Part 3

Hyla boulengeri (Cope)

Scytopis boulengeri Cope, Bull. U.S. Natl. Mus., 32:12, December 1, 1887 [Holotype.--USNM 13974, from "Nicaragua"; J. A. McNiel, collector].

Hyla boulengeri: Günther, Biologia Centrali-Americana, Reptilia and Batrachia, p. 267, June 1901. Noble, Bull. Amer. Mus. Nat. Hist, 38:339, June 1918. Taylor, Univ. Kansas Sci. Bull., 35:856, July 1, 1952.

Diagnosis.--Size large (Male to 49 mm., Female to 53 mm.); skull as long as wide; frontoparietal fontanelle present; snout subacuminate; canthus not pronounced; choanae large; tongue cordiform, slightly longer than broad; interorbital triangle tubercular; skin on dorsum tuberculate; tarsal fold reduced or absent; thighs, shanks, and tarsi boldly barred with dark brown and pale yellow-green in life.

Description.--Head flattened, longer than wide; snout projecting beyond lower lip; loreal region oblique; canthus not pronounced; length of eye less than interorbital distance; tympanum large, about 70 per cent of diameter of eye; interorbital triangle distinct; arms short; fingers lacking web; palmar tubercle tripartite; subarticular tubercles distinct; long tubercle on base of first finger; discs truncate; legs long; tarsal fold reduced or absent; inner metatarsal tubercle rounded, larger than outer, both elevated; subarticular tubercles distinct; one phalanx free of web on second, third, and fifth toes, three free on fourth toe (Fig. 1A and B); skin tuberculate on dorsum, less so on flanks; skin of belly granular, that on chest and throat weakly granular; tongue cordiform, longer than wide, free and notched behind; vocal slits large, lateral to tongue.

In life, dorsum tan or brown with dark spots on snout, head, and scapular region; interorbital triangle and blotch posteriorly on dorsum dark brown; flanks pale green; groin pale green or orange, mottled with dark brown; thighs tan or brown above with dark transverse bars on anterior and posterior surfaces; spaces between bars green or orange; inner surfaces of shanks and outer surfaces of tarsi brown and orange; foot brown above; forelimbs brown and pale green above, weakly barred; belly creamy white with scattered brown spots; vocal sac creamy white flecked with brown; lower jaw brown with white spots on lips (Pl. 1A).

In preservative, head and dorsum dark brown with triangular spot between eyes; dark spots on head and scapular region and dark brown blotch posteriorly on dorsum; flanks creamy white with brown spots; groin creamy white mottled with dark brown; thighs brown above with dark brown transverse bars on anterior and posterior surfaces; inner surfaces of shanks and outer surfaces of tarsi barred with pale brown; dorsal surface of foot mottled brown and creamy white; ventral surface of foot and toes pale brown; forelimbs faintly barred with pale brown; belly white with a few pale brown spots; vocal sac flecked with pale brown; lower jaw marked with small white spots on lips.

Variation.--Geographic variation is evident in the snout-vent length, tibia length, and foot length, all in relation to snout-vent length, and the relative size of the tympanum to the eye (Table 1). The largest specimens are from the humid Pacific lowlands of Costa Rica; individuals from the Caribbean lowlands of Costa Rica, Canal Zone, and South America are smaller. A general trend for increase in size extends from South America to the Pacific lowlands of Costa Rica.

Most variation in color does not seem to be correlated with geography; color variation is nearly as great within a given population as between separated populations. However, most specimens from Rincón de Osa, Puntarenas Province, Costa Rica, are dusky brown, but a few are darker. In comparison with specimens from the Caribbean lowlands of Central America, specimens from the Pacific slopes in Costa Rica have a darker interorbital triangle. In some specimens from the latter area rugosities are present on the borders of the interorbital triangle, on the snout, on the upper eyelid, and on the heel. Specimens from the Caribbean lowlands are less tuberculate, and most individuals from there lack rugosities on the tarsus. Living individuals from Puerto Viejo, Heredia Province, Costa Rica, and from the Canal Zone, Panamá, are brown above with a metallic green tint. Rugosities are present on the posterior edges of the forelimbs in some specimens from throughout the range. In most respects, specimens from the Canal Zone resemble those from the Caribbean lowlands of Costa Rica more than they resemble those from the Pacific lowlands of Costa Rica, but some individuals from the Canal Zone are less metallic above and have small white spots dorsally on the body, head, and limbs.

A moderate amount of color change from night to day has been noted. At night, a male from Puerto Viejo, Heredia Province, Costa Rica, was grayish tan above with slightly darker markings; the flanks were pale yellowish green. By day, the dorsum was brown with darker markings, and the throat was pale gray with white flecks; the rest of the venter was creamy white. The groin was pale green with black mottling; the anterior and posterior surfaces of the thighs and inner edges of the tarsi were greenish yellow with black bars.

TABLE 1.--Geographic Variation in Size and Proportions in Males of Hyla boulengeri. (Means in parentheses below observed ranges.)

