Description
Breviceps rosei is a frog that was first identified by Power in 1926, and its species description is based on a single specimen collected on the Cape Flats. It has a small body, with females reaching a snout-vent length up to 36 mm while males are generally shorter than 15 mm. Consistent with the Breviceps genus, B. rosei has a narrow mouth and moderately built legs. It tends to have a rounded chin and a prominent snout. Its eyes are located at a distance 11 ⅔ times into the length of the body, which is greater than the distance between its nostril and anterior angle. The slender fingers and toes taper toward the tips, with the fourth finger being ⅔ as long as the second finger and the toe being slightly shorter than the second. The outer metatarsal forms a large, hard, subcircular pad. Conversely, its inner metatarsal is large with a blunt edge, positioned 30 degrees to the axis of the longest toe. Its palms, as well as the bases of its fingers and toes, are covered with large, circular tubercles. Its body is mostly smooth with faint blister-like growths. The forehead, subocular region, area of the head behind the eyes, sides of the body, and abdominal region have a fine granular texture. The surfaces of the chin and upper arms also have a faint granular feel. Meanwhile, the upper surfaces of the legs and feet are smooth to the touch while the soles of its feet are wrinkled (Power 1926, Channing 2001).

DIAGNOSIS:

Breviceps rosei is smaller with a smoother, more slender body than B. gibbosus; it also has a longer snout. The angle of B. gibbosus’s metatarsal tubercle is different, and the respective pelvic arch dimensions of both species differ (Power 1926). Breviceps gibbosus also has a densely granular belly that lacks the ventral smoothness of B. rosei. Breviceps sylvestris has dorsal paravertebral ridges that are not found in B. rosei. On their feet, B. rosei does not have the fleshy webbing of B. macrops. It is deficient in a visible tympanum seen in B. verrucosus, B. poweri, and B. acutirostris. It has singular tubercles on its fore-digits unlike the double tubercles observed in B. namaquensis. Breviceps rosei also has an outer toe as long as it is wide, while B. poweri has a minute outer toe (Channing 2001).

COLORATION:

In life, B. rosei is characterized by its dark color with vague brown markings on its head. It has brown patches on its forehead between its eyes and on the side of its head behind its eyes. On the ventral surface, its sides and belly are whitish, speckled with black. Wavy black lines streak the submental region and chest (Power 1926).

VARIATION:

Occasionally, a thin stripe is present along the vertebrae with a perpendicular line joining the two hindlimbs through the vent. This stripe often appears jagged, with many gaps or branches. Male throats are slightly granular and darker than female throats. The underside of B. rosei can also be slightly granular (Channing 2001).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: South Africa

View distribution map in BerkeleyMapper.

Breviceps rosei is found in the low-lying sandy areas along the southwestern Cape Coast, Cape Peninsula (van Dijk 1982), and Cape Flats of South Africa. These areas are known for their dense sedges and other low coastal vegetation (Channing 2001). They are also characterized by winter rainfall, with precipitation typically starting in late May with sporadic showers and intensifying from June to the end of September (Visser 1979). Breviceps rosei settle in the soils of coastal thickets, vegetated dunes, and in the fynbos heathlands closer inshore. No elevation has been recorded for this species (IUCN 2013).

Life History, Abundance, Activity, and Special Behaviors
Male B. rosei begin their mating call from midwinter in July and continue with sporadical calls into summer in January. The call sounds like a short whistle with a dominant frequency of 2.1 kHz and a duration of 0.1 seconds. To make their calls, B. rosei often climbs fallen sedges from 30 cm to a meter above ground (Channing 2001).

Callings males drop out of vegetation when disturbed or interrupted. Since it falls from such a high vantage point, it sometimes becomes entangled in dense sedge stems and is forced to wriggle and worm its way back to earth (Channing 2001).

Females approach the males at ground level. During amplexus, the male assists the female as they burrow by making digging motions with his hind feet. Females lay eggs in burrows created with the help of the male, who remains glued to her back. During burrowing, glued male and female B. rosei have been observed to have “waterproofed” themselves by forming a mucous cocoon. It is suggested these eggs directly develop inside the burrow like other Breviceps species (Channing 2001). Breviceps rosei lays eggs in the spring, since the waterlogged, moist conditions of winter can potentially harm the eggs (Visser 1979).

Evidence of competition exists between B. rosei and B. montanus, since they share habitats in Hout Bay. This may contribute to B. montanus associating with bedrock soils, which B. rosei tends to avoid (van Dijk 1982).

They are parasitized by the Cosmocercoid nematode, Aplectana capensis, which attaches to the B. rosei's large intestine (Baker 1981).

Larva
Like all other Breviceps, the offspring of B. rosei undergoes direct development in the egg (Minter 1998).

Trends and Threats
Breviceps rosei is highly adaptable and not significantly at-risk. Urbanization, industrialization, tourism, and agricultural development lead to habitat loss for this species. Invasive alien species and diseases also affect the B. rosei population. (IUCN 2013).

Relation to Humans
There are no reports of B. rosei being utilized in human trade.

Possible reasons for amphibian decline

General habitat alteration and loss
Intensified agriculture or grazing
Urbanization
Predators (natural or introduced)
Introduced competitors

Comments

PHYLOGENETIC RELATIONSHIPS:

Optimized Maximum Likelihood and Bayesian Inference trees were derived from partial sequences of the 12S and 16S ribosomal rRNA genes as well as RAG1, BDNF, SLC8A3 nuclear genes. The analysis found that B. rosei is most closely related to B. montanus. The two species also form a clade with B. gibbosus (Nielsen 2018).

References

Baker, M. R. (1981). Cosmocercoid nematode parasites from frogs of southern Africa. Koedoe 24, 25-32. [link]

Channing, A. (2001). Rain Frogs, Rubber Frogs—Family Microhylidae. In Amphibians of Central and Southern Africa (pp. 209–236). Cornell University Press. [link]

IUCN SSC Amphibian Specialist Group. (2013). Breviceps rosei. The IUCN Red List of Threatened Species 2013: e.T57719A3062565. [link]. Accessed on 07 September 2023.

Minter, L. R. (1998). Aspects of the reproductive biology of Breviceps. Unpublished PhD thesis. University of the Witwatersrand, Johannesburg. [link]

Nielsen, S. V., Daniels, S. R., Conradie, W., Heinicke, M. P., Noonan, B. P. (2018). Multilocus phylogenetics in a widespread African anuran lineage (Brevicipitidae: Breviceps) reveals patterns of diversity reflecting geoclimatic change. Journal of Biogeography, 45(9), 2067–2079. [link]

Visser, J. (1979). Calling and spawning dates of the south-western Cape Frogs. The Journal of the Herpetological Association of Africa 21, 21-28. [link]

Species Account Citation: AmphibiaWeb 2024 Breviceps rosei: Rose's Rain Frog <https://amphibiaweb.org/species/2381> University of California, Berkeley, CA, USA. Accessed Dec 28, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 28 Dec 2024.

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