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NATURAL HISTORY.
SURVEY

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FIELDIANA • ZOOLOGY

Published by
CHICAGO NATURAL HISTORY MUSEUM

Volume 39 July 28, 1960 No. 39

Notes on Toads of the Genus Pelophryne

Robert F. Inger

Curator, Division of Reptiles and Amphibians

In a review of the Philippine Amphibia (Inger, 1954), Nectophryne
lighti Taylor was placed in the synonymy of Pelophryne brevipes
(Peters). The type and only specimen of lighti, a juvenile (15 mm.)
from Agusan Province, Mindanao, had been destroyed in Manila
during World War II. A comparison of the original descriptions
indicated that the two forms differed only in coloration.

In May, 1956, a field party under the leadership of Dioscoro S.
Rabor, from Silliman University, Dumaguete City, Negros Oriental,
collected eight specimens of Pelophryne (CNHM 81588-95), from
Mount Malindang, Zamboanga, Mindanao. As this uniform series
agrees with the description of lighti in coloration and differs from the
sample of brevipes at hand in several other characters, these toads are
referred to Pelophryne lighti (Taylor), here recognized as a distinct
species. They differ from Taylor's description (1920, p. 338) only
in having small, conical tubercles on the top of the head and in having
coarsely granular ventral surfaces. In the type both areas were said
to be smooth. Snout-vent length ranges from 16.3 to 18.5 mm. in
seven of the toads; in the eighth it is only 12.6 mm.

The new series shows that lighti differs from brevipes in coloration
much more than the original descriptions indicate. The latter has a
light gray or brown dorsum with an hourglass figure beginning
between the eyes, a dark lateral band, and a light venter marked
with dark blotches. Pelophryne lighti is brown above and somewhat
darker laterally and ventrally; the only markings are small light
spots on the venter and obscure dark crossbars on the limbs.

In brevipes the tympanum is obscured by skin and is less than

half the eye diameter. In lighti the tympanum is clearly exposed and

one-half to three-fourths the eye diameter. The tips of the outer

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416 FIELDIANA: ZOOLOGY, VOLUME 39

tinctly dilated into truncate disks (Inger, 1954, fig. 40) resembling
the finger tips of both species.

Since larvae of Pelophryne have never been recorded, a small series
collected in Davao Province, Mindanao, is described here. Five
larvae (CNHM 50953) were found at 3,000 feet on Mount McKinley
by Chicago Natural History Museum's Philippine Zoological Expedi-
tion, whose field notes read as follows: "Tadpoles originally from
deeply shaded broken bottle; reared." One tadpole was preserved in
a limb bud stage and the others were allowed to develop until the
fore limbs erupted. Snout- vent length in the last four has the range
of 4.6-4.8 mm. As the hand and foot have the characteristic form
of Pelophryne and the back has the distinctive hourglass figure, this
series can be safely associated with brevipes, adults of which were
collected in the same area. A description of the young tadpole
(fig. 72) follows:

Body ovoid, 4.2 mm. long, 2.4 mm. wide; eye dorsolateral, its own
diameter away from tip of snout; oral disk subterminal, circular,
diameter 0.8 mm., slightly larger than diameter of eye; lips feebly
crenulate; one row of labial teeth anterior to mouth, teeth widely
separated, only ten in number; no posterior labial teeth; beaks weak,
serrated, whitish except for brown margins; no visible spiracle; gut
feebly coiled; anal tube median, without visible opening; hind limb
bud corresponding to stage V of Rana pipiens (Taylor and Kollros,
1946); length of limb bud twice its diameter, slightly bent; tail
6.3 mm., leaf -like, margins subparallel, tip broad; ventral fin slightly
deeper than upper; both fins deeper than tail muscle.

Reduction of the labial teeth is probably not a reflection of an
early stage of development, for the maximum number of tooth rows
is usually found in larvae of early limb bud stages (Gosner and Black,
1954; Inger, 1956).

The feeble coiling of the gut in a larva of limb bud stage suggests
that the tadpole subsists entirely on yolk. Complete larval depend-
ence on yolk is accompanied by a similarly coiled gut in Kalophrynus
pleurostigma (Inger, op. cit.). The degenerate mouth parts of the
Pelophryne tadpole are consistent with the suggested diet. So is the
large size of Pelophryne ova.

Enlarged ova in a Pelophryne albotaeniata (22.8 mm.) vary from
1.5 to 2.5 mm., and in a second albotaeniata (19.2 mm.) from 2.1 to
2.5 mm. In one P. lighti (17.9 mm.) egg size varies from 2.0 to
2.5 mm., and in a P. misera (18.7 mm.) measures about 2 mm.
These are proportionately enormous ova; even large species of Bufo

590. S

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flPt3* INGER: TOADS OF THE GENUS PELOPHRYNE 417

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rarely have ova greater than 2.0 mm. (Wright and Wright, 1949,

p. 137; Inger, 1954, p. 241). Ansonia, another Malaysian bufonid,

has eggs averaging close to 2 mm. (Noble, 1927; Inger, op. cit.),

Fig. 72. Tadpole of Pelophryne brevipes (total length 10.5 mm.). Top, lateral
view; center, ventral view; bottom, oral disk.

but they are relatively smaller because snout-vent length of female
Ansonia is almost always over 25 mm.

Clutch size in Pelophryne is correspondingly specialized. The
number of enlarged ova in one ovary of each of the females listed
above are, respectively, 6, 5, 4, 5. The five brevipes larvae noted
above probably represent most of one clutch. As in the case of
relative egg size, Pelophryne departs farther from Bufo than Ansonia,
which has approximately 75-85 ova per ovary (Inger, op. cit.).

418 FIELDIANA: ZOOLOGY, VOLUME 39

Clutch size in Bufo, of course, may reach astronomical numbers
(Smith, 1947).

The basic specialization of Pelophryne is toward increasing ter-
restriality (as compared to other bufonids). Pelophryne brevipes
and P. albotaeniata have been found only on forest floor or on
low vegetation (Inger, op. cit.). Rabor's series of lighti were also
found on the forest floor. Oviposition seems to take place in such
small rain-filled depressions that, even in breeding, Pelophryne appar-
ently avoids the more characteristic aquatic situations.

REFERENCES

Gosner, L. L., and Black, I. H.

1954. Larval development in Bufo woodhousei fowleri and Scaphiopus holbrooki
holbrooki. Copeia, 1954: 251-255.

Inger, R. F.

1954. Systematics and zoogeography of Philippine Amphibia. Fieldiana, Zool.,

33: 183-531.
1956. Some amphibians from the lowlands of North Borneo. Fieldiana, Zool.,

34: 389-424.

Noble, G. K.

1927. The value of life history data in the study of the evolution of the Amphibia.
Ann. New York Acad. Sci., 30: 31-128.

Smith, H. M.

1947. On the number of eggs laid by certain species of Bufo. Science, 105: 619.

Taylor, A. C, and Kollros, J. J.

1946. Stages in the normal development of Rana pipiens larvae. Anat. Rec,
94: 7-24.

Taylor, E. H.

1920. Philippine Amphibia. Phil. Jour. Sci., 16: 213-359.

Wright, A. G. and A. A.

1949. Handbook of frogs and toads of the United States and Canada, xii +
640 pp. Comstock Publishing Co., Ithaca, N. Y.