========================================================================= | | Snout-vent| Tibia | | | | length | length/ |Tympanum/|Foot length/ Locality | N | (mm.) | snout-vent| eye | snout-vent --------------------+----+-----------+-----------+---------+------------- Costa Rica: Tilarán | 23 | 37.4-48.7 | 0.52-0.58 |0.62-0.76| 0.39-0.45 | | (43.8) | (0.55) | (0.71) | (0.42) | | | | | Costa Rica: Rincón | 10 | 41.4-46.1 | 0.54-0.60 |0.68-0.80| 0.40-0.45 de Osa | | (44.0) | (0.57) | (0.74) | (0.43) | | | | | Costa Rica: Alajuela| 13 | 35.6-43.1 | 0.55-0.60 |0.63-0.78| 0.41-0.46 Province | | (39.8) | (0.57) | (0.69) | (0.44) | | | | | Costa Rica: Puerto | 25 | 37.5-42.9 | 0.51-0.62 |0.63-0.79| 0.38-0.46 Viejo | | (41.6) | (0.55) | (0.71) | (0.43) | | | | | Costa Rica: Suretka | 9 | 38.7-42.0 | 0.56-0.58 |0.53-0.72| 0.35-0.45 | | (41.0) | (0.56) | (0.62) | (0.42) | | | | | Panamá: Canal Zone | 16 | 36.7-42.9 | 0.52-0.58 |0.70-0.78| 0.40-0.44 | | (39.0) | (0.54) | (0.74) | (0.42) | | | | | Venezuela: Santomé | 4 | 35.5-40.9 | 0.45-0.48 |0.63-0.67| 0.36-0.40 | | (38.5) | (0.46) | (0.65) | (0.38)

TABLE 2.--Comparison of Mating Calls in the Hyla rubra Group. (Means in parentheses below observed ranges.)

============================================================================ | |Notes| | | | Major frequencies | | per |Duration| Pulses|Fundamental| (cps) | |call | of note| per | frequency |--------------------- Species | N |group| (sec.) | second| (cps) | Lower | Upper ---------------+---+----+---------+-------+-----------+---------+----------- H. boulengeri | 8 | 1 | 0.24- | 80-120| 70-74 |1400-1820|2520-3182 | | | 0.47 | (101)| (71) | (1611) | (2840) | | | (0.35) | | | | | | | | | | | H. foliamorta | 7 | 1 | 0.23- | 50-60 | 52-61 | 912-1026|2736-3477 | | | 1.86 | (51) | (56) | (918) | (3055) | | | (0.69) | | | | | | | | | | | H. elaeochroa |15 | 2-95| 0.12- | 40-50 | 48-65 |1254-1586|2562-3477 | | (19)| 0.24 | (42) | (57) | (1499) | (2911) | | | (0.17) | | | | | | | | | | | H. s. staufferi|18 | 2-77| 0.13- |100-130| 96-130 |1582-1872|1962-3744 | | (23)| 0.23 | (120) | (106) | (1743) | (3056) | | | (0.18) | | | | | | | | | | | H. s. altae | 7 | 2-22| 0.14- |110-130| 104-117 |1853-2106|3379-4056 | | (11)| 0.18 | (120) | (112) | (2008) | (3775) | | | (0.15) | | | |

Cranial Osteology.--The skull of Hyla boulengeri is as long as it is wide, and is flat; the premaxillary is small and bears 13 to 17 teeth (mean for 6 specimens, 14.9). The alary processes of the premaxillaries are widely separated, concave posteriorly, and vertical. Ventrally, the premaxillary is connected to the prevomer by bony tissues. The maxillary is slender and bears 70 to 91 teeth (mean for 6 specimens 78.1). The pars facialis of the maxillary is laterally convex and about four times as high as the pars dentalis.

The nasal is large (its length about 40 per cent of total length of skull), and pointed anteriorly and posteriorly in dorsal view. The nasals are separated anteromedially by the cartilaginous septum nasi. One or two protuberances are present on the midlateral concavity of the nasal. Posteriorly, the nasal overlaps the sphenethmoid and articulates with the palatine. Dorsally the sphenethmoid is large, pentagonal, and completely ossified. The frontoparietal is elongate, smooth, and bears a small supraorbital process on the anterior edge of the orbit. A keyhole-shaped frontoparietal fontanelle is present; the fontanelle is narrow anteriorly and wide posteriorly.

The bony part of the proötic is separated dorsally from the squamosal by the cartilaginous crista parotica. The squamosal is small, its anterior arm slender and pointed. The posterior arm of the squamosal is pointed terminally and articulates with the proötic medially.

The prevomer is large and elongate. Anteriorly the prevomer is connected to the maxillary-premaxillary articulation; posteriorly, the prevomer is separated from the sphenethmoid by cartilage. Each prevomer bears six to nine teeth. The palatine is present and edentate. The anterior end of the parasphenoid is broad (less pointed than in Hyla foliamorta). The pterygoid is slender and well developed.

