Description
Schismaderma branchi is a moderate-sized toad described from four male specimens and one female specimen. The males have a snout-vent length range of 53.8 - 66.7 mm and the female is 68.7 mm. The head is generally triangular, being slightly longer than it is wide. The short snout is approximately one third the length of the head and extends slightly beyond the upper jaw. The snout is rounded in all views. The nostrils are small, located closer to the snout than they are to the eyes, and directed dorsolaterally. The space between the nostrils is relatively flat. The canthus rostralis is rounded and the loreal region is concave. The eyes are prominent, but do not project beyond the margin of the head in the dorsal view. In the lateral view, half of the eye projects beyond the margin of the head. The eye diameter is larger than the distance between the eye and the nostril but smaller than the interorbital distance. The pupil is elliptical and oriented horizontally. The distinct tympanum is slightly larger than the diameter of the eye. There are no parotoid glands. Both the ventral and dorsal skin is granular, and the dorsal side has flat warts and conical asperites. There is a large ridge of glands that extends from above the tympanum to near the leg insertion. The limbs are robust and well-developed. The hand is approximately the same length as the forearm. The relative finger lengths are IV > III > I > II. There is no webbing on the hands and the fingers lack terminal discs and bulbs. The nuptial pads are inconspicuous. The legs are robust, with the thigh being slightly longer than the tibiofibula, and the tibiofibula being longer than the foot. A tarsal fold is present. The foot has a prominent ovular inner metatarsal tubercle that is more than half the size of the shortest toe and twice the size of the outer metatarsal tubercle. The space between the metatarsal tubercles has an oval skin abrasion. The relative toe lengths are IV > III = V > II > I and the toes have rounded tips. The first three phalanges of the fourth toes lack webbing, but webbing reaches the distal phalanges on the rest of the toes. The toes have small, singular subarticular tubercles (Baptisa et al. 2021).

DIAGNOSIS:

Like the only other member of its genus, S. carens, S. branchi has horizontal pupils, obvious tarsal folds, an external tympanum, glandular dorsolateral ridge connecting the tympanum to the groin, no external parotoid gland, no hard claws on toes as adults, reddish dorsal coloration, and a white ventrum with black reticulations. These features distinguish the genus from other African bufonids. However, the two species can be differentiated by a variety of morphological characters, coloration, and geography. Specifically, S. branchi is on average smaller than S. carens. There are also fewer tubercles on the hands and feet of S. branchi and the ones that are present are smoother and overall less prominent. Schismaderma branchi also has a larger inner metatarsal tubercle when compared to the shortest toe than S. carens does. Additionally, the ventral surfaces of S. branchi are mottled heavier with black than S. carens, which either has few black markings or none at all. And, from the few specimens available, it seems that the majority of S. branchi lack paired dorsal sacral markings while the majority of S. carens have them (Baptista et al. 2021).

COLORATION:

In life, the dorsal coloration is bright red with sacral markings. The conical asperities on the dorsum have a pale edge and very minute dark tip. The iris is golden. However, the species was only observed in its breeding season and it is unclear whether their coloration varies seasonally like in S. carens (Baptista et al. 2021).

After being preserved in formalin for four years, the red dorsal color faded to a dull, uniform grayish-brown color. Most specimens had no dorsal markings, but one had a pair of mid-dorsal, dark blotches. The center of the tympanum is paler than the rest of the tympanum, which is a similar color as the dorsum. The lateral ridge is darker below and lighter above. The flanks are slightly darker than the dorsum and have black splotches. The dorsal surfaces of the fore- and hind limbs have smaller dark blotches, with the forelimb background color being white like the ventrum while the background color of dorsal surface of the hind limbs is similar to the color of the dorsal body. The ventral side is white with extensive black mottling, which is slightly thicker anteriorly. The ventral background coloration extends to the dorsal surface of the fingers. The soles of the hands and feet are black except for white tubercles. The webbing is also black with a thin white edge and the vocal sac is gray (Baptista et al. 2021).

VARIATION:

There is some variation in coloration of the specimens that have been collected (see above). Additionally, females seem to be larger than males (Baptista et al. 2021).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Angola

View distribution map in BerkeleyMapper.

As of 2023, S. branchi has only been found at four sites, all within 5 km of each other along one road in central Angola. This road passes over small tributaries of the Lussechi and Loge rivers between the towns of Mussolo and Quirima. The nearby town of Quirma has an elevation of approximately 1300 meters. All specimens that have been observed were found in small but relatively deep temporary ponds that lacked vegetation besides flood grass. The surrounding environment consists of mesic woodlands and savannas with a nearby floodplain. While individuals have only been found in the Luando River sub-basin, it is likely that the true distribution is wider than the 5 km that the species has been found in, as the region is under-surveyed (Baptista et al. 2021).

