Description
Rhombophryne ellae is a sturdy-body frog described from one female specimen with a snout-vent length of 24.9 mm. Its head width (9.6 mm) is 48% larger than its head length (6.5 mm). When the snout is viewed from a dorsal and lateral perspective, it appears rounded. The nostrils are closer to the snout tip rather than to the eye. Its canthus rostralis is concave and distinct from the other species in its genus. The loreal region of the species is also concave without any presence of dermal folds on it. The eye diameter is ~67% wider than horizontal tympanum diameter. Rhombophryne ellae a distinct supratympanic ridge that is rounded along the tympanum and ends once it reaches the anterior side of the forelimbs (Scherz 2020).

Overall, the arms of R. ellae are relatively skinny compared to other species within its genus. The inner metacarpal tubercle is present, albeit with no outer metacarpal tubercle. With only one female holotype in preservation, males of this species have not been observed, so the presence of nuptials pads are unknown. The subarticular tubercles can be described as rounded and flat, containing no division between them. The fingers have no webbing as well. The specimen’s fourth finger is only slightly smaller than its second, as seen with the relative lengths coming out to be 1 < 4 < 2 < 3. The fingertips are not expanded or reduced in the species (Scherz 2020).

The hind limbs appear similar to the forelimbs in that they are rather slender in life and preservation. When the hind limb is adpressed forward over its body, the tibiotarsal articulation reaches the eye of the species. This is emphasized by the fact that its tibiofibula length is approximately half the size of the snout-vent length, with a ratio of the two measurements being 0.46. The outer metatarsal tubercle is present, however, it is rather weak and round. A round and enlarged inner metatarsal tubercle is also present in the species. The toes of the species don’t include webbing and the relative lengths of these toes are 1 < 2 < 5 < 3 < 4. The third toe happens to be particularly longer than the fifth toe. The second, third, and fourth toes appear to be slightly pointed compared to the first and fifth toes. (Scherz 2020)

Along the dorsal and ventral sides of R. ellae, the skin is smooth, albeit having few pustules throughout the specimen. The dorsolateral folds are absent in this species as well (Scherz 2020).

Rhombophryne ellae is primarily differentiated from the various members in its genus due to the flash-orange coloration found on its posterior thighs. It has a distinctive snout-vent length measurement of 24.9 mm in its subadult to adult female, giving it a smaller body size when compared species such as R. botabota and R. laevipes. The absence of the superciliary spines also very easily distinguishes this species from the similar species such as R. serratopalpebrosa, R. geuentherpetersi, R. coronata, and R. vaventy. Rhombophryne ellae also has notable differences from its most closely related species, consisting of R. testudo, R. matavy, and R. coudreaui due to its smoother skin texture along its dorsal side and with its comparatively more narrow head. The latter difference is emphasized by R. ellae’s head width being 30% less than the average width of the previously mentioned species (Scherz 2020).

Rhombophryne ellae, after a year in preservation, has a brown coloration on its dorsal side, accompanied by two darker spots at the suprascapular region. It displays distinct black inguinal spots throughout as its body as well. On the left side of the snout is a lighter area of coloration that is not observed on the right side. Dark-grey crossbands are found on the thigh, shank, and antebrachium within both forelimbs and hind limbs. Similarly, the hands and feet are mottled with lightly colored annuli right before all of the fingertips. Towards the ventral side of the specimen, the abdomen is colored translucent cream with the chin and rest of the scapular regions being mottled cream and olive-brown (Scherz 2020).

Because the species was described from one specimen, no variation was available during the original species’ description (Scherz 2020).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Madagascar

View distribution map in BerkeleyMapper.

Rhombophryne ellae is currently known only from a single specimen that was collected in the rainforest of Montagne d’Ambre National Park, Antsiranana Region, Madagascar. The specimen was found at 892 m a.s.l (Scherz 2020).

Trends and Threats
Given that the species and its data was observed through a single individual, threats, trends, and threat status were unknown at the time of the species description.

Possible reasons for amphibian decline

Disease

Comments
Bayesian Inference and Maximum Likelihood Analysis were used to create phylogenies of Rhombophryne utilizing the sequences of mitochondrial markers 16s rRNA and COI. Rhombophryne ellae shares a clade with an undescribed Rhombophryne species. Yet another undescribed Rhombophryne is the next most related species. The clade formed by those three species is sister to a clade composed of R. matavy and R. testudo. However, this last relationship is not heavily supported (Scherz 2020).

Mark Scherz, who described Rhombophryne ellae, dedicated the frog to his partner, Dr. Ella Z. Lattenkamp. Scherz named the frog to celebrate Dr. Lattenkamp’s successful defense of her dissertation using her first name (Scherz 2020).

References

Scherz, M.D. (2020). ''Diamond frogs forever: a new species of Rhombophryne Boettger, 1880 (Microhylidae, Cophylinae) from Montagne d'Ambre National Park, northern Madgascar.'' Zoosytematics and Evolution, 96(2), 313-323. [link]

Species Account Citation: AmphibiaWeb 2020 Rhombophryne ellae <https://amphibiaweb.org/species/9210> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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