South American Journal of Herpetology, 1(1), 2006, 79-86 © 2006 Brazilian Society of Herpetology THE TADPOLE OF LEPTODACTYLUS ELENAE (ANURA: LEPTODACTYLIDAE), WITH THE DESCRIPTION OF THE INTERNAL BUCCAL ANATOMY CYNTHIA P. A. PRADO 1,3 AND ANNE D’HEURSEL 2 1 Departamento de Zoologia, Instituto de Biociências, Universidade Estadual Paulista, Caixa Postal 199, 13506-900 Rio Claro, São Paulo, Brazil. E-mail: cpap@rc.unesp.br 2 St. Paul’s School, R. Juquiá 166, 01440-903 São Paulo, SP, Brazil. E-mail: ahb@stpauls.br 3 Corresponding author. ABSTRACT: The external morphology and internal buccal characteristics of Leptodactylus elenae tadpoles are described and compared with other Leptodactylus species. The external morphology and anatomy of the buccal cavity of L. elenae are similar to other Leptodactylus in the fuscus group and suggest a pond-larval diet. The most variable features among Leptodactylus species are the lingual papillae number and the lateral ridge papillae. The latter are small and lack terminal branches in tadpoles of L. elenae. Leptodactylus tadpoles exhibit variable morphology, sometimes convergent with other genera in the family. However, it seems that both external larval morphology and internal buccal features support the current groups of Leptodactylus. KEY WORDS: Leptodactylus, tadpole, external morphology, internal oral anatomy, Pantanal, Brazil INTRODUCTION Adult and larval traits are important tools to resolve or examine relationships among amphibian taxa (e. g., Eterovick and Sazima, 2000). Larval buccal anatomy has also been used to help understand species rela- tionships (Viertel, 1982; Kaplan and Ramírez-Bautis- ta, 1996; d’Heursel and de Sá, 1999). The genus Leptodactylus belongs to the Neotropi- cal family Leptodactylidae and is one of the most di- versified groups in South America (Heyer and Max- son, 1982) with approximately 66 recognized species (Frost, 2004). This genus is traditionally divided into four species groups: ocellatus, melanonotus, pentadacty- lus, and fuscus (Heyer, 1969). Frogs of the Leptodac- tylus fuscus group are comprised of about 25 species (Frost, 2004) that deposit eggs in foam nests placed on land, in subterranean chambers constructed by males; exotrophic larvae (sensu Thibaudeau and Altig, 1999) in advanced stages are released by floods or rain to lentic or lotic water bodies (Prado et al., 2002). Tadpoles of some species of the fuscus group have already been described (Lescure, 1972; Heyer, 1978; Sazima and Bokermann, 1978) and a review of larval characters was provided by Langone and de Sá (2005); however, tadpoles of several species remain unknown. Leptodactylus elenae Heyer, 1978 is a member of the fuscus group that is widely distributed in the semi- arid Chaco, cerrado, caatinga, and dry forests from the eastern slopes of Bolivia to Mato Grosso, Brazil, and south through Paraguay to north-central Argenti- na (Heyer and Heyer, 2002). Here we describe the external morphology and the internal buccal anatomy of L. elenae tadpoles and compare them to other Lep- todactylus species. MATERIALS AND METHODS Tadpoles were collected with a sieve in a tempo- rary rain puddle, on 17 October, 2000, in the south Pan- tanal, municipality of Corumbá (19°34’S; 57°00’W), Mato Grosso do Sul State, Brazil. Description of ex- ternal morphology and drawings were based on tad- poles at stages 35-36 (Gosner, 1960). Terminology of external morphological traits and measurements fol- low Altig and McDiarmid (1999). Measurements of total length, body length, tail length, maximum body height, and maximum body width were made with a digital caliper to the nearest 0.01 mm. The remaining measurements were made under a stereomicroscope Zeiss ® Stemi SV11, with an ocular micrometer. Three individuals were dissected for observation of the inter- nal buccal anatomy (stage 33, BL = 8.36 mm, TL = 20.98 mm; stage 36, BL = 8.62 mm, TL = 21.01 mm; stage 39, BL = 9.27 mm, TL = 29.07 mm). Terminology of internal surface fea- tures follows Wassersug (1976). Tadpoles were iden- tified based on individuals raised to metamorphosis in the laboratory. Voucher L. elenae tadpoles (CFBH 9329) and juveniles (CFBH 8387-8388) are housed at