Description
Aplastodiscus aulophonus is a frog described from six males and one female that are approximately 34.8 - 39.6 mm in length from snout to vent in males, and 35.1 mm in the female. This frog is slim in both body and limbs. The skin is smooth except for the regions surrounding the gular, pectoral, and abdominal regions, as well as the ventral surface of the frog’s thighs. The head is longer than it is wide and has a distinct canthus rostralis. The internarial area is flat, and the nostrils do not protrude from the head. Internarial distance ranges from 2.0 - 2.2 mm in males, and 1.8mm in the female. The eyes are a distance of 3.8 - 4.3 mm from the nostrils and protrude from the head in males, and 3.9 mm in the female. The eyes are large, with a diameter of 3.3 - 3.8 mm in males and 3.5 in the female. The pupil is oval and horizontally oriented. The tympanum is also large, ranging from 3.0 to 3.4 mm (2.7 mm in the female), and is marked by a distinct tympanic annulus. The forearms have a dermal ridge from the elbow to the fourth finger along the ventrolateral side. The hands have four fingers, each ending in a small disc. The disc diameter of finger III ranges from 1.5 - 2.2 mm and 1.7 mm in the female. Measurements for the dics of fingers I, II, and IV were not reported. Subarticular tubercles were present on each finger and were rounded and nonbifid. The fingers have a relative length of I < II < IV < III. Lateral fringes are present, although nuptial pads are notably absent. The hind legs of the male are long and measure 18.4 - 20.1 mm when extended, the legs of the female measure 18.5 mm. Each leg ends in a foot with five long toes, each with round discs. A tarsal fringe spans from toe V to the heel, and tubercles are present on the sole and toes. Toe length order is as follows: I < II < III < V < IV. Individual diameters of each toe were not taken, but the diameter of toe IV ranged from 1.6 - 1.9 mm in males, and 1.5 mm in the female (Marinho et al. 2024).

DIAGNOSIS: (How this species is different from similar species)

At the time of the species description, five species had been identified within the Aplastodiscus albosignatus species group in addition to Aplastodiscus aulophonus. Aplastodiscus aulophonus is not distinctive from those members by any obvious physical characteristics. Instead, its vocalization sets it apart from other species. The vocalization of A. aulophonus is unvaried and unpulsed. The most commonly occurring frequency of these calls is 2132 – 2347 Hz. The average call duration spans 141 - 229 ms (Marinho et al. 2024).

COLORATION:

In life, according to Marinho et al. (2024) A. aulophonus demonstrates physiological chlorosis, and its body is bright green. The color on the belly is lighter, ranging from yellow to light green. Melanophores cover the frog’s dorsal surface, concentrated at the head flank. In addition to the bright green, the flanks also present a blueish hue. The eyes are vibrant red, with black pupils surrounded by a silver ring. The eye can appear more red or orange, depending on the frog.

When the species is preserved in ethanol, it loses its green and blue hues. What remains is a pale cream; the melanophores remain white and are visible against the cream background. The frog’s eardrum becomes translucent, while the pupil is a lighter shade of orange/red than it was in life. Webbing on fingers and toes also becomes somewhat translucent, and the subarticular tubercles become more visible (Marinho et al. 2024).

VARIATION:

There were not enough specimens collected to determine variation in female Aplastodiscus aulophonus. The singular female collected was smaller, on average, than the male specimens, but more data would be needed to draw conclusions. The six male specimens collected showed differences in the concentration of melanophores. Variation in shade of color is also seen on the flank and ventral side. The most noticeable variation is present in iris color, which ranges from bright orange to deep red (Marinho et al. 2024).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Brazil

View distribution map in BerkeleyMapper.

Aplastodiscus aulophonus can only be found in the States of Espírito Santo and Minas Gerais, Brazil along the northern Serra da Mantiquera. This region is known for its lush grasslands and forests. Aplastodiscus aulophonus lives in the interior forests of these mountains, often near shallow but fast-moving water sources. All specimens in this study were collected at 1,264 m above sea level, in Parque Estadual do Forno Grande (Marinho et al. 2024).

Life History, Abundance, Activity, and Special Behaviors
Scientists observed Aplastodicus at multiple heights, from the canopy of small trees to branches 30 cm off the ground (Marinho et al. 2024).

The most distinctive trait of the Aplastodiscus aulophonus is its call. Marinho et al. (2024) analyzed the vocalization based on 4 traits: Call Duration, Call Rise Time, Frequency Modulation, and Dominant Frequency of the two (of three) emphasized harmonic bands. The two harmonic bands emphasized were the first (H1) and the third (H3). The call of A. aulophonus is notable for its advertisement call length of 141 - 229 ms. Its fundamental frequency is 725 - 797 Hz, without frequency modulation. The dominant frequency coincides with either H1 or H3. The call rises for 34 - 60% of the overall call duration, the oscillogram of which is elliptical (Marinho et al. 2024).

Only one, incomplete courtship ritual was observed by scientists. During this event, one female was present along with two males. The female approached Male I and first touched her snout to the male’s snout. She then touched the side of his head with her hand. The female then jumped on top of the male, facing opposite directions. Male I continued to call at irregular frequencies, as he had been during the ritual. The female then jumped off Male I and moved toward Male II. She did not repeat any other behaviors with Male Two. The female did not appear to be interested in reproducing with either male and began to leave. At this point, all specimens were collected (Marinho et al. 2024).

Aplastodiscus cavicola is sympatric with Aplastodiscus aulophonus, although the former is more abundant. Aplastodiscus cavicola is more commonly found in clearings and burrows, while Aplastodiscus aulophonus is found in trees. The lack of significant morphologic differences makes identifying the two species difficult when collected (Marinho et al. 2024).

Larva
Researchers were unable to observe the larval stage of Aplastodiscus aulophonus, although Marinho et al (2024) theorizes they are similar to other species of Aplastodiscus that reside near shallow streams.

Comments

PHYLOGENETIC RELATIONSHIPS:

Aplastodiscus refers to the genus of frog species distributed throughout the Atlantic forests of Brazil and neighboring Argentina.

References
Marinho, P., Santos, M. T., Faivovich, J., Lyra, M. L., Giaretta, A. A., Haddad, C. F. B., and Carvalho, T. R. (2024). A new species of the Aplastodiscus albosignatus Group (Hylinae: Cophomantini) from the Northern Mantiqueira Mountain Range. Herpetologica, 80(1), 51-66. [Link]

Species Account Citation: AmphibiaWeb 2024 Aplastodiscus aulophonus: The Flute Frog (English) <https://amphibiaweb.org/species/9874> University of California, Berkeley, CA, USA. Accessed May 9, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 9 May 2025.

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