Boophis calcaratus is a medium-sized treefrog, with a body size of 29.5–39.5 mm, absence of an outer metatarsal tubercle, and absence of femoral gland, features also assigned to the genus Boophis. Lack of webbing between finger and yellowish marbling on the posterior flanks and inguinal region, typical from the subgenus Sahona. Presence of distinct heel tubercles and protruding nostrils.
Similar species: it is rather similar in morphology to the other Sahona species, but it presents a small dermal tubercle on the heels. Distinguished from B. lichenoides by the lack of dermal fringes on arms, legs and lower lips. Distinguished from the other described Boophis species with heel tubercles by the absence of hand webbing.
B. calcaratus has a dorsal dark to lighter brown coloration with many small, sharply delimited darker spots and markings and a transversal dark band between the eyes. The upper surfaces of fore- and hind legs show distinct dark brown crossbands. Crossbands also present on lower arm and hand (to tip of longest finger), but not on the upper arm. Small light tubercles on the shank. Iris beige with turquoise periphery. Blackish flanks with rounded whitish spots. Venter anteriorly whitish, posteriorly creme. Throat is generally grey, with white spots and markings of different size. Enlarged whitish tubercles can be seen in the cloacal region. After more than ten years in alcohol the colouration is still largely similar to that in life.
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Madagascar
Boophis calcaratus is only known from three localities in eastern Madagascar: Ambavaniasy, Nosy Boraha (close to Ambodifototra) and Betampona and occupies forest edges or degraded rainforests with an elevation range between 0 and 800 m above sea level. Individuals from Ambavaniasy occupy eucalypt forest; in Betampona they are found next to ponds and swampy area, surrounded by secondary vegetation.
Life History, Abundance, Activity, and Special Behaviors
Individuals of this species are mainly nocturnal and is usually found sitting on branches and leaves 1.5-3 m high. Males start calling at the sunset, and are heard during the night from branches and leaves up to at least 2 m high, or even on the ground, near ponds and slow moving streams.
Call (from Betampona): Two kinds of call are identified for this species: Type A call consists of a rapid series of 4-8 notes and lasts between 394-676 ms. Note duration is quite variable, ranging between 8-58 ms and duration of inter-note intervals is 11-114 ms. Note repetition rate is 9.0-10.5/s. Intensity is rather inconstant through the series varying from note to note. Notes are not distinctly pulsed, but each note is composed by several sound emission peaks (sequential wave crests) and the last 2-5 are markedly more intense. Frequency ranges 0.5-5.5 kHz: Three notes in the beginning of the analyzed call have a structure of some poorly defined harmonics. The type B call consists of an even faster series of 11-17 notes with a note repetition rate of 11.8-16.7/s. A series lasts about 707-1135 ms. Each note has a duration of 5-72 ms and the interval between notes is about 16-104 ms. In general the last 2-4 notes are longer, and slightly more separated from each other. In this call type notes are unpulsed as well, although it is also possible to distinguish up to 12 sound emission peaks per each note. Intensity increases from the first notes and decreases towards the last notes of the series. The frequency ranges from 0.5 to 5.0 kHz with a dominant frequency of 0.75-2 kHz. Interval between two calls is 32-67 s regardless the type of call.
Eggs and tadpoles: unknown
Trends and Threats
Not enough data to make an assessment of its risk of extinction.
Phylogenetic Relationships: Molecular work has confirmed the assignment of this species to the subgenus Sahona, which appears to group all the species in a clade.
Etymology: The specific epithet is an adjective derived from the Latin word calcar (spur). Named after the characteristic spine-like heel tubercles of the new species.
This species, like others in the Madagascan frog genus Boophis, has colorful eyes. Do eye color differences serve a function in some anuran taxa? Within the genus Boophis, many pairs of closely related "sibling" species are very similar in morphology and distinguishable mainly by advertisement calls and iris coloration. This contrasts with the speciose genus Mantidactylus, where only a few sibling species have different iris coloration.
Could the eye color differences function as a visual mechanism for reproductive isolation? Although iris coloration is probably not visible at night, when the pupils enlarge and the iris is reduced to a thin margin around the pupil, a number of Boophis species are also diurnally active after heavy rains. Perhaps in this genus eye coloration functions in conspecific recognition, as Glaw and Vences (1997) hypothesized. For more on this topic (and some alternative hypotheses) see their paper, which can be downloaded as a .pdf here.
Glaw, F., and Vences, M. (1997). ''Anuran eye colouration: definitions, variation, taxonomic implications and possible functions.'' Herpetologia Bonnensis, 1997, 125-138.
Glaw, F., and Vences, M. (2007). Field Guide to the Amphibians and Reptiles of Madagascar. Third Edition. Vences and Glaw Verlag, Köln.
Rosa, G.M. and Andreone, F. (2010). ''Bioacoustic data of the recently described Boophis calcaratus (Anura: Mantellidae: Boophinae), a cryptic treefrog from Eastern Madagascar.'' Zootaxa, 2426, 61-64.
Vallan, D., Vences, M., and Glaw, F. (2010). ''Forceps delivery of a new treefrog species of the genus Boophis from eastern Madagascar (Amphibia: Mantellidae).'' Amphibia-Reptilia, 31, 1-8.
Written by Gonçalo M. Rosa (goncalo.m.rosa AT gmail.com), Departamento de Biologia Animal, Faculdade de Ciências da Universidade de Lisboa, Portugal
First submitted 2010-10-05
Edited by Kellie Whittaker (2010-10-14)
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