AmphibiaWeb - Fritziana mitus


(Translations may not be accurate.)

Fritziana mitus Walker, Wachlevski, Nogueira da Costa, Nogueira-Costa, Garcia & Haddad, 2018
family: Hemiphractidae
genus: Fritziana
Species Description: Walker M, Wachlevski M, Nogueira-Costa P, Garcia PCA, Haddad CFB 2018 . A new species of Fritziana Mello-Leitao 1937 (Amphibia: Anura: Hemiphractidae) from the Atlantic Forest, Brazil. Herpetologica 74: 329-341.
Fritziana mitus
© 2022 Henry Miller Alexandre (1 of 2)
Conservation Status (definitions)
IUCN Red List Status Account
National Status None
Regional Status None


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Fritziana mitus is an egg-brooding frog of the family Hylidae that was only recently identified as a separate species from the closely related Fritziana fissilis. The snout-vent length varies from 17.43 – 28.35 mm in females and 16.16 – 23.67 mm in males. The mean head width to head length ratio in males is 93% and 84 - 109% in females. The eyes are located anterolaterally with small tubercles on the upper eyelid and between the eyes. The tympanum is only slightly visible. The ratio of tympanum diameter to disc diameter in toe IV can be a diagnostic measurement and ranges of the ratios are 55 – 115 % in females and 59 – 135 % in males. Overall there was an 89% tympanum to disc ratio based on all specimens.The surface of the dorsum is smooth. The skin of the stomach region is grainy and the throat can either be smooth or slightly grainy. The forearms have a row of tubercles and the fingers exhibit developed, expanded, and non-emarginate discs. There is no webbing present and the relative length of fingers is as follows from shortest to longest: III, II, V, IV. There are also rounded subarticular tubercles, an elliptic and developed thenar tubercle, and two elliptical, developed, and parallel palmar tubercles. On the hindlimbs, there are a row of tubercles present on the tarsus. The tibia is slightly longer than the thigh and both parts together are roughly the same as the snout-vent length. The foot has few supernumerary tubercles, an elliptic and developed inner metatarsal tubercle, and a rounded but only slightly evident outer metatarsal tubercle The toes exhibit moderately sized and expanded adhesive discs that have vestigial interdigital webbing between toes II thru V and no webbing between toes I and II. The subarticular tubercles are rounded. The relative toe lengths are: I, II, III, V, IV from shortest to longest. The cloaca is posteriorly directed and located around the upper thighs (Walker et al. 2018).

Despite being part of the same brooding pouch, F. mitus tadpoles may be at different stages of development. In stage 35 of their development, F. mitus tadpoles display elongated and elliptical body shapes. Two tadpoles in stage 35 were recorded with total lengths of 14.8 and 15.8 mm, body lengths of 5.9 and 5.4 mm, tail lengths of 10.3 and 11.2 mm, body widths of 3.5 mm for both specimens, and body heights of 3.0 and 3.1 mm. In the dorsal view, the snout is rounded and from the lateral view it is truncated. The tadpole nostrils are located closer to the lip than to the eyes and are elliptical in shape. The nostril opening is both anteriorly located and directed. In this confirmation, the nostril is not visible from the dorsal view. The eyes are located dorsally and are anterolaterally directed. Eye diameter is approximately 16.9% of the total body length. The oral disc of the tadpole is located ventrally and, when viewed from that perspective, it can account for 28.6% of the body’s width. The mouth is bordered by a single row of papillae with a large dorsal gap is present. This species does not have any submarginal rows of papillae or labial teeth, but the jaw sheaths are completely serrated and developed. The upper jaw has a U-shaped appearance while the lower jaw has a V-shaped appearance. The spiracle has a sinistral placement and is short, ventral, and connected to the body from the inner wall. The vent tube has a dextral placement with a wide opening, relatively equal length and width, and is attached to the ventral fin. From the lateral view, the dorsal fin originates on the tail musculature and grows in height in the first third of the tail before becoming parallel to the tail in the final two thirds. The ventral fin remains parallel to the musculature throughout the length of the tail (Walker et al. 2018).

When compared to similar species in its genus, adult F. mitus are relatively smaller in size and have a proportionately wider head than F. ohausi and F. izecksohni, and a longer head than F. goeldii, F. tonimi, and F. fissilis specimens. Additionally, F. mitus can be distinguished from other members of the genus by their mucronate snout tips, round subarticular tubercles, black wrist stripe, and relatively larger tympanum to IV toe diameter ratios. Fritziana mitus females can be differentiated from F. goeldii, F. ohausi, and F. tonimi by their closed dorsal pouch during their egg incubation period, unlike the other species whose pouches are not fully closed (Walker et al. 2018).

