Description
Platypelis laetus is a plump, arboreal frog from the Microhylidae family. It is a small to medium-sized frog that was described from three males, two females, and one specimen of undetermined sex. The adult male snout-vent length is 24.3 - 25.6 mm, snout-vent length was not given for the females. It has a head that is shorter than wide but narrower than the body. Its snout is rounded slightly in the dorsal view, but in the lateral view is blunt with protuberant nostrils closer to the snout tip than eye. It has a straight, distinct canthus rostralis and a straight loreal region that is slightly oblique. The distinct tympanum is smaller than the eye diameter, and the supratympanic fold that starts at the eye’s posterior border extends to the insertion of the forelimb. It has smooth skin on its dorsal and ventral sides, but has some granular texture on its belly. There are no dorsolateral folds. It has robust forelimbs and a small, round outer metatarsal tubercle. There is also a distinct prepollex or inner metatarsal tubercle that protrudes from the base of the first finger. The hands are without webbing but do have lateral fringes on their broadly rounded to slightly bilobate fingers. The relative finger lengths are 1 < 2 < 4 < 3, and the tips expand into discs. The fingers have single subarticular tubercles, and no nuptial pads. The hind limbs are slender with a tibia length that is 47% of the snout-vent length. When the hind limb is adpressed along the body, the tibiotarsal articulation reaches the area between the forelimb and tympanum. There is no outer metatarsal tubercle but there is a small, oval inner metatarsal present. It has weakly developed toe webbing with slight yet noticeable webbing between the third and fourth toe. The relative toe lengths are 1 < 2 < 3 < 5 < 4 with the broadly rounded to somewhat bilobate toes being relatively flattened with broad discs. The subarticular tubercles of the toes are also singular (Rakotoarison 2020).

DIAGNOSIS:

Platypelis laetus can be differentiated from other species such as P. grandis, P. alticola, P. pollicaris, P. tuberifera, and P. cowanii by its relatively smaller size. Compared to P. tetra, P. barbouri, P. karenae, P. ravus, and P. ando, P. laetus is larger. It can be further distinguished from P. grandis by having smooth skin on its dorsal surface; from P. tuberifera by its dark dorsal pattern on a not flattened body; from P. pollicaris and P. mavomavo by having a third toe that is relatively shorter than the fifth; from P. tsaratananaensis by having a larger, rounded body and no vomerine teeth; from P. milloti by having a green throat and no red ventral color as well as a specific pattern on its back; and from P. barbouri and P. ranjomena by having no red color on its ventral nor its limbs. Platypelis laetus can be distinguished by its short call of 73 - 83 ms compared to that of P. alticola, P. ando, P. barbouri, P. karenae, P. pollicaris, P. ranjomena, P. ravus, P. tuberifera, C. berara, C. fortuna, C. maharipeo, C. noromalalae, C. occultans, C. phyllodactyla, and C. puellarum. Platypelis milloti have shorter calls than P. laetus (Rakotoarison et al. 2020).

COLORATION:

In preservation, the dorsum is a light beige color. There may be a brown, teddy-bear-shaped patch speckled by cream color that starts between the eyes and goes down to the inguinal region. At the nostril, there is a lot of brown. The lateral surface is light beige and is dotted with small browns. This coloration continues to the ventral side and the chin. Its arms have brown crossbands on a background of beige. On the thigh, the dorsal surface is beige with light brown crossbands, the posterodorsal side is beige speckled with light brown and the ventral surface is beige, but is speckled with brown in the cloacal region. The ventral surfaces of the shank, tarsus, and foot are beige (Rakotoarison et al. 2020). Photos of coloration in life can be found in Rakotoarison et al. (2020).

VARIATION:

Variation between the holotype and two male paratypes are overall consistent. However, while holotype had a plump body and a teddy-bear pattern on the dorsum, a skinny paratype without the pattern was also present. Relative toe length is also variable, with the third toe being both distinctly and only slightly shorter than the fifth. In life, the dorsal surface may have irregular granules. And lastly, in preservative, the individuals may vary in the darkness of coloration (Rakotoarison et al. 2020).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Madagascar

View distribution map in BerkeleyMapper.

Platypelis laetus is only known to occur in Northern Madagascar in the Soratat Massif at high elevations of 1339 - 1541 m above sea level. It occurs in rainforests at these locations (Rakotoarison et al. 2020).

Life History, Abundance, Activity, and Special Behaviors
Platypelis laetus seem to be montane specialists and live in forests of palm and bamboo in high elevations where they have been collected in bamboo node holes at 5 m above the ground. They have also been found 4 m above the ground in palm trees (Rakotoarison et al. 2020).

Male P. laetus have been observed to begin calling around dusk. Their advertisement calls are distinguished as a single short tonal note that is repeated at consistent intervals over a long period of time. Calls were observed at 15°C and lasted 73 - 88 ms (83.4 ± 4.3 ms) at a dominant frequency of 4707 - 4793 Hz (4742 ± 38 Hz) and had an inter-note interval of 1465 - 2378 ms (1940 ± 255 ms) (Rakotoarison et al. 2020).

Eggs that are presumed to belong to P. laetus have been found in water-filled bamboo nodes. These eggs are white and at least two different developmental stages have been documented in the same hole at the same time (Rakotoarison et al. 2020).

Larva
Members of the Platypelis genus have nidicolous endotrophic tadpoles (Rakotoarison et al. 2020). However, as of 2024, little specific information is available for P. laetus tadpoles.

Whitish tadpoles, which are presumed to be P. laetus, were found in a water-filled bamboo node that was 1 m from the ground with an adult (Rakotoarison et al. 2020).

Trends and Threats
The species authority noted that the bamboo forest in which P. laetus is found is under high pressure because of local cattle grazing. As a result they recommend an IUCN status of “Critically Endangered” (Rakotoarison et al. 2020).

Possible reasons for amphibian decline

Intensified agriculture or grazing

Comments

PHYLOGENETIC RELATIONSHIPS:

References
Rakotoarison, A., Scherz, M. D., Köhler, J., Ratsoavina, F. M., Hawlitschek, O., Megson, S., Vences, M., and Glaw, F. (2020). Frogs of the genus Platypelis from the Sorata Massif in northern Madagascar: Description of a new species and reports of range extensions. Zoosystematics and Evolution, 96(1), 263–274. [link]

Species Account Citation: AmphibiaWeb 2024 Platypelis laetus <https://amphibiaweb.org/species/9199> University of California, Berkeley, CA, USA. Accessed Oct 11, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 11 Oct 2024.

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