Chiriqui Harlequin Frog

Atelopus chiriquiensis, the Chiriqui Harlequin Frog, is a moderately-sized frog with males reaching 28-34 mm and females 36-49 mm (Savage 2002). The head is angular and longer than it is wide, and lacks a visible tympanum (Savage 2002). The canthus rostralis is well-defined in this species (Savage 2002). The undersides of the hands and feet are wrinkled and fleshy (Savage 2002). Paired metarsal and subarticular tubercles are present. Toes have extensive webbing. Adult males have paired vocal slits and a single subgular vocal sac, located internally, as well as brown nuptial pads on the thumbs (Savage 2002). Occasionally adults of either sex will have prominent small spicules along the anterior flank (Savage 2002). This species is highly variable in color. Males have a uniformly yellow, chartreuse, lime green or brownish red coloration (Leenders 2001; Savage 2002). On occasion males will also have a pattern consisting of thin black reticulations, or fine dark vermiculations (Savage 2002). Females are more variable in color, and are rarely similar to the males in coloration (Savage 2002). Many females have an orange or orange-red stripe, outlined in black, which begins at the snout and then splits into two stripes running down the sides of the back to the groin (Savage 2002; Leenders 2001). The stripes may also break up into long splotches (Savage 2002). In both sexes the ventrum is usually yellow, and generally without pattern; females sometimes have a broad black and red reticulum ventrally (Savage 2002). Both females and males have orangish or greenish eye color, and sometimes they may even have an eye of each color (Leenders 2001). The iris is gold (Savage 2002). This species has weakly developed and relatively inconspicuous poison glands, which are scattered over the head and dorsum (Leenders 2001), distinguishing it from related species. In contrast, Atelopus varius has no differentiated glandular areas, and Atelopus senex has very prominent glands (Savage 2002). A. chiriquiensis tadpoles are gastromyzophorous, with 2/3 denticle rows, and resemble those of Atelopus varius (Savage 2002).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=4366&-Find).

A. chiriquiensis occurs in the cool, humid cloudforest in the Talamanca Mountain range from Costa Rica to Panama. This species is found at elevations of 1400-2500 meters. There is some variation in habitat selection between sexes (Leenders 2001). Males prefer areas near streams and females prefer shaded forest habitat (Lips 1998).

Atelopus chiriquiensis is diurnal (Savage 2002). Males are territorial and use both calls and physical combat with other intruding male frogs to maintain their territorial boundaries (Savage 2002). Breeding takes during the dry season in Panama (February) (Lindquist and Swihart 1997), or in the early wet season in Costa Rica (May to July) (Savage 2002). Advertisement calls have been described as a buzz or a pulsed call (Savage 2002). Chiriqui Harlequin Frogs in Parque Internacional La Amistad, Provincia de Chiriqui, Panama, were observed mating (Lindquist and Swihart 1997). The habitat consisted of swift montane streams with water temperatures of 10.8 degrees C and air temperatures of 17.6 degress C, in cloud forests of 2005-2100 meters. Mating behavior occurred during both daytime and nighttime. The observed mating sex ratio was 1 female to 7 males. Females are on average 1.5x the size of males. Amplexus is axillary (Lindquist and Swihart 1997), and is initiated well before egg laying (Savage 2002). Frogs of the genus Atelopus are known for remaining in amplexus for extended periods of time, even up to several weeks (Leenders 2001). Males not in amplexus with a female were observed trying to dislodge other males from females, but these attempts were not successful. Amplectant mating pairs submerge themselves completely in the stream for 15-30 minutes, either to avoid attempts by other males to disrupt the mating, or possibly for females to look for egg laying sites (Lindquist and Swihart 1997). Female egg laying behavior was observed in the laboratory. Female A. chiriquiensis chose to deposit eggs in small containers containing partial amounts of unchlorinated water. Eggs were laid in a continuous process over an 8-10 hour period, producing in total two strings of ~364 unpigmented eggs. The eggs were all laid in a massive clutch, making it difficult to separate eggs without breaking the strings. The strings measured 36-44 cm in length, with an egg density of 11-13 eggs per 25 mm segment. Egg diameter was measured at 2.05 mm, and in its protective gel case the diameter was 3.63 mm. During egg laying the male performed a leg-kicking action, in which he kicked his leg 2-3 times before the female would lay 3-5 eggs onto the string. A possible reason for the leg-kicking behavior was to provide a tactile cue to the female to help her synchronize her egg release with milting. The eggs in the laboratory did not develop (Lindquist and Swihart 1997). When researchers returned to the original breeding site in August they found that most Chiriqui Harlequin Frogs had left the area. Only a very small number of amplectant pairs and single individuals were left, suggesting migration within the species. Migration appeared to be tied to the local rainfall patterns (Lindquist and Swihart 1997). These toads produce tetrodotoxin, a potent neurotoxin (Leenders 2001).

This species has not been observed over its normal range/distribution in recent years and is possibly extinct (Leenders 2001). In Finca Jaguar, Costa Rica, Lips (1998) reported that the Chiriqui Harlequin Frog was most abundant in 1991. Tadpoles and adults were seen in the area, but no juveniles. By 1994 the mark and recapture rate of Chiriqui Harlequin Frogs was extremely low, suggesting these frogs had migrated away from the area (Lips 1998). By 1996 there were only 5 individuals found in this area, with a female biased sex-ratio (Lips 1998). Potential reasons for population decline include 1)habitat destruction; 2)introduced fish; 3)environmental contamination; and 4)pathogen outbreaks (Lips 1998).

Atelopus chiriquiensis, the Chiriqui harlequin frog or Lewis' stubfoot toad, is an extinct species of toad in the family Bufonidae that was found in the Cordillera de Talamanca in Costa Rica and western Panama (Province and Bocas del Toro Provinces). Its natural habitats were stream margins in lower montane wet forests and rainforests. Its elevational range was 1,400–2,500 m (4,600–8,200 ft) asl.