Description
This is a small species of Guibemantis, until recently confused with G. punctatus Overall body color is tan or olive with abundant very small spots over the entire dorsal surface. Paired rostral stripes (black and gold) are present as are small white rings of pigment proximal to each finger or toe disc. Sexually mature males at one locality (Sainte Luce) ranged from 18-23 mm SVL; females were of similar size (range 17-25 mm SVL). Males have paired subgular vocal sacs and well-defined femoral glands on the ventral surface of the thighs.

G. annulatus can be distinguished from G. punctatus by having a lighter dorsal ground color, rounded dorsal spots that are smaller and more regular, digits with conspicuous light “rings” just proximal to each toe or finger disc, the presence of an unbroken gold (in life) rostral stripe medial to a black rostral stripe, small dark spots on the dorsal surfaces of limbs (vs thick bars in G. punctatus), a relatively longer femur, tibia and foot, a wider head, a wider internarial distance, males with larger femoral glands, and DNA sequence differences.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Madagascar

View distribution map in BerkeleyMapper.

While it can be locally somewhat common, at present G. annulatus is known from only three low-elevation rainforest sites in extreme southeastern Madagascar: Mandena, Sainte Luce and the Agnalaro Forest near Lake Ambavasohihy. In low-elevation forests, it is exclusively found in the leaf axils of Pandanus plants.

Life History, Abundance, Activity, and Special Behaviors
This species is a specialist of Pandanus ('screw pine') plants. Eggs are laid on Pandanus leaves above water filled leaf axils (clutch size averages 25 at Sainte Luce). Males and/or females may attend the egg clutches for up to six days or more before hatched embryos drop into the water to continue development. Tadpoles are detritivores and the larval stage lasts from two to three months. Tadpoles of this species are competitively superior to those of a syntopic species Guibemantis wattersoni but have a longer larval period. Recently metamorphosed juveniles average 9 mm SVL. Breeding is confined to the rainy season (December – March), though calling has been heard outside this span after heavy rains. Calling only occurs during the day. To the human ear, the advertisement call of G. annulatus sounds like a simple, soft “click”. These are emitted as single notes or in a succession of twos or threes at a peak frequency of approximately 4500 Hz. Mark-recapture studies have suggested that the maximum life span is less than 14 months. Populations at Sainte Luce have a highly female-biased sex ratio. Reported predators include an unidentified heteropodid spider and the colubrid snake Ithycyphus oursi.

Trends and Threats
This species was somewhat common at Sainte Luce from 2000-2002, occupying approximately 20% of surveyed plants during this period. However, very little lowland (littoral) rainforest remains in this area. Habitat destruction is the largest threat to this regional endemic.

Relation to Humans
Locals use Pandanus leaves to make baskets, etc. This can damage the host plants.

Comments
Transferred to the recently erected genus Guibemantis; older literature will often list this species under the genus Mantidactylus. Guibemantis annulatus is in the "G. pulcher" group (subgenus Pandanusicola).

Species authority: Lehtinen et al. (2011).

Etymology: The specific epithet annulatus refers to the white “rings” found below each finger or toe disc.

References

Lehtinen, R. M. (2002). ''The use of screw pines (Pandanus spp.) by amphibians and reptiles in Madagascar. .'' The Herpetological Bulletin, 82, 20-25.

Lehtinen, R. M. (2003). ''Parental care and reproduction in two species of Mantidactylus (Anura: Mantellidae).'' Journal of Herpetology, 37, 766-768.

Lehtinen, R. M. (2004). ''Tests for competition, cannibalism and priority effects in two phytotelm-dwelling tadpoles from Madagascar.'' Herpetologica, 60, 1-13.

Lehtinen, R. M. (2005). ''Competitive interactions and distributional dynamics in two Malagasy frogs.'' Journal of Tropical Ecology, 21, 569-576.

Lehtinen, R. M. (2009). ''The natural history of two plant-breeding frogs from Madagascar, Guibemantis bicalcaratus and G. punctatus (Anura: Mantellidae).'' Salamandra, 45, 39-49.

Lehtinen, R. M., Glaw, F., and Vences, M. (2011). ''Two new plant-breeding frog species (Anura: Mantellidae, Guibemantis) from southeastern Madagascar.'' The Herpetological Journal, 21, 95-112.

Lehtinen, R. M., and Carfagno, G. L. F. (2011). ''Habitat selection, the included niche and coexistence in plant-specialist frogs from Madagascar.'' Biotropica, 43, 58-67.

Species Account Citation: AmphibiaWeb 2012 Guibemantis annulatus: Ring-wearing Tree Frog <https://amphibiaweb.org/species/7653> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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