Description
Synapturanus danta is a small sized, fossorial frog described from two adult male and one juvenile specimen. The adult males had a snout-vent length of 17.6 and 17.9 mm while the juvenile was 7.5 mm. Females are unknown. The head is flat on top from the profile and is somewhat wider than it is long. The snout is long and projects past the lower jaw where the rounded tip of the nose extends out; the tip is rounded from both a dorsal and lateral view, resembling that of a Tapir. The nares are located towards the side of the head and are closer to the end of the snout than to the eyes. The canthus rostralis is markedly rounded and the loreal region is deeply sunken and grooved. The eyes are small, about half the size of the distance between the eye and the naris (nostril). The supratympanic fold is slightly visible from the posterior corner of the eye to the neck. The tympanum can hardly be seen. The body is stout with smooth skin on both the dorsal and ventral sides from head to cloaca (Chávez et. al 2022).

The forelimbs are stout. A thenar tubercle is present but not obvious, and the palmar tubercle is small and oval shaped. An unpigmented, glandular supracarpal pad is visible. The short fingers have fingertips that tapered, except for finger III. Fingers lack discs or webbing, with pre- and postaxial fringes present that are especially developed on Fingers II and III where they stretch towards the base of each finger. The relative length of fingers pressed against a surface in order from longest to shortest is III, IV, II, I. Subarticular tubercles are not present on the fingers (Chávez et. al 2022).

The hindlimbs are stout. The inner and outer metatarsal tubercle are not visible, and the metatarsal fold is absent. The toes are unwebbed with slender pre- and postaxial fringes. The relative lengths of toes pressed against a surface in order from longest to shortest is IV, II, V, II, I. The toes lack discs with tapering on toes I, IV, and V. Toes II and III are expanded. Subarticular tubercles not visible on toes (Chávez et. al 2022).

DIAGNOSIS:

The appearance of S. danta is generally easy to distinguish from most of its counterparts, aside from S. rabus and S. salseri, by the flat head in lateral view in S. danta, which differs from the convex head shape in the lateral view that is common in other species in the genus. More specific differences are that S. danta can be differentiated from S. ajuricaba by having a non-visible tympanum, slightly larger eyes, an advertisement call with a dominant frequency range of 1.73 - 1.81 kHz (compared to S. ajuricaba’s dominant frequency range of 1.01 - 1.12 kHz), and by an absence of spots on the dorsal surface. From S. mesomorphus, S. mirandariberoi and S. zombie, S. danta can be distinguished by having a more slender body shape (rather than the robust body shape in S. mirandariberoi and S. zombie), a non-rounded fingers or rounded disc on the fourth finger (such as in S. zombie), a visible palmar tubercle, an absence of thenar and metatarsal tubercle, an advertisement call with a higher dominant frequency range of 1.73 - 1.81 kHz, and by the absence of speckles or spots on the dorsal surface. Synapturanus danta can be distinguished from S. rabus by having a slightly larger eye, lacking a canthal stripe in adults, lacking a visible tympanum, and having an advertisement call with a note length of 0.054 - 0.063 seconds, which is longer than that of S. rabus. Synapturanus danta can be distinguished from S. salseri by generally being a smaller size with a mean snout-vent length 17.8 mm (compared to 26.4 mm in S. salseri), by having a visible palmar tubercle, not having outer or inner metacarpal tubercles, not having stripes or spots on the dorsal surface of its body, and by having an advertisement call with a dominant frequency ranging from 1.73 - 1.81 kHz (1.10 - 1.47 kHz in S. salseri) (Chávez et. al 2022).

COLORATION:

In life, the dorsal side and flanks of S. danta is a chocolate brown without spots or blotches. A stripe along the canthus rostralis and upper eyelid was found in the juvenile. The snout and glandular supracarpal are both unpigmented and white. The throat and ventral surface of the limbs are a cinnamon brown or pinkish brown while the chest and belly are translucent cyan with white melanocyte spotting (Chávez et. al 2022).

In preservative, the dorsal surface and flanks are a dark brown. The snout is yellow and the chest and belly regions are a creamy yellow with brown speckles closer to the flanks. The ventral surfaces of the limbs are a yellowish brown (Chávez et. al 2022).

VARIATION:

Sexual dimorphism is unknown as no females were collected. In the juvenile specimen, a cyan-white discontinuous canthal stripe stretching from the upper eyelid to the groins is present. Juvenile dorsal coloration is dark brown with tiny pale-orange spots on dorsal surfaces of limbs, which are not present on adult male specimens. Variations between adult male specimens collected include, ventral cyan-white coloration extending to the edge along with the flank in one male and the underside of the feet being black in the other male (Chávez et. al 2022).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Peru

View distribution map in BerkeleyMapper.

