Description
Platypelis olgae has a small, slender body size in which the adult snout-vent length reaches 20 – 22 mm. The head is slightly longer than its width and the snout is rounded. The nostrils are closer to the tip of the snout than to the eye and are almost laterally directed. The canthus rostralis is subtle and concave. The loreal region is unmarked. The tympanum is about the size of the eye, somewhat distinct, and has an equally distinct, straight supratymanic fold. The forelimbs and hindlimbs are relatively slender. The digits on forelimbs are broad and flattened with traces of webbing found between the third and fourth fingers and indistinct subarticular tubercles. The relative lengths are as follows: 1 < 2 < 4 < 3. The first finger has a large distinct inner metacarpal tubercle at its base. Males, further, have a distinct prepollical tubercle, which is a large bump on the inside of the palm All fingers and toes have enlarged, slightly triangular pads at the tips. The toes are also broad and flattened, but webbing is hardly detectable. The relative length of toes are as follows: 1 < 2 < 5 < 3 < 4. The outer metatarsal tubercle is absent and the inner metatarsal tubercle is indistinct, small, and flat. The dorsal skin lacks dorsolateral folds and is smooth. The ventral skin is also smooth on the chest and throat; however, the belly is moderately granular (Rakotoarison et al. 2012).

Platypelis olgae is distinguished from Cophyla phyllodactyla, C. berara, P. alticola, P. cowanii, P. grandis, P. mavomavo, P. milloti, P. pollicaris, and P. tuberifera by its smaller body size. An adult Platypelis olgae reaches a snout vent length of 20 - 22 mm while the other species mentioned above have a snout-vent lenghts of 23 - 105 mm. Furthermore, Platypelis olgae lacks or has rudimentary vomerine teeth while all the previously mentioned species, including P. tsaratananaensis and P. tetra, have vomerine teeth. Platypelis olgae has a green-yellow ventral side that sets it apart from all the species except P. mavomavo and juvenile P. grandis (Rakotoarison et al. 2012).

Platypelis barbouri, P. ravus, and C. occultans are three species that are small and have no vomerine teeth. However, there are ways to distinguish them from P. olgae. Platypelis olgae has a green-yellow ventral side while P. barbouri has a red ventral side. Platypelis ravus lacks the three symmetrical dorsal dark patches and C. occultans has a green-yellow venter while P. olgae’s is grey. Platypelis olgae can be distinguished by molecular relationships and genetics divergence (Rakotoarison et al. 2012).

In life, the ventral side of the body and limbs of a Platypelis olgae has a green to yellowish hue with most coloration concentrated at the throat. Dorsally, there are three symmetrical dark patches that appear to have no distinct pattern. In addition, there is no obvious distinction between the dorsal and lateral color (Rakotoarison et al. 2012).

After about two years in preservation, the dorsal side of the organism is uniformly brown with a lighter brown coloration anterior to the eyes. The forelimbs and hindlimbs are also dorsally brown with white dots that are more pronounced on the hands and feet. The dark crossbands on the limbs are not distinguishable. On the ventral side, the throat is white and brown, the chest is brown and yellowish, the belly is dark brown and whitish, and the limbs are brown and yellowish (Rakotoarison et al. 2012).

Two known male specimens, the holotype and paratype, both have small tubercles on the dorsal sides. The female, however, is smoother. Compared to the holotype, both paratypes had a yellow ventral color and less dark patterns. In addition, the mitochondrial DNA fragment studied showed no differentiation in both the holotype and the female paratype (the male paratype was not sequenced). In all three specimens, the third finger is as long as the fourth finger. However, the third toe is as long, or is longer than the fifth toe. None of the specimens had distinct vomerine teeth; however, a presence of rudimentary vomerine teeth may be possible (Rakotoarison et al. 2012).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Madagascar

View distribution map in BerkeleyMapper.

This species occurs in northern Madagascar on the Tsaratanana mountain range. Platypelis olgae was found in two locations at 2500 m elevation on Tsaratanana. The holotype (ZCMV 12402, adult male) was collected between Bepia and Andranomadio with no accurate data on the geographical coordinates or altitude of where it was found. However, it is assumed it was found within the altitude ranges of 2294 and 2503 m. The paratypes (ZCMV 12428, female; DRV 6225, male) were both collected on June 18, 2010 at Amboditsaratanana, 14.08019°S, 48.98536°E, 2457 m. Both paratypes were found among leaf litters and layers of moss on the ground. However, no further information is available (Rakotoarison et al. 2012).

Life History, Abundance, Activity, and Special Behaviors
The holotype of Platypelis olgae was found during the daytime on a small log that was knocked over. The two paratypes were spotted among moss layers and leaf litters. There is no available data on the reproduction, calls of the species, abundance, and natural history of Platypelis olgae (Rakotoarison et al. 2012).

However, given the known information on cophyline frog reproduction (non-feeding tadpoles in water-filled phytotelmes or other cavities, or in terrestrial foam or jelly nests) and the use of bamboo plants for tadpole rearing in its sister species, to P. tsaratananaensis, it is possible P. olgae also uses some sort of water-filled cavity for reproduction too (Rakotoarison et al. 2012).

Trends and Threats
While no specific trends or threats are available for P. olgae, the area in which it lives, the Tsaratanana Massif, has an unusual number of microendemic species threatened with extinction from habitat loss, habitat destruction, cattle grazing, and logging. >Platypelis olgae is further restricted to a narrow mountain range and its near by areas (Rakotoarison et al. 2012).

Possible reasons for amphibian decline

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

Comments
The species authority is: Rakotoarison A, Glaw F, Vieites D, Raminosoa N, and Vences M. 2012. Taxonomy and natural history of arboreal microhylid frogs (Platypelis) from the Tsaratanana Massif in northern Madagascar, with description of a new species. Zootaxa 3563:1-25.

The phylogenetic tree based on the DNA sequences of the 16S rRNA gene clearly shows a distinct presence of four genetic lineages in Tsaratanana Massif. Those four genetic lineages are P. olgae, P. alticola, P. tsaratananaensis, and P. sp. 8. Platypelis olgae is sister to P. tsaratananaensis (Rakotoarison et al. 2012).

Platypelis olgae is dedicated to Professor Olga Ramilijaona, the former head of the zoology department at UADBA, in recognition of his hard work in developing zoological science in Madagascar (Rakotoarison et al. 2012).

Possible junior synonyms of P. olgae are Paracophyla tuberculata, Platypelis barbourii, Platyhyla verrucosa, Platyhyla voeltzkowi, Cophyla tuberculata and all junior synonyms of Platypelis grandis (Rakotoarison et al. 2012).

References

Rakotoarison, A., Glaw, F., Vieites, D., Raminosoa, N., Vences, M. (2012). ''Taxonomy and natural history of arboreal microhylid frogs (Platypelis) from the Tsaratanana Massif in northern Madagascar, with description of a new species.'' Zootaxa, 3563, 1-25.

Species Account Citation: AmphibiaWeb 2015 Platypelis olgae <https://amphibiaweb.org/species/7942> University of California, Berkeley, CA, USA. Accessed Dec 26, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 26 Dec 2024.

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