In life, the female holotype’s coloration has a brownish-yellow dorsal region with a brownish interorbital fleck on its head, two parallel brownish stripes with creme outer edges that extend laterally from the back of the eye to the midbody, and a dark brown wrist band. Adults may also have a uniform color pattern or a bronze blotch covering the entire dorsal surface of the head. Fritziana mitus has a pale bronze iris with a red horizontal stripe running across the eyes. There is dark coloration on the backs of their finger discs and the finger tips may be blackened. From a lateral view, the upper jaw has irregular dark spots. The most common pattern displayed on F. mitus is an interorbital triangle, however, this feature can be absent. Following the triangle are two parallel lines running along the length of the back to the midbody (Walker et al. 2018).

In preserved specimens, there may or may not be a bronze mark on the head, as the color does not appear to preserve well. Other traits that may be lost in preservation include the dark brown wrist stripe, blackened fingertips, and other forelimb stripes and dots (although these are believed to be rare). Overall, general color patterns are thought to be retained but with paler coloration when preserved (Walker et al. 2018).

In preservative, tadpole coloration is light brown with very small dark brown blotches dorusms. Their sides are lighter than their backs. The coloration changes to a light cream color starting at the base of the tail with small dark brown blotches concentrated in the tail musculature. In the final third section of the tail, F. mitus tadpoles have a translucent ventral region with a light brown body. The body also has translucent features in the beige oral disc, cloaca tube and spiracle (Walker et al. 2018).

Between F. mitus specimens, there is variation in snout shape, in patterning, and by sex. The majority of specimens (72.5%) studied displayed rounded snouts (from the lateral view), but other specimens also possessed truncate or protruding snouts. From the dorsal view, snouts can appear round, truncate, pointed, or subvoid. The presence of a dorsolateral stripe that starts at the snout is another variation that can be observed. When the stripe is present, it may extend to the tympanum, mid-body, or cloacal region. More variations include dorsal coloration, which can range from greenish, yellowish, bronze, or light brown, tubercles on the forearms, and patterning on the hind limbs. Male F. mitus possess nuptial pads on the base of Finger II that aid in amplexus and have beige or brown coloration. Males also have vocal slits that are located at either side of the floor of the mouth. Females display variation depending on the presence or absence of eggs in their brooding pouch during the reproductive period. If eggs are absent, a female may possess a skin crest on her dorsum from the empty pouch. If present, the female possesses a flat layer of eggs with no particular pattern across her back (Walker et al. 2018).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Brazil

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Fritziana mitus occurs in the Atlantic Forest of the southeastern Brazilian states: São Paulo, Parana, Santa Catarina, and Rio Grande do Sul. This distribution is the largest and most southern-ranging of any species in the genus Fritziana (Walker et al 2018). The species lives in dense tropical forests wherever epiphytic bromeliad plants are found. While an elevational range has not been established as of 2021 for this species, similar species from the genus that share habitats have been discovered from 500 to 1800 m above sea level (Potsch de Carvalho-e-Silva and Telles 2010).

Life History, Abundance, Activity, and Special Behaviors
Like many amphibians, F. mitus tends to exhibit nocturnal behavior with increased activity during dusk and at night (Walker et al. 2018).

Although several individuals have been found on forest floors and on non-bromeliad leaves, it is thought that F. mitus is primarily arboreal, spending a majority of its time, especially the early stages of development, in epiphytic bromeliads that are usually of the genus Vriesea and about 1 - 3 m above the forest floor. Fritziana mitus may also occasionally be found in bushes (Walker et al. 2018).

Not much is known about the true abundance of this species. It is highly likely that many accounts of F. mitus have been misidentified under similar species in the genus with overlapping morphological traits. Although no reports of quantitative estimates were found, F. mitus populations are thought to increase in abundance during the rainy season, which ranges from September to March due to their reliance on rainwater for reproduction (Walker et al. 2018).

Fritziana mitus is part of a group of Anura known as “egg-brooding hylids” and exhibits a reproductive mode with oviparity and parental care shown by females who brood their eggs in pouches on their bodies. Female F. mitus have dorsal egg-brooding pouches for incubation with a medial opening that runs along the length of the pouch. Unlike some other species in the genus, F. mitus’ brooding pouch remains closed during incubation (Walker et al. 2018).

A female can brood around 7 - 10 eggs in her pouch at a time and it is believed that the larvae obtain their nourishment solely from the yolk in their eggs. Tadpoles are thought to experience endotrophic development, as suggested by their reduced mouth structures and the lack of any food substance except yolk having ever been found in F. mitus tadpole specimens. Once the eggs hatch, the females deposit their tadpoles into the rainwater that accumulates in epiphytic bromeliads to develop (Walker et al. 2018).

