Chapter II: Part 2

The mating call of _Hyla elaeochroa_ consists of short notes, repeated at intervals of about 0.40 second. Each note has a duration of 0.12 to 0.24 second. The fundamental frequency varies from 48 to 65 cycles per second, and the notes have 40-50 pulses per second; the dominant frequency is at about 2,900 cycles per second (Table 2, Pl. 4A).

The eggs are deposited in a mass in the water near floating vegetation. William E. Duellman informed me that he observed hatchlings oriented vertically with the tip of the mouth at the surface of the water. They gradually sank to bottom, but swam back to surface again. No additional information is available concerning early development. Tadpoles have been found in shallow grassy ponds in clearings and in temporary woodland ponds.

_Tadpoles._--Three hundred and thirty-one tadpoles in various stages of development are available. Thirty-five tadpoles in stage 35 have a mean body length of 8.1 mm. (8.0-9.0 mm.), tail length of 17.7 mm. (15.0-19.5 mm.), and total length of 25.9 mm. (23.0-27.5 mm.). The largest tadpole examined is in stage 40 and has a total length of 34.5 mm. (Table 6).

A typical tadpole, stage 35 of development (KU 104134, from Puerto Viejo, Heredia Province, Costa Rica), has a body length of 9.1 mm., tail length of 17.7 mm., and a total length of 26.8 mm. Other characters are as follows: body depressed anteriorly; body length greater than depth of tail; internarial space as broad as interorbital distance; nostril equidistant between eye and tip of snout; eyes moderately large; mouth anteroventral and triangular; median fourth of upper lip bare; rest of lip bordered by one row of papillae; clumps of small papillae at corners of mouth; tooth rows 2/3; upper rows equal in length; second row interrupted medially; lower rows shorter than upper rows, diminishing in length; beak rather weak with small serrations; spiracle short and nearer eyes than anus; anal opening not reaching edge of ventral fin; caudal musculature attenuated distally (Figs. 2B and 3B).

TABLE 6.--Sizes of Tadpoles of _Hyla elaeochroa_ in Relation to Developmental Stages. (Means in parentheses below observed ranges; measurements in mm.)

------+---+-------------+-------------+--------------
Stage | N | Body length | Tail length | Total length
------+---+-------------+-------------+--------------
24 | 2 | 4.0-4.0 | 8.5-9.0 | 12.5-13.0
| | (4.0) | (8.8) | (12.8)
| | | |
25 |64 | 5.0-6.5 | 8.5-15.0 | 13.5-21.5
| | (5.7) | (11.8) | (17.6)
| | | |
27 |30 | 7.0-7.5 | 13.0-16.0 | 20.0-23.0
| | (7.1) | (14.2) | (21.3)
| | | |
30 |15 | 7.0-8.0 | 13.0-16.5 | 20.0-24.0
| | (7.3) | (15.0) | (22.4)
| | | |
32 |30 | 7.5-8.5 | 15.0-17.0 | 22.5-25.0
| | (7.8) | (16.1) | (23.8)
| | | |
35 |35 | 8.0-9.0 | 15.0-19.5 | 23.0-27.5
| | (8.1) | (17.7) | (25.9)
| | | |
37 |22 | 8.5-9.5 | 16.0-22.0 | 25.0-31.0
| | (9.0) | (18.8) | (27.8)
| | | |
39 |14 | 9.5-10.5 | 19.0-24.9 | 28.5-33.5
| | (9.9) | (21.1) | (31.0)
| | | |
40 |27 | 7.0-11.5 | 15.0-23.0 | 23.0-34.5
| | (9.1) | (22.0) | (31.2)
| | | |
43 |10 | 8.0-12.0 | 11.0-17.0 | 20.0-26.0
| | (10.2) | (13.5) | (23.7)
| | | |
45 |16 | 10.0-12.0 | 1.0-7.0 | 12.0-17.0
| | (11.2) | (3.4) | (14.6)
| | | |
46 |45 | 11.0-13.0 | |
| | (11.8) | |

In life, dorsum yellowish tan with gray-brown mottling; belly and ventrolateral surfaces silvery-gold or white; black stripe from tip of snout to eye; two black blotches below eye, another blotch extending from eye to base of caudal musculature; caudal musculature and fins gray-brown. In preservative, yellowish tan and silvery-gold colors lost; black reticulations present on tail.

_Remarks._--Cope (1876:105) described _Hyla elaeochroa_ from Sipurio, Limon Province, Costa Rica. He based his description on a small specimen, 26.0 mm. in snout-vent length, having a dorsum uniformly colored and lacking an interorbital triangle and blotches on the thighs. Cope (1887) described pigmented specimens from Nicaragua as _Hyla quinquevittata_, which he diagnosed as having dark brown bars on the hind limbs and five dark brown longitudinal stripes on the dorsum, the median one of which was expanded anteriorly so as to form a large triangular spot between the eyes. He thought this species was related to _Hyla eximia_ Baird and noted that "the hinder legs are much larger; the muzzle is more acuminate and the color bands are much wider" than in _eximia_. Cope did not compare _quinquevittata_ with _elaeochroa_, which he had described ten years before. Guenther (1901:268), Noble (1918:340), and Nieden (1923:251) regarded both _elaeochroa_ and _quinquevittata_ as valid species. Dunn and Emlen (1932:25) regarded both as synonyms of _Hyla rubra_, but they made no qualifying statements. Taylor (1952:859) placed _quinquevittata_ as a synonym of _elaeochroa_ and indicated that _rubra_ was another species.

