Herpetologica, 62(1), 2006, 96–108 Ó 2006 by The Herpetologists’ League, Inc. A NEW SPECIES OF THE HYPSIBOAS BENITEZI GROUP FROM THE WESTERN AMAZON BASIN (AMPHIBIA: ANURA: HYLIDAE) JULIA ´ N FAIVOVICH 1,5 ,JIR ˇ I ´ MORAVEC 2 ,DIEGO F. CISNEROS-HEREDIA 3 , AND JO ¨ RN KO ¨ HLER 4 1 Herpetology, Division of Vertebrate Zoology, American Museum of Natural History, Central Park West at 79 th Street, New York, NY 10024-5192, USA, and Department of Ecology, Evolution, and Environmental Biology, Columbia University 2 Department of Zoology, National Museum, 11579 Praha 1, Czech Republic 3 Universidad San Francisco de Quito, Ave. Interoceanica y Calle Diego de Robles, Campus Cumbaya´, edif. Maxwell, Casilla Postal 17-12-841, Quito, Ecuador 4 Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, 53113 Bonn, Germany; and Department of Zoology, Hessisches Landesmuseum Darmstadt, Friedensplatz 1, 64283 Darmstadt, Germany ABSTRACT: A new species of the Hypsiboas benitezi group is described from the western Amazon Basin. The new species is characterized by its medium size (SVL 24.4–31.2 mm in adult males, 26.0–36.0 mm in adult females), absence of nuptial excrescences, palpebral membrane lacking golden reticulation, and a mental gland in males. The dorsal surfaces of living frogs are bright yellowish green to tan, and frequently bear an X- shaped mark; the parietal peritoneum, pericardium and sclera are covered by guanophores. The new species differs from other members of the Hypsiboas benitezi group (H. benitezi, H. lemai, H. microderma, H. pulidoi, H. rhythmicus, and H. roraima), by the combination of a dorsal X-shaped marking, absence of golden reticulation on palpebral membrane, and central portion of abdominal parietal peritoneum, pericardium, and sclera covered by guanophores. The new species has been confused with Hyloscirtus albopunctulatus (as Hyla albopunctulata) in the past, but the study of the type series of the latter indicates that they represent different species. Hypsiboas hutchinsi is excluded from the H. benitezi group and transferred to the H. semilineatus group, as it shares with H. geographicus and H. semilineatus the absence of a projecting spine in the prepollex (the only known species of Hypsiboas with this character state), presence of pigmented nuptial excresences, reticulated palpebral membrane, and finely tuberculated skin. Key words: Amphibia; Anura; Hylidae; Hypsiboas nympha; New species; Western Amazon Basin THE WESTERN Amazon Basin of Colombia, Ecuador and Peru holds a remarkably high biological diversity with regard to amphibians. For example, 112 frogs have been recorded from the Iquitos region, northeastern Peru (Rodrı´guez and Duellman, 1994) and 120 amphibian species from a single site, the Tiputini Biodiversity Station, in Amazonian Ecuador (Cisneros-Heredia, 2003). Recent fieldwork in these regions and the study of collections led to the discovery of a new species of Hypsiboas. This new species was included in the recent analysis and taxonomic revision of the family Hylidae by Faivovich et al. (2005), whose most parsimonious trees showed it to be nested within a group of western amazonian and Guayana highland species (Hypsiboas benitezi, H. lemai, H. microderma, H. roraima, and other undescribed species). This clade was named the Hypsiboas benitezi group, and is supported mainly by molecular data, and by the presence of what was termed a ‘‘flat’’ mental gland. Besides the already mentioned species, Faivo- vich et al. (2005) tentatively included H. hutchinsi, H. pulidoi, and H. rhythmicus in this group. Goals of this paper include (1) the de- scription of the new species, (2) a discussion of differences between the new species and Hyloscirtus albopunctulatus, a species of the H. bogotensis group (Faivovich et al., 2005) with which it had been confused in the past, and (3) briefly discuss the composition of the Hypsiboas benitezi group, as further study indicates that H. hutchinsi should be excluded from it. MATERIALS AND METHODS Thirty-one specimens of the new species were examined, along additional material that is listed in the Appendix. Snout dorsal out- lines follow Heyer et al.’s (1990) standards. Webbing formulae follow Savage and Heyer’s (1967) convention as subsequently modified by Myers and Duellman (1982). All other terminology is that of Duellman (1970). Ab- breviations used throughout the text are: DF3, 5 CORRESPONDENCE: e-mail, julian@amnh.org 96