The specific name "kutuku" is derived from the Shaur language and is in reference to the Subandean Cordillera of Kutukú Cordilera, where the species was first collected for science (Ron et al. 2024).

Description
Centrolene kutuku is a glass frog that was described from two males with snout-vent lengths of 21.5 and 21.9 mm. The snout itself slopes in the lateral view but is slightly subacuminate to round in the dorsal view. Its eye diameter is larger than the width of Finger III’s disc and the tympanic annulus is almost completely visible with the exception of the uppermost border; the supratympanic fold is present. Interestingly, it possesses no vomerine teeth despite having the dentigerous process of vomer present. Centrolene kutuku’s dorsal skin is microspiculate with copious tubercles on both its head and its body. Adult males have short humeral spines that barely protrude through their skin. Its ventral skin is granular. The liver is lobed, with its hepatic peritoneum translucent. In its cloacal area, it has two large subcloacal warts and elevated, abundant, enameled, pericloacal warts; there is an absence of other cloacal ornamentation. The upper arm is thin while the forearm is robust. There is a short spine at the humerus that is barely perceptiable and does not pierce the skin. Along the postaxial edge of Finger IV and the hand there is a dermal fringe with a slightly enameled ulnar fold. The prominent palmar tubercle is elevated and round while the thenar tubercle is elliptical. There are many distinct supernumary tubercles on the hands. There is a conceal prepollex. The relative finger lengths are III > IV > II > I and the formula for finger webbing is II (2^- – 2⁺) – 3^- III (2⁺) – (2 ½ – 2 ⅓) IV with webbing absent between fingers I and II. The finger tips widen into discs and are nearly truncated. The disc on finger III is slightly larger than all the discs on the toes. The subarticular tubercles are rounded and slightly elevated. Nuptial excrescences can be found on dorsolateral side of thumbs. The hind limbs are slender with the tibia being longer than the foot. The heel does not have warts. Along the postaxial edge of Toe V there is another dermal fringe, with slightly enameled metatarsal and tarsal folds. The large inner metatarsal tubercle is elliptical and the small outer metatarsal tubercle is round. There are distinct, low supernumerary tubercles. The formula for toe webbing is I (1 – 1 ½) – (2 – 2⁺) II (1^- – 1⁺ – 2^-) III (1⁺-1 ½) – 2 IV (1 ½ – 1) V. The toe tips end in blunt discs with no papilla. The subarticular tubercles of the toes are low (Ron et al. 2024).

Diagnosis

Centrolene kutuku is similar to C. camposi, C. ericsmithi, C. heloderma, and C. zarza because of having humeral spines in males, having a green dorsum with light dots, lacking dark marks, and having elevated dermal ornamentations, dorsal tubercles, and warts. Additionally, C. kutuku and C. heloderma’s dosum have abundant tubercles, though C. heloderma differs by having pustular dorsal skin; an outer tarsal fold with low, white tubercles; and a gray-lavender dorsum when in preservative. Centrolene camposi differs from C. kutuku by having a sloping snout in lateral view, a barely visible tympanic annulus, a thick yellowish-white labial stripe that continues into a fainter, yellow lateral line, and a larger body size in males. Meanwhile, C. ericsmithi differs from C. kutuku as C. ericsmithi’s tympanic annulus is barely visible, its dorsal skin has dispersed spicules, a notably larger body size in males, yellowish-green flanks, and a green dorsum with a thick, yellowish-white labial stripe that continues into a faint yellowish lateral line in life. Finally, C. zarza differs from C. kutuku in that it has a rounded snout with elevated warts at the tip when in dorsal view, shagreen dorsal skin that has scattered warts of varying sizes, abundant, elevated, enameled warts on both its head and flanks, a larger body size in males, and a green dorsum with yellowish-green dots with enameled warts (Ron et al. 2024).

Coloration

In life, C. kutuku is a vibrant green on all dorsal surfaces with light green dots and the tympanic membrane is colored like the surrounding skin. It has a cream iris with gray reticulation and green bones. Its parietal peritoneum is white, with iridophores covering half of its ventral side. The pericardium is also covered by iridophores and all other visceral peritonea are translucent. In preservative, C. kutuku is lavender with lighter tubercles on all dorsal surfaces and has a white supralabial stripe. Its dorsal surfaces on its limbs are clearer and have slightly lighter dots than the rest of the body (Ron et al. 2024).

Variance

Individuals may vary by having more contrasting enamel coloration on limbs and by having lower dorsal tubercles. Sexual dimorphism is unknown as no female specimens were collected at the time of the species description (Ron et al. 2024).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Ecuador

View distribution map in BerkeleyMapper.

At the time of the species description, C. kutuku was only known from the type locality in Ecuador, on the western slope of the Kutukù Subandean cordillera in the Montane Evergreen Forest, between 2,255 and 2,264 m in elevation. That being said, the distribution of C. kutuku is likely much greater than the single type locality, as collections in Kutukú have been limited. Both collected specimens were found in primary Montane Evergreen Forest, near running water (Ron et al. 2024).

Life History, Abundance, Activity, and Special Behaviors
All collected male specimens were found on leaves a few hundred cm above the ground, near running water (Ron et al. 2024).

Trends and Threats
The locality in which C. kutuku has been discovered is not a protected area and is 2.7 km from nearby agricultural land. The species authority recommended a “Data Deficient” listing for its IUCN listing at the time of species description (Ron et al. 2024).

Comments
Maximum likelihood analysis of 12S rRNA, 16S rRNA, ND1, and seven nuclear genes found that C. kutuku is sister to C. camposi, a species found on the opposite side of the Andes, with a divergence time of 2.7 Mya. This is unusual, as there are only two other known examples of this type of relationship in the family Centrolenidae: Cochranella granulosa and C. resplendens, and Teatohyla amelie and T. pulverata, both of which have much higher divergence times of > 7 Mya. This is likely an example of peripatetic speciation, dispersal for C. camposi was likely possible due to the relatively low elevations of the Andes in southern Ecuador (Ron et al. 2024).

References
Barrio-Amorós, C. L., F. J. M. Rojas-Runjaic, and J. C. Señaris. (2019). Catalogue of the amphibians of Venezuela: Illustrated and annotated species list, distribution, and conservation. Amphibian & Reptile Conservation, 13(1: e180), 1–198. [link]

Ron, S. R., García, D., Brito-Zapata, D., Reyes-Puig, C., Figueroa-Coronel, E., and Cisneros-Heredia, D. F. (2024). A new glassfrog of the genus Centrolene (Amphibia, Centrolenidae) from the Subandean Kutukú Cordillera, eastern Ecuador. Zoosystematics and Evolution, 100(3), 923-939. [link]

Species Account Citation: AmphibiaWeb 2024 Centrolene kutuku: Kutukú Glassfrog <https://amphibiaweb.org/species/9862> 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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