_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 Panamá through Costa Rica to eastern Nicaragua, and on the Pacific lowlands of southeastern Costa Rica and extreme western Panamá. 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 Chitaría, 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 Ciéncias Agrícolas), 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 Tilarán, 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). _Limón_: Bataán, KU 30327-36; La Lola, KU 64478-98, 68281-2 (skeletons); Los Diamantes, KU 31800-02, 64476-7; Peralta, KU 31816-21; Puerto Limón, 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 Rincón de Osa, KU 102208-41, 104298 (tadpoles). [Illustration: Fig. 6. Map showing locality records for _Hyla elaeochroa_ (circles) and _H. rubra_ (dots).] Panamá: _Bocas del Toro_: Almirante, KU 80079; Isla Bastimentos, KU 96008-11; Río Cricamola, 3.7 km from coast, KU 96012. _Chiriquí_: Río Gariché, 8.3 km ESE Paso de Canoas, KU 101571-2. _Hyla staufferi_ Cope