Incilius fastidiosus (Cope, 1875)
Pico Blanco Toad
© 2010 Division of Herpetology, University of Kansas (1 of 1)
The dorsal ground color of adult toads is brown to black, nearly uniform in color or with red, rusty, or pink warts and tubercles. A light mid-dorsal stripe is usually present; there are no transverse dark limb bars. Ventral coloration is brown to black and mottled with lighter pigments (Savage 2002).
Males have no vocal slits or sacs. They lack an advertisement call but do have a weak release trill. Adult males have hypertrophied forelimbs and a discrete light nuptial pad on the thumb (Savage 2002).
Bufo fastidiosus larvae are small, reaching a total length of 15.99 mm at stage 36. The body is ovoid and the mouth is anteroventral. The snout is rounded in a dorsal outline and directed dorsolaterally. Nostrils and eyes are dorsal with the nostrils slightly closer to eyes than snout tip. The spiracle is lateral and sinistral, and the vent tube is medial. The tail and fins are moderate in size, with a small caudal fin that is subovoid to round at the tip. The larval oral disk is medium and emarginated. Beaks and 2/3 rows of denticles are present. The upper jaw sheath is moderately wide and finely serrated, with the medial section forming a straight line and the lateral processes abruptly tapering posterolaterally. The lower jaw sheath is about equal in width to the upper, also finely serrate, and strongly V-shaped. Body coloration is a uniform chocolate brown, with a dark gray venter. Caudal musculature is dark olive brown, and the fins are a translucent olive brown with dark speckles. (Lips and Krempels 1995)
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Costa Rica, Panama
Life History, Abundance, Activity, and Special Behaviors
Males typically position themselves along the edges of 5-15 cm deep seepage pools. Males do not call (they lack vocal sacs) but give a release trill and vibration when handled. Males amplex any toad encountered but immediately release other males, presumably as a response to the release trill and vibration (Lips and Krempels 1995). Bufo fastidiosus undergoes inguinal amplexus, where the male clasps the female around her pelvic region and rests his feet on her thighs. This position is maintained for several hours (Graybeal and de Queiroz 1992). Upon arrival at the pools, females are immediately amplexed by 2-10 males, forming balls of toads in the pools. Females remain limp and immobile while males vie for amplexus (Lips and Krempels 1995). Lips and Krempels (1995) reported that three dead females were found after the peak of the breeding period, apparently drowned by the weight of amplexing males.
Females deposit their eggs in small pools formed after heavy rains during the late dry to early wet season (April-May). The eggs are black and yellow, and they are laid during the day in long single strands. Small indentations between the eggs give the strands a rosary-like appearance. The strands are not usually attached to vegetation, but when desiccated they stick to emergent plants and branches. Eggs are large, and clutch size is about 80-90 eggs per female. Two envelopes encase each egg, a thick outer one and an inner vitelline membrane that is barely distinguishable. There are no partitions between eggs. In the lab, hatching took place by stage 17 (day 4-5) and metamorphosis in 60-70 days (Lips and Krempels 1995).
The tadpoles are well camouflaged against the silt substrate of pools, and the larvae aggregate in groups near the bottom of the small pools in areas of flowing water. The reason for this aggregation may be a behavioral response or a result of the small pool size (Lips and Krempels 1995). Bufo fastidiosus also exhibits a defensive posture in which all four feet are planted, the pelvic region is elevated, and the head is lowered. This position is similar to one used by Osornophryne percrassa (Graybeal and de Queiroz 1992).
Trends and Threats
Possible reasons for amphibian decline
General habitat alteration and loss
A Spanish-language species account can be found at the website of Instituto Nacional de Biodiversidad (INBio).
Graybeal, A., and de Queiroz, K. (1992). ''Inguinal amplexus in Bufo fastidiosus with comments on the systematics of bufonid frogs.'' Journal of Herpetology, 26(1), 84-87.
IUCN, Conservation International, and NatureServe. (2006). Global Amphibian Assessment: Bufo fastidiosus. [Internet]. www.globalamphibians.org. Accessed 12 October 2007.
Lips, K.R., and Krempels, D.M. (1995). ''Eggs and tadpole of Bufo fastidiosus Cope, with comments on reproductive behavior.'' Copeia, 1995(3), 741-746.
Savage, J. M. (2002). The Amphibians and Reptiles of Costa Rica:a herpetofauna between two continents, between two seas. University of Chicago Press, Chicago, Illinois, USA and London.
Originally submitted by: Christin Hong (first posted 2007-10-24)
Edited by: Kellie Whittaker (2009-11-02)
Species Account Citation: AmphibiaWeb 2009 Incilius fastidiosus: Pico Blanco Toad <https://amphibiaweb.org/species/167> University of California, Berkeley, CA, USA. Accessed Jun 5, 2023.
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Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 5 Jun 2023.
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