snout-vent length is 23.6 mm. Slight variation in the ratio of tibia
length to snout-vent length exists throughout the range; more variation
exists in the ratio of the diameter of the tympanum to that of the eye;
the tympanum is proportionately larger in northern populations (Table
7). The primary differences between Panamanian and more northern
populations are in size, color pattern on the dorsum and shanks, amount
of webbing between the toes, and duration of notes in the mating call
(Table 2, Pl. 4).

The color in Panamanian _staufferi_ is gray or gray-brown with a pair
of distinct, complete, dark brown dorsolateral stripes, a pair of
entire paravertebral stripes, and in some specimens a vertebral stripe.
About five per cent of the individuals have interrupted stripes on the
dorsum, whereas in the more northern populations complete paravertebral
stripes are present in less ten per cent of the specimens; when
complete stripes are present, they are irregular. The dorsal ground
color in non-Panamanian specimens is brown, olive-brown, or dark brown.

Transverse bars are present on the shanks in _Hyla staufferi_ from
Costa Rica northward to Mexico, whereas in Panama all the individuals
have a longitudinal stripe on the shank (Table 7, Pl. 2). The
interorbital spot or bar is more noticeable in northern populations
than in specimens from Panama. Frogs from Costa Rica and northward have
the toes about three fourths webbed, whereas in Panama the toes are
about two fifths webbed. The mating calls of the northern and
Panamanian populations are similar, but the notes have a longer
duration in the northern populations and a higher dominant frequency in
Panamanian populations.

_Hyla staufferi_ is the most variable member of the _Hyla rubra_ group
in Central America. The Panamanian populations are geographically
separated from the Costa Rican and more northern populations by an area
of tropical rainforest in the Golfo Dulce region in southeastern Costa
Rica and adjacent Panama. _Hyla staufferi_ does not occur on the
Caribbean versant of Costa Rica and Panama. The Golfo Dulce region and
the Caribbean versant are humid and inhabited by _Hyla elaeochroa_.
_Hyla staufferi_ is an inhabitant of subhumid and xeric areas.

On the basis of the discontinuous variation in several characters which
correlate with the disjunct distribution of the two populations, two
subspecies of _Hyla staufferi_ are recognized. The accounts that follow
a