Red-Banded Rubber Frog, Red-banded Frog, South African Snake-Necked Frog
© 2003 John White (1 of 20)
The common name derives from the rubber-like appearance and texture of the frog's smooth and shiny skin, which feels dry when handled. This frog has shiny black or dark brown skin with continuous or interrupted vivid red or orange bands extending from the snout over the eyelids to the back of the body. There is also a large red or orange spot on the posterior dorsum, in the caudal region. Limbs have red bars or spots. Ventrally this frog is light brown or gray with dense, distinct white spotting (Wager, 1986; Passmore and Carruthers, 2005). Males have a black throat. (Wager, 1986; Zweifel, 2003).
The tadpole of P. bifasciatus reaches 37 mm in total length, with a body length of 12 mm and tail length of 25 mm (Wager, 1986). It has a tail that narrows to a thin, whiplike flagellum (Wager, 1986). Eyes are at the sides of the head (Zweifel, 2003). Both external gills and suckers are present at hatching. The tadpole's appearance is unusual, with a pointed head and slit-like terminal mouth that lacks keratinized jaws, teeth, and papillae. The upper lip is straight and flat, while the lower lip is spatulate, shaped like a V and projecting slightly (Donnelly et al., 1990). No flaps are present on the lips, unlike the related species P. annectens, which has labial flaps on either side of the lower lip, adjacent to the infralabial prominence, and P. microps, which has a large flap on the upper lip (Donnelly et al., 1990). The spiracle is medial and opens near the vent (Donnelly et al., 1990) and is somewhat enlarged, at 2 mm wide (Wager, 1986). The body is mostly transparent, except for the coiled intestine, and has tiny black dots on the mid-back (Wager, 1986). Tail fins have black, sometimes red, narrow bands along the outside edges (Wager, 1986).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Angola, Botswana, Congo, the Democratic Republic of the, Kenya, Malawi, Mozambique, Namibia, Somalia, South Africa, Swaziland, Tanzania, United Republic of, Zambia, Zimbabwe
Life History, Abundance, Activity, and Special Behaviors
During the mating season, P. bifasciatus breeds in temporary rain pools (Zweifel, 2003). These frogs will gather in a large chorus, which may sometimes consist only of this species (rather than a multi-species group) to breed soon after a rainstorm (Wager, 1986). While swimming, they inflate and float, with all four legs kicking over short distances; in contrast, over long swimming distances they kick only with the back legs (Wager, 1986). Males call from shallow water or the water's edge, remaining exposed while calling (Passmore and Carruthers, 2005). The call is loud and audible for over a kilometer, and consists of a melodious high-pitched "porreeeee," or a slightly lower "perrooooo" with a duration of about 2 seconds and a pause of about 5 seconds in between calls (Wager, 1986).
Amplexus is axillary (Zweifel, 2003). Females deposit a clutch of about 600 eggs (Wager, 1986) up to 1,500 eggs (Zweifel, 2003). The egg mass is attached to floating vegetation (Wager, 1986). Eggs have a diameter of 1.3 mm within jelly capsules of 5 mm, and the whole egg mass is about 75 mm in diameter (Wager, 1986).
Tadpoles hatch after four days (Wager, 1986). The tadpole of P. bifasciatus is a midwater nektonic filter-feeder (Passmore and Carruthers, 2005). The V-shaped lower lip constantly moves in and out, to suction in water containing microorganisms such as unicellular algae, desmids, diatoms, and Volvox (Wager, 1986). Since a large amount of water needs to be suctioned, the spiracle through which the water enters is correspondingly enlarged at 2 mm in width (Wager, 1986). During filter-feeding, the tadpole suspends itself motionless at a steep angle in the water column, except for the tail tip vibration and sucking mouth (Wager, 1986). However, it is also capable of rapid and agile movement (Wager, 1986). Larval development takes approximately a month (Wager, 1986). Metamorphosis occurs at a body size of about 13 mm (0.5 inches) (Zweifel, 2003).
The secretions from P. bifasciatus skins can cause skin irritation in humans (Jaeger, 1971), and are lethal to many other anurans, in addition to being highly toxic to mammalian heart cells (Passmore and Carruthers, 2005). The mechanism of toxin action appears to be through potassium channels (Passmore and Carruthers, 2005).
Frogs of the families Microhylidae and Hemisotidae have the ability to aim their tongues laterally, independent of head or jaw movements, when shooting them out to capture prey. Phrynomantis bifasciatus shows the most extreme lateral aim of any frog known, extending its tongue over an arc of more than 200 degrees in the frontal plane. This means P. bifasciatus can extend its tongue to capture prey at an angle of greater than 90 degrees from the midline of the head (in other words, it can even aim slightly backwards). This lateral tongue aiming is controlled by a muscular hydrostatic mechanism (in common with other frogs of the families Microhylidae and Hemisotidae) (Meyers et al., 2003).
Trends and Threats
Donnelly, M.A., de Sa, R.O., and Guyer, C. (1990). ''Description of the tadpoles of Gastrophryne pictiventris and Nelsonophryne aterrima (Anura: Microhylidae), with a review of morphological variation in free-swimming microhylid larvae.'' American Museum Novitates, 2976, 1-19.
IUCN, Conservation International, and NatureServe. 2006. Global Amphibian Assessment: Phrynomantis bifasciatus. www.globalamphibians.org. Accessed on 11 January 2008.
Jaeger, R. G. (1971): ''Toxic reaction to the skin secretions of the frog, Phrynomerus bifasciatus.'' Copeia, 1971, 160-161.
Meyers, J. J., O'Reilly, J. C., Monroy, J. A., and Nishikawa, K. C. (2003). ''Mechanism of tongue projection in microhylid frogs.'' The Journal of Experimental Biology, 207, 21-31.
Wager, V. A. (1986). Frogs of South Africa: Their Fascinating Life Stories. Delta Books, Craighall.
Zweifel, R. G. (2003). ''Banded rubber frog, Phrynomantis bifasciatus.'' Grzimek's Animal Life Encyclopedia, Volume 6, Amphibians. 2nd edition. M. Hutchins, W. E. Duellman, and N. Schlager, eds., Gale Group, Farmington Hills, Michigan.
Written by Kellie Whittaker, Peera Chantasirivisal (Kris818 AT berkeley.edu), UC Berkeley
First submitted 2005-10-20
Edited by Kellie Whittaker (2008-01-16)
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