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Description
Stumpffia kibomena is a small frog of the microhylidae family with a snout-vent length of 17.1 - 21.2 mm. No size difference has been described between the sexes. The body shape is slender and head width is wider than head length but narrower than body width. Lack of maxillary and vomerine teeth - a diagnostic trait of the Stumpffia genus - is observed in S. kibomena. When viewed from both above and in profile, the snout appears to be rounded. The nostrils do not protrude from the snout and are oriented in a lateral fashion. The tympanum is clearly visible and relatively large in size, but smaller than the eye diameter. The ratio of tympanum diameter to eye diameter can range from 0.63 - 0.88. A supratympanic fold is not clearly visible. The dorsal and ventral sides are smooth and there are no dorsolateral folds clearly visible (Glaw et al. 2015).

The forelimbs of S. kibomena are slim. One subarticular tubercle is present on each forelimb, but they are difficult to distinguish. No outer metacarpal tubercles are distinguishable (Glaw et al. 2015). Each hand has four fingers, and the first finger is shorter than the other fingers (Rakotoarison et al. 2017 - Vertebr. Zool.). The relative finger length is generally as follows: I < II < IV < III. No webbing is present between fingers, and expanded discs are also absent (Glaw et al. 2015).

As with the forelimbs, the hind limbs of S. kibomena are slim. The tibia length is half of snout-vent length. No outer metatarsal tubercles are present, but there are distinguishable - if minute - inner metatarsal tubercles present. When adpressed to the body, the joint connecting the tibia and tarsus of the hind limb extends to the eye (Glaw et al. 2015). Each foot has five toes, and the first toe is shorter than the other toes (Rakotoarison et al. 2017 - Vertebr. Zool.). The fifth toe is markedly shorter than the third toe. The relative toe length is generally as follows: I < II < V < III < IV. Near the first toe, an outgrowth is present; it likely indicates a nuptial pad. No webbing is present between toes, and expanded discs are also absent (Glaw et al. 2015).

DIAGNOSIS: (How this species is differentiated from similar species)

The primary distinguishing characteristic between S. kibomena and frogs of the Plethodontohyla and Rhombophryne genera is vomerine teeth. All Plethodontohyla and Rhombophryne have vomerine teeth, but these teeth are conspicuously absent in S. kibomena. Another character that can - with two exceptions - be used to distinguish S. kibomena from Plethodontohyla and Rhombophryne frogs is the shorter snout-vent length of S. kibomena. The exceptions are R. mangabensis and R. minuta, which are both similar in size to S. kibomena. In these cases however, the presence/absence of vomerine teeth can still be used as a distinguishing character (Glaw et al. 2015).

Distinguishing characteristics between S. kibomena and Madecassophryne truebae include dorsal skin texture, tympanum size, and ventral side coloration. The dorsal skin of S. kibomena is smoother in comparison to M. truebae. The tympanum of S. kibomena is larger in relation to its eye size; in M. truebae, the ratio of tympanum size to eye size is about 0.2, while in S. kibomena this ratio can range from 0.63 - 0.88. Most notably, M. truebae lacks the distinct red coloration that is present on S. kibomena’s ventral side (Glaw et al. 2015). Instead, the ventral side of M. truebae is white in color (Rakotoarison et al. 2017 - Salamandra).

Stumpffia kibomena is distinguishable other Stumpffia species by a combination of coloration, size, the lack of digit discs, and calls. More specifically, it can be differentiated from all other all other known species of Stumpffia frogs by its vivid red ventral coloration. Additionally, with the exception of S. grandis, black coloration on the throat distinguishes S. kibomena from other Stumpffia. However, ventral coloration can still differentiate S. grandis from S. kibomena; S. kibomena has distinctive red coloration on its ventral side while S. grandis has black and blue patterning on its ventrum. Both S. kibomena and S. roseifemoralis having rust-colored dorsal skin, but S. roseifemoralis has only one dorsal blotch that is not well-defined while S. kibomena has multiple, well-defined dorsal blotches. Additionally, on the ventral side, S. roseifemoralis has mottled yellow, gray, and brown skin while S. kibomena has distinctive red coloration. A distinguishing characteristic between S. kibomena and S. gimmeli is dorsal skin color with S. gimmeli having gray or brown dorsal coloration with no distinct blotches. In contrast, the dorsal skin of S. kibomena is rust-colored and interspersed with dark brown to black blotches. Stumpffia kibomena is larger (17 - 21 mm) than S. analamaina, S. angeluci, S. contumelia, S. davidattenboroughi, S. gimmeli, S. huwei, S. iharana, S. larinki, S. maledicta, S. madagascariensis, S. mamitika, S. miery, S. obscoena, S. psologlossa, S. pygmaea, S. sorata, S. yanniki, S. tetradactyla, and S. tridactyla, of which none exceed a snout-length length of 18 mm. The lack of expanded toe/finger discs in S. kibomena distinguishes them from S. be, S. hara, S. helenae, S. megsoni and S. staffordi, which all show some degree of expansion. Acoustically, S. kibomena iterates its call much more rapidly than other Stumpffia species. More specifically, S. kibomena is differentiated from S. psologlossa by the lack of pulsation in S. kibomena’s calls. In contrast, pulsation is present in the calls of S. psologlossa (Glaw et al. 2015, Rakotoarison et al. 2017 - Vertebr. Zool.).

COLORATION: (In life and/or in preservative)

In life, the abdomen and ventral sides of the fore- and hind limbs feature distinctive red coloration. On the dorsal side, the skin is rust-colored, and interspersed with dark brown to black blotches. These blotches often run the length of the dorsum. A triangular blotch originates between the eyes and ends partway down the dorsum. On the throat, black coloration is present (Glaw et al. 2015).

