''Blommersia angolafa'' is a species of

frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...

s in the family

Mantellidae The Mantellidae are an amphibian family (biology), family of the order (biology), order Frog, Anura (frogs and toads), and are Endemism, endemic to the Indian Ocean islands of Madagascar and Mayotte. At first glance, the diminutive, brightly-col ...

. This recently described species is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to eastern

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

. The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

is derived from the term “angolafa” or “angolafo”, which is the Malagasy vernacular name used by the

Betsimisaraka people The Betsimisaraka ("the many inseparables") are the second largest ethnic groups of Madagascar, ethnic group in Madagascar after the Merina and make up approximately fifteen percent of the Malagasy people. They occupy a large stretch of the easte ...

for the ''

Dypsis ''Dypsis'' is a genus of flowering plants in the family Arecaceae. They are slender, evergreen palms with yellow flowers carried in panicles amongst the pinnate leaves. Many ''Dypsis'' species have aerial branching (above the main trunk), a rare ...

'' palm species (mostly for ''Dypsis lastelliana''), whose leaves and

prophyll In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also look ...

s are the habitat for this frog.

Description

''Blommersia angolafa'' is a small frog, with a body size of 17–21 mm, enlarged tips on fingers and toes, and without any dark area in the tympanic and frenal region, present in the other ''

Blommersia ''Blommersia'' is a genus of frogs in the mantellid subfamily Mantellinae. This genus is restricted to Madagascar. At present it contains 11 species. It was formerly a subgenus of the genus ''Mantidactylus ''Mantidactylus'' is a frog genus i ...

''. ''B. angolafa'' has a rather uniform dorso-lateral colouration, shading from yellowish–light brownish to dark brown, with light-bluish spots on the flanks and light-bluish terminal parts of the fingers and toes. The species also appears to be chromatically

sexually dimorphic Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

. In fact, males differ from females in having a light colouration, while females are more brownish. ''Blommersia angolafa'' is similar to '' B. grandisonae''. Although both ''B. angolafa'' and ''B. grandisonae'' have enlarged finger tips, they are much more developed in ''B. angolafa''.

Eggs and tadpoles

Egg clutches are found only from December onwards; they are glued to the inside walls of palms' dead prophylls filled with water and fallen on the ground. Several different stages of tadpoles can be found sharing the water accumulated within the same fallen prophyll. Under captive conditions, all the eggs of a single clutch hatched after a period of 7–10 days, and the total duration of the larval development was 57–70 days.

Distribution and habitat

''Blommersia angolafa'' occurs at four forest blocks in eastern Madagascar:

Masoala ''Masoala'' is a genus of flowering plant in the family Arecaceae. It contains the following species, both endemic to Madagascar:Jumelle, Henri Lucien. 1933. Annales du Musée Colonial de Marseille, sér. 5, 1(1): 8. * ''Masoala kona'' Beentje ...

, Ambatovaky, Zahamena and

Betampona Betampona is a rural commune in Madagascar. It belongs to the district of Fenerive Est, which is a part of Analanjirofo Region. The population of the commune was estimated to be approximately 8,562 inhabitants in 2018.Troisieme Recensement Gener ...

and occupies rain forest with an elevation range between 90 m (Ankavanana River,

Masoala Peninsula Masoala National Park, in northeast Madagascar, is the largest of the island's protected areas. Most of the park is situated in Sava Region and a part in Analanjirofo. Created in 1997, the park protects 2,300 square kilometres of rainforest and ...

) and 508 m (Vohitsivalana, RNI de Betampona). It is found both in primary and secondary forest, due to the tolerance of some ''Dypsis'' palms to occur in secondary rain forest at Betampona. The observed elevational distribution at Betampona ranged from 332–548 m asl. Andreone ''et al.'' suggest that this species may also occur at other rain forest sites that fall within this elevational and latitudinal range for eastern Madagascar, such as

Makira The island of Makira (previously known as San Cristóbal) is the largest island of Makira-Ulawa Province in Solomon Islands. It is third most populous of the Solomon Islands after Malaita and Guadalcanal, with a population of 55,126 as of 2020 ...

and

Mananara Nord Mananara Nord or Mananara Avaratra is a municipality in Madagascar. It belongs to the district of Mananara Nord, which is a part of Analanjirofo Region. The population of the commune was 35,148 in 2018. It is situated at the Route Nationale N ...

Life history, activity and special behaviours

A peculiar aspect characterising this species is its novel life history and reproductive mode. Both sexes live and breed in a phytotelmic habitat of water accumulated within fallen prophylls and fallen leaf sheaths of at least three species of ''Dypsis'' palms. Within these

phytotelma Phytotelma (plural phytotelmata) is a small water-filled cavity in a terrestrial plant. The water accumulated within these plants may serve as the habitat for associated fauna and flora. A rich literature in German summarised by Thienemann (19 ...

ta, egg laying and complete larval development occur. Andreone ''et al.'' never observed individuals outside dead fallen ''Dypsis'' phytotelmata that were lying on the forest floor or that contained rainfall.

Call

The advertisement call of ''B. angolafa'' starts at the end of September and continues mostly continuously until the end of February to early March. Calling males are usually heard during the dusk and early at night. The call consists of two notes, rather similar to those described for '' B. grandisonae'' and '' B. domerguei''. Note of type 1 is a long and clearly pulsed note with a duration of 221–233 ms and consisting of 9–11 pulses that are repeated with a pulse repetition rate of 44–52 per second. One such pulsed note is followed by an irregular series of up to 13–29 notes of type 2 which are shorter and of irregular structure. Notes of type 2 can be short clicks consisting of a single main pulse and with a duration of 10–17 ms (n=2) or can consist of up to eight distinctly separated pulses each and then have durations of 63–86 ms, with all intermediate states occurring so that a clear distinction of further different note types is not possible. Intervals between notes of type 2 in a note series have a duration of 73–191 ms. The frequency appears as a more or less regular band between about 2,500–5,500 Hz; although, the fundamental frequency may be higher than 2,500 Hz.

Trends and threats

''B. angolafa'' are only known from phytotelmata of ''

'' palms. These palms are suffering from selective logging and deforestation. Thus, the conservation situation for'' B. angolafa'' is potentially and negatively affected by the palms' threatened status. Most of the ''Dypsis'' palms (or at least ''

Dypsis lastelliana ''Dypsis'' is a genus of flowering plants in the family Arecaceae. They are slender, evergreen palms with yellow flowers carried in panicles amongst the pinnate leaves. Many ''Dypsis'' species have aerial branching (above the main trunk), a rare ...

'') are also threatened by selective logging habitat destruction, fire, harvesting for palm heart, and plant and seed collection by palm enthusiasts.

Phylogenetic relationships

Andreone ''et al.'' suggest that the reproductive mode of ''B. angolafa'' is a

derived character In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...

, having evolved from the more typical reproduction in

lentic A lake ecosystem or lacustrine ecosystem includes biotic (living) plants, animals and micro-organisms, as well as abiotic (non-living) physical and chemical interactions. Lake ecosystems are a prime example of lentic ecosystems (''lentic'' ref ...

water bodies. The general scarcity of lentic habitats in Malagasy rain forests may have provided the conditions that favoured the evolution of this phytotelmic breeding strategy.

References

External links

''Blommersia angolafa''
AmphibiaWeb: Information on amphibian biology and conservation
''Blommersia angolafa''
ARKive: Ultimate multimedia guide to the world's endangered species {{DEFAULTSORT:Blommersia Angolafa Mantellidae Endemic frogs of Madagascar Amphibians described in 2010