Taylor (1958:37) described _Hyla dulcensis_ from the humid tropical forests of Golfo Dulce, Puntarenas Province, Costa Rica. He thought this species was "related to _H. elaeochroa_ but differs in its somewhat larger size, smaller finger and toe discs, the obsolete canthus rostralis; the loreal region concave and the choanae larger." Duellman (1966a:270) compared adults, tadpoles, and mating calls of _dulcensis_ and _elaeochroa_ and concluded that a single species was involved.

_Hyla elaeochroa_ can be easily confused with the closely related _Hyla staufferi_. Although the durations of the calls are similar, the call of _elaeochroa_ has only about one third the number of pulses per second, a much lower fundamental frequency, and a lower dominant frequency than that of _staufferi_. _Hyla elaeochroa_ is larger and has a less pointed snout than does _staufferi_. Although the skulls of the two species are similar, that of _elaeochroa_ differs in having broad palatines and comparatively larger nasals that are truncate anteriorly. In _staufferi_ the nasal is rounded anteriorly and the palatine is absent.

_Distribution._--_Hyla elaeochroa_ occurs on the Caribbean lowlands from western Panama through Costa Rica to eastern Nicaragua, and on the Pacific lowlands of southeastern Costa Rica and extreme western Panama. Most localities where it has been collected are below 800 meters, but the species has been found at two localities above 1000 meters (El Silencio and Pacuare, Cartago Province) on the Caribbean slopes of the Cordillera de Talamanca, Costa Rica (Fig. 6).

_Specimens Examined._--Nicaragua: _Zelaya_: El Recreo, UMMZ 79721 (9).

Costa Rica: _Alajuela_: Laguna Monte Alegre, KU 64499. _Cartago_: 2 km E Chitaria, KU 107058; El Silencio, 14.4 km NE Turrialba, KU 107059-60; 4.6 km ENE Pacuare, KU 64451-75, 64628-37; 4 km S Pavones, KU 64500; Turrialba (Instituto Interamericano de Ciencias Agricolas), KU 30305-26, 24616-57, 30337-54, 31776-91, 31803, 31807-15, 64413-50, 68283-87 (skeletons), 68390-1 (young), 35042 (eggs), 25207-8 (skeletons), 25221 (skeleton), 41073-83 (skeletons). _Guanacaste_: 2 km E Tilaran, KU 86356-77, 87667-8 (young). _Heredia_: Puerto Viejo, KU 36696, 46466, 64501-17, 68288-91, 68387, 68388-9 (young), 91803 (young), 91688-9, 104134 (tadpoles), 104135 (young), 104354-6 (skeletons); 1.5 km N Puerto Viejo, KU 64518-23, 68386 (tadpoles); 1 km S Puerto Viejo, KU 84985-6 (skeletons), 87669 (young), 87772-3 (skeletons). _Limon_: Bataan, KU 30327-36; La Lola, KU 64478-98, 68281-2 (skeletons); Los Diamantes, KU 31800-02, 64476-7; Peralta, KU 31816-21; Puerto Limon, KU 31792-99; Suretka, KU 36467-79, 36697, 41084. _Puntarenas_: 5 km NW Buenos Aires, KU 107057; 10 km E Esparta, KU 87666 (tadpoles); Golfito, KU 32166-8; 8 km E Palmer Norte KU 93939; 10.7 km SE Palmar Sur, KU 93938 (skeleton), 93940-51, 93952 (eggs), 93953-6 (tadpoles); Piedras Blancas, KU 103646-59; 4.5 km W Rincon de Osa, KU 102208-41, 104298 (tadpoles).

Panama: _Bocas del Toro_: Almirante, KU 80079; Isla Bastimentos, KU 96008-11; Rio Cricamola, 3.7 km from coast, KU 96012. _Chiriqui_: Rio Gariche, 8.3 km ESE Paso de Canoas, KU 101571-2.

_Hyla staufferi_ Cope

_Hyla staufferi_ Cope, Proc. Acad. Nat. Sci. Philadelphia, 17:165,
October 1, 1865 [Holotype.--USNM 15317, Orizaba, Veracruz, Mexico;
Francis Sumichrast collector].

_Diagnosis._--Small frogs (Male to 29 mm., Female to 31.6 mm.); skull longer than wide; palatine absent; large cartilaginous crista parotica present; snout flat, elongate and protruding; dark interorbital bar and dorsal stripes usually present.

