Description
Pristimantis astralos is a frog with an adult snout length of 23.6 - 27.2 mm for males and 25.6 - 32.6 mm for females. The head is longer than wide, and slightly narrower than the body. In the dorsal and lateral views the snout is bluntly rounded. The dorsolaterally directed nostrils are protuberant. The lips are rounded with two conical postrictal tubercles or a short, fused ridge of postrictal tubercles. In the dorsal view, the canthus rostralis is straight, and in the profile it is rounded. The loreal region is somewhat concave. The distance from the nostril to the eye is smaller than the eye diameter, but slightly longer than the eyelid width. The eyes are oriented dorsolaterally, and the eyelids do not have tubercles. The tympanum is distinct with a narrow supertympanic fold that is distinct and extends from the margin of the upper eyelid diagonally, over the upper margin of the tympanum, to the insertion of the arm. The dorsal surfaces of the body are tuberculated with a poorly defined dorsolateral fold. The flanks have tubercles that merge into short ridges. There are a few scattered tubercles on the tuberculated skin of the upper hind limbs, but the inner surface is smooth and the posterior and ventral surfaces of the thigh are areolate. The skin on the throat and chest is shagreen while the belly is coarsely areolate. There is a short cloacal sheath. There are small tubercles on the outer surfaces of the ulna. The palm has a bifid outer palmar tubercle and distinct, oval supernumerary tubercles, which are half the size of the subarticular tubercles. The fingers have narrow lateral fringes and prominent, well-defined subarticular tubercles, which are round in the ventral view and conical in the lateral view. The fingers end in broadly expanded, round discs with circumferential grooves. Finger I is shorter than Finger II. Males have nuptial pads. The hind limbs are longer than the forelimbs, but still short and slender. There are no conical tubercles on the heels, but there are minute tubercles on the outer surfaces of the tarsus. There is a short tarsal fold on the inner edge. The inner metatarsal tubercle is ovoid and twice the size of the ovoid outer metatarsal tubercle. The distinct plantar supernumerary tubercles are about one-fourth the size of the well-defined subarticular tubercles, which like the fingers, are round in the ventral view and conical in the lateral. The basally webbed toes have narrow lateral fringes. The webbing is most prominent between toes IV and V, and the fringe of Toe V is undulated. The relative toe length is I < II < III < V < IV and the toes end in slightly truncated, expanded discs with circumferential grooves that are of similar size to the fingers (Lehr et al. 2021).

DIAGNOSIS:

Pristimantis astralos can be differentiated from other closely related species by morphology and coloration. More specifically, P. astralos has dorsolateral folds, and dark dorsal coloring like P. attenboroughi, but P. attenboroughi lack vocal slits, nuptial pads, and bumps and grooves on the body. Pristimantis ardalonychus have a dark dorsum, tympanic membrane and annulus, however it lacks the bumps and grooves present on the dorsum and has females of a smaller size. Pristimantis atrabracus have a tympanic membrane and annulus, with fringes on the extremities like P. atsralos, however males of the former species don’t have nuptial pads. Pristimantis coronatus have similar coloring on the dorsum, however the coloring on the groin is orange and red. Pristimantis vilcabambae have the same coloration on the dorsum and groin, however it doesn’t have dorsolateral folds, a tympanic membrane or annulus, vocal slits, or nuptial pads (Lehr et al. 2021).

COLORATION:

In life, P. astralos have a black dorsal background color spotted with white on the dorsum, flanks, and dorsal limbs. The background color of the area around the groin and the anterior surfaces of the thigh is a dark charcoal, but returns to black on the posterior surfaces of the thigh. The chest and belly are light grey and dark brown with a reticulated brown line along the ventral midline. The throat is greyish purple with a pale grey tint. The palms and plantar surfaces, including the digits, are brown. The iris is dark copper and has fine black lines. In preservative, the dorsal spotting becomes creamy white, the black background coloration becomes dark charcoal. Areas that were previously dark charcoal become creamy. The colors on the chest and belly become cream and dark brown. The throat and the ventral surface of the thighs, palms, planter and digits are cream. The iris becomes pale bluish grey (Lehr et al. 2021).

VARIATION:

There is variation in both skin morphology and coloration. The dorsal folds vary from prominent to poorly defined. The prominence of the tubercle ridges on the flanks is also variable. Some specimens have fused postrictal tubercles while others have two distinct postrictal tubercles. Coloring ranges from dark black to dark brown. The groin area is speckled in some specimens and solid white in others (Lehr et al. 2021).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Peru

View distribution map in BerkeleyMapper.

Pristimantis astralos was found in the Cajamarca region of Peru at an elevation 2400 - 3500 meters. More specifically, at the time of the species description, the species was only known from one locality in a concession region of the Mina Cerro Corona-Gold Fields in La Cima, Comunidad Tingo. The habitat there, now destroyed, included high Andean grasslands with feather grass and bromeliads of the species Puya fastuosa (Lehr. E et al. 2021).

Life History, Abundance, Activity, and Special Behaviors
Pristimantis astralos was primarily found in larger P. fastuosa plants, often under dead leaves at the bases of the plant, where the microclimate was more humid. They were often found in groups including juvenile and adult males and females (Lehr et al. 2021).

Other herpetofauna found in the area included Pristimantis chimu, P. pinguis, P. simonsii, and a lizard, Stenocercus stigmosus, which all also used P. fastuosa for refuge (Lehr et al. 2021).

Trends and Threats
Since 2014 local mineral mines have destroyed much of the habitat of P. astralos. It is unclear if there is suitable habitat in the vicinity, but the species has been extirpated from the type locality. The plant that the species appeared to rely on, P. fastuosa, has a current conservation status of “Endangered” and the species authority for P. astralos recommend a conservation status of “Critically Endangered” for this frog (Lehr et al. 2021).

Possible reasons for amphibian decline

General habitat alteration and loss
Mining

Comments

PHYLOGENETIC RELATIONSHIPS:

Based on Maximum Likelihood analysis of 16S rRNA, P. astralos is most closely related to the P. simonsii. However, this relationship, along with the relationship with many other related species, is not strongly supported (Lehr et al. 2021).

ETYMOLOGY:

The species epithet, “astralos” comes from Greek, meaning “spotted with stars” It was given this name because of the speckled white blotches on its back that appear like stars against its solid black body (Lehr et al. 2021).

References

Lehr, E., Lyu, S., Catenazzi, A. (2021). "A new, critically endangered species of Pristimantis (Amphibia: Anura: Strabomantidae) from a mining area in the Cordillera Occidental of northern Peru (Región Cajamarca)." Salamandra, 57, 15-26. [link]

Species Account Citation: AmphibiaWeb 2023 Pristimantis astralos <https://amphibiaweb.org/species/9325> University of California, Berkeley, CA, USA. Accessed Jan 2, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 2 Jan 2025.

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