Life History, Abundance, Activity, and Special Behaviors
Specimens were observed in small but relatively deep temporary ponds that lacked vegetation besides flooded grass. However, the species is thought to be terrestrial outside of the breeding season like the conspecific S. carens (Baptista et al. 2021).

Schismaderma branchi, which develop deep red coloration in the mating season, typically mate during the early rains, occurring between September and October. Breeding occurs during the day, in both small temporary pools, which range from 2 to 5 meters across and 1 to 2 meters deep, and in murky, rain-filled depressions. The small pools are often associated with small streams connected to inland lakes, however, the toads were not found in the latter two water sources (Baptista et al. 2021).

Chorusing males call loudly while floating in the shallow edges of the ponds with distinct, deep “whoob, whoob” vocalizations consisting of a single, repeated, pulsed note that last for 0.70 - 0.80 seconds at 1.81 - 2.73 second intervals for an average call rate of 24.57 calls/minute. Notes had 61 - 64 pulses per note and a pulse repetition rate of 76.05 - 87.98 pulse/second. The dominate frequency was 375.0 Hz, but had a frequency bandwidth of 281.25 - 562.5 Hz. Male calls can alternate or overlap between individuals (Baptista et al. 2021).

Single strings of eggs are left floating in the water, attached to vegetation (Baptista et al. 2021).

Sympatric amphibian species are Afrixalus wittei, Hyperolius angolensis, H. benguellensis, H. cinnamomeoventris, Kassina senegalensis, Leptopelis bocagii, Ptychadena anchietae, Sclerophrys gutturalis, and S. pusilla (Baptista et al. 2021).

Larva
At Gosner stage 26, the body length is 5.3 - 7.8 mm and the total length is 13.7 - 17.8 mm, making the tail 135% of the body length. The body is round to ovoid, with the width and the height being about equal. In the dorsal view the snout is rounded while in the lateral view it is oblique. The round nostrils are large, positioned laterally, and closer to the snout than the eyes. The moderately-sized eyes are positioned and directed dorsally with an obvious central parietal eye. Near the dorsal junction of the head and body, there is a vascularized horse-shoe-like flap, whose posterior edge is free of the body. The mouth is directed ventrally. The small, sinistral spiracle is positioned laterally at the mid-body and joined to the body wall. The intestines are visible through the ventral skin (Baptista et al. 2021).

Tadpoles are extremely similar in morphology and behavior to those of S. carens with oval bodies, a horse-shoe-like vascularized fold of skin on the back, and forming compact schools of individuals (Baptista et al. 2021).

In preservative, the body is dark brown-black with a pale ventrum that has scattered dark spots. The skin on the anterior ventrum is transparent. The tail musculature has heavier pigmentation than the fins (Baptista et al. 2021).

The vascularized horse-shoe-like flap of skin on the back of Schismaderma tadpoles is hypothesized to help with oxygen uptake in the anoxic temporary ponds in which they breed (Baptista et al. 2021).

Once they hatch, the tadpoles swim around in dense schools (Baptista et al. 2021).

Trends and Threats
Schismaderma branchi is only known from a small area and, as of the species description, not found in nearby protected areas. However, the locality it is found in does not appear threatened and the species appears to be well-suited to some habitat disturbance, like the closely related S. carens. All individuals have been found in close association with roads and many individuals have been found breeding in artificial ponds caused by road construction. However, like all amphibians, fungal infections, human related factors like pesticide use, and predators are concerns for S. branchi (Baptista et al. 2021).

Possible reasons for amphibian decline

Local pesticides, fertilizers, and pollutants
Disease

Comments

PHYLOGENETIC RELATIONSHIPS:

Maximum Likelihood and Bayesian analyses using 12S, 16S, and COI mtDNA and CXCR4 and Rag1 nuclear DNA have found that S. branchi is sufficiently distinct from the only other member of the genus, S. carens, to warrant species status. The same study also found that two of the closest related genera to Schismaderma are the monotypic Didynamipus and Nimbaphrynoides (Baptista et al. 2021).

ETYMOLOGY:

Schismaderma branchi is named after late scientist William Roy Branch (1946–2018) who was fundamental in the revival of African herpetology. He also was one of the first to suggest that this new-found Angolan population of Schismaderma may represent a distinct species than the more widespread S. carens (Baptista et al. 2021).

References
Baptista, N. L., Pinto, P. V., Keates, C., Edwards, S., Rodel, M.-O., & Conradie, W. (2021). A new species of red toad, Schismaderma Smith, 1849 (Anura: Bufonidae), from Central Angola. Zootaxa, 5081(3), 301–332. [link]

Species Account Citation: AmphibiaWeb 2023 Schismaderma branchi: Angolan Red Toad <https://amphibiaweb.org/species/9468> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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