Tadpoles of the genus _Ptychohyla_ are adapted to live in mountain
streams. The bodies are streamlined, and the tails are long and have
low fins (Figs. 4 and 5). The mouths are large and directed ventrally.
Tadpoles of the two groups of species have strikingly different
mouthparts.
[Illustration: FIG. 5. Tadpoles of
(A) _Ptychohyla schmidtorum schmidtorum_ (KU 60051),
(B) _P. schmidtorum chamulae_ (KU 58199), and
(C) _P. ignicolor_ (KU 71716).]
Lips of tadpoles of the _Ptychohyla euthysanota_ group (Fig. 6 A-D)
are folded laterally; there are 4/6 or sometimes 4/7 tooth-rows. A
lateral "wing" projects on either side of the upper beak. The beaks
have blunt, peglike serrations. Lips of tadpoles of the _Ptychohyla
schmidtorum_ group (Fig. 6 E-G) are greatly expanded and form a
funnel-shaped disc; there are 3/3 short tooth-rows. There is no
lateral projection or "wing" on either side of the upper beak. The
beaks have long, pointed serrations.
[Illustration: FIG. 6. Mouthparts of tadpoles of _Ptychohyla_:
(A) _P. euthysanota euthysanota_ (KU 60042),
(B) _P. euthysanota macrotympanum_ (KU 60049),
(C) _P. leonhardschultzei_ (KU 68556),
(D) _P. spinipollex_ (KU 60053),
(E) _P. schmidtorum schmidtorum_ (KU60051),
(F) _P. schmidtorum chamulae_ (KU 58199), and
(G) _P. ignicolor_ (KU 71716). x 10.]
Variation in certain structural details and in coloration is discussed
for each species and subspecies in the systematic accounts that
follow. Sizes, proportions, and numbers of tooth-rows are tabulated in
Table 2.
TABLE 2.--COMPARISON OF CERTAIN LARVAL CHARACTERS IN THE SPECIES OF
PTYCHOHYLA. (MEANS ARE IN PARENTHESES BELOW THE RANGES.)
==============================+=========+=======+============+==========
| Number |Maximum| Head length|
Species | of | total |------------|Tooth-rows
|specimens| length|Total length|
------------------------------+---------+-------+------------+----------
_P. euthysanota euthysanota_ | 23 | 40.8 | 30.9-37.3 | 4/6
| | | (33.5) |
_P. euthysanota macrotympanum_| 13 | 43.3 | 30.6-33.4 | 4/6
| | | (32.7) |
_P. leonhardschultzei_ | 7 | 47.5 | 29.2-32.7 | 4/6
| | | (31.1) |
_P. spinipollex_ | 32 | 45.0 | 30.2-35.9 | 4/7
| | | (33.0) |
_P. schmidtorum schmidtorum_ | 14 | 42.5 | 28.9-31.2 | 3/3
| | | (29.9) |
_P. schmidtorum chamulae_ | 4 | 45.0 | 26.9-29.3 | 3/3
| | | (27.8) |
_P. ignicolor_ | 2 | 39.6 | 29.6-29.8 | 3/3
| | | (29.7) |
------------------------------+---------+-------+------------+----------
Evidence on the pattern of development of tooth-rows indicates that
the inner rows develop first. A small tadpole of _P. euthysanota
euthysanota_ has six lower rows and three fully developed upper rows
and only the beginning of the first (outer) upper row. A small tadpole
of _P. euthysanota macrotympanum_ has four upper rows and five lower
rows. In a small tadpole of _P. leonhardschultzei_ the three upper and
four lower tooth-rows are well developed; the first upper and fifth
lower rows are beginning to develop, and the sixth lower row is
absent. In small tadpoles of _P. spinipollex_, the sixth lower row is
poorly developed, and the seventh row is absent; large individuals
normally have seven lower rows. A small tadpole of _P. schmidtorum
chamulae_ has 3/2 tooth-rows.