_Description._--Head flat, especially in females, longer than wide; snout long, protruding beyond mouth; loreal region concave; canthus ill-defined; length of eye greater than internarial distance or width of eyelid; length of eye less than interorbital space; tympanum distinct; interorbital spot irregular; supratympanic fold faint; arms short; fingers free of webs; discs on third and fourth fingers equal to diameter of tympanum; inner metatarsal tubercle on base of first finger distinct; first finger shorter than second; palmar tubercle distinct (Fig. 1C); legs short (usually less than 50 per cent of snout-vent length); tarsal fold absent; metatarsal tubercles small, outer tubercle smaller than inner; subarticular tubercles small, simple, distinct; toes less than half webbed (Fig. 1D); skin smooth above with a few small pustules on head, scapular region, flanks, and supratympanic region; arms and legs smooth; skin of belly coarsely granular; posteroventral surfaces of thighs finely granular; tongue small, rounded, longer than wide, slightly free and notched posteriorly; vocal slits small, lateral to tongue; choanae moderate in size.

_Variation._--The largest males of _Hyla staufferi_ are from Jalapa, Guatemala, and from San Salvador, El Salvador. In these samples the average snout-vent length is 27 mm. In Panamanian specimens the average 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 apply equally to each.

_Cranial Osteology._--The skull of _Hyla staufferi_ is flat and longer than wide. The premaxillary is small and bears 9 to 13 teeth (mean for 5 specimens, 11.3). The alary process of the premaxillary is small, concave posteriorly and vertical. Ventrally, the premaxillary is united to the prevomers by partially ossified cartilage. The maxillary is slender and usually bears 49 to 70 teeth (mean for 5 specimens, 60.7). The pars facialis of the maxillary is convex and less than twice the height of the pars dentalis.

The nasal is large, rounded anteriorly, and pointed posteriorly in dorsal view. The nasal comprises about 40 per cent of the total length of the skull. Anteromedially the two nasals converge; posteriorly they overlap the sphenethmoid. The nasals lack a concavity in the midlateral surface. Dorsally, the sphenethmoid is wider than long, roughly pentagonal in shape; the frontoparietal is elongate, narrow, and smooth, with a small supraorbital process anteriorly. The frontoparietal fontanelle is narrow anteriorly and wide posteriorly.

TABLE 7.--Geographic Variation in Size and Color in Males of _Hyla staufferi_. (Means in parentheses below observed ranges.)

=================================================================
| | |Complete dorsal|
| |Snout-vent | stripes |Barred shanks
Locality | N |length (mm.)| (per cent) | (per cent)
---------------+-----+------------+---------------+--------------
Veracruz | 47 | 23.0-27.3 | 0.0 | 100
| | (25.4) | |
| | | |
Campeche | 20 | 24.6-27.5 | 0.0 | 100
| | (25.5) | |
| | | |
Oaxaca | 75 | 24.0-28.7 | 9.3 | 100
| | (26.4) | |
| | | |
Chiapas | 20 | 23.2-27.8 | 10.0 | 100
| | (25.5) | |
| | | |
Guatemala | 22 | 25.0-29.0 | 10.9 | 100
| | (26.9) | |
| | | |
El Salvador | 21 | 24.7-28.6 | 0.0 | 100
| | (27.0) | |
| | | |
Honduras | 34 | 20.6-27.0 | 3.3 | 100
| | (24.9) | |
| | | |
Nicaragua | 67 | 21.5-26.8 | 3.0 | 92.7
| | (24.9) | |
| | | |
Costa Rica | 54 | 20.7-26.6 | 5.5 | 98.1
| | (24.2) | |
| | | |
Total | 360 | 20.7-29.0 | 5.4 | 98.3
Non-Panamanian | | (25.9) | |
| | | |
Panama | 72 | 21.7-26.0 | 94.5 | 0.0
| | (23.6) | |

Only a narrow connection exists between the posterior, pointed arm of the squamosal and the lateral edge of the prooetic. The crista parotica is visible dorsally along the lateral edge of the bony prooetic. The squamosal is narrow anteriorly and posteriorly.

The prevomers are short and separated anteriorly by partly ossified cartilage of the overlying solum nasi. The prevomer is joined to the premaxillary by cartilage. The posterior margin of the prevomer articulates directly with the sphenethmoid. The anterolateral and posterolateral processes of the prevomers form the incomplete bony internal margin of the choanae. Each prevomer bears three to six teeth. The palatine is absent. The anterior part of the parasphenoid is narrow and ends in a point. The pterygoid is slender and weakly developed.

_Natural History._--Throughout its range _Hyla staufferi_ occurs in subhumid forests and savannas; consequently, the breeding activities are limited by the seasonal occurrence of rainfall, which accumulates in temporary ponds where this species breeds. Clasping pairs and gravid females have been found mostly from June to August throughout its range. This species was observed calling at Finca Taboga, Guanacaste Province, Costa Rica, in mid-July. The males were calling from temporary grassy and weedy ponds in which _Hyla microcephala_ also was calling, but the two species had different calling sites. _Hyla staufferi_ called at stations at heights of five to 80 cm. near the edge of the pond, whereas _Hyla microcephala_ called from emergent vegetation in the middle of the pond. Charles W. Myers informed me that at Penonome, Cocle, Panama, he found _staufferi_ calling from grass in puddles where _microcephala_ was absent, and at El Cano, Cocle, Panama, _staufferi_ was calling from higher sites ("several inches to a few feet above water") than _microcephala_.

