The Systematics of the Frogs of the Hyla Rubra Group in Middle America

by Juan R. León

Fig. 2. Tadpoles of (A) Hyla boulengeri (KU 104295) and (B) Hyla elaeochroa (KU 104134), × 3.

Fig. 3. Mouthparts of tadpoles of (A) Hyla boulengeri (KU 104295) and (B) Hyla elaeochroa (KU 104134), × 25.

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).

In Central America, Hyla boulengeri can be confused only with Hyla foliamorta; the latter is restricted to central and eastern Panamá and northern Colombia. The snout of foliamorta is more pointed and protruding, and the vocal sac is darker than in boulengeri; the groin of foliamorta usually is creamy white, whereas boulengeri usually has a dark spot. The skulls differ in that boulengeri has a frontoparietal fontanelle, the prevomer is larger and elongate, anteriorly connected to the premaxillary, and posteriorly separated from the sphenethmoid by cartilage; foliamorta lacks a fontanelle, the prevomer is smaller, anteriorly separated from the premaxillary by cartilage, but connected by a bony suture to the sphenethmoid. The mating call of boulengeri differs by having shorter notes, twice as many pulses per second, a higher fundamental frequency, and more closely approximated major frequencies than does that of foliamorta.

Hyla boulengeri need not be compared in detail with the other Central American members of the Hyla rubra group, because all of them are smaller and have shorter snouts, smoother skin, and dissimilar color patterns.

Distribution.—In Central America Hyla boulengeri inhabits the forested lowlands in locally humid areas in Guanacaste Province, Costa Rica, and in the humid Golfo Dulce region of Costa Rica; it occurs on the Carribbean lowlands from central Nicaragua to South America, where it ranges to Guyana and Ecuador. The highest elevations where H. boulengeri has been found are 620 meters at Turrialba, Cartago Province, and 700 meters at Tilarán, Guanacaste Province, Costa Rica (Fig. 4).

Specimens Examined.—Costa Rica: Alajuela: 9 km N Ciudad Quesada, near La Florencia, USC 8059 (4); 18 km N Florencia, USC 2624; Laguna Monte Alegre, KU 64334; Las Playuelas, 11 km S Los Chiles, USC 7216, 7217 (2), 7219; 3 km NE Muelle del Arenal, USC 2644 (5). Cartago: Turrialba, KU 24741. Guanacaste: 7 km N Liberia, USC 8096 (2), 8138 (6); 13.6 km N Liberia, USC 8151, 8171 (2); 20.5 km S Liberia, USC 8205; Taboga, 20 km SE Las Cañas, KU 102170, USC 7166; 4 km NE Tilarán, USC 8023; 6 km NE Tilarán, USC 523 (3), 6262, 7019. Heredia: Puerto Viejo, KU 64323-7 (skeletons), 104351-3 (skeletons), 64330-3, 103592-620; 1 km NE Puerto Viejo, UMMZ 126042; 1 km S Puerto Viejo, KU 84983-4 (skeletons), 86317-22, 87774 (skeleton); 4.2 km W Puerto Viejo, KU 64329, 64328 (skeleton). Limón: Mountain Cow Creek, near Banano, KU 37031, 41067 (skeleton); 3 km S Río Tortuguero, AMNH 69057; Suretka, KU 36482-8, 36699. Puntarenas: 4.8 km S Bahía Rincón on NW side Río Rincón, USC 705; Parrita, USC 6163; 4.5 km W Rincón de Osa, KU 102177-9, 104295-6 (tadpoles); 6 km SW Rincón de Osa, KU 102171-6; 4.4 km NW Villa Neilly, USC 8003; 10.5 km WNW Villa Neilly, KU 64321. San José: 21 km WSW San Isidro el General, KU 34104-6.