Rose's Toad, Rose’s Mountain Toad, Rose’s Toadlet, Striped Mountain Toad, and Cape Mountain Toad
It has been noted that the tadpoles of C. rosei have been able to grow up to a total length of 21 mm in a slender conformation (du Preez and Carruthers 2009). The upper and lower tail fins are set parallel to each other and meet relatively parallel to the body of the tadpole (Channing 2001). The tail tip is blunt and rounded. The eyes are dorsolaterally located and the nostrils are small and lie closer to the eyes than the snout (du Preez and Carruthers 2009). The nostrils are spaced widely and approximately equivalent in distance as the eyes are from each other (du Preez and Carruthers 2009). The spiracle is located on the sinistral side of the body while the vent is located medially where the body and tail meet (Channing 2001). The mouth is located ventrally with a single row of papillae located at the mouth corners. For the labial tooth row formula, one source noted that it was 2(2)/3; however, an early source cited that it was 1(1)/3(1) (Channing 2001; du Preez and Carruthers 2009).
According to Atlas and Red Data Book of the Frogs of South Africa, Lesotho and Swaziland, C. rosei “cannot be confused with any other toad in its distribution range” (Minter et al. 2004) presumably because of its lack of a tympanum. Differentiating between C. rosei and C. tradouwi, is not difficult. Firstly, their ranges do not overlap. Morphologically and behaviorally, in contrast to C. rosei, C. tradouwi has a tympanum and an advertisement call, both of which the former lacks. Capensibufo rosei also “lays eggs in strings of jelly,” rather than as single eggs as C. tradouwi does (Minter et al. 2004). Also in contrast to C. rosei, C. tradouwi the anterior third of the parotid is not the widest part and the latter has a vertebral strip, white flecks on the belly that may fuse to form short lines, and a smaller parotid to snout-urostyle length ratio. From C. deceptus, C. rosei can be differentiated by the latter lacking a tympanum, a rounded umbraculum (vs. angular), and typically lacking a vertebral strip. From C. magistratus, C. rosei can be differentiated by the latter having incomplete dark rings without a thin outer white ring around their dorsal spots, a rounded umbraculum, having the widest part of the parotoid being the anterior third, typically lacking a vertebral strip, and having a solid colored or lightly speckled belly. From C. selenophos, the focal species can be differentiated by having incomplete dark rings without white lines around their dorsal spots, having the widest part of the parotid being the anterior third, typically not having a vertebral band, and having a solid or lightly speckled belly instead of white spots on a darker background (Channing et al. 2017).
Coloration of adult amphibians, as described in live specimens, ranges from grey to brown on the upper body surface. The underside is primarily white, although grey shading and dark markings may be present. The limb coloration is continuous with body coloration. The upper body has dark spots and blotches (Minter et al. 2004). A light vertebral stripe and a pair of dorsolateral bands are often present (du Preez and Carruthers 2009). The inverted, pear-shaped parotoid glands are usually red or orange, and other markings of this color may be found elsewhere on the upper body (Minter et al. 2004). There is also a pale interorbital bar (du Preez and Carruthers 2009). There is no sexual dimorphism in coloration and patterning. As for metachrosis, during the breeding season a bright pink oval patch appears below the vent in both sexes (Minter et al. 2004). The purpose of this patch is unknown, though some believe it may be involved in chemical attraction (Channing 2001). The iris is bronze in color.
Live specimens of tadpoles are dark in color, with the inner part of the tail being darker than the outermost part of the tail (du Preez and Carruthers 2009). The eggs are pigmented (Minter et al. 2004).
The literature is primarily in agreement with each other regarding coloration. However, Channing’s Amphibians of Central and Southern Africa says that the back is black or dark brown while all other sources say coloration ranges a shade lighter, from grey to brown (Channing 2001). This could be a matter of Channing not being explicit about if the coloration is in life or in preservative. Additionally, as noted above, there was dissent over the labial row tooth formula for tadpoles: Channing’s early book noting a 1(1)/3(1) formula while a more recent field guide by du Preez and Carruthers noting a 2(2)/3 formula (Channing 2001; du Preez and Carruthers 2009). Other features include sexual dimorphism of vent positions, male vents opens downwards while female vents open upwards (Minter et al. 2004).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: South Africa
The species is found on mountaintops and plateaus. This particular species has been noted to seek refuge among the native flora of the peninsula (Channing 2001). The species associates with small, temporary pools of water - although bodies of water are present year-round - primarily during the breeding season. These pools are relatively shallow (2 - 6 cm in depth) and consist of a dark, rocky foundation with a layer of peat and moss on top (Channing 2001; Minter et al. 2004).
Life History, Abundance, Activity, and Special Behaviors
Developed C. rosei do not call. They lack a tympanum and middle-ear elements that normally play a role in hearing; it is unknown how the females of this species are attracted by the males (Channing 2001). It is also unknown whether or not the frogs (males or females) engage in territorial behaviors. Information on what type of amplexus the males use when breeding has not been observed (Minter et al. 2004).
Breeding takes place in late winter to early spring, which is August to September in the Southern Hemisphere (Channing 2001) in large aggregations (Channing et al. 2017). Female C. rosei are oviparous and lay their eggs in small, shallow ponds formed during the rainy winter (Minter et al. 2004). Breeding pools range in size from 20 x 20 x 2 cm to 250 x 150 x 6 cm. The vegetation around the breeding pools primarily consists of restios, which are rush-like plants endemic to South. The species has not been recorded laying eggs in any moving water (Minter et al. 2004). The eggs, usually less than 100, are laid in single “strings” where each dark, beady egg (~1.6 mm in diameter) is connected to one another by a jelly-like tube (Channing 2001). An interesting behavior of C. rosei is that they lay very large egg masses, up to a thousand eggs in a single pool, and when they are disturbed or threatened the adults have been known to hide under the egg mass (Minter et al. 2004).
