Mini mum Scherz, Hutter, Rakotoarison, Riemann, Rödel, Ndriantsoa, Glos, Roberts, Crottini et al., 2019
|Species Description: Scherz MD, CR Hutter, A Rakotoarison, JC Riemann, M-O Rödel, SH Ndriantsoa, J Glos, SH Roberts, A Crottini, M Vences, and F Glaw. 2019. Morphological and ecological convergence at the lower size limit for vertebrates highlighted by five new miniaturised microhylid frog species from three different Madagascan genera. PLoS One 14: e0213314.|
© 2019 Mark D. Scherz and Andolalao Rakotoarison (1 of 2)
The forelimb is slender and its length (sum of the hand, upper arm and lower arm lengths) is 50% of the average snout vent length. The outer metacarpal tubercle is rounded, while the inner metacarpal is indistinguishable from the reduced first finger. The hand is not webbed, and has single subarticular tubercles that are only distinct on the third finger. The first, second, and fourth fingers of M. mini are all strongly reduced, while the third finger is broadened at the base. The relative finger lengths are 1 < 4 < 2 < 3. The finger tips are not expanded into discs (Scherz et al. 2019).
The hindlimbs are also slender, and its length (sum of foot, thigh, and tibiofibular lengths) is about 150% that of the snout vent length. The tibiofibular length is 50% of the snout vent length. The lateral metatarsalia are strongly connected, and the inner metatarsal tubercle is indistinguishable from the completely reduced first toe. The outer metatarsal tubercle is absent. The toes are not webbed, and the first toe is absent. The second and fifth toes are strongly reduced, and the relative lengths for toes in M. mini is 2 < 5 < 3 < 4 (Scherz et al. 2019).
All members of the genus Mini are similar to species of the genus Stumpffia. However, M. mum has curved clavicles, which are not present in Stumpffia species (S. contumelia and S. obscoena do not have clavicles, and S. tridactyla has straight or absent clavicles). Mini mum also differs from most Stumpffia frogs through its fingers and toes. Fingers 1, 2, and 4 are strongly reduced and toe 1 is absent, distinguishing M. mum from all Stumpffia frogs except S. tridactyla, S. contumelia, and S. obscoena. Within the Mini genus, M. mum possesses a strong lateral color border that is weak or absent in M. scule and M. ature, respectively (Scherz et al. 2019).
Mini mum can also be diagnosed by call. Its calls are similar to those of S. contumelia, S. miery, S. obscoena, and S. tridactyla. However, M. mum calls are longer in duration (duration 74.8 ± 7.0 ms) and higher in frequency (8089 ± 140 Hz) than S. contumelia (duration 42 ± 4 ms and frequency 7493 ± 50 Hz). Mini mum has shorter calls (duration 74.8 ± 7.0 ms) with a lower frequency (8089 ± 140 Hz) when compared to S. obscoena (duration 144 ± 8 ms and frequency 8361 ± 69 Hz). Mini mum has a slightly longer inter-call interval than S. miery (4299.8 ± 1604.9 ms vs 3102 ± 456 ms). Mini mum calls are shorter in duration (duration 74.8 ± 7.0 ms) and higher in frequency (8089 ± 140 Hz) than S. tridactyla (duration 132 ± 23 ms and frequency 7244 ± 200 Hz) (Scherz et al. 2019).
In alcohol, the dorsum is metallic silver down the center of the trunk with lighter silver on the lateral regions. Mini mum is bluish silver on the head, and has dark oblong markings in the inguinal region. A strong dorsolateral color border is present, and it extends from the side of the head to the legs. The lateral coloration fades from an ebony color to the more burnt umber coloration of the venter. This coloration is especially dark anteriorly, with flecks of beige that get larger posteriorly until the posterior abdomen, which is beige. Dorsally, the arms are silver but become ebony laterally and ventrally. Dorsally, the legs are a spotted cream and grayish brown color, with a darker cloacal region. The legs are brown and flecked with beige ventrally. In life, coloration is browner and less iridescent but otherwise the same. Mini mum has a red iris (Scherz et al. 2019).
The snout vent length ranges from 8.2 - 9.7 mm in males and is around 11.3 mm in females. Specimens with darkened throats are usually males. The species seems to vary little in morphology, however coloration is highly variable. Lateral and ventral colouration is more or less consistently dark brown with light flecks, but rarely the flecks are bright bluish-white laterally. The strength of the flank color border varies from strong to weak. Dorsal colouration also varies from solid tan to mottled beige and dark brown (Scherz et al. 2019).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Madagascar
Life History, Abundance, Activity, and Special Behaviors
One female specimen examined contained four eggs (Scherz et al. 2019)
Trends and Threats
The genus name is derived from the English prefix "mini-", meaning a small version of an object. The full name Mini mum is a pun based on the English word “minimum” (Scherz et al. 2019).
Scherz, M. D., Hutter, C. R., Rakotoarison, A., Riemann, J. C., Rödel, M. O., Ndriantsoa, S. H., et al. (2019). "Morphological and ecological convergence at the lower size limit for vertebrates highlighted by five new miniaturised microhylid frog species from three different Madagascan genera." PLoS ONE, 14(3). [link]
Tu, N., Yang, M. H., Liang, D., Zhang, P. (2018). "A large-scale phylogeny of Microhylidae inferred from a combined dataset of 121 genes and 427 taxa." Science Direct, 126, 85-91. [link]
Originally submitted by: Jessica Pan (2022-02-22)
Description by: Jessica Pan (updated 2022-02-22)
Distribution by: Jessica Pan (updated 2022-02-22)
Life history by: Jessica Pan (updated 2022-02-22)
Trends and threats by: Jessica Pan (updated 2022-02-22)
Comments by: Jessica Pan (updated 2022-02-22)
Edited by: Ann T. Chang (2022-02-22)
Species Account Citation: AmphibiaWeb 2022 Mini mum <https://amphibiaweb.org/species/8987> University of California, Berkeley, CA, USA. Accessed Mar 22, 2023.
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Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 22 Mar 2023.
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