Description

Female holotype measured 53.6 mm SVL. This species can be diagnosed by the following combination of characters: (1) dorsum uniform brown in coloration; (2) flanks and hidden surfaces of thighs gray with black vertical bars; (3) ventral region cream with black blotches; (4) cloacal region quite swollen, bordered by a transverse dermal fold; (5) fingers with basal webbing; (6) toes about 1/2 webbed (Duellman 1973).

Other characters include: head the same width as body; snout truncate in both dorsal and lateral view; nares closer to tip of snout and not protuberant; internarial area flat; canthus rounded; loreal region somewhat concave; lips rounded and thick; eyes somewhat large but not protuberant; top of head flattened; prominent supratympanic fold, obscuring dorsal edge of tympanum; tympanic annulus visible. Forearm robust; low, scalloped ulnar fold and distinct wrist fold present; axillary membrane is lacking; fingers are long and basally webbed, with the tips expanded into small discs; Finger III disc is equal in width to the tympanum; subarticular tubercles are large and flattened; supernumerary tubercles are present on proximal segments of fingers; palmar tubercle bifid, low; prepollex enlarged and oval-shaped. Hind limbs slender; inner metatarsal tubercle flattened and elliptical; toes are elongated, one-third webbed, and have discs smaller than fingers; subarticular tubercles are round and large; supernumerary tubercles are round, small and present on proximal segments of toes. Cloaca has transverse dermal fold above it and is encircled by a swollen glandular region with a cleft running from the opening to the ventral surfaces of the thighs. Skin is smooth dorsally; weakly granular on chest, belly, and proximal posteroventral thigh surfaces. Tongue round; prevomerine teeth number 11-13 (Duellman 1973).

In life, this frog has a solid brown dorsum, while the flanks and concealed surfaces of the limbs are blue with black bars. The venter has black and blue marbling. The iris is silver with black reticulations. Juveniles are grayish brown with faint darker markings; in juveniles the thighs show narrow transverse brown bands, the flanks are cream with tiny brown spots, and the venter and concealed surfaces of the thighs are cream-colored (Duellman 1973).

This species resembles H. calcarata, H. fasciata, and H. raniceps in having vertical black bars on the flanks and hidden surfaces of the thighs, but H. larinopygion has a distinctive swollen cloacal region as well as ventral patterning, in contrast to the white venters of these three species (Duellman 1973).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Colombia, Ecuador

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (6 records).

Occurs in the Andes of Colombia (Cordillera Central, Cordillera Occidental, and the eastern slopes of the Nudo del Pasto) and Ecuador (Province of Carchi, Province of Imbabura), between 1,900 m and 3,100 m asl (Stuart et al. 2008). The distribution is patchy (Stuart et al. 2008). This species has been found in bromeliads or on vegetation near streams in both primary and secondary forest (Stuart et al. 2008). The type locality is a wooded ravine running through cleared pasture (Duellman 1973).

Life History, Abundance, Activity, and Special Behaviors
The adult female holotype was found during the day, in a terrestrial bromeliad growing on tree roots sticking out of a ravine bank (Duellman 1973). A juvenile was found at night, on a bush near a stream at the ravine's bottom (Duellman 1973). Breeds in streams (Stuart et al. 2008).

Trends and Threats
Although H. larinopygion is common where found, populations are patchily distributed and numbers are declining. This species occurs in protected areas within both Colombia and Ecuador. In Ecuador the range overlaps with the Reserva Ecológica Cotacachi-Cayapas (Stuart et al. 2008).

Possible reasons for amphibian decline

Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Local pesticides, fertilizers, and pollutants

Comments
The specific epithet refers to the distinctive swollen cloacal region, and derives from the Greek word larinos, for fat, and pygos, for buttocks (Duellman 1973).

References

Duellman, W. E. (1973). ''Descriptions of new hylid frogs from Colombia and Ecuador.'' Herpetologica, 29, 219-227.

Stuart, S., Hoffmann, M., Chanson, J., Cox, N., Berridge, R., Ramani, P., Young, B. (eds) (2008). Threatened Amphibians of the World. Lynx Edicions, IUCN, and Conservation International, Barcelona, Spain; Gland, Switzerland; and Arlington, Virginia, USA.

Species Account Citation: AmphibiaWeb 2010 Hyloscirtus larinopygion <https://amphibiaweb.org/species/842> University of California, Berkeley, CA, USA. Accessed Dec 3, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 3 Dec 2024.

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