Description
Aglyptodactylus chorus is a mantellid frog described from three presumably males and three female specimens. The male snout-vent range was 38.8 – 39.8 mm and the female range was 51.3 – 60.7 mm. The head is somewhat broader than the body with a pointed snout in dorsal view. The nostrils are directed dorsolaterally, the canthus rostralis is straight and distinct, and the loreal region is slightly concaved. The species has a round, distinct tympanum that is 2/3rds the size of the eye diameter. The supratympanic fold is distinct. The overall body shape and limbs are slender. The palms have a flat, oval outer metacarpal tubercle and a slightly elevated and elongated inner metacarpal tubercle. The fingers have a distinct, single subarticular tubercle, a relative finger length of 2 < 4 < 1 < 3, mildly developed terminal discs without circummarginal grooves, and no webbing. Males have nuptial pads on the first finger. When adpressed to the body, the tibiotarsal articulation reaches beyond the snout. The foot has an elongated inner metatarsal tubercle but no outer metatarsal tubercle. The toes have distinct, single, round subarticular tubercles, a relative length of 1 < 2 < 3 < 5 < 4, and a webbing formula of 1(0.5), 2i (1), 2e (0), 3i (1.5), 3e (0), 4i (1.5), 4e (1), 5 (0). The last metatarsal appears deeply separated. The skin on the dorsum and throat is smooth, but the venter is slightly granular (Köhler et al. 2015).

Aglyptodactylus chorus can be differentiated from other species of Aglyptodactylus by the combination of the absence of marbling on the surfaces of the posterior thigh, absence of a vertebral line, presence of dark lines and blotches in the loreal region, well-developed webbing of the toes, and a slender body. More specifically, A. chorus can be differentiated from A. australis by the former being smaller, being more slender, and lacking marbling on the thighs. The focal species can be differentiated from A. laticeps and A. securifer by the former having a narrower head, having more extensive toe webbing, and having a smaller inner metatarsal tubercle. The absence of marbling on the posterior thighs, absence of a vertebral line, and a more pointed snout differentiates A. chorus from A. madagascariensis. Only a longer advertisement call and genetics can differentiate A. chorus from A. inguinalis. Moreover, the call of A. chorus is distinct from the calls of other Aglyptodactylus by displaying a lower pulse reputation rate. The call has shorter note duration than A. australis, A. madagascariensis, and A. securifer. The call has a similar range in pulse repetition rate and note duration to A. laticeps, but A. chorus lacks increases in pulse rate within notes (Köhler et al. 2015).

After four years in preservative, the head, dorsum, and dorsal surfaces of the limbs of the holotype were greyish. The upper lip was white. There were dark, irregular interorbital markings that extended onto the eyelid. The pupils were white and the iris was black. The loreal and temporal regions were greyish with the loreal region having small dark brown spots. There was a dark brown line on the supratympanic fold and an irregular dark brown blotch posterior to the tympanum. On the dorsum there were small brownish spots and elongated markings. Small black markings could also be found on each side of the inguinal region. The flanks were cream-colored. The arms were grey and had one dark crossband on the lower portion. There were also small back spots on the inner side of the lower arm. The posterior side of the upper arm had dark spotting. The dorsal surfaces of the hands were white and covered with very small grey spots and the dorsal surfaces of the feet were cream with small grey spots. The thighs and shanks had dark crossbands and the surface of the posterior thigh had a reticulated pattern. On the dorsal surface of the feet, there are two or three narrow crossbands and the ventral surfaces of feet were grey. The belly and throat were cream in addition to the anterior venter and ventral surfaces of the arms. The cloacal region was dark brown (Köhler et al. 2015).

In life, the dorsal surface was yellow-cream with some golden tint. This gold tint was not present in the loreal and tympanal regions. The venter was yellow-white with the throat appearing darker. The iris periphery was gold with fine brown reticulation and a black pupil. There was dark brown spotting on the palmar and plantar surfaces. The nuptial pads were dark brown. The color patterning of the rest of the animal was similar to coloration in preservative (Köhler et al. 2015).