Natural History.--Hyla boulengeri inhabits humid lowland tropical forests and breeds in temporary ponds. Clasping pairs and gravid females were observed at Puerto Viejo, Heredia Province, Costa Rica, on June 21, 1966. Males were calling from depressions in decaying logs and stumps, in forked stems, and from leaves of broad-leafed plants near the pond. Males were observed in late July and early August calling from Calathea and Heliconia leaves at the edge of a pond in the wet forest of the Osa Peninsula. William E. Duellman informed me that he collected calling males in January at El Real, Darién, and in March at Almirante, Bocas del Toro, Panamá. Taylor (1952) found calling males in June at Turrialba, Cartago Province, Costa Rica, and Dunn (1931a) observed males calling in July, November, and December in Panamá. Gravid females have been found from April to August. Breeding activities of Hyla boulengeri always seem to be associated with temporary ponds; in Central America breeding apparently takes place throughout most of the year.

The mating call of Hyla boulengeri consists of one short, moderately low-pitched note. Each note has a duration of 0.24 to 0.47 second and is repeated at intervals of one second to several minutes. The notes have 80 to 120 pulses per second, a fundamental frequency of about 70 cycles per second, and a dominant frequency of 2,840 cycles per second (Table 2, Pl. 3A).

The eggs are deposited in a mass in the water. No information is available concerning early development. Tadpoles in advanced stages of development were found in a temporary pond at Rincón de Osa, Puntarenas Province, Costa Rica. The pond was about 10 cm. deep, had a muddy bottom and lacked vegetation. Three recently metamorphosed young were found in mid-August, 1966, on grass at the edge of another temporary pond in the forest.

Tadpoles--Twelve tadpoles are available. These were collected at Rincón de Osa, Puntarenas Province, Costa Rica. The maximum size represented is 34.0 mm., total length (stage 42 of development).

A typical tadpole in stage 36 of development (KU 104295) has a body length of 12.0 mm., tail length of 20.0 mm., and total length of 32.0 mm. Other characters are as follows: depth of tail equal to length of body; body deeper than wide; distance between eye and nostril equal to that between nostril and tip of snout; mouth anteroventral, upper and lower lips bare; papillae present laterally; tooth rows 2/3; upper rows about equal in length; first upper row slightly, and second upper row widely, interrupted medially; lower rows about equal in length, shorter than upper rows; third lower row containing 5-10 large teeth; beak strong, serrate; spiracle nearer anus than eye; anal aperture not extending to border of ventral fin; caudal musculature slender posteriorly, extending to tip of pointed tail; dorsal fin extending to middle of body, slightly deeper than ventral fin; posterior three fourths of tail spotted; rest of tail and body gray-brown or transparent; hindlimbs flecked or spotted with brown (Table 3, Fig. 2A and 3A).

TABLE 3.--Sizes of Tadpoles of Hyla boulengeri in Relation to Developmental Stages. (Means in parentheses below observed ranges; measurements in mm.)

======================================================= Stage | N | Body length | Tail length | Total length --------+---+-------------+-------------+-------------- 30 | 1 | 11.0 | 22.2 | 33.2 | | | | 35 | 1 | 11.0 | 12.0 | 23.0 | | | | 36 | 3 | 9.5-12.0 | 20.0-21.5 | 31.0-32.0 | | (11.2) | (20.5) | (31.7) | | | | 38 | 2 | 11.5 | 22.0 | 33.5 | | | | 42 | 2 | 10.5-13.0 | 21.0-22.0 | 32.5-34.0 | | (11.8) | (21.5) | (33.3) | | | | 44 | 2 | 14.0-15.0 | 8.0-15.0 | 22.0-30.0 | | (14.5) | (12.5) | (26.0) | | | | 46 | 1 | 15.0 | 15.0 |

A recently metamorphosed young has a snout-vent length of 15 mm.; the head is as long as wide, the eyes are prominent; the limbs are weakly barred; the skin is rugose above and granular below. The venter is immaculate; the dorsum and limbs are gray-brown in preservative (pale green in life). The interorbital space, supratympanic fold, and scapular region are darker than the rest of the body; the fingers lack webbing; the webbing on the foot is the same as in adults; small metatarsal tubercles are present, but the tarsal fold is absent.

Remarks.--Cope (1887:12) described Scytopis boulengeri from Nicaragua. Günther (1901:267) placed boulengeri in the genus Hyla, and stated that Cope possibly placed boulengeri in the genus Scytopis on the supposition that it had an accumulation of "sebaceous glands" above the tympanum. Noble (1918:339) redescribed Hyla boulengeri on the basis of three specimens from Zelaya Province, Nicaragua, and noted that the glands were not prominent in any of the specimens. Duellman (1956:8) showed that Scytopis hebes (generotype of Scytopis by monotypy) is a Phrynohyas, and thus placed Scytopis Cope, 1862, in the synonymy of Phrynohyas Fitzinger, 1843.

Dunn and Emlen (1932:25) placed Hyla lancasteri Barbour in the synonymy of Hyla boulengeri; the former was known solely from one juvenile. They made no qualifying statements, but probably they were impressed by the strongly barred thighs, a coloration known among Central American hylids at that time only in Hyla boulengeri (Duellman, 1966a:271). Taylor (1952:856) followed Dunn and Emlen with reservation and noted some differences. Duellman (1966a:271) showed that the holotype of lancasteri was a juvenile of a species subsequently named as Hyla moraviaensis by Taylor (1952:865).