Description
Breviceps passmorei is a small or medium-sized frog, described from 19 males and 2 females. The males ranged in snout-vent length from 25.5 - 35.9 mm and the females were 43.2 and 46.9 mm in snout-vent length. The snout is short. The eyes are very small with horizontal pupils. It is difficult to distinguish the tympanic chamber. The skull has no ethmoid structure and has a single, forward contracting, toothless upper jaw. The whole body is nearly spherical, making the separation of the head and body difficult to distinguish. Their limbs are very short, strong and robust. The dorsum is granular (Minter et al. 2017).

Breviceps passmorei can be differentiated from other Breviceps species by, morphology, call, geography and habitat, and genetics. Breviceps passmorei has smaller eyes than B. branchi, B. macrops, and B. namaquensis. A facemask in B. passmorei separates it from B. acutirostris, B. fuscus, B. gibbosus, and B. macrops. Breviceps passmorei has a unique call duration and pulse that differentiates it from its relatives; B. passmorei has longer calls - with a mean duration of 0.305 s - compared to 0.193 s B. adspersus, 0.198 s in B. bagginsi, 0.05 s in B. mossambicus. However, it's call is shorter than B. verrucosis, which is 0.612 s. The strongly pulsed call of B. passmorei distinguishes it from the pulsatile calls of B. carruthersi and the tonal calls of B. macrops, B. namaquensis, B. poweri, and B. sopranus (Minter et al. 2017).

In life, B. passmorei is light brown to orange-brown with dark, scattered blotches that form a reticulated pattern on the dorsum. There are also 3 - 6 paravertebral patches and four dorsolateral patches. The tubercles are various shades of brown, bloack, and white with black tubercles in the regions near the spine and in dorsolateral patches and are unpigmented/white in the lateral regions. There is an interorbital bar and a light vertebral line that extends from the bar to the urostyle. The abdomen is white (Minter et al. 2017).

In preservative, the body is brown to dark grey and the blotches become dark. The paravertebral patches range from beige to dark grey. The dorsolateral patches are pale but distinct. The interobital bar is less conspicuous and ranges from beige to dark brown. The vertebral line ranges in distinctiveness (Minter et al. 2017).

There is little morphological variation, although the degree of dorsal granulation and coloration has some variation (Minter et al. 2017).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: South Africa

View distribution map in BerkeleyMapper.

The type locality for B. passmorei is to the west of Tembe Elephant Reserve, near the Phongolo River in the KwaZulu Natal Province, South Africa. All the sites where specimens are found were in sandy loam to clay loam soils with disturbed, but natural roadside vegetation (Minter et al. 2017).

Life History, Abundance, Activity, and Special Behaviors
Breviceps passmorei is a relatively rare species that prefers open, moist grassland, and forest or forest fringes. They are associated with water bodies after rains (Minter et al. 2017).

Males usually call in the evening and night after heavy summer rain from both concealed (under vegetation) and exposed sites to attract females. The calls may be very strongly pulsed with 21 - 63 pulses and a pulse rate per second of 86.47–163.2. Condensed calls occur under optimum conditions in groups of 2 to 3 calls. Groups of calls last 0.411 - 0.638 seconds with the period between calls ranging from 0.824 - 3.058 seconds. The call rate ranged from 19.73 - 98.6 calls per minute with a dominant frequency range of 1690 - 2110 Hz. Individual call durations range from 0.192 - 0.432 seconds (Minter et al. 2017).

During amplexus, the skin produces an adhesive secretion (Minter et al. 2017).

Trends and Threats
At the time of its description, B. passmorei, had only been found near the Tembe Elephant Reserve, in areas disturbed by a road (Minter et al. 2017). Its limited range makes it potentially susceptible to habitat loss. However its location near the Tembe Elephant Reserve may provide some protection against this. As of 2022, the species has not been assessed by the IUCN Red List.

Comments
Breviceps passmorei was recognized as a full species in part from phylogenetic analysis conducted on mitochondrial 16S rDNA sequences from eight Breviceps species. The Bayesian inference analysis shows B. passmorei formed a polytomy with B. carruthersi and a specimen assumed to be B. sopranos (Minter et al. 2017). This was supported in 2021 with a Maximum Likelihood analysis on 12S, 16S, RAG1, and SLC8a3 genes with B. passmorei being sister to B. carruthersi and the next most closely related clade being composed of B. adspersus pentheri, B. bagginsi, B. sopranos, along with four unnamed species (Heinicke et al. 2021).

Breviceps passmorei was named after Neville Passmore, for his great contributions and publications to South African herpetology in bioacoustics, particularly in frogs (Minter et al. 2017).

References

Heinicke, M.P., Beidoun, M.H., Nielsen, S.V., Bauer, A.M. (2021). “Phylogenetic analysis of ‘Breviceps adspersus’ documents B. passmorei Minter et al., 2017 in Limpopo Province, South Africa.” Herpetology Notes, 14: 397-406. [link]

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]

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]

Species Account Citation: AmphibiaWeb 2023 Breviceps passmorei: Passmore's Rain Frog <https://amphibiaweb.org/species/8666> University of California, Berkeley, CA, USA. Accessed May 5, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 5 May 2025.

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