Description
Hyalinobatrachium dianae has a snout-vent length ranging from 27.8 - 29.4 millimeters. The head width is slightly greater than the body width. The backside of its head is flat. The lip appears rounded when viewed from above. It has a compact snout with nostrils that are pointed towards the sides. The region between the nostrils is curved outwards. It has large eyes that face towards the front. The region between the eye and the snout is slightly curved outwards, and there is a noticeable ridge that connects between them. The skin on the head is somewhat coarse in texture, though the chin is smooth. The tympana are covered in skin and not visible. The backside of the body and the limbs are coarse, though the flanks, thighs, and underside of the body are slightly less so. The arms are short, and the hands are relatively big. There is a faint white fleshy projection extending from the elbow that runs down the arm and terminates on the disc of Finger IV. The relative disc widths of the fingers are as follows, from longest to shortest: I > III ≈ IV > II. Fingers I and II have noticeable subarticular and supernumerary tubercles, whereas Fingers III and IV do not. There is no webbing between fingers I and II, primitive webbing between fingers II and III, and modest webbing between fingers III and IV. The relative lengths of the fingers are as follows, from shortest to longest: II < I < IV < III. The legs are fairly long and slender, with fairly rounded and compact toe discs. The subarticular tubercles on the toes are small, rounded, and moderately raised. The inner metatarsal tubercles are stretched out and mildly elevated, whereas the outer metatarsal tubercle is indistinct from the other tubercles in the surrounding area. The toes are modestly webbed. The relative lengths of the toes are as follows, from shortest to longest: I < II < III < V < IV. Hardened, faint white tubercles are found underneath the cloaca. There is a dark, ovate structure present on the back, just off to the side of the midline of the pelvis (Kubicki et al. 2015).

This species can be distinguished from other centrolenids by the characteristics mentioned in the above description. Furthermore, its lack of yellow spots on the back distinguishes it from the following Hyalinobatrachium species: H. anachoretus, H. aureoguttatum, H. chirripoi, H. colymbiphyllum, H. fleischmanni, H. talamancae, H. vireovittatum. Additionally, H. talamancae and H. vireovittatum have green stripes running down the midline of their back. Hyalinobatrachium dianae can furthermore be distinguished from H. valerioi, which has a netted pattern on its back, and H. pellucidum, which only has a single tonal note call (Kubicki et al. 2015).

In life, the back is lime green, and has no yellow spots. The granules on the back are a bit lighter in color than the back itself. The hands and feet are pale green-yellow. The background of the iris is white, though there are also minute dark spots present, which become more concentrated around the pupil. The tubercles underneath the cloaca are faintly white in color. The aforementioned ovate structure on the backside of the pelvis is black. The underside is transparent, and the bones are white. The liver and digestive organs are surrounded by a white lining. The heart and veins are red, as are the blood vessels surrounding the transparent lungs. The gall bladder is yellow and transparent. In preservative, the back is pale and creamy yellow, and the only discernible color features of the back are the diffused minute black spots and the black ovate structure by the pelvis (Kubicki et al. 2015).

The previously described dark ovate structure on the backside of the pelvis may differ in its orientation, being located just off to the right or to the left of the midline of the body (Kubicki et al. 2015).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Costa Rica

View distribution map in BerkeleyMapper.

This species is currently only known from three sites in the Caribbean foothills of Costa Rica in the provinces of Heredia and Limón. It has been observed at 400 - 900m asl in wet forest and premontane rainforest (Kubicki et al. 2015).

Life History, Abundance, Activity, and Special Behaviors
This nocturnal frog is found in primary and secondary wet forests. Typical for many centrolenids, males and egg masses have been found above dry substrate in areas that may become connected to streams in heavy rains, instead of above areas of water. Males are also known to defend clutches. Egg masses range in size from 31 - 68 eggs and can be found from 0.5 - 5m above the ground on the undersides of leaves (Kubicki et al. 2015).

Only the holotype advertisement call has been analyzed. At 22.7^oC, he had a long metallic whistle-like advertisement call. It is very fast but the intensity is weak. Note durations are 0.40 - 0.55 s and the dominate frequency was 3.35 - 3.44 kHz (Kubicki et al. 2015).

Trends and Threats
This species is only known from a handful of individuals. No population trends are known. There do not appear to be any current threats, although it may be subject to declines from climate change or future habitat changes (Kubicki et al. 2015).

Relation to Humans
It lives in remote regions not subject to much habitat modification (Kubicki et al. 2015).

Comments
The species authority is: Kubicki, B., Salazar, S., Puschendorf, R. (2015). "A new species of glassfrog, genus Hyalinobatrachium (Anura: Centrolenidae), from the Caribbean foothills of Costa Rica." Zootaxa, 3920(1), 69-84.

Hyalinobatrachium dianae is sister to H. chirripoi and H. colymbiphyllum. Together, these three species are sister to H. talamancae and H. vireovittatum. In all, these five species are sister to H. valerioi and H. fleischmanni (Kubicki et al. 2015).

The species epithet dianae is dedicated to the senior author’s mother, Janet Diane Kubicki, who was influential in supporting the author’s passion for natural history, fishes, and amphibians. It is also a reference to Diana, the Roman goddess of the hunt, who resided in forested mountains, much like the authors’ pursuit of amphibians within the forested mountains of Costa Rica (Kubicki et al. 2015).

This frog has been featured on social media for its resemblance to Kermit the Frog, a character from The Muppet Show (Gannon 2015).

References

Gannon, M. “Kermit the Frog Look-Alike Discovered in Costa Rica”. LiveScience. www.livescience.com. 22 April 2015.

Kubicki, B., Salazar, S., Puschendorf, R. (2015). ''A new species of glassfrog, genus Hyalinobatrachium (Anura: Centrolenidae), from the Caribbean foothills of Costa Rica.'' Zootaxa, 3920(1), 69-84.

Species Account Citation: AmphibiaWeb 2015 Hyalinobatrachium dianae: Diane's bare-hearted glassfrog <https://amphibiaweb.org/species/8312> University of California, Berkeley, CA, USA. Accessed Jan 28, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 28 Jan 2025.

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