PROC. BIOL. SOC. WASH. 93(3), 1980, pp. 655-661 THE CALLS AND TAXONOMIC POSITIONS OF HYLA GIESLERI AND OLOLYGON OPALINA (AMPHIBIA: ANURA: HYLIDAE) W. Ronald Heyer Abstract. — The advertisement calls of Hyla giesleri, H. microps, Ololy-gon catharinae and O. opalina are described. The call data together with morphological differences indicate that Hyla giesleri is a species distinct from H. microps, with which it is currently placed, and that Ololygon opal-ina is a full species, not a subspecies of Ololygon catharinae as originally described. The calls in each species pair differ in several species specific coding features; small behavioral and morphological adjustments can ac-count for these differences. Field recordings of advertisement calls of frogs from southeastern Brazil clarify the taxonomic positions of two species of hylid frogs, Hyla giesleri and Ololygon opalina. Duellman (1977) and Lutz (1973) included Hyla gies-leri Mertens in the synonymy of Hyla microps Peters, following the syn-onymy of Bokermann (1966). Lutz (1968) described opalina as a new sub-species of Hyla catharinae. Lutz (1973) and Duellman (1977) maintained this relationship. I follow Fouquette and Delahoussaye (1977) and consider catharinae a member of the genus Ololygon. The data presented in this paper demonstrate that Hyla giesleri is specifically distinct from Hyla mi-crops and that Ololygon opalina is a distinct species within the Ololygon catharinae complex. Methods and Materials Field recordings made with an Uher CR-134 stereo cassette recorder were analyzed using a Kay Sonagraph model 6061 B, a Hewlett Packard 7402 A strip chart recorder and a Briiel and Kjaer 2121 frequency analyzer. Spec-imens are deposited in the Museu de Zoologia, Sao Paulo, and National Museum of Natural History, Washington, D.C. (USNM). Hyla giesleri The advertising call is intensity modulated, beginning relatively quietly and ending loudly. The call (Fig. lA) consists of about 30 discrete pulses (two calls analyzed have 27 and 32 pulses) at an average pulse rate of about 100 per second. The duration of the entire call is about 0.3 s, and the du-
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