Stuart (1948:34) reported breeding individuals from La Libertad, Guatemala, after rainfall in late May, and Schmidt and Stuart (1941:239) reported _staufferi_ breeding in July in the Salama basin, Alta Verapaz, Guatemala. Stuart (1935:38) and Duellman (1960:63 and 1963:226) agreed that this species breeds early in the rainy season. However, Rand (1957:519) stated that in El Salvador "these frogs did not begin to call until almost a month and a half after the beginning of the rains." Blair (1960:133) reported that males call in June and July in Chiapas, Oaxaca, Veracruz, and Tamaulipas, Mexico.

The mating call of this species is a series of closely spaced notes having a fundamental frequency of about 100 cycles per second. Each note has a duration of 0.13 to 0.23 second, repeated at intervals that are longer than the duration of the call. The notes are moderately low-pitched and have a dominant frequency of more than 3,000 cycles per second and about 120 pulses per second (Table 2).

_Tadpoles._--Measurements of the 33 tadpoles that are available are given in Table 8. The largest tadpole examined is in stage 38 and has a total length of 29.5 mm.

A typical tadpole in stage 38 of development (KU 104162, 5 km ESE Cordoba, Veracruz, Mexico) has a body length of 10 mm., tail length of 19.5 mm., and a total length of 29.5 mm. Other characters are as follows: body as deep as wide, depressed anteriorly; body as long as depth of tail; interorbital space greater than distance between eye and snout but equal to internarial space; nostril equidistant between eye and tip of snout; distance between spiracle and eye less than distance between eye and snout; eyes large, situated dorsolaterally; mouth anteroventral, approximately triangular in outline; one row of papillae covering lower lip and all except median fourth of upper lip; scattered papillae at corners of mouth; tooth rows 2/3; first upper row entire, second row interrupted medially, shorter than first; lower rows shorter than upper rows; beak weak; spiracle short and nearer eyes than anus; anal opening not reaching edge of ventral fin; dorsal fin barely extending onto body; caudal musculature pointed distally.

TABLE 8.--Sizes of Tadpoles of _Hyla s. staufferi_ in Relation to Developmental Stages. (Means in parentheses below observed ranges; measurements in mm.)

======================================================
Stage | N | Body length| Tail length | Total length
--------+---+------------+-------------+--------------
25 | 3 | 6.0-7.0 | 12.0-13.0 | 18.0-20.0
| | (6.7) | (12.5) | (19.2)
| | | |
26 | 2 | 7.0-7.5 | 14.0-15.0 | 21.5-22.0
| | (7.3) | (14.5) | (21.8)
| | | |
27 | 9 | 7.0-8.0 | 13.0-17.0 | 21.0-25.0
| | (7.6) | (14.5) | (22.0)
| | | |
32 | 1 | 8.5 | 15.5 | 24.0
| | | |
36 | 2 | 8.0-10.0 | 16.5-17.0 | 25.0-26.5
| | (9.0) | (16.8) | (25.8)
| | | |
38 | 6 | 9.0-10.0 | 19.0-20.5 | 28.0-29.5
| | (9.6) | (19.5) | (29.1)
| | | |
41 | 1 | 10.0 | 14.0 | 24.0
| | | |
42 | 6 | 11.0-14.0 | 10.0-13.0 | 20.0-29.0
| | (11.8) | (11.9) | (24.8)
| | | |
45 | 1 | 12.5 | 0.5 | 13.0
| | | |
46 | 1 | 13.0 | -- | --

In life, body pale olive-tan, belly silvery white with pinkish-orange reticulations in some specimens; tail creamy white with silvery flecks and black or brown reticulations. In preservative, tan and pinkish-orange coloration lost; body transparent, reticulations on tail present.

_Remarks._--_Hyla staufferi_ was described by Cope (1865:195) on the basis of specimens from Orizaba, Veracruz, Mexico. He described the color pattern as "color above dark olive, with a short black bar over each scapula, and one from eye to eye, with a trace along the coccyx." Cope (1887:14) placed _staufferi_ as a subspecies of _Hyla eximia_, but he did not justify his action. Guenther (1901:262) also considered _staufferi_ to be conspecific with _eximia_ without making any qualifying statement. Dunn and Emlen (1932:24) named _Hyla culex_ from Tela, Honduras, on the basis of a male (MCZ 16098) having a snout-vent length of 25.1 mm., and a female (USNM 20267) from Patuca, Honduras. They diagnosed the species as having "discs larger than tympanum ... black interorbital triangle, traces of black dorsal marking; three black bars on anterior and posterior face of thighs, two black bars on tibia, on tarsus and on forearm." The holotype now is faded but has some of the pattern described. Dunn and Emlen did not compare _culex_ with _staufferi_ but did compare it with _boulengeri_ and _rubra_.