In preservative (70% ethanol for 10 years), the distinctive red ventral color is not seen - the skin on the abdomen and ventral sides of fore- and hind limbs is instead yellow. The area around the cloaca is distinguishable on the ventral side by its brown coloration. The dorsal skin is brown with small, white speckles. The blotches on the dorsal side are black in color, and the throat region is a deep brown color (Glaw et al. 2015).

VARIATION:

The dorsal side of the frog may or may not feature tubercles (Rakotoarison et al. 2017 - Vertebr. Zool.).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Madagascar

View distribution map in BerkeleyMapper.

Stumpffia kibomena is currently only known to from the Andasibe region of eastern Madagascar, though it’s possibly found in other forested regions of the country. The species typically lives at the ground level in the leaf debris of rainforest or eucalyptus forest, or even in low-lying ferns. (Glaw et al. 2015). Stumpffia kibomena can be found at elevations 850 - 950 m above sea level (IUCN 2020).

Life History, Abundance, Activity, and Special Behaviors
While S. kibomena is considered rare, as it has only been found in Eastern Madagascar and has only been observed/captured a few times despite multiple surveys taking place in its habitat, it is known to be a terrestrial species. Stumpffia kibomena has been observed to be active both day and night (Glaw et al. 2015).

Stumpffia kibomena calls during the day. It emits a simple single note over consistent intervals, typically 1.2 - 1.3 per second with a call duration of 70 - 76 ms, an inter-call interval of 770 - 813 ms, and a dominant frequency of 3900 – 4300 Hz. Between notes there is an evident frequency modulation with frequency increasing over the call (Glaw et al. 2015).

It has been suggested that their bright red underbelly might be a form of aposematism, but again, this isn’t certain (Glaw et al. 2015).

Little is known about their reproductive behaviors due to the limited number of specimens that have been observed in the wild (Rakotoarison et al. 2017 - Vert. Zool.).

Trends and Threats
There aren’t any threats specific to S. kibomena, but there are ongoing threats to its known habitat that have led scientists to assume that the S. kibomena population is declining. These threats are primarily related to habitat loss due to deforestation. This deforestation is happening as a result of urbanization, fire suppression efforts, logging, and agricultural land use. However, this species can only be found in protected areas, namely the Zahamena-Ankeniheny protected area, but is also probably found in other protected areas like Andasibe National Park, Analamazoatra Special Reserve and Andasibe-Mantadia National Park (IUCN 2020).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Urbanization
Habitat fragmentation

Comments

PHYLOGENETIC RELATIONSHIPS:

Based on Maximum Likelihood analysis of 16S rRNA mtDNA, S. kibomena is sister to the clade composed of S. achillei, S. analanjirofo, and S. fusca. The next most closely related species is S. grandis (Rakotoarison et al. 2017 - Vert. Zool.)

As of 2021, the genus Stumpffia had over 40 species; many of those recently discovered, as there were only 15 described by 2015 (Glaw et al. 2015, Rakotoarison et al. 2017 - Vert. Zool.) There are thought to be even more, but there are relatively few physical differences between species, and many of the taxa are thought to be very small in size and only endemic to specific areas. Stumpffia is one of three terrestrial cophylines found in Madagascar; the other two are Rhombophryne and Madecassophryne (Glaw et al. 2015).

When it was first discovered, S. kibomena was classified as a Rhombophryne (Glaw et al. 2015).

ETYMOLOGY (Origin or explanation of scientific name):

The species either, “kibomena” comes from the Malagasy language spoken in the region where S. kibomena is found. “Kibo” means “venter”, and “mena” means “red”, referring to the bright red belly and legs that distinguishes S. kibomena from other taxa (Glaw et al. 2015).

References

Glaw, F., Vallan, D., Andreone, F., Edmonds, D., Dolch, R. Vences, M. (2015). “Beautiful bright belly: A distinctive new microhylid frog (Amphibia: Stumpffia) from eastern Madagascar.” Zootaxa 3925(1), 120–128 [link]

IUCN SSC Amphibian Specialist Group. (2020). “Rhombophryne kibomena (amended version of 2016 assessment).” The IUCN Red List of Threatened Species 2020: e.T79680110A177167158. https://dx.doi.org/10.2305/IUCN.UK.2020-3.RLTS.T79680110A177167158.en. Downloaded on 19 February 2021.

Rakotoarison, A., Scherz, M.D., Glaw, F., Köhler, J., Andreone, F., Franzen, M., Glos, J., Hawlitschek, O., Jono, T., Mori, A., Ndriantsoa, S.H., Raminosoa, N.R., Riemann, J.C., Rödel, M., Rosa, G.M., Vieites, D.R., Crottini, A., Vences, M. (2017). "Describing the smaller majority: integrative taxonomy reveals twenty-six new species of tiny microhylid frogs (genus Stumpffia) from Madagascar." Vertebrate Zoology, 67(3), 271-398. [link]

Rakotoarison, A.., Scherz, M., Glaw, F., Vences, M. (2017). “Rediscovery of frogs belonging to the enigmatic microhylid genus Madecassophryne in the Anosy Massif, south-eastern Madagascar.” Salamandra 53, 507–518. [link]

Species Account Citation: AmphibiaWeb 2022 Stumpffia kibomena <https://amphibiaweb.org/species/8313> University of California, Berkeley, CA, USA. Accessed Apr 16, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 16 Apr 2024.

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