Description
Breviceps carruthersi is a very spherical shaped frog, like most species in the genus. It has an average snout-vent length of 34 mm. Like other species in the genus, it has an almost non-existent snout, indistinguishable tympanum, small eyes, and horizontal pupils. Breviceps carruthersi has glandular skin with irregular folds and multiple tubercles of varying sizes, making it appear bumpy. Its vent is terminal. This frog has very short limbs that are held close to the body when at rest, no webbing on the digits, and a very short outer toe (Minter et al. 2017).

The very short outer toe differentiates B. carruthersi from most other species except B. acutirostris, B. adspersus, B. bagginsi, B. mossambicus, B. passmorei, B. poweri, B. rosei and B. sopranus. It can be distinguished from all other species by its advertisement call, which is pulsating, except for B. branchi, whose call is unknown. Other Breviceps have either pulsed or tonal calls (Minter et al. 2017).

In life, this species has a light-orange to brown coloration on its dorsum with darker tubercles forming a border around patches of color similar to that of B. adspersus, B. poweri and B. bagginsi. Breviceps carruthersi has a visible facial mask, dark black stripes running from its bottom eyelid to the base of its arms, and a milky white smooth ventrum (Minter et al. 2017).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: South Africa

View distribution map in BerkeleyMapper.

Breviceps carruthersi’s geographical distribution is limited to only one location, Hluhluwe, Northern KwaZulu-Natal in South Africa at elevations that range from 88 m to 123 m. Breviceps carruthersi can be found inhabiting areas with three habitat types. Two are the Southern Lebombo Bushveld and Western Maputaland Clay Bushveld vegetation types. It is also found in soils that contain more sand like material such as the Maputaland Coastal Belt, but Breviceps carruthersi is seen less so in this habitat type than the other two types (Minter et al. 2017; Mucina and Rutherford 2006).

Life History, Abundance, Activity, and Special Behaviors
Breviceps carruthersi is a rare, largely nocturnal amphibian that can be difficult to locate due to their fossorial nature (Nielsen 2018). There is no evidence of its association with water bodies (Minter 1998).

The breeding season of B. carruthersi occurs between late November and January when there is an abundance of rain, and choruses usually begin after the first heavy rain, but low temperatures can delay breeding (Minter 1998).

Only the males vocalize, and their purpose is for courtship. These calls are pulsatile. Most of the calls observed did not have easily distinguishable amplitude modulation, but those that did had a gradual increase and a sharp fall at the end of the call, with no frequency modulation present. The frequency of the calls was between 2182 – 2481 Hz, with a mean of 2378 Hz. The duration was between 0.05 - 0.10 seconds with a mean of 0.07. The calls are made primarily from exposed surface positions, while some were made from shallow depressions in the ground. During calls, the white stripe separating the gular patch from the dark eye stripe is conspicuous as the vocal sac inflated, which might function as a visual signal (Minter et al. 2017).

Normal amplexus is impossible because males are significantly smaller than females. To make up for it, both males and females of the species secrete an adhesive that allows them to remain attached during the mating process (Minter 1998).

Females of the species are oviviparous and lay eggs in batches of 20 - 50 beneath the soil, or underneath rocks and logs, and deposit a layer of eggless capsules on top of them (Minter 1998). Due to a lack of viable aquatic environment, the species is direct developing (Schweiger et al. 2017). Females remain close to their egg chamber until development is complete, lasting between 6 and 8 weeks, but the reason for her presence is unknown. After the eggs hatch, the offspring turn the remaining eggless capsules and liquid into a froth and remain there until completing their development (Minter 1998).

They are poor dispersers (Schweiger et al. 2017).

Adults are insectivores and consume ants, termites, beetles, caterpillars, and other small arthropods. Breviceps carruthersii are prey upon by various snakes and birds such as the night adder, vine snake, olive thrush, and fiscal shrike (Minter 1998). They do not have aposematic body coloration, but have camouflage patterning and color (Minter et al. 2017)

Trends and Threats
This specific population is stable for now, but because of their limited distribution, they are still likely to be of conservation concern (Measey 2011; Reeder 2019). The biggest threats are loss of habitat to urbanization and climate change (Channing et al. 2013; Stanley and Bates 2014; Travers et al. 2014; Stuart et al. 2004; Reeder 2019). Breviceps carruthersi does not occur in any protected areas, but is found in a private game reserve, called Phinda Game Reserve, which is somewhat preserved for human recreational purposes (Minter et al. 2017).

Possible reasons for amphibian decline

General habitat alteration and loss
Urbanization
Climate change, increased UVB or increased sensitivity to it, etc.

Comments

PHYLOGENETIC RELATIONSHIPS:

Breviceps carruthersi is not found within 180 – 3600 km of most other species in this genus (Minter et al. 2004). Furthermore, they are allopatrically diverged due to unsuitable habitats as climate change occurred over time (Nielsen 2018). As such, B. carruthersi is considered a geographically isolated species (Minter et al. 2004).

ETYMOLOGY:

The species epithet, “carruthersi” is in honor of Vincent Carruthers who has produced numerous books and articles on South Africa and especially the frog species found there (Minter 2017).

References

Channing, A., Schmitz, A., Burger, M., Kielgast, J. (2013). “A molecular phylogeny of African Dainty Frogs, with the description of four new species (Anura: Pyxicephalidae: Cacosternum).” Zootaxa, 3701, 518– 550. [link]

Minter, L. R. (1998). Aspects of the reproductive biology of Breviceps. Unpubl. Ph. D. thesis, University of the Witwatersrand.

Minter, L.R., Burger, M., Harrison, J.A., Braack, H.H., Bishop, P.J., and Kloepfer, D. (eds.) (2004). Atlas and Red Data Book of the Frogs of South Africa, Lesotho and Swaziland. Volume 9 SI/MAB Series. Smithsonian, Washington D.C..

Minter, L.R., Netherlands, E.C., Du Preez, L.H. (2017). "Uncovering a hidden diversity: two new species of Breviceps (Anura: Brevicipitidae) from northern KwaZulu-Natal, South Africa." Zootaxa, 4300.2, 195–216. [link]

Mucina, L., Rutherford, M.C. (2006). The Vegetation of South Africa, Lesotho and Swaziland. South African Biodiversity Institute, Pretoria, South Africa.

Nielsen, Stuart 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]

Phaka, F.M., Netherlands, E.C., Kruger, D.J.D., Du Preez, L.H. (2019). Folk taxonomy and indigenous names for frogs in Zululand, South Africa. J Ethnobiology Ethnomedicine 15, 17. [link]

Reeder, Elsabe, Jani. (2019). “Amphibians of Northern KwaZulu-Natal: A Phylogenetic Study”. North-West University. [link]

Schweiger, S., Naumann, B., Larson, J.G., Möckel, L., Müller, H. (2017) “Direct development in African squeaker frogs (Anura: Arthroleptidae: Arthroleptis) reveals a mosaic of derived and plesiomorphic characters.” Organisms Diversity & Evolution, 17, 693–707. [link]

Stuart, S. N., Chanson, J. S., Cox, N. A., Young, B. E., Rodrigues, A. S. L., Fischman, D. L., and Waller, R. W. (2004). ''Status and trends of amphibian declines and extinctions worldwide.'' Science, 306, 1783-1786.

Species Account Citation: AmphibiaWeb 2023 Breviceps carruthersi: Isinana sakwaPhinda (Zulu) <https://amphibiaweb.org/species/8665> University of California, Berkeley, CA, USA. Accessed Sep 14, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 14 Sep 2024.

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