Dunn (1933:61) named _Hyla altae_ from Summit, Canal Zone. His description was based on a male (MCZ 17972) having a snout-vent length of 25.1 mm., the color pattern was described as "gray with four darker dorsal stripes ... a faint trace of mid-dorsal striping...." Dunn defined the _Hyla rubra_ group and recognized _boulengeri_, _altae_, _culex_, and _rubra_ as members. _Hyla elaeochroa_ and _staufferi_ were omitted from his key to the group in Central America.

Kellogg (1932:174) compared _staufferi_ with _eximia_ and concluded that the two were probably distinct species. Stuart (1935:38) considered _altae_ to be a synonym of _culex_. Gaige (1936:293) considered _altae_ and _culex_ to be conspecific but regarded _staufferi_ as a different species. She also suggested that _staufferi_ was not related to _eximia_ but belonged to the _rubra_ group. Taylor (1952:865) and Duellman (1966a:274) considered _altae_ and _culex_ to be synonyms of _staufferi_.

The only other worker besides Cope and Guenther to consider _Hyla staufferi_ as a member of the _eximia_ group was Blair (1960:129), who suggested the relationship on the basis of similarities in the structure of the calls of _eximia_ and _staufferi_. Taylor (1938:421) and Smith and Taylor (1948:78) excluded _staufferi_ from the _eximia_ group on the basis of morphological characteristics. I consider _culex_ to be inseparable from _staufferi_, whereas _altae_ is recognizable as a Panamanian subspecies of _staufferi_.

_Hyla staufferi staufferi_ Cope, New Combination

_Hyla staufferi_ Cope, Proc. Acad. Nat. Sci. Philadelphia, 17:195,
October 1865 [Holotype.--USNM 15317, Orizaba, Veracruz, Mexico;
Francis Sumichrast collector], Brocchi, Mission Scientifique au
Mexique et dans L'Amerique Centrale, 1881, p. 36. Boulenger,
Catalogue, of the Bratrachia Salientia s. Ecaudata, p. 400,
February 1, 1882. Kellogg, Bull. U.S. Natl. Mus., 160:173, March
31, 1932. Smith and Taylor, Bull. U.S. Natl. Mus., 194:88, 1948.
Taylor, Univ. Kansas Sci. Bull., 35:862, July 1, 1952. Rand,
Fieldiana Zool. Chicago Nat. Hist. Mus., 34:518, April 18, 1957.
Duellman, Univ. Kansas Publ, Mus. Nat. Hist., 17:274, June 17,
1966.

_Hyla eximia staufferi_ Cope, Bull. U.S. Natl. Mus., 32:14, January
16, 1887.

_Hyla eximia_ (part): Guenther, Biologia Centrali-Americana,
Reptilia and Batrachia, p. 261, June 1901. Nieden, Das Tierreich,
Anura I, p. 245, June 1923.

_Hyla culex_ Dunn and Emlen, Proc. Acad. Nat. Sci. Philadelphia,
84:24, March 22, 1932 [Holotype.--MCZ 16098, Tela Honduras; Raymond
A. Stadelman collector]. Stuart, Misc. Publ., Univ. Michigan Mus.
Zool., 29:38, October 1935. Gaige, Carnegie Inst. Washington Publ.,
457:293, 1936.

_Diagnosis._--Small frogs (Male to 29 mm., Female to 31.6 mm.); dorsolateral stripes irregular; paravertebral stripes usually broken; two or three transverse bars on shanks; thighs spotted or not; arms usually barred; interorbital bar usually present; toes about three fourths webbed; color brown, tan, or olive-green.

_Variation._--Three hundred and sixty males chosen at random from throughout the range have snout-vent lengths of 20.7 to 29 mm. (25.9 mm.). The smallest individuals are from Costa Rica and Nicaragua (means 24.2 and 24.4 mm., respectively). The largest individuals are from Guatemala and El Salvador (mean of each 27.0 mm.). The ratio of the diameter of the tympanum to that of the eye is more than 60 per cent in most samples, but in those from Costa Rica and British Honduras it is smaller. The color pattern is highly variable. Some specimens are dark brown or pale brown in color. Incomplete dorsal stripes are present in 94.6 per cent of the specimens, and transverse bars are present on the shanks in 98.3 per cent of the specimens. The interorbital spot varies from transverse to longitudinal in position, and an irregular white line extends from the upper jaw to the arm in some specimens (Table 7).

_Distribution._--_Hyla staufferi staufferi_ inhabits savanna and subhumid and xeric forests in the lowlands and moderate elevations from southern Tamaulipas southward to Nicaragua on the Caribbean versant and from Guerrero, Mexico to northwestern Costa Rica on the Pacific lowlands (Fig. 7). Duellman (1963:226) commented that a specimen from Chinaja, Guatemala, possibly was transported there in the cargo from Toocog, because with this one exception the species is unknown in tropical rainforest in Guatemala.

