Breeding Habits of the Toad Bufo coccifer in Costa Rica, with a Description of the Tadpole

Abstract

-The breeding habits of Bufo coccifer were studied in northwestern Costa Rica between 1971 and 1974. This species breeds during the rainy season, at least from May through August. Males chorus from areas of shallow water. Their calls resemble those of Mexican representatives of the species in pulse rate and duration, but are closer to those of other Costa Rican and Panamanian populations in dominant frequency. Thus, our data do not clearly support recognition of Bufo cycladen as a distinct species for the Mexican populations. Amplexus is axillary, and two strings of eggs are extruded simultaneously during oviposition. Tadpoles, described for the first time in this paper, are secretive and do not aggregate. Development to metamorphosis requires about 5 weeks. Bufo coccifer Cope is a medium sized toad known from localities primarily along the Pacific versant of Mexico and Central America from sea level to about 2000 m elevation (Zweifel, 1965; Porter, 1964a, 1965; Meyer and Wilson, 1971). The mating calls of the Mexican and Central American populations of Bufo coccifer differ (Zweifel, 1965; Porter, 1965). These vocal characteristics, together with slight morphological differences, were used to justify recognition of the Mexican populations as a distinct species, Bufo cycladen (Lynch and Smith, 1966). Porter (1967) argued that Bufo cycladen was a nomen dubium. Although Smith and Smith (1976) recognized the distinctness of the Mexican populations, little information has been published on the species in the past 15 years. The tadpole has not been described. During the course of our work on the reproductive ecology and behavior of frogs in the Tropical Dry Forest formation of northwestern Costa Rica, we obtained considerable data on the breeding biology of Bufo coccifer. Herein, we report our observations and describe the tadpole of this species. STUDY SITE.-The study area was located on the property of Estaci6n Experimental Enrique Jimenez Nufiez in Guanacaste Province, Costa Rica. This station, owned and operated by the Ministerio de Agricultura y Ganaderia of Costa Rica lies about 13.6 km SW Canfas in a zone of Tropical Dry Forest (Tosi, 1969). General site descriptions of the area exist (e.g., Orians and Paulson, 1969; Holdridge et al., 1971; Sawyer and Lindsey, 1971; Janzen, 1973; McDiarmid et al., 1977). However, these papers refer primarily to the forested regions of the farm, particularly those in riparian areas. Although individual Bufo coccifer occasionally are found in forest habitats, these toads are located more commonly in areas where the forest has been cleared for pasture or cultivation. Observations were made in two types of cleared areas. One was a pasture about 2.4 by 1.0 km located at the base of Cerro Eskameca and adjacent hills (Fig. 1). The somewhat irregular pasture (ca. 10 m elev.) is sown with various introduced forage grasses and supports small weedy herbs (e.g., Compositae, Malvaceae, Euphorbiaceae), vines (e.g., Cucurbitaceae, Leguminosae, Bignoniaceae), small saplings of various forest trees (especially Enterolobium cyclocarpum), and a number of leguminous shrubs. One of the shrubs, Mimosa pigra, grew in dense stands covering large areas. Usually, toward the end of each dry season, the pasture areas were plowed and all surface vegetation was turned under. With the first rains, new grass sprouted, and cattle and horses were turned out to graze. Within the pasture areas three ponds filled in May or June and, except in E SOUTHWESTERN ATURALIST 26(4):353-363 NOVEMBER 20, 1981 This content downloaded from 157.55.39.224 on Wed, 14 Dec 2016 05:03:07 UTC All use subject to http://about.jstor.org/terms The Southwestern Naturalist FIG. 1.-Irrigation canal (above), flooded pasture (middle), and flooded roadside (below) at Estaci6n Experimental Enrique Jimenez Nuiiez, used as breeding sites by Bufo coccifer. 'LI IIIWI L C-lC1----I 354 vol. 26, no. 4 -....,-'' .,. __M ._liB36 . ^ This content downloaded from 157.55.39.224 on Wed, 14 Dec 2016 05:03:07 UTC All use subject to http://about.jstor.org/terms McDiarmid and Foster-Costa Rican Bufo coccifer