Anthony's Poison Arrow Frog

Adult males reach sizes between 19-24.5 mm snout-vent length, while females grow slightly bigger at 21.5-26.5 mm snout-vent length (Caldwell and Summers 2003, as E. tricolor; see Comments section for note on taxonomy). Hind limbs are short and powerful. As is the case for all dendrobatids, divided scutes are present on the fingers and toes (Caldwell and Summers 2003). Adults are red with yellow or white oblique lateral and mid-dorsal stripes (Graham et al. 2004).Epipedobates anthonyi is part of the Epipedobates tricolor clade, considered in the literature as either a separate species (e.g. Schulte 1999), or conspecific with E. tricolor (e.g. Santos et al. 2003, but see Graham et al. 2004 for debate), or pooled with E. tricolor (e.g. Summers and Clough 2001). Thus, descriptions may apply to E. tricolor as well as E. anthonyi in some instances (see Graham et al. 2004 for a review). The type locality of E. anthonyi is in southwestern Ecuador (Salvia, El Oro Province), while that of E. tricolor lies in central Ecuador, on the western slopes of the Andes (El Porvenir, Bolívar Province) (Darst and Cannatella 2005).

Occurs in the El Oro, Azuay, and Loja provinces of southwestern Ecuador and the Piura, and Tumbes departments of northwestern Peru, from 153-1,769 m above sea level. It has also been reported from Ancash but this record is considered doubtful. The type locality is in southwestern Ecuador (Salvia, El Oro Province). This species is found in subtropical dry forest and moist lowlands near streams, including degraded forest (Coloma et al. 2004).

Adults are diurnal and terrestrial, often active in early morning and late afternoon in dense vegetation near small pools of water (Caldwell and Summers 2003). Dendrobatid breeding occurs during the rainy season, during which time males are territorial (Caldwell and Summers 2003). The advertisement call is a trill, with tonal structure (Zimmermann 1989). Territories include nesting sites, where the female lays the eggs during cephalic amplexus (Zimmermann 1989). During amplexus, before the female lays her eggs, the male gives courtship calls, which consist of a short series of croaks (Zimmermann 1989).Clutches consist of 15-40 eggs which are roughly 2 mm in diameter (Coloma et al. 2004; Zimmermann 1989). Eggs are laid in leaf litter (Coloma et al. 2004). Parental care is given by the male, who guards the eggs for up to two weeks until they hatch (Zimmermann 1989). The male also moistens the eggs periodically and will engage intruding frogs in physical combat to defend the clutch (Zimmermann 1989). On hatching, the male carries all tadpoles on his back simultaneously to a nearby pool of water or stream, where the larval stage is completed without any further parental involvement (Zimmermann 1989; Coloma et al. 2004). Development takes about sixty days, culminating in metamorphosis into froglets that are about 11 mm in snout-vent length (Zimmermann 1989). The gastrulation phase of early development in this species has been studied in depth (Moya et al. 2007). Adults eat tiny arthropods, mostly small insects (Coloma et al. 2004).Since this species has skin toxins, the red coloration of adults is considered aposematic (warning potential predators of toxicity), although the toxicity of E. anthonyi/ E. tricolor is less than for other species of dendrobatid frogs (Summers and Clough 2001). This species is considered abundant but declining (Coloma et al. 2004).

Epipedobates anthonyi is considered an abundant species in southern Ecuador but the population is declining due to habitat degradation from waterway pollution. It is not known whether part of this species’ habitat occurs in a protected area (Coloma et al. 2004).

Frogs in the genus Epipedobates produce lipophilic skin toxins consisting of piperidine-based alkaloids (Toft 1995). Epipedobates anthonyi is less toxic than species in the genera Phyllobates and Dendrobates (Graham et al. 2004). E. anthonyi rarely has class A or B pumiliotoxins, and 3,5-disubstituted indolizidines are not found at all (Summers and Clough 2001). Skin secretions of Epipedobates have been used in medical research. Epibatidine, a lipophilic skin toxin, is a piperidine-based alkaloid which acts as a non-opioid painkiller by binding to nicotinic acetylcholine receptors, and has been found to be 200 times more potent than morphine. Although published papers on epibatidine refer to E. tricolor (e.g. Daly et al. 1987, Myers et al. 2000), the species used is very likely to have been E. anthonyi, based on the type localities for each (Graham et al. 2004; Darst and Cannatella 2005). Despite the analgesic properties of this trace skin secretion, Daly et al. (2000) state that native Ecuadorians did not have knowledge of it, nor did they make use of either frog species for medicinal purposes. Although epibatidine is effective as an analgesic, it is also toxic in low doses, with the toxicity thought to be due to binding to many different nicotinic acetylcholine receptor subtypes. A number of derivatives of epibatidine with greater specificity and potentially lower toxicity have been synthesized in the laboratory. Several are being investigated as potential novel analgesic drugs, since this class of compound is both potent and does not induce tolerance over time as morphine does (Daly et al. 2000).As is the case for other dendrobatid skin toxins, epibatidine appears to be derived entirely from dietary sources. E. tricolor/E. anthonyi frogs collected from a cocoa plantation contained trace amounts of epibatidine, while those collected from a nearby banana plantation did not. In addition, captive frogs lacked epibatidine entirely. Thus the dietary source of epibatidine is likely to be present in low quantities and not universally distributed (Daly et al. 2000). This species has also been used in research on amphibian developmental biology (Moya et al. 2007).

Anthony's poison arrow frog (Epipedobates anthonyi) is a species of poison dart frog in the family Dendrobatidae. The species is endemic to Ecuador and Peru.