the internal nares. We
interpret the flattened head as an adaptation to bottom-crawling
habits. The relative position of the two species of Leurognathus
is clear: intermedia, with vomerine teeth and a simple pattern, is an
early step, whereas marmorata is the end product. The wider vertical
range of intermedia bears this out, indicating greater tolerance of a
less specialized species. The larger size of marmorata is not a valid
contradiction of this explanation, as size may have been secondarily
acquired in correlation with a preference for larger streams.

162 FIELDIANA: ZOOLOGY, VOLUME 31

REFERENCES

BAILEY, J. R.

1937. Notes on plethodont salamanders of the southeastern United States.
Occ. Pap. Mus. Zool., Univ. Mich., 364, pp. 1-10.

BISHOP, S. C.

1924. Notes on salamanders. Bull. New York State Mus., 253, pp. 87-102,

3 pis.
1928. Notes on some amphibians and reptiles from the southeastern states

with a description of a new salamander from North Carolina. Jour. Elisha

Mitchell Sci. Soc., 43 (3 and 4), pp. 153-170, pis. 23-26.

1943. Handbook of salamanders. Comstock Publ. Co., Ithaca, N. Y. xiv +
555 pp., 144 figs., 56 maps.

DUNN, E. R.

1917a. The salamanders of the genera Desmognathus and Leurognathus. Proc.

U. S. Nat. Mus., 53, pp. 393-433.
1917b. Reptile and amphibian collections from the North Carolina mountains,

with especial reference to salamanders. Bull. Amer. Mus. Nat. Hist., 37,

pp. 593-634, pis. 57-61.

1924. A new specimen of Leurognathus marmorata. Copeia, 127, pp. 31-32.
1926. The salamanders of the family Plethodontidae. Smith Coll. Anniv. Publ.,

Northampton, Mass, viii + 441 pp., 3 pis., 86 maps.

FOWLER, H. W. and DUNN, E. R.

1917. Notes on salamanders. Proc. Acad. Nat. Sci. Phila., 1917, pp. 7-28,
pis. 3-4.

KING, WILLIS

1944. Additions to the list of amphibians and reptiles of Great Smoky Moun-
tains National Park. Copeia, 1944, p. 255.

MOORE, J. P.

1899. Leurognathus marmorata, a new genus and species of salamander of the
family Desmognathidae. Proc. Acad. Nat. Sci. Phila., 1899, pp. 316-323,
pi. 14.

POPE, C. H.

1924. Notes on North Carolina salamanders with especial reference to the egg-
laying habits of Leurognathus and Desmognathus. Amer. Mus. Nov., no. 153,
pp. 1-15, 2 figs.

1928. Some plethodontid salamanders from North Carolina and Kentucky with
the description of a new race of Leurognathus. Amer. Mus. Nov., no. 306,
pp. 1-19, 1 fig.

RHOADS, S. N.

1895. Contributions to the zoology of Tennessee. No. 1, reptiles and amphib-
ians. Proc. Acad. Nat. Sci. Phila., 1895, pp. 376-407. '

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