Though only 28–32 mm in length at maturity, this species is one of the largest in the 16-species genus, dwarfed only by some individuals of Mantella viridis.
 Related Mantella species typically range from 18–31 mm in morphology for adult individuals.
Mantella frogs generally exhibit sexual dimorphism, with the females (28–32 mm) of this species being slightly larger than the males (24–28 mm).
This difference in size becomes prominent after approximately 10–12 months of age.

Most individuals in this species display specific unique characteristics that distinguish them from other Mantella species, such as a "light rostral line above the eyes" and "tiger-like markings on the hind limbs" of "orange with irregular black stripes", as seen in the images above.
However, a wide variety of phenotypes exist, which manifest in front limb colors ranging from light greens to vibrant oranges and yellows, and are sometimes mistaken or imported into the international marketplace as Mantella cowanii.


Moreover, the "front limbs and femurs are yellow to greenish in appearance, with this coloration continuing up the flanks into a large, rounded flank blotch", which mirrors the commonplace appearance of the species Mantella madagascariensis, known as the painted mantella.
These blotches "contrast with the black dorsum and striking orange and black legs" in both species, making it difficult for distributors, vendors, herpetologists, breeders, collectors, and pet owners to acquire the correct species.
The easiest way to differentiate the two species is to note the "sky-blue, horseshoe-shaped marking" present on the throat of the painted mantella, as well as the lack of "flashmarks on the lower hindlimbs" on the Baron's mantella.
Due to their similar appearance, the Baron's mantella is sometimes informally called a "painted mantella" as well, despite the painted mantella being a distinct species altogether.

As seen in the pictures above, M. baroni demonstrates strong aposomatic features on their front limbs, hind limbs, and rostral line.
   Similar aposomatic features – such as bright colorations, striking color differentials, and otherwise unconventional patterning – are common to all 16 species of Mantella, to varying levels of veracity (some species of Mantella have weaker toxicity and primarily use bright colors as a form of mimicry).
Despite resembling the similarly-small poison dart frogs of Latin America, which also communicate their toxicity to potential predators through aposematism, Mantella species like the Baron's mantella are only distant taxonomic relatives.
The existence of these similarities between these two families is an example of convergent evolution.
Though only 28–32 mm in length at maturity, this species is one of the largest in the 16-species genus, dwarfed only by some individuals of Mantella viridis.  Related Mantella species typically range from 18–31 mm in morphology for adult individuals. Mantella frogs generally exhibit sexual dimorphism, with the females (28–32 mm) of this species being slightly larger than the males (24–28 mm). This difference in size becomes prominent after approximately 10–12 months of age.
Most individuals in this species display specific unique characteristics that distinguish them from other Mantella species, such as a "light rostral line above the eyes" and "tiger-like markings on the hind limbs" of "orange with irregular black stripes", as seen in the images above. However, a wide variety of phenotypes exist, which manifest in front limb colors ranging from light greens to vibrant oranges and yellows, and are sometimes mistaken or imported into the international marketplace as Mantella cowanii. 

Moreover, the "front limbs and femurs are yellow to greenish in appearance, with this coloration continuing up the flanks into a large, rounded flank blotch", which mirrors the commonplace appearance of the species Mantella madagascariensis, known as the painted mantella. These blotches "contrast with the black dorsum and striking orange and black legs" in both species, making it difficult for distributors, vendors, herpetologists, breeders, collectors, and pet owners to acquire the correct species. The easiest way to differentiate the two species is to note the "sky-blue, horseshoe-shaped marking" present on the throat of the painted mantella, as well as the lack of "flashmarks on the lower hindlimbs" on the Baron's mantella. Due to their similar appearance, the Baron's mantella is sometimes informally called a "painted mantella" as well, despite the painted mantella being a distinct species altogether.
As seen in the pictures above, M. baroni demonstrates strong aposomatic features on their front limbs, hind limbs, and rostral line.    Similar aposomatic features – such as bright colorations, striking color differentials, and otherwise unconventional patterning – are common to all 16 species of Mantella, to varying levels of veracity (some species of Mantella have weaker toxicity and primarily use bright colors as a form of mimicry). Despite resembling the similarly-small poison dart frogs of Latin America, which also communicate their toxicity to potential predators through aposematism, Mantella species like the Baron's mantella are only distant taxonomic relatives. The existence of these similarities between these two families is an example of convergent evolution.
Mantella baroni