_Specimens Examined._--Mexico: _Campeche_: 5 km S Champoton KU 71296-7; 7 km W Escarcega, KU 71298-308; 13 km W, 1 km N Escarcega, KU 71309-10, 75090-4. _Chiapas_: 32 km S Arriaga, KU 57789-92; 4 km N Ixtapa, KU 5776-81; 3.6 km SW Las Cruces, KU 37740; 17 km S Las Cruces, KU 57793-4; 24 km S Las Cruces, KU 104160 (tadpoles); 11 km S Tapachula, KU 57782-8, 60000 (young). _Guerrero_: El Limoncito, near La Venta, KU 31392-401; Mexcala, near Balsa River, KU 31391; Organos, S El Trienta, KU 31390. _Oaxaca_: 26 km N Matias Romero, KU 33878-82; 2.5 km S Pochutla, KU 59924-7 (skeletons); 5 km S Pochutla, KU 57795-801; 3.2 km E Tapanatepec, KU 37877-902; 17.6 km WNW Tapanatepec, KU 65033-4; Temascal, USC 8243 (8); 3.2 km S Tolocita, KU 39657-8; 0.5 km Tuxtepec, KU 87073-81, 87610 (tadpoles); 17 km S Tuxtepec, KU 65035-7; 1 km W Zanatepec, KU 104161 (tadpoles). _Quintana Roo_: Isla Cozumel, 3.5 km N San Miguel, KU 71710-11 (young). _San Luis Potosi_: Valles, KU 31490. _Tabasco_: Teapa, UMMZ 118887 (3), 119203 (13); 9.6 km N Teapa, UMMZ 119202; 24 km N Teapa, UMMZ 119961 (5); 29 km N Teapa, UMMZ 119960; 3.5 km S Villahermosa, UMMZ 119201 (2); 17.6 km S Villahermosa, UMMZ 119200 (8). _Tamaulipas_: 1 km E Chamal, UMMZ 110706; Gomez Farias, UMMZ 110701 (3); 5 km SE Gomez Farias, UMMZ 110705; 8 km NE Gomez Farias, UMMZ 11282 (2), 11283 (3); Kilometer 615 between Rio Limon and Llera, UMMZ 80455 (2); 5 km W San Geraldo, UMMZ 110702 (4), 110703 (3); 8 km W San Geraldo, near Rio Frio, UMMZ 110704 (5). _Veracruz_: 3 km SW Boca del Rio, KU 10494-8; 5 km SW Boca del Rio, KU 23701; 5 km ESE Cordoba, KU 104162 (tadpoles); Cuautlapan, KU 57098-102, 26787; Hacienda Tamiahua, Cabo Rojo, KU 62871; 2 km ENE Mata Oscura, KU 105627; 5 km SE Paso del Toro, KU 40144; Portrero Viejo, KU 23911-2, 26786, 27413, 57094-7.

Guatemala: _Alta Verapaz_: Chinaja, KU 57769; Finca La Cubilquitz, UMMZ 90871, 90872 (5), 91379 (2). _Baja Verapaz_: 1 km S San Jeronimo, UMMZ 84077 (7), 84078 (14). _Chiquimula_: 1.6 km SE Chiquimula, UMMZ 98114 (2); Esquipulas, UMMZ 106784 (4), 106785 (14). _El Peten_: No specific locality, USNM 25143, 24825-6; La Libertad, FMNH 27096-7, KU 57770, UMMZ 75339 (15), 75340 (15), UMMZ 94341-2. _Esquintla_: 20 km N San Jose, AMNH 74369-76. _Guatamala_: 16 km NE Guatamala, KU 43539. Izabal: Puerto Barrios, TCWC 16671-73, 16646-56; 2.5 km NE Rio Blanco, KU 57774-5. _Jalapa_: Jalapa, UMMZ 106788 (44). _Jutiapa_: Finca La Trinidad, UMMZ 107730 (12), 107731 (16); Jutiapa, UMMZ 106786 (2). _Zacapa_: 14 km ENE Mayuelas, KU 57773; 7 km ENE Rio Hondo, KU 57771-2, 59999 (young).

British Honduras: BELIZE: Belize, FMNH 4406. _El Cayo_: San Agustin, UMMZ 80741 (8). _Stann Creek_: 10 km S Stann Creek on Hummingbird Highway, UMMZ 125720-1.

El Salvador: _Cuscatlan_: 7 km WNW Cojutepeque, TNHC 32004-10. _La Libertad_: 16 km NW Santa Tecla, KU 43540-1. _La Union_: 2.5 km Santa Rosa, TCWC 16669-70. _Morazan_: Dividendero, USNM 73288-92. _San Salvador_: San Salvador, FMNH 65101-06, KU 61932-44, 61989-92, 62152 (eggs), USNM 117588, 118391 (3), 118394; 1.6 km NW San Salvador, KU 43162-3.

