Description
Atlantihyla melissa is a tree frog with a male snout-vent length range of 30.4 - 38.8 mm and female snout-vent length range of 30.9 - 43.9 mm. In the dorsal view the snout is rounded and in the lateral view it is truncated. The nostrils are slightly protuberant and the frog possesses a weak vertical rostral ridge. The canthus rostralis is distinct and rounded, and the loreal region is concave. The pupil is horizontal elliptical. The tympanum is round and distinct with the upper edge touching or covered by a well-developed supratympanic fold that extends from behind the eye, but not connected to the eye, to a point above the insertion of the forelimb. The top of the head is flat. The dorsal skin is smooth while the ventral surfaces are weakly granular. There are also some weak tubercles on the eyelids. There are no ventrolateral glands. The cloaca is directed posteroventrally and located at the mid-level of the thighs. On the posterior edge of the cloaca, there are several folds radiating out. The upper arm is slightly less robust than the forearm, which has a row of elevated ulnar tubercles on the ventral side. An ossified and bluntly rounded prepollx is present. The number of nuptial spines on Finger I varies from 39 - 53. Adult males in breeding condition also have patches of large, epidermal projections that are next to one another in a bell-shaped patch on the interior surface of each thumb. Fingers have a webbing formula of 1 ¾ – 2 ¾ III 2⁺ – 2 IV, with lateral keels on the unwebbed parts of the fingers, and a relative finger length of I < II < IV < III. Fingers also have round, globular subarticular tubercles with the distal tubercles being weakly divided on finger III and bifid on finger IV. The finger discs are large. When the hind limbs are adpressed at right angles to the body, the heels overlap. There is a weak inner tarsal fold, but no outer tarsal fold. A tubercle is present on the heel. The long toes have a webbing formula of I 1⁺ - 2 - II1⁺ - 2 III 1⁺ - 2 IV 2 - 1⁺V and a relative length of I < II < III ≈ V < IV. The subarticular tubercles are round. The toe discs are similar in size to the finger discs (Townsend et al. 2020).

DIAGNOSIS:

At the time of the species description there were two other species of frogs in the genus Atlantihyla: A. spinipollex and A. panchoi. Atlantihyla melissa differs from A. panchoi in that A. panchoi has a white upper lip. Atlantihyla melissa can be differentiated from A. spinipollex because the focal species is smaller, has a larger head, longer shanks, longer note duration during advertisement call, and more pulses per note compared to A. spinipollex (Townsend et al. 2020).

Though the distribution of A. melissa is allopatric with respect to the two other members of the genus, it does occur in sympatry with four other species of tree frogs that can be found near streams: Duellmanohyla salvavida, Isthmohyla insolita, Plectrohyla chrysopleura, and what is presumed to be Plectrohyla guatemalensis. Duellmanohyla salvavida is distinguishable from A. melissa because they have differences in coloration and nuptial spines. Atlantihyla melissa tends to have dorsal coloration that is uniform grayish brown or with light/dark spots or mottling and large nuptial spines in males, while D. salvavida has uniformly green dorsal coloration and small nuptial excrescences. Traits that distinguish them from Isthmohyla insolita include a smooth dorsal surface, large nuptial spines in adult males, and mottled/colorless chin coloration, as I. insolita have a rough dorsal surface, small nuptial excrescences, and a broad stripe on their chin. Atlantihyla melissa’s slightly enlarged prepollex that lacks a protruding distal end distinguishes them from P. chrysopleura, which have a flat prepollex with a blunt distal end, and from P. guatemalensis, which have a prepollex with two large curved spines (Townsend et al. 2020).

COLORATION:

In life, A. melissa has a wide variety of coloration and patterns, including in their iris. Males have irises that range from a salmon color to a darker red, while in females the iris color ranges from an olive to a cinnamon-brown color and is more subdued. While, neither dorsal or ventral coloration is sexually dimorphic, there is a lot of individual variation in the dorsal pattern, which can be uniform in coloration, have small to medium sized dark spots, be extensively mottled, have small pale spots, a large and irregular dark spot, or have a middorsal stripe. With regards to ventral variation, most individuals have a pale ventrolateral stripe, which can be pale to a bright yellow. Some individuals also have venters that are gray to purple in color, while others exhibit pale to a bright yellow color instead. These yellow-colored individuals can also have centers that are pale yellow or immaculate with the ventral surfaces on the fore- and hind limbs being a greenish yellow to bright yellow in color. Most of the time, the chins and throats are immaculate, but occasionally they will have dark spots (Townsend et al. 2020).

VARIATION:

Atlantihyla melissa is sexually dimorphic in both size and iris coloration. There is also individual variation in dorsal and ventral coloration (Townsend et al. 2020). See coloration above for details.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Honduras

View distribution map in BerkeleyMapper.

