2ool.J. Linn. Soc.,4 8 , p p . 135-140. With 1 plate and 1figure
A new tree-frog from Guyana
COLEMAN J. GOIN
Department of Zoology, University of Florida
AND
J. D. WOODLEY
Department of Zoology, Oxford University”
Accepted for publication&ly 1968
A new species of Hyla is described, from the Pakaraima Mountains of Guyana. It superficially resembles members of the H . geographica group.
CONTENTS
.
Introduction
.
Description of the locality.
Description of the species
.
Discussion
Acknowledgements .
,
Reference
.
.
.
.
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PAGE
135
135
136
140
140
140
INTRODUCTION
While a member of the Oxford University Expedition to British Guiana, 1959, the
junior author collected seven specimens of a species of tree-frog that seems to be
undescribed. They were found on the top of Mt. Kanaima, near Amatuk Falls on the
Potaro River.
DESCRIPTION O F THE LOCALITY
The Guiana Highlands of northern South America extend from Venezuela into
Guyana as the Pakaraima Mountains. The north-eastern edge of their lowest plateau,
150 miles from the coast, forms an escarpment which rises 1500-2000 feet above the
lowland plain. This escarpment is dissected by various streams, of which the most
notable is the Potaro River, which has cut back a 15-mile gorge, at the head of which it
falls sheer for over 700 feet as the famous Kaieteur Fall. At the mouth of the gorge, on
the left bank of the river, the first bluff of the escarpment is known as Mt. Kanaima. It
stands about one-and-a-half miles from the river, three miles from the Amatuk Falls, at
which was the main camp site of the expedition.
The whole area is covered by tropical rain forest whose physiognomy varies with the
drainage conditions. In the Amatuk area the principal formations (using the terminology
of Beard, 1955) are ‘dry rain forest’, ‘rain forest’ and ‘seasonal-swamp forest’.
* Present address: Department of Zoology,University of the West Indies, Kingston, Jamaica.
COLEMAN
J. GOINAND J. D. WOODLEY
136
A trail was cut from Amatuk Falls to Mt. Kanaima; it climbed a steep talus slope and
came to the foot of the sheer cliff which crowns much of the escarpment. A few hundred
yards along, erosion had made it possible to scramble up onto the plateau. At this point
the edge is capped by white sands and bears a low seasonal-swamp woodland. Behind
it, on the edge of an extensive gabbro sill, is dry evergreen forest.
The seasonal-swamp woodland is traversed by a few little streams which drop over
the edge of the cliff but are so reduced in the dry season (September-November) that
they may scarcely reach it. Clouds are an additional source of moisture and the trees,
which include many palms, are very ‘mossy’. There is a considerable layer of herbs of
the family Rapateaceae.
The brow of Mt. Kanaima was visited by J.D.W. on four occasions (nine days in all)
between 19 August and 25 October, 1959. All specimens of the new frog, which was
heard calling on all visits, were taken between dusk and 23.00 hours on low vegetation,
mostly in the seasonal-swamp woodland, but two in the adjacent dry evergreen forest.
The mountain on which this species was collected probably got its name from the
belief that it is inhabited by a ‘kanaima’, a spirit sorcerer of evil disposition who is
active at night. We think it appropriate therefore that this little frog be known as
Hyla kanaima sp. nov.
Type. British Museum (Natural History) 1965.230, adult female collected from low
vegetation on Mt. Kanaima, near Amatuk Falls on the Potaro River, British Guiana, at
2300 feet elevation on 2 October, 1959, by J. D. Woodley.
Paratypes. Six, all from the same locality but collected on different dates:
United States National
Museum
Guyana Museum
Museo de Biologia,
Universidad Central de
Venezuela
Museum of Comparative
ZOOIOgy
British Museum (Natural
History)
Oxford University
Museum
F 1.66
154214
adult female
adult male
20 August
20 August
1959.
1959.
6042
adult male
29 September
1959.
51271
adult male
3 October
1959.
1965.808
immature
29 September
1959.
10296
immature
1 October
1959.
Diagnosis. A rather large Hyla without webbing between the fingers and with
reduced webbing between the toes; with the vomerine teeth in one continuous or two
contiguous transverse series behind the choanae; a dermal heel appendage in the form
of a rounded mound of unpigmented tissue rather than a sharp, elongate spur; a small
tympanum; a clear palpebral membrane; and a dorsal pattern of thin, dark, broken
lines on a yellowish background.