Honduras: _Atlantidad_: Ceiba, USNM 117592. _Choluteca_: Choluteca, KU 85361-6; 2 km E Choluteca, UMMZ 118395 (7); 3.2 km NE Choluteca, KU 100500-01; 6.2 km E Choluteca, KU 65046-56; 10 km E Choluteca, KU 65045: 5 km S Choluteca, USC 2700 (4). _Colon_: Isla Guanaja (Islas de la Bahia), TCWC 21551, TNHC 32011. _Cortes_: Agua Azul, TCWC 19178-9; East side Lago Yojoa, KU 65038-44. _El Paraiso_: Valle de Jamastran, AMNH 54800-04. _Francisco Morazan_: Escuela Agricola Panamericana, AMNH 54963-73; 14.5 km NW Comayaguela, KU 100499; El Zamorano, KU 103224; 29 km N Tegucigalpa, TNHC 32003, 32012.

Nicaragua: _Chinandega_: Finca San Isidro, 10 km S Chinandega, KU 85311-33. _Managua_: 13 km E Managua, KU 85339; 2 km S Tipitapa, KU 85334-8. _Rivas_: 9.5 km SE Rivas, KU 85355-6; 18 km SE Rivas, KU 85354; 7.7 km NE San Juan del Sur, KU 85346-53; 16.5 km NE San Juan del Sur, KU 85340-5; 5 km SE San Pablo, KU 43151-61. _Zelaya_: Isla Grande del Maiz, KU 85357-60.

Costa Rica: _Alajuela_: _Los Chiles_, USC 7215 (2), 7217. _Guanacaste_: 4 km W Bagaces, USC 7019 (5); Finca Taboga, KU 102265-5; 12 km S La Cruz, USC 8091; Las Canas, KU 41113 (skeleton); 27 km N Las Canas, USC 8171 (5); Guardia, Rio Tempisque, USC 8214; 10 km N Guardia, KU 102266-7; 1.6 km N Guayabo de Bagaces, USC 7023 (3); Liberia, KU 36510-22; 4 km W Liberia, KU 36449-64, USC 102 (10), 103 (9), 104 (7), 105; 6 km N Liberia. USC 8096; 8 km NNW Liberia, KU 65032; 14.5 km N Liberia, USC 8079, 8138 (2); 14.5 km S Liberia, USC 8238 (5); 6 km N Nicoya, USC 8229 (11); 4 km S Nicoya, USC 8230, 8231; Penas Blancas, KU 102263; 8.6 km ESE Playa del Coco, USC 8137 (14); 21 km E Playa del Coco, USC 8138 (2); Santa Cruz, USC 8232 (2); 3 km E Santa Rosa, TCWC 16663-68; Tenorio, KU 32159; Tilaran, KU 36509. _Puntarenas_: 10 km WNW Esparta, KU 65022-9, 68614 (skeleton); 4.5 km WNW Esparta, KU 65030; 12 km WNW Esparta, KU 65031; 6 km E Esparta, KU 86477; Hotel Maribella, KU 32157-8; 3 km W Puntarenas, TCWC 16657-62.

_Hyla staufferi altae_ Dunn, New Combination

_Hyla altae_ Dunn, Occas. Papers Boston Soc. Nat. Hist., 8:61, June
7, 1933 [Holotype.--MCZ 17972, Summit, Canal Zone, Panama; Emmett
R. Dunn collector].

_Hyla culex_: Stuart, Misc. Publ. Univ. Michigan Mus. Zool., 29:38,
October 1, 1935. Gaige, Carnegie Inst. Washington Publ., 457:293,
1936.

_Hyla staufferi_: Taylor, Univ. Kansas Sci. Bull., 35:862, July 1,
1952. Duellman, Univ. Kansas Publ., Mus. Nat. Hist., 17:274, June
17, 1966.

_Diagnosis._--Small frogs (Male to 26 mm., Female to 27 mm.); dorsolateral and paravertebral stripes complete; longitudinal dark gray stripe on shank; thighs unmarked; interorbital bar usually absent; toes about three fifths webbed; gray to brownish gray above.

_Variation._--_Hyla staufferi altae_ is less variable in size, proportions, and color pattern than is _H. s. staufferi_. The size varies from 21.7 to 26 mm. (23.6) in 72 males. The ratio of tibia to snout-vent length is 0.42 to 0.50 (0.45), slightly less than in the northern subspecies. In color pattern 94.5 per cent of the individuals have complete dorsal stripes, and all have a longitudinal stripe on the shank (Table 7).

_Distribution._--This subspecies is restricted to subhumid forests and savannas on the Pacific lowlands of Panama. _Hyla s. altae_ is presently known to occur from Chepo in east-central Panama through the Azuero Peninsula to Concepcion, Chiriqui, in western Panama (Fig. 7).