The tadpoles hatch from the eggs, which can take up to a total of 12 days due to the fact that they must exit the capsule that encases the eggs in a string-like manner (Minter et al. 2004). Parental care has not been observed in this species and it can be presumed that the adults do not perform parental behaviors (Minter et al. 2004).
The larvae prefer small, shallow ponds with dark substrate, which match their coloration and therefore would aid their ability to camouflage. It takes about 51 days before tadpoles of this species metamorphose (Channing 2001).
The diet of adult C. rosei is unknown but tadpoles of this species have been seen eating egg capsules as well as feeding on toad carcases (du Preez and Carruthers 2009). Anti-predator behavior has not been observed due to a lack of information on predators and prey of C. rosei (Minter et al. 2004).
It has not been determined whether or not the species produces toxins but it has been noted that their parotid glands (as well as other elevations on their skin) are colored red/orange, which is usually an indicator of aposematism (Minter et al. 2004).
Trends and Threats
In 2011, a national exercise prioritized the species for conservation work (Cressey et al. 2015). But in a 2015 survey, the species was not found in at least four known breeding sites described in the 1980s. This suggests local extinction, although it is possible individuals were present but unable to be found (Cressey et al. 2015). It is believed that a review on C. rosei by the IUCN would result in a relisting from vulnerable to endangered, which would highlight the need for more conservation action (Cressy et al. 2015). During field surveys it was noticed that the number of tadpoles were lower at Cape Point. This could be because of natural fluctuations in population size, but it raises concerns about the long-term survival of the population. The small population could suffer even more because of the genetic drift caused by a small breeding pool (Cressey et al. 2015). Because of all this, a research team studying the species suggests that because of their isolation from other populations, both Cape Peninsula populations should be managed as separate units. They also believe that conservation efforts need to focus on the growth and protection of each population and their environments. Ideally, the different populations would be connected using historically viable habitats because it would increase genetic diversity (Cressey et al. 2015).
Between 2010 and 2017, C. rosei was confirmed to be a species complex including at least four distinct clades. The IUCN Red List status was determined based on the full complex and not on the individual species. Thus it is likely that the species is in more dire conditions. As of 2017, only two known breeding populations were known with several other populations having disappeared by unknown causes (Tolley et al. 2010, Channing et al. 2017).
Possible reasons for amphibian decline
General habitat alteration and loss
Capensibufo rosei was initially placed in the genus Bufo until Grandison (1980) erected the genus Capensibufo. Until 2017, the genus only had two species, C. rosei and C. tradouwi, which could be differentiated by range and the lack of a tympanum in the former (Channing et al. 2017).
Prior to 2010, only two species of Capensibufo were recognized. However based on Bayesian, Maximum Likelihood, and Maximum Parsimony analysis of ND2 and 16S mitochondrial DNA, it was acknowledged that C. tradouwi had two distinct lineages and C. rosei had at least four distinct lineages (Tolley et al. 2010). In 2017, three new species in the C. rosei complex were described and named, C. deceptus, C. magistratus, and C. selenophos (Channing et al. 2017). From the two studies, it appears that C. rosei is equally related to the clade formed by the population from du Toitsberg (C. deceptus) and to the clade formed by populations from Klein River Mountain (C. selenophos), Akkedisberg, Landdroskop (C. magistratus), Jonaskop, and Hawekwas.
The species C. rosei was named after Walter Rose, a Cape naturalist and herpetologist who contributed quite a bit to the knowledge of frog natural history (du Preez and Carruthers 2009; Channing et al. 2017).
Channing, A. (2001). Amphibians of Central and Southern Africa. Cornell University Press, Ithaca, NY.
Channing, A., Measey, G.J., de Villiers, A.L., Turner, A.A., Tolley, K.A. (2017). ''Taxonomy of the Capensibufo rosei group (Anura: Bufonidae) from South Africa.'' Zootaxa, 4232(2), 282-292.
Cressey, E.R., Measey, G.J., Tolley, K.A (2015). ''Fading Out of View: the Enigmatic Decline of Rose’s Mountain Toad Capensibufo rosei.'' Oryx, 49(3), 521-528.
Du Preez, L., and Carruthers. V. (2009). A Complete Guide to the Frogs of Southern Africa.
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..
South African Frog Re-assessment Group (SA-FRoG), IUCN SSC Amphibian Specialist Group. 2010. Capensibufo rosei. The IUCN Red List of Threatened Species 2010: e.T3776A10070549. Accesses February 6, 2017 from http://dx.doi.org/10.2305/IUCN.UK.2010-3.RLTS.T3776A10070549.en
Tolley, K. A., de Villiers, A. L., Cherry, M. I., Measey, G. J. (2010). ''Isolation and high genetic diversity in dwarf mountain toads (Capensibufo) from South Africa.'' Biological Journal of the Linnean Society, 100, 822–834.
Written by Candice Rose, Jonah Pyo, Kassandra Schneider (crrose AT ucdavis.edu, jypyo AT ucdavis.edu, kschneider AT ucdavis.edu), University of California Davis
First submitted 2017-07-27
Edited by Ann T. Chang; updated by Ann T. Chang (2017-07-29)
Species Account Citation: AmphibiaWeb 2017 Capensibufo rosei: Rose's Toad <http://amphibiaweb.org/species/319> University of California, Berkeley, CA, USA. Accessed Nov 15, 2019.
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Citation: AmphibiaWeb. 2019. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 15 Nov 2019.
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