No data was available on the type of amplexus utilized. The mating call performed by males was described by researchers in 2015 who initially identified the call under the species name F. fissilis. The mating call frequency is thought to have a range of 3000 – 3375 Hz, which is comparatively higher than the frequency of calls of other similar species in the genus (Walker et al. 2018). No recordings or descriptions of the call exist, but the closely related F. fissilis exhibits a low rattle sound with two distinguishable note pulses, the first pulse being much longer than the second (Duellman and Gray 1983).

No documentation of the F. mitus diet was found, however multiple other species of the Hylidae family are known to consume a range of invertebrates such as arthropods, annelids, and nematodes as well as vegetative material (Muñoz-Guerrero et al. 2007) and it is likely that F. mitus shares a similar range of prey. Additionally, no information on F. mitus’ predators could be found as of 2021.

Trends and Threats
As of 2021, this species is not listed on the IUCN Red List. However, F. fissilis is a closely related species with a similar and often overlapping geographical range that is currently listed as “Least Concern” (Potsch de Carvalho-e-Silva and Telles 2010).

With the relatively new description of F. mitus, it is believed that a significant portion of the F. fissilis population and geographic range may actually belong to F. mitus. Because so much of the F. fissilis population may actually be F. mitus, F. fissilis should be reclassified on the IUCN Red List website as "Data Deficient" and F. mitus should be given the designation of “Least Concern” (Walker et al. 2018).

The range of the species is within the mountains of southeastern Brazil and nearly the entire species distribution is located within a protected area. While rollbacks on protected areas do occur, the population is believed to thrive within the Serra dos Orgaos mountain range (Walker et al. 2018).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Habitat fragmentation

Bayesian analysis of 16S ribosomal RNA in Fritziana concluded that F. mitus is sister to an unnamed Fritziana species from the state of Minas Gerais in Brazil. The next most closely related species is F. ulei (Walker et al. 2018).

Phylogenetically, F. mitus is distinct from other Fritziana species by the addition of approximately 200 additional base pairs to the mitochondrial 12S gene associated with the proline tRNA gene. This change makes F. mitus unique not only among Fritziana but also among all other Anura as well. (Walker et al. 2018).

The species epithet, “mitus” is from the Greek word for “thread in reference to the unique gene sequence of the species’ mitochondrial DNA (Walker et al. 2018).


Duellman, W. E., and Gray, P. (1983). "Developmental biology and systematics of the egg-brooding hylid frogs, genera Flectonotus and Fritziana." Herpetologica, 39(4), 333-359.

Muñoz-Guerrero, J., Serrano, V.H., Ramírez-Pinilla, M.P. (2007). “Microhabitat use, diet and time of activity of four sympatric Neotropical hylid frogs (Anura: Hylidae).” Caldasia, 29(2), 413-425 [link]

Walker, M., Wachlevski, M., Nogueira-Costa, P., Garcia, P. C. A., Haddad, C. F. B. (2018). “A new species of Fritziana Mello-Leitão1937 (Amphibia: Anura: Hemiphractidae) from the Atlantic Forest, Brazil.” Herpetologica, 74(4), 329–341. [link]

de Carvalho-e-Silva, S.P., Telles, A.M. (2010). “Fritziana fissilis.” The IUCN Red List of Threatened Species. Downloaded on 17 Feb 2021.

Originally submitted by: Cody Ornbaun, Kamila Rodriguez, Marisol Ibarra Zea (2021-09-01)
Description by: Cody Ornbaun, Kamila Rodriguez, Marisol Ibarra Zea (updated 2021-09-01)
Distribution by: Cody Ornbaun, Kamila Rodriguez, Marisol Ibarra Zea (updated 2021-09-01)
Life history by: Cody Ornbaun, Kamila Rodriguez, Marisol Ibarra Zea (updated 2021-09-01)
Trends and threats by: Cody Ornbaun, Kamila Rodriguez, Marisol Ibarra Zea (updated 2021-09-01)
Comments by: Cody Ornbaun, Kamila Rodriguez, Marisol Ibarra Zea (updated 2021-09-01)

Edited by: Ann T. Chang (2021-09-01)

Species Account Citation: AmphibiaWeb 2021 Fritziana mitus <> University of California, Berkeley, CA, USA. Accessed Jul 14, 2024.

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Citation: AmphibiaWeb. 2024. <> University of California, Berkeley, CA, USA. Accessed 14 Jul 2024.

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