_Specimens Examined._--Panama: _Canal Zone_: No specific locality, TNHC 24406; 2.8 km SW Fort Kobbe, KU 101679. _Chiriqui_: 14.4 km E Concepcion, AMNH 69799-801; 6.6 km N David, TNHC 32013-4; 2 km S David, AMNH 68802. _Cocle_: 1 km NE El Cano, KU 101662-75; El Valle de Anton, AMNH 59601-5, KU 77333-47; 7 km SSW Penonome, KU 101654-61. _Los Santos_: Tonosi, KU 101246 (tadpoles), 101697-701. _Panama_: 2 km WSW Chepo, KU 101680-8; 6 km WSW Chepo, KU 77324-27; El Cangrejo (Panama), KU 101676-8; Nueva Gorgona, AMNH 69991, 69798; 1.5 km W Pacora, KU 77328-32; 2 km N Tocumen, KU 101689-95; 8 km NE Tocumen, KU 101696.

EVOLUTIONARY HISTORY

My assumptions regarding the evolutionary history of the _Hyla rubra_ group in Central America were derived partly from interpretations of the evolutionary history of other animal groups (Simpson, 1943, 1965; Dunn, 1931b; Stuart, 1950; Duellman, 1958, 1960, 1963, 1965; and Duellman and Trueb, 1966). The origin and early evolution of the group probably occurred prior to the Mid-Pliocene in the lowlands of South America, because the greatest diversity of the group is in Brazil. Differentiation into two or more subgroups took place in South America prior to the late Pliocene. At the end of the Pliocene, shortly after the closure of the Colombian Portal, many South American animals migrated into Central America (Simpson, 1943, Maldonado-Koerdell, 1964, and Savage, 1966). It is likely that the _Hyla rubra_ group entered Central America at that time; apparently two stocks (_rubra-elaeochroa-staufferi_ stock and _boulengeri-foliamorta_ stock) migrated into Central America.

_Hyla elaeochroa_ is closely related to _rubra_ and probably differentiated from _rubra_ through spatial isolation. Thus, we have _elaeochroa_ in Central America and _rubra_ in South America; most likely only in relatively recent times has _rubra_ migrated into eastern Panama from northern South America. The differentiation and dispersal of _elaeochroa_ and _staufferi_ took place in Central America after the Pliocene. Probably the events of the Pleistocene resulted in the isolation of populations. One of these (_Hyla staufferi_ stock) was restricted in the subhumid Pacific lowlands, whereas the _Hyla elaeochroa_ stock occupied the tropical wet forests of the Caribbean lowlands. _Hyla elaeochroa_ apparently more closely resembled the parental stock by being restricted to the tropical rain forests, whereas _staufferi_ adapted to subhumid environments and thereby was able to disperse throughout most of the subhumid regions of Central America.

After geographical separation took place the initial genetic divergence between the two populations was maintained by means of ecological and ethological isolating mechanisms. Under these circumstances it can be supposed that the different ecological preferences of _elaeochroa_ and _staufferi_ depend on the climatic changes that took place during the Pleistocene. On this basis it may be proposed that when the original prototype broke up into the two incipient species, the _staufferi_ stock became physiologically and behaviorally adapted to subhumid conditions and dispersed into dry areas of the lowlands of Middle America. The tropical evergreen forests on the Caribbean side of lower Central America and the uplift of the Talamanca range in the Pliocene were barriers to the dispersal of _staufferi_. Consequently, this frog dispersed along the Pacific lowlands.

At the present time _staufferi_ occupies the length of the Pacific lowlands in Central America, except in the rainforest of the Golfo Duce region, which apparently is a relict stand and now separates the ranges of two subspecies of _Hyla staufferi_. This species crossed the central Nicaraguan lowlands and reached the Caribbean lowlands of Nicaragua and nuclear Central America. The species migrated through the subhumid corridor in northern Honduras and eastern Guatemala (Comayagua Valley in Honduras and the Motagua Valley of Guatemala) to the Isthmus of Tehuantepec. Duellman (1960) hypothesized "that during the times of glacial advances (Pleistocene) the lowlands of the Isthmus probably were more extensive and had more semiarid tropical environments than at the present" and that when semiarid environments were continuous from the Pacific slope across the isthmus to the Gulf lowlands _staufferi_ and other amphibians migrated northward to southeastern Tamaulipas, Mexico.

_Hyla elaeochroa_ dispersed along Caribbean lowland routes. This species not only occurs in the wet forests of the Golfo Dulce region but also in Guanacaste. It is possible that _elaeochroa_ entered Guanacaste and moved to the Golfo Dulce region when the intervening area was less xeric than now (Duellman, 1966b). _Hyla elaeochroa_ extended its range to eastern Nicaragua, but even though northeastern Nicaragua has over 2,000 mm. of precipitation annually (Vivo Escoto, 1964), this species has not spread into Honduras and Guatemala.

_Hyla boulengeri_ is widespread in Amazonian and northern South America, whereas _foliamorta_ occurs only in eastern Panama and in north-central Colombia. The ancestral _boulengeri-foliamorta_ stock probably invaded Central America in the late Pliocene and dispersed through humid forested environments to Nicaragua. Apparently a peripheral population established itself in the dry Pacific lowlands of Panama. This population differentiated from _boulengeri_ of the humid Caribbean lowlands and evolved into _foliamorta_, which subsequently expanded its range into Colombia.

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_Transmitted February 7, 1969._