Incilius luetkenii (Boulenger 1891)

Bufo luetkenii is a large toad, with SVL for adult males ranging from 77 to 96 mm and adult females from 73 to 107 mm. Males are easy to identify by their distinct pale yellow-brown to yellow-green coloration and large size (Savage 2002).The head is rounded when viewed from above. Skin is co-ossified to the skull. Well-developed black-tipped cranial crests are present. Parotoid glands are very small and oval in shape. Tympanum height is about 1/2 the eye diameter. Finger I is longer than finger II. Toes are partly webbed. Inner metatarsal tubercle is raised and elongated; outer metatarsal tubercle is elongated. Adult males have paired vocal slits, and a single internal subgular vocal sac that distends during calls. Dorsal surfaces of body and limbs are warty, with none to few lateral warts enlarged. Venter is finely granular. Adult males have a black nuptial pad on the upper and medial surfaces of Fingers I and II, extending onto outer edge of thenar tubercle (Savage 2002). Adult males, and some adult females, are a uniform pale yellow brown to yellow green color. Males have a dirty yellowish green throat. The majority of females are dark brown, olive green, or rusty brown, and have a broad yellow middorsal stripe along with a broad dark lateral stripe; sometimes light dorsolateral stripes are also present in females. Juveniles and some females have black spots in a linear pattern and often chevron-shaped markings on the shoulder. Both juveniles and females (if patterned) also have dark transverse bars on the upper surface of the limbs, but limb barring is absent in adult males. The venter is dirty yellow (Savage 2002). Tadpoles are moderately sized, reaching a total length of 29 mm. The body is ovoid in shape with a rounded tail tip. Nostrils are dorsal and eyes are dorsolateral. The spiracle is sinistral and lateral while the vent tube is medial. The mouth is anteroventral and directed ventrally. The oral disc is small and emarginate with a broad gap in the A2 denticle row above the mouth, and a single row of labial papillae on either side of the mouth. Coloration is black dorsally and gray ventrally, with black caudal musculature and the upper fin mottled with the lower fin having scattered dark dots (Savage 2002).The type locality appears to be erroneous; Savage (2002) notes that Boulenger (1891) described this toad as being from Cartago in Cartago Province, Costa Rica. However, all subsequent records are from areas nowhere near Cartago, in the Pacific lowland dry forest (Savage 2002).Karyotype is 2N=22, with six pairs of large chromosomes and five pairs of small chromosomes, all metacentric or submetacentric. Chromosome 1 has a secondary constriction (Bogart 1972).A Spanish-language species account can be found at the website of Instituto Nacional de Biodiversidad (INBio) (http://darnis.inbio.ac.cr/FMPro?-DB=UBIpub.fp3&-lay=WebAll&-Format=/ubi/detail.html&-Op=bw&id=4374&-Find).

This species is found in the Pacific lowlands from Chiapas, Mexico to central Costa Rica at 6 to 300 meters a.s.l.; on the Atlantic versant in dry interior valleys of Guatemala and Honduras up to 1,300 meters a.s.l.; and the upper drainage of the Río San Juan in Costa Rica at 10 to 436 meters a.s.l. Bufo luetkenii inhabits mostly lowland dry forest, but is also occasionally found in lowland and premontane moist forest. It is also frequently found in open areas such as disturbed pastureland (Savage 2002).

During the first half of the rainy season, occurring from June to August, adults gather around temporary pools (Savage 2002). This species also may breed in ditches and permanent or temporary streams (Savage 2002). Males call from shore, at the water's edge, and the call is a trill lasting approximately 4 seconds, with a dominant frequency of 1.6 to 1.95 kHz (Savage 2002). It is then repeated at intervals of 1 to 4 seconds (Savage 2002). In captive breeding, it has been observed that eggs are laid in two strings, which can hold 1,000 to 5,600 eggs (Haas and Köhler 1997). Each egg is about 1.5 mm in diameter and surrounded by 1.5 mm of gelatinous material (Haas and Köhler 1997). Larvae hatch in three days at a total length of 5 mm (Haas and Köhler 1997). In captivity, metamorphosis took place 36 days post-hatching, with newly metamorphed toadlets 9-12 mm in SVL (Haas and Köhler 1997). Small juveniles are about 20 mm in SVL (Haas and Köhler 1997). During the dry months of November to May (the dry season) this species presumably stays in underground hiding places (Savage 2002). This species is nocturnal (Savage 2002).

Common throughout much of its range; occurs within multiple protected areas. No known threats (Bolaños et al. 2004).