Synapturanus danta is only known from the Lower Putumayo River Basin, Loreto, Peru which is in the northeastern part of the country, close to the Colombian border. All of the individuals captured and used to describe this species were found in the Putumayo River basin around 107 m of elevation, in a habitat classified as Amazon Peatlands (Chávez et. al 2022).

Life History, Abundance, Activity, and Special Behaviors
Not much is known in general about this genus due to it being primarily fossorial. However, S. danta is likely nocturnal based on the fact the specimens were calling and were collected at night and other members of the genus are thought to be nocturnal. The abundance of this species is unknown (Chávez et. al 2022).

All of the individuals captured and used to describe this species were found underneath roots of Clusia spp.. The vegetation in these Peatlands typically consists of treelet species, which are abundant in forests in the Loreto region of Perú as well as a number of fern species. The peatlands are a seasonally saturated ecosystems, sometimes with a mix of saturated pools and dry spots and sometimes drier periods. The specimens were collected during a more or less saturated period of time, though unsaturated spots were present. The two adult males were caught in unsaturated areas within chambers at a depth of 15 - 30 cm. The only juvenile collected was captured at a depth 5 cm. All individuals were observed within 3 - 4 meters from each other (Chávez et. al 2022).

Males of the species have an advertisement call that was observed to take place at night. Adult males emit single tonal notes from underground with a mean note length of 0.059 seconds, every 4.083 seconds on average. The dominant frequency is 1.763 kHz on average with somewhat of a downward modulation. The call appears to have a harmonic structure (Chávez et. al 2022).

Synapturanus species have been observed in underground chambers, where they dig and deposit their eggs that will undergo endotrophic development (Fouquet et al. 2021).

The genus Synapturanus is likely a myrmecophagous (termite and ant) specialist (Fouquet et al. 2021).

Trends and Threats
The Putumayo region, where S. danta is found, is notable as being the last Amazon tributary to not have existing or proposed dams and little deforestation. No known threats are currently recorded due to a deficiency of information, but potential dams or deforestation in the future may potentially jeopardize this species (Chávez et. al 2022).

Comments

PHYLOGENETIC RELATIONSHIPS:

Maximum Likelihood analysis of 16s mtDNA split the genus Synapturanus into western, central, and eastern clades. Synapturanus danta is a member of the western clade, and sister to an undescribed species from Serra do Divisor, Acre, Brazil. The next most closely related clade consists of undescribed species from Ecuador and Venezuela, followed by S. rabus to complete the western clade (Chávez et. al 2022).

ETYMOLOGY:

Synapturanus danta’s species epithet is based off of its elongated “nose” resembling that of the Amazon tapir, known as a “danta” in Spanish. The first researchers and locals to find and describe the amphibian initially called it the “Tapir frog” prior to its final scientific name being given. The species name danta pays homage to the initial descriptive name (Chávez et al. 2022).

References
Chávez, G., Thomson, M.E., Sánchez, D.A., Chávez-Arribasplata, J.C., Catenazzi, A. (2022). A needle in a haystack: Integrative taxonomy reveals the existence of a new small species of fossorial frog from Peru. Evolutionary Systematics​ 6, 9-20. [link]

Fouquet, A., Leblanc, K., Framit, M., Réjaud, A., Rodrigues, M. T., Castroviejo-Fisher, S., Peloso, P. L. V., Prates, I., Manzi, S., Suescun, U., Baroni, S., Moraes, L. J. C. L., Recoder, R., Marques de Souza, S., Dal Vecchio, F., Camacho, A., Ghellere, J. M., Rojas-Runjaic, F. J. M., Gagliardi-Urrutia, G., Tadeu de Carvalho, V., Gordo, M., Menin, M., Kok, P. J. R., Hrbek, T., Werneck, F. P., Crawford, A. J., Ron, S. R., Mueses-Cisneros, J. J., Zamora, R. R. R., Pavan, D., Simões, P. I., Ernst, R., & Fabre, A. (2021). Species diversity and biogeography of an ancient frog clade from the Guiana Shield (Anura: Microhylidae: Adelastes, Otophryne, Synapturanus) exhibiting spectacular phenotypic diversification. Biological Journal of the Linnean Society, 132(2), 233–25. [link]

Species Account Citation: AmphibiaWeb 2023 Synapturanus danta: Tapir Frog <https://amphibiaweb.org/species/9492> University of California, Berkeley, CA, USA. Accessed Sep 24, 2023.

Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 24 Sep 2023.

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