Atlantihyla melissa occurs in the western portion of Cordillera Nombre de Dios, Departments Atlantida and Yoro, Honduras. The distribution is centered in the Rio Jilamito Valley and extends south into the broadleaf riparian zones on the leeward slopes of those peaks. Their elevation range is 780 - 1,680 m (Townsend et al. 2020).

Life History, Abundance, Activity, and Special Behaviors
Atlantihyla melissa is abundant in riparian zones along fast flowing rivers and streams with rocky substrates, riffles, and pools. They are typically found at night on vegetation that overhangs the water. However, males can be heard intermittently calling in March, April, June, and July from concealed position during the day (Townsend et al. 2020).

Adult males have advertisement calls that last 8.28 - 13.19 s and consist of a series of 5 - 6 long pulse notes in a continuous call series, with each note increasing in amplitude. The final note of each call is the strongest, but they can be followed by a faint trailing note. There are two harmonics in each note, lasting 0.47 - 1.3 s, and having a repetition rate of 0.405 - 0.604 calls/s and an inter-note interval of 1.04 - 1.79 s. There are 5 - 12 pulses per note with each pulse lasting 0.013 - 0.052 s, and having a repetition rate of 5.669 - 11.086, a peak amplitude of 287 - 2982 U, and an inter-pulse interval of 0.035 - 0.106 s. The dominant frequency of the whole call series is 3421.9 Hz (Townsend et al. 2020).

Females found in March had well-developed eggs in their oviducts. Metamorphs emerge from the water in June and July (Townsend et al. 2020).

Larva
At Gosner stage 36, a tadpole had a total length of 43.5 mm, a body length of 13.5, and a body width of 7.1 mm. Tadpoles have a compressed body with a broad snout in the dorsal view and a rounded snout in the lateral view. The anterolateral-directed nostrils are small and closer to the snout than the eyes. The eyes are positioned dorsolaterally and the eye width is more than half the length of the distance between the eyes. The oral disc is ventral and large. It is surrounded by 2 - 3 continuous rows of marginal papillae and 4 - 5 rows of sub-marginal papillae lateral to the jaw sheath. The labial tooth row formula is 5 - 6/8 - 9 with most rows showing some degree interruption or fragmentation. A single spiracle opening can be found on the midline of the body, about two-thirds the distance from the tip of snout to posterior end of body. The vent tube is short and dextral. The tail is more than twice the length of their body. The tail has shallow fins with tail musculature that is slightly taller at the midlength than either fin. The tail musculature does not reach the end of the tail (Townsend et al. 2020).

In preservative, the body is a mottled grayish-tan. The tail musculature is pale tan and blotched with brown. The fins are translucent with dark spots on the anterior portion of the dorsal fin and dark flecking in the other portions (Townsend et al. 2020).

Tadpoles are abundant in pools and emerge as metamorphs in June and July (Townsend et al. 2020).

Trends and Threats
Despite being abundant along the Río Jilamito and its tributaries at La Liberacíon, Townsend et al. (2020) recommend that A. melissa be considered “Critically Endangered” due to its small distribution of less than 25 km², which is located in a threatened part of highland forest. This part of the forest has undergone deforestation and development, posing an imminent threat to the remaining A. melissa populations (Townsend et al. 2020).

Comments

PHYLOGENETIC RELATIONSHIPS:

Bayesian analysis of 12s and 16s mtDNA and POMC, Rag-1, and RHO nDNA found that A. melissa is sister to A. spinipollex. The next most closely species is A. panchoi (Townsend et al. 2020).

ETYMOLOGY:

This frog was named after Isis Melissa Medina-Flores, a field biologist from Mangulile in the Department of Lancho, Honduras. She participated in the discovery and description of A. melissa along with two other species endemic to Texiguat. On November 5th, 2016, she was separated from a group while hiking down the summit of the highest peak in Honduras, disappearing without a trace. She was never found (Townsend et al. 2020).

References

Townsend, J. H., Herrera-B., L. A., Hofmann, E. P., Luque-Montess, I. R., Ross, A. N., Dudek Jr., D., Krygeris, C., Duchamp, J. E., Wilson, D. L. (2020). "A critically endangered new species of polymorphic stream frog (Anura: Hylidae: Atlantihyla) from the montane rainforest of Refugio de Vida Silvestre Texiguat, Honduras." Vertebrate Zoology, 70(4), 731-756. [link]

Species Account Citation: AmphibiaWeb 2022 Atlantihyla melissa: Texiguat Stream Frog <https://amphibiaweb.org/species/9296> University of California, Berkeley, CA, USA. Accessed Mar 27, 2023.

Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 27 Mar 2023.

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