Individuals differ in number of dark dorsal markings, patterning, size of dark spots in the loreal region, presence of dark interorbital markings, amount of facial spotting, and coloration of the lower lip (cream-colored to white). The venter may have grey spots and the dorsum may be reddish brown (Köhler et al. 2015).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Madagascar

View distribution map in BerkeleyMapper.

Aglyptodactylus chorus is found in the anthropogenically modified landscape of Madagascar in Maroantsetra, Ambodivoahangy, and the Befanjana forest near Manompana between 10 - 24 m asl. The southern limits of its range are uncertain but may be between Melvinany and Tampolo (Köhler et al. 2015, IUCN 2016).

Life History, Abundance, Activity, and Special Behaviors
Males call in large, synchronous choruses at night from swampy areas, such as rice plantations, at the edge of forests. The synchronous nature of the chorus made locating any one individual difficult and may have evolved as an anti-predatory strategy (Köhler et al. 2015).

The advertisement call is soft and consisted of 3 – 4 distinctly pulsed notes lasting 73 – 140 ms that were repeated in regular intervals. Notes consisted of 4 – 6 well-spaced pulses that repeated at an average of 37.3 pulses per second. Amplitudes increased within notes and calls as they progressed. The frequency ranged from 900 – 4000 Hz and had a maximal call energy between 2756 – 2820 Hz (Köhler et al. 2015).

Single individuals could also be found during the day on the forest floor (Köhler et al. 2015).

Blommersia variabilis, Boophis tephraeomystax, and Guibemantis cf. kathrinae could also be heard calling at the same time as A. chorus (Köhler et al. 2015).

Trends and Threats
Köhler et al. (2015) classified A. chorus as “Least Concern” in accordance with the IUCN criteria, however, by 2016 the IUCN Red List had upgraded the status to “Near Threatened” because of risks of declining populations from the species living in degraded and anthropogenic habitats in lowland rainforests and on the rainforest floor. Despite their adaptability and resilience to environmental disturbances, ongoing deforestation, fire control on cattle pastures, and the rate of forest loss has threatened the species survival (IUCN 2016).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Drainage of habitat
Habitat fragmentation

Comments
The species authority is: Köhler, J., Pabijan, M., Glaw, F., Vences, M. (2015). “Integrative taxonomic revision of mantellid frogs of the genus Aglyptodactylus (Anura: Mantellidae).” Zootaxa 4006(3): 401-438.

Based on Maximum Likelihood and Bayesian Inference analyses of 539 base pairs of 16S rRNA, A. chorus is most closely related to A. inguinalis. The clade formed by those two species is sister to A. laticeps (Köhler et al 2015).

The species epithet, “chorus” is from the Latin noun referencing the calling behavior of the species where males call in closely synchronized, large choruses (Köhler et al 2015).

The species was previously referred to as Aglyptodactylus sp. aff. Madagascariensis “East” in 2007 by Glaw and Vences.

Based on ANCOVA analyses of external morophology, A. chorus, A. inguinalis, and A. madagascariensis have only faint and inconsistent differences. This is hypothesized to be due to morphological convergence caused by adapting to the same general habitat (Köhler et al 2015).

References

IUCN SSC Amphibian Specialist Group. 2016. Aglyptodactylus chorus. The IUCN Red List of Threatened Species 2016: e.84500529A84579483. http://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T84500529A84579483.en. Downloaded on 22 March 2017.

Köhler, J., Pabijan, M., Glaw, F., Vences, M. (2015). ''Integrative taxonomic revision of mantellid frogs of the genus Aglyptodactylus (Anura: Mantellidae).'' Zootaxa, 4006(3), 401-438.

Species Account Citation: AmphibiaWeb 2018 Aglyptodactylus chorus <https://amphibiaweb.org/species/8372> University of California, Berkeley, CA, USA. Accessed Jan 8, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 8 Jan 2025.

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