Description

Diagnosis: This species can be distinguished from most species in the genus Pristimantis by the following characters: (1) Toe V slightly longer than Toe III; (2) Toe V reaching to approximately the level of Toe IV's penultimate subarticular tubercle; (3) toe discs not expanded or only slightly expanded (Guayasamin and Funk 2009).

Pristimantis bicantus is most similar to species in the P. myersi group (including P. festae, P. floridus, P. gladiator, P. hectus, P. leoni, P. myersi, P. ocreatus, P. pyrrhomerus, P. repens, P. scopaeus, and P. xeniolum. It differs from the species in the myersi group by having sexual dimorphism in tympanic annulus size (males have larger tympana) and by lacking tarsal tubercles. Only two other species in this group inhabit the same biogeographical region, the Amazonian slope of the Andes Mountains: P. gladiator and P. festae. P. bicantus is most likely to be confused with P. gladiator, from which it can be distinguished by having vomerine teeth (absent in P. gladiator), lacking ulnar and tarsal tubercles (present in P. gladiator), and groin coloration in life (gray groin which may or may not have a reddish tint in P. bicantus, vs. a black groin with reddish-orange spots in P. gladiator) (Guayasamin and Funk 2009).

It can be distinguished from other species in the P. myersi group by (1) the lack of tarsal tubercles (vs. presence of tarsal tubercles in P. floridus, P. leoni, P. myersi, P. pyrrhomerus, and P. xeniolum); (2) the lack of ulnar tubercles (present in P. hectus, P. leoni, P. myersi, and P. xeniolum; (3) upper eyelid with low tubercles (vs. upper eyelid with subconical tubercles in P. leoni, or single subconical tubercle in P. repens); (4) slightly expanded discs on outer fingers (vs. finger discs not expanded in P. festae or P. ocreatus); (5) no lateral fringes on toes (toe lateral fringes present in P. festae); (6) in preservative, venter is pale cream (vs. black venter, often with cream spots, in P. festae); (7) in life; venter is translucent with a gray-orange tint (vs. olive brown venter in P. repens); (8) presence of finger pads (vs. pads absent on inner fingers for P. ocreatus); (9) visible tympanic membrane and annulus (vs. tympanum and annulus not visible in P. scopaeus); (10) presence of vomerine teeth (vs. vomerine teeth absent in P. xeniolum); (11) males with vocal slits (vs. vocal slits absent in P. xeniolum) (Guayasamin and Funk 2009).

Description: Adult males measure 12.0-15.8 mm SVL. Adult females measure 17.0-21.7 mm SVL. Snout rounded in both dorsal and lateral view. Distinct canthus rostralis, slightly concave loreal region, nares slightly protuberant. Cranial crests, occipital folds and dorsolateral folds are absent. Low, nonconical tubercles on upper eyelid. Tympanic membrane and tympanic annulus are sexually dimorphic, larger in males than females. Supratympanic fold obscures anterodorsal and posterodorsal edges of tympanic annulus. Two nonconical postrictal tubercles are present. Dorsum shagreened with small scattered tubercles. Venter weakly areolate. No discoidal fold or anal sheath. Head shagreened. Upper flank with many low warts. Vomerine dentigerous processes bear two to eight teeth each. Finger II is longer than Finger I. Discs on Fingers II-IV are slightly expanded. All disc covers have ventral pads that are almost elliptical and are defined by grooves. Hind legs are relatively robust. The tarsus lacks tubercles on the heel, inner and outer edges. Ulnar tubercles are also absent. Inner metatarsal tubercle is about 1.5-2.5x the length of the outer metatarsal tubercle. Toes lack webbing and lateral fringes. Toe III is shorter than Toe V. Disc on Toe IV is greater than those on outer toes. Males have larger tympana and vocal slits, but lack nuptial pads (Guayasamin and Funk 2009).

Coloration in life: Brown (light or dark) dorsum with dark markings, usually including a darker indistinct interorbital bar, sometimes with a W-shaped occipital mark or chevron markings). Dorsolateral light stripe is sometimes present. Snout sometimes pale. Dark stripe runs from posterior orbit through top half of tympanum, ending above the insertion of the arm. Flanks are light brown or gray, and may have diagonal dark bars. Whitish cream to light brown throat with two dark brown marks on the center of the throat. Venter translucent, light orangish-gray, with black and white speckling. Groin and concealed thigh surfaces are gray, sometimes with a reddish or salmon tint. Posterior thigh below cloacal opening has dark brown blotch with light border. Legs are barred. Iris pale yellow, with orange pupillary ring and a horizontal, medial dark red bar (Guayasamin and Funk 2009).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Ecuador

View distribution map in BerkeleyMapper.

Endemic to Ecuador. Found on the Amazonian slope of the Andes at elevations of 2100-2300 m ASL in primary and secondary forests. Known only from the type locality, cloud forest surrounding the Yanayacu Biological Station. Generally found on the forest floor or in low vegetation, 0-80 cm above the ground (Guayasamin and Funk 2009).

Life History, Abundance, Activity, and Special Behaviors
This species is nocturnal, and is one of the two most abundant frog species found in the vicinity of Yanayacu Biological Station, with the other abundant species being P. petersi (Guayasamin and Funk 2009).

P. bicantus was heard to produce two types of advertisement calls: short calls and long calls. Typical mating calls included a few short calls followed by many long calls. Sometimes short calls could be heard alone, but long calls were always made following short calls. Short calls had 1-3 pulses and an average fundamental frequency of 3134-3186 Hz. Long calls averaged 15.5-18.9 pulses, produced at a more rapid rate than for short calls, and a lower mean fundamental frequency of 2831-2973 Hz. The long calls are said to sound like a fingernail being dragged over the tooth of a comb (Guayasamin and Funk 2009).

Trends and Threats
Over the two-year study period, two-thirds of individuals were found in primary forest while one-third were found in secondary forest, indicating that this species is at least somewhat tolerant of habitat disturbance (Guayasamin and Funk 2009).

Comments
The species name bicantus refers to the two distinct call types (Guayasamin and Funk 2009). P. bicantus was referred to as Eleutherodactylus sp. 3 in Funk et al. (2003).

References

Funk, W. C., Almeida-Reinoso, D., Nogales-Sornosa, F., and Bustamante, M. R. (2003). ''Monitoring population trends of Eleutherodactylus frogs.'' Journal of Herpetology, 37, 245-256.

Guayasamin, J., and Funk, W. (2009). ''The amphibian community at Yanayacu Biological Station, Ecuador, with a comparison of vertical microhabitat use among Pristimantis species and the description of a new species of the Pristimantis myersi group.'' Zootaxa, 2220, 41-66.

Species Account Citation: AmphibiaWeb 2010 Pristimantis bicantus <https://amphibiaweb.org/species/7375> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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