Desert rain frog, Boulenger's short-headed frog, Melkpadda (Afrikaans), Woestynreenpadda
© 2004 Robert C. Drewes (1 of 4)
Diagnosis: Breviceps macrops has a globose body, short snout and large eyes. It can be distinguished from other rain frogs in southern Africa by the combination of a smooth venter with a transparent vascular window (this character alone distinguishes it from all except B. namaquensis; see photo of the venter in Du Preez and Carruthers 2009); a weakly developed (if present) single basal subarticular tubercle on the hand (double in B. namaquensis); specialized feet, which are paddle-like and smooth and have thick fleshy webbing (unique to B. macrops); exceptionally large and protruding eyes (present also in B. namaquensis); lack of a facial mask (present in B. fuscus, B. gibbosus, sometimes present in B. acutirostris), and locality; this species is confined to a rather narrow coastal strip in northwest Namaqualand (Du Preez and Carruthers 2009).
Description: Breviceps macrops is a short and stout frog, with a body length ranging from 4 mm to 6 mm (Boulenger 1907). It is a specialized burrower, with a spherical body and paddle-like feet (Channing and Wahlberg 2011). The venter has a transparent vascular window in the central and posterior regions of the abdomen. The tympanum is not visible in this species (Boulenger 1907). Eyes are strikingly large and prominent in this small frog (Boulenger 1907). Subarticular tubercles on the hand are absent or weakly developed; if present they are always single (Channing 2001). The extremely short limbs make it impossible for this frog to hop, although it can walk (Boulenger 1907). The coloration of this frog is predominantly yellow and brown, closely matching that of its habitat (Boulenger 1907). The dorsal surface bears smooth warts (Boulenger 1907). Dorsal markings are unique to individual frogs and identification of individuals can be made by photographs (Channing and Wahlberg 2011), although Channing (2001) also reports that the dorsal pattern is usually concealed by a layer of sand adhering to the skin. Males have a deeply wrinkled gular region (Du Preez and Carruthers 2009).
This frog has extensive webbing on its feet, in contrast to other members of the genus Breviceps. Carruthers and Passmore (1978) conjecture that the foot webbing enables traction on loose sand, as the frog moves about on the surface of its sand dune habitat at night (based on its distinctive tracks).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Namibia, South Africa
Life History, Abundance, Activity, and Special Behaviors
This frog is nocturnal, emerging after dark from under the sand on both misty and clear nights. It searches for dung, where it feeds on beetles and moths, and can be followed by its distinctive tracks in the sand dunes (Channing 2001).
At McDougall's Bay, reproduction peaked between June and October, with juveniles found present only during that time span (Channing and Wahlberg 2011). The call is a subdued long drawn-out rising whistle with a dominant frequency of 1.3 kHz and duration of about 200 ms (Channing 2001), with males calling from small excavated depressions or from exposed positions after periods of onshore fog (Du Preez and Carruthers 2009). Males may call in choruses, where one male initiates a call and is subsequently followed by others (Channing 2001). Clutch size is not known for B. macrops, but for other species in the genus Breviceps, clutches range from 13-43 eggs (Channing and Wahlberg 2011).
Individuals were collected at a depth of 10-20 cm below the sand dune's surface; at this depth the sand is moist. A buried frog can be located by a small conical mound of sand on the dune surface, created during the process of its digging down under the surface (Carruthers and Passmore 1978).
Trends and Threats
Namaqualand is rich in diamond and copper deposits. Diamond mining activities (via strip mining) have altered the habitat and caused pollution due to runoff (Smallberger 1975; Channing and Wahlberg 2011), as well as fragmenting populations (Minter 2004). Encroachment by humans has further contributed to habitat loss (Smalberger 1975). Housing development in coastal sand dune areas is threatening habitat as well (Channing and Wahlberg 2011).
Possible reasons for amphibian decline
General habitat alteration and loss
Boulenger, G. A. (1907). ''Description of a new engystomatid frog of the genus Breviceps from Namaqaaland.'' The Annals and Magazine of Natural History; Zoology, Botany, and Geology. 7th series, 20, 46-47.
Carruthers, V. C., and Passmore, N. I. (1978). ''A note on Breviceps macrops Boulenger.'' The Journal of the Herpetological Association of Africa, 18(1), 13-15.
Channing, A. (2001). Amphibians of Central and Southern Africa. Cornell University Press, Ithaca.
Channing, A., and Wahlberg, K. (2011). ''Distribution and conservation status of the desert rain frog Breviceps macrops.'' African Journal of Herpetology, 60(2), 101-112.
Cowling, R. and Pierce, S. (2001). Namaqualand: A Succulent Desert. South Africa Fernwood Press, Johannesburg.
Du Preez, L., and Carruthers. V. (2009). A Complete Guide to the Frogs of Southern Africa.
Minter, L. R. (1998). Aspects of the reproductive biology of Breviceps. Unpubl. Ph. D. thesis, University of the Witwatersrand.
Minter, L. R. (2004). ''Breviceps macrops Boulenger, 1907.'' Atlas and Red Data Book of the Frogs of South Africa, Lesotho and Swaziland. SI/MAB Series #9. Smithsonian Institution, Washington, D. C., 180-182.
Smalberger, J. M. (1975). Aspects of the History of Copper Mining In Namaqualand 1846-1931. C. Struik, Cape Town.
Van Jaarsveld, E. (1987). ''The succulent riches of South Africa and Namibia.'' Aloe, 24, 45-92.
Written by Nery Castillo (ncastillo AT csustan.edu), CSU Stanislaus
First submitted 2011-06-23
Edited by Kellie Whittaker (2011-12-20)
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