IUCN threat status:

Critically Endangered (CR)

Comprehensive Description

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Description

The snout-vent length for females of this frog species ranges from 39.5-49.9 mm, while males are smaller at 28.2-34.6 mm. It is relatively slender. Males have a broader, longer head, and thicker forearms. The snout is flat, subtriangular, extends beyond the lower jaw, and is obtusely pointed in dorsal view. The canthus is straight and angular. The interorbital space is flat. Eye diameter is equal to the distance between the eye and the nostril. The pupil is a mix between slit-shaped and round. No tympanic membrane, tympanic ring, or ostia pharyngea are present. The thumb is half the length of the hand and has two phalanges. Finger III is long. The tips of fingers II, III, and IV are broadened. There is basal webbing between fingers II and III, but the webbing is either absent or extremely minimal between fingers III and IV. This species has long hind limbs and feet. Toes have swollen tips and are 50-75% webbed. There are outer and inner metacarpal and metatarsal tubercles. The palm may have a few faint, round, supernumerary tubercles, and there are distinct subarticular tubercles at most phalangeal joints of all toes, and fingers II, III, and IV. In males, finger I has a nuptial excrescence. There are small, rounded, glandular warts on the dorsolateral and lateral head surfaces behind the eye. The warts continue in a row down the dorsal surface to the groin and onto the dorsal surfaces of the arms and legs, and partly onto the hand and tarsus (Lötters et al. 2004). This species was redescribed after it was noted that the original type material actually represented a related species from Central America, Atelopus varius (Lötters et al. 2004).

The dorsal surface is yellowish-green to olive green. The ventral surface fades into yellowish-cream on the belly and throat. There is a dark brown or black lateral stripe that passes all the way from the snout to the groin. Black stippling and marbling is present on all dorsal surfaces. Also present is a more or less defined cross-pattern behind the head (sometimes described as an "X" at the nape of the neck) and sometimes a chevron mark in the sacral region. The ventral surfaces of the limbs and flanks are widely marked with dark brown or black (Lötters et al. 2004).

Tadpoles of the genus Atelopus have large abdominal suckers that enables them to cling to rocks in rushing stream waters (Lötters 2007). Atelopus cruciger tadpoles have longer tails (61% of the body length) than other Atelopus species (Mebs 1980).

This species was first described by Lichtenstein and von Martens (1865).

The genus Atelopus, with 113 described and putative species, appears to be the most threatened clade of amphibians (La Marca et al. 2005). At least 30 species appear to be extinct, having been missing from all known localities for at least 8 years (La Marca et al. 2005). Only 52 of the surviving species have sufficient data with which to evaluate population trends; of these, 81% (42 of 52) have population sizes that have been reduced by at least half (La Marca et al. 2005). Only 10 of the 52 species appear to have stable populations (La Marca et al. 2005). Higher-elevation species (those living at least 1000 m asl) have been hit the worst, with 75% (21 of 28) having disappeared entirely (La Marca et al. 2005). In Venezuela there are ten endemic Atelopus species (La Marca and Reinthaler 1991); nine are classified as Critically Endangered and one is thought extinct (Rodríguez and Rojas-Suárez 1995; Rodríguez-Contreras et al. 2008; Stuart et al. 2008). Chytridiomycosis is thought to be a primary factor in the decline and disappearance of species in this genus (La Marca et al. 2005). Most Atelopus species are restricted to very limited areas (no more than two localities) and occur along mid- to high-elevation streams (1500-3000 m asl, though the maximum vertical range is from sea level to permanent snow; Lötters 2007), a habitat preference frequently associated with the co-occurrence of chytridiomycosis (La Marca et al. 2005). Habitat loss has occurred within the ranges of many Atelopus species, but does not appear to be a major factor in the decline of most Atelopus species; 22 species declined despite occurring in protected areas (La Marca et al. 2005). Many Atelopus species are local endemics, putting them at particular risk of extinction, with at least 26 species known only from a single population inhabiting a narrow altitudinal range (La Marca et al. 2005). Due to their restricted ranges, they are thought to have limited ability to adapt to warming climatic conditions (Lötters 2007).

Defenders of Wildlife and SSN recommended in 2009 to the United States that Atelopus cruciger should be included in Appendix II in CITES (Convention on International Trade in Endangered Species), during COP15 (the UN Climate Change Conference 2009). Since a small population of this species is only found in Northern and Southern versants of the Corillera de la Costa of Venezuela, submitting this species into Appendix II would enact recommendations for controlling commercial trade. However, the Dept. of U. S. Fish and Wildlife noted that unless Venezuela requested assistance or "significant additional information is received" pertaining to the species trade or population status, Atelopus cruciger would not be submitted into Appendix II.

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