A NEWTREE-FROG
FROM
GUYANA
137
Although the relationships of this species are not clear, it is superficially somewhat
similar to the H . geographica complex. From geographica it differs in having smaller
choanae, a different type of vomerine tooth patches, in lacking reticulations on the
palpebral membranes and webbing between the fingers and in having a quite different
type of dermal heel appendage. From calcarata it likewise differs in all of the above
characters except that in both cakarata and kanaima the palpebral membranes are clear.
It may also be related to H . benitezi but it differs in having dermal appendages on the
heel, in its reduced webbing on the hands and feet, in a more slender build, and in
pattern.
Description of type (Fig. 1). Vomerine teeth in a continuous, rather heavy, transverse
series, lying on a level with the posterior borders of the rather large, oval choanae;
FIGURE
1. The type (British Museum (Natural History) 1965.230) of Hyla kunuimu, from Mt.
Kanaima, near Amatuk Falls, Potaro River, Guyana. Dorsal view, underside of hand and foot,
side of head, and roof of mouth.
tongue two-thirds as wide as mouth-opening, broadly rounded, its posterior border not
free and without a notch. Snout large, rather rounded whenviewed from above, truncate
in profile, the upper jaw extending a little beyond the lower; nostrils lateral rather
than superior, slightly projecting, their distance from end of snout about one-fourth that
138
COLEMAN
J. GOINAND J. D. WOODLEY
from eye, separated from each other by an interval equal to about one-half their distance
from eye. Canthus rostralis well defined; loreal region concave and very oblique, the
upper lip flaring out strongly below it. Eye large, very prominent, its diameter equal to
its distance from nostril; palpebral membrane not reticulate; interorbital distance
slightly less than width of upper eyelid, which is half again as wide as the distance
between nostrils. Tympanum small but distinct, about one-third the diameter of the
eye, separated from eye by a distance nearly equal to its own diameter. Fingers without
a trace of web at base, fourth a full disk longer than second, just reaching to disk of
third which just covers the tympanic area; no projecting rudiment of a pollex; no ulnar
ridge; toes slightly webbed at base, the web on the fourth toe broadly reaching the
middle of the ante-antepenultimate phalanx on the medial side and to the same level as
a low ridge on the lateral side ; third and fourth toes subequal, disk of fourth covering
about one-third the tympanic area; a distinct oval inner and a smaller less distinct
rounded outer metatarsal tubercle; no tarsal ridge; a minute dermal appendage on heel
formed from the uppermost of a pair of small, clear, unpigmented rounded warts on
each heel. Body rather elongate, in post-axillary region about two-thirds the greatest
width of head; when hindleg is adpressed, heel reaches tip of snout; when limbs are
laid along the sides, knee and elbow considerably overlap; when hindlegs are bent at
right-angles to body, heels overlap greatly. No patagium extends from the back of the
upper arm to the side of the body. Skin of upper parts rather smooth except in the region
above the insertion of the arm and behind the tympanum, where it is coarsely granular,
A smaller, but distinct, granular area on the posterior surface of the thighs below the
vent. Skin of throat and chest smooth, that of belly and lower surface of thigh uniformly
and rather coarsely granular ;no traces of a skinfold across chest ;adult female, no vocal
sac. Skin of head not co-ossified with skull, roof of skull not exostosed.
Dimensions of type. Head and body 48.0 mm; head length 17.3 mm; head width 17.1
mm; femur 23.3 mm; tibia 24.6 mm; heel-to-toe 30-1mm; hand 13.8 mm.
Colour in alcohol of type. Dorsal ground colour light tan. The entire dorsal pattern is
made up of narrow, medium brown lines and dots. A line originates on the posterior
margin of each eye and passes backward and medially to meet its fellow from the other
side in the middle of the back above the region of the axillae. A short pair of curved lines
margin the back (one on each side) just anterior to the sacral hump and there is a short
line above the sacro-iliac articulation on each side. Elsewhere on the dorsum the lines
are short or even reduced to rounded dots which give the dorsum the appearance of
being thinly speckled. Along the sides between the axillae and groins the dark markings
are in the form of rather thickly scattered, discrete, rounded spots. The dorsal surface
of the thighs is marked by six or seven narrow cross-bands of brown and similar, but less
distinct, cross-bands occur on the dorsal surfaces of the shanks and arms. At a glance
the entire under surface seems immaculate but close inspection reveals rather thickly
scattered, very minute, specks of black, particularly on the chin and throat and on the
under surfaces of the thighs.
Vuriution. The most striking variation noted among the adults is in size. The females
are distinctly larger than the males as can be seen from the following table.
