Description
Hyalinobatrachium adespinosai is a glass frog that has a male snout-vent length range of 20.5 - 22.2 mm. No female specimen were collected. The head is expanded and is broader than it is long. The snout is truncated when viewed both dorsally and laterally. The flat loreal region is nearly erect. The elliptical nostrils slightly protrude and the canthus rostralis is well defined. The small eyes are directed anterolaterally. The dentigerous process of the vomer lacks teeth. The tympanum annulus is slightly visible through the transparent skin, and the tympanic membrane is differentiated. The choanae are oval-shaped and large. The tongue is round, and all but the last fifth of the tongue is attached to the mouth. The vocal slits extend along the base of the mouth, parallel to the tongue. Enameled glands are not present in the bottom of the upper jaw (Guayasamin et al. 2019).

There is no humeral spine present. Relative lengths of fingers are as follows; I < II < IV < III, and the finger disks are round. There is less webbing between fingers in Fingers I - III, with a formula of I 3 - 2⁺ II 1⁺ - 3 ⅓ III 2 - 2 IV. The prepollex is camouflaged. The rounded subarticular tubercles are muted, and a few small supernumerary tubercles are present. The palmar tubercle is slight and round while the thenar tubercle is ovoid in shape. Nuptial excrescences are shaped like a small pad on the outside of Finger I. The hind limbs are slim. The discs of toes are also rounded. The inner metatarsal tubercle is slight, and the outer metatarsal tubercle is rounded and difficult to differentiate. The formula for the feet webbing is as follows: I 1 - 2^- II 1 - 2 ⅓ III 1⁺ - 2 ⅓ IV - 2⁺ - 1V. The cloacal opening begins at the same level as the upper thighs. The cloacal fold is lightly enameled and surrounded by small tubercles. The kidneys, visible through the transparent skin, are rounded and resemble beans, and the liver is bulbous (Guayasamin et al. 2019).

Hyalinobatrachium adespinosai is distinguishable from other species in the genus because of its transparent pericardium. However, it is morphologically similar to three taxa: H. anachoretus, H. pellucidum, and H. esmeralda. These species can be differentiated by their calls. Hyalinobatrachium adespinosai and H. anachoretus have pulsed calls while the latter two species have tonal vocalizations. Hyalinobatrachium adespinosai has a call that is longer, has more pulses per note, and is produced at a higher rate than the call of H. anachoretus. Toe webbing (Toe IV) is less extensive in H. adespinosai compared to H. anachoretus. Lastly, H. adespinosai is geographically separated from populations of H. anachoretus by the Marañon valley, a distance of 473 km (Guayasamin et al. 2019).

In life, the dorsal skin appears yellowish green to bright green with gray-black melanophores and some yellow specks. Melanophores are absent from fingers except for their presence on Finger IV, Toes IV and Toe V. The iris of the eye is very pale yellow. Like most glass frogs, the parietal peritoneum and pericardium are transparent, and the red heart is always visible. The pericardium has a thin layer of iridophores, as do the ulnar and tarsal folds. The visceral peritoneum of both the gall bladder and urinary bladder are transparent, and these organs can be seen. The ventral vein is red, and the liver and visceral peritonea are white. The bones are white (Guayasamin et al. 2019).

In preservation, the dorsal skin is cream colored with sprinkles of purple melanophores. The iris is silvery white with a few melanophores. The visceral peritoneum lacks iridophores while the pericardium has a thin layer of them (Guayasamin et al. 2019).

Most of the variation observed can be seen in the hand webbing of H. adespinosai individuals. Some individuals may have webbing that covers more or less area than the holotype’s webbing (Guayasamin et al. 2019).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Ecuador

View distribution map in BerkeleyMapper.

Hyalinobatrachium adespinosai is only known from the type locality: San Jacinto River, Tungurahua Province, Ecuador. This locality has an altitude of 1795 m above sea level. All individuals were found on the underside of leaves along the river. The section of river where they were found has rapids and fast-moving water. They were observed at canopy level, 4 - 16 m above ground level (Guayasamin et al. 2019).

Life History, Abundance, Activity, and Special Behaviors
This species seems to be abundant in the type locality, where numerous advertisement calls were heard. The species is difficult to find as it occupies the canopy level, approximately 4 to 16 m high, and this may explain its absence from previous herpetological surveys in the locality (Guayasamin et al. 2019).

Males were found to call from July to August. Based on the recording of nine individuals, the call sounds like a cricket. Each call is composed of a single and high-pitched pulsed note. The dominant frequency is at 4,645–5,203 Hz. The first harmonic is at 9,336 – 9,754 Hz and the second harmonic is at 14,159 – 14,444 Hz. Calls have a duration of 0.38 – 0.44 s and there can be 2.0 – 11.0 s between each call (Guayasamin et al. 2019).

One male was found guarding an egg clutch containing 22 embryos. This parental guarding behavior is common in glassfrogs (Guayasamin et al. 2019).

Trends and Threats
At the time of the species description, very few specimens of H. adespinosai had been collected, so the conservation status could not be accurately and completely assessed (Guayasamin et al. 2019).

Comments

The phylogenetic relationships of Hyalinobatrachium is inferred from 16S mitochondrial rRNA sequences. Hyalinobatrachium adespinosai is nested within other members of a monophyletic clade of known Hyalinobatrachium species. Hyalinobatrachium adespinosai is the sister taxa of H. anachoretus and H. pellucidum (Guayasamin et al. 2019).

The most closely related species, H. anachoretus, H. pellucidum, and Hyalinobatrachium yaku, share several traits with H. adespinosai. These traits include the presence of a red heart exposed ventrally, transparent ventral parietal peritoneum, digestive tract and liver covered by iridophores, absence of humeral spines, white bones, male calling from the underside of leaves, female placement of eggs on the underside of leaves and male provided extended parental care (Guayasamin et al. 2019).

The species epithet, "adespinosai", is in honor of Adela Espinosa, an Ecuadorian conservationist and owner of the natural preserve where the type specimens were found (Guayasamin et al. 2019).

This species is morphologically cryptic and like other glass frogs can be easily differentiated by its advertisement call. Hyalinobatrachium species are found in the lowlands of the Andes mountains. The linearity of the Andes mountain is thought to promote speciation as the species likely have a narrow thermal range (Guayasamin et al. 2019).

References

Guayasamin J., Vieira J., Glor R., and C. Hutter (2019). ""A new glassfrog (Centrolenidae: Hyalinobatrachium) from the Topo River Basin, Amazonian slopes of the Andes of Ecuador"." Amphibian & Reptile Conservation, 13(2), 133-144.

Species Account Citation: AmphibiaWeb 2021 Hyalinobatrachium adespinosai: Adela’s Glassfrog <https://amphibiaweb.org/species/9105> 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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