Part 7

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 Panamá. Hyla staufferi does not occur on the Caribbean versant of Costa Rica and Panamá. 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) | | | | | | Panamá | 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 proötic. The crista parotica is visible dorsally along the lateral edge of the bony proötic. 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 Penonomé, Coclé, Panamá, he found staufferi calling from grass in puddles where microcephala was absent, and at El Caño, Coclé, Panamá, 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 Salamá 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, México.

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 Córdoba, Veracruz, México) 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, México. 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. Günther (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 Günther 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, México; 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): Günther, 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, México to northwestern Costa Rica on the Pacific lowlands (Fig. 7). Duellman (1963:226) commented that a specimen from Chinajá, Guatemala, possibly was transported there in the cargo from Toocog, because with this one exception the species is unknown in tropical rainforest in Guatemala.