As far as dorsal pattern is concerned, the five adults are rather similar. The second
adult female is very similar to the type in dorsal pattern even down to some of the
A NEWTREE-FROG
FROM
GUYANA
139
details. In two of the males the narrow lines extending backward and inward do not
quite meet in the middle of the back and then each swerves outward and backward to
disappear on the side, just below the sacral hump, thus forming a pair of reversed
parentheses on the back. In the other adult male the dorsal pattern is more like that of
the type (see Fig. 1)and in it the narrow stripes extending backward from the eyes meet
in the middle of the back to form a V-shaped mark as they do in the two females.
Head and body length
Specimen
Sex
BM(NH) 1965.230
USNM 154214
GM F 1.66
MCZ 51271
MBUCV 6042
Q
9
d
d
d
(=)
48.0
46.3
37.8
37.3
37.0
Ventrally, all of the adults have tiny flecks of pigment on the chin and throat but
these are rather uniformly distributed over the entire chin in the females, while they are
more concentrated along the edge of the chin in the males.
One of the immature specimens is quite melanistic and much darker than any other
in the series but even in it the pattern of thin lines can be discerned on the back. In the
other immature individual (BM(NH) 1965.808)the pattern is quite similar to that of the
adult females but the dorsal lines, instead of being narrow like pencil lines, are distinctly
broadened, being in their narrowest part about as wide as the diameter of the tympanum. This specimen has a head and body length of 32.2 mm; the other has a broken
back, but measures approximately 33 mm.
In the type, the three males, and in one of the immature specimens, the vomerine
teeth are essentially arranged in one continuous series while in the other adult female
and the other juvenile the teeth are in two separate but contiguous masses.
Colour in life. At night the frogs were mostly very pale. In the morning the dorsal
ground colour ranged from pale yellow-brown to dark orange-brown. The immature
specimenwith the broad dorsal lineswas described as ‘blotchy marbled brick-brown and
white’. The bars on the thighs were described on one specimen as brown, on another as
dark grey.
Voice. The voice of an adult male (MBUCV 6042) was recorded on 29 September
when the air temperature was between 19” and 21°C. The call may be described as
follows :
Type of call
Dominant frequency
Call rate
Duration of call
A brief ‘pee-peep’
Between 3400 and 3800 c/s
15-35 per minute
0-11-0.12 seconds
Each call consists of two notes of overall duration 0.040-0.050 second, separated by an
interval of 0.025 second. Each note consists of two to four pulses and most of the
energy is concentrated into 0.020-0.030 second (about two pulses), the beginning and
140
COLEMAN
J. GOIN
AND J. D. WOODLEY
end of the note being very weak, and the second noteslightly stronger than the first. The
pulse rate is irregular, but its range is approximately 80-95 c/s.
DISCUSSION
Although this species does have a minute dermal spur on the heel, it seems to be
quite different from the dermal heel spurs on such forms as HyZu cuZcuratu and H.
geogruphicu. In the latter species the spur consists of a single, slender, pointed projection of skin which is pigmented just like the rest of the skin. On each heel of kunuimu,
on the other hand, there are two rounded, clear, unpigmented, hemispherical mounds,
one above the other, when the heels are flexed. The lower one is a simple elevated
mound while the upper one looks as though it has been mashed to one side and thus
forms a somewhat crescent-shaped spur. In no case are these drawn out into a fine point
as they are in H. cukurutu or H. geogruphicu. The reason they appear so in the figure of
the type is that there they are shown in side view. I n surface view they appear as
somewhat distorted, rounded disks.
The frogs of the lowlands of Guyana are moderately well known, but very few collections have been made in mountain localities. Many of the lowland species have Amazonian ranges, but HyZu Kunuimu and other new forms from the same locality probably
also occur in Venezuela and may be indigenous to the Guiana highlands.
ACKNOWLEDGEMENTS
The frogs were collected while the junior author was a member of the Oxford University Expedition to British Guiana, 1959. We are indebted to the many benefactors of
the expedition and to its leader, Professor A. J. Cain. Information about the locality was
provided by Dr B. A. Whitton, botanist to the expedition, and about ‘kanaima’ by
Dr A. J. Butt. Dr R. S. Cowan arranged for the speed-correction of the recordings, Mr
C. J. C. Rees prepared the oscillographs and Mr Paul Laessle made the drawing of the
type. The senior author’s study of South American tree-frogs is supported by a grant
(GB-1339) from the National Science Foundation. All of these we would like to thank.
REFERENCE
BEARD,J. S., 1955. The classificationof tropical American vegetation types. Ecology, 36: 89-100.
EXPLANATION OF PLATE
PLATE
1A. Hyla kanaitna. PLATE
1B.The habitat of Hyla kaMima in the type locality