Description
Hyperolius davenporti, also known as the East African Spiny Throated Reed Frog, is a Hyperolius frog that is commonly found around the southern highlands of East Africa. This species is small to moderate-sized with a snout-vent length range of 17.3 - 20.2 mm in males and two females having snout-vent lengths of 26.9 and 27.0 mm. The species has a blunt but slightly curved snout. The head is generally wider than long and the head to body length ratio is about 0.37. The internarial distance is about equal to the distance from the nostril to the eye. The canthus rostralis is angular, appearing convex in the horizontal plane, but concave in the vertical plane. The distance between the eyes (in males is 3.8 ± 0.2 mm and 5.2 ± 0.2 mm in females) is greater than the interorbital distance, and the pupils are horizontal. Males of the species have a gular flap that is generally thick, roundly shaped, not bilobed, and narrows anteriorly, which results in the overall shape being relatively hexagonal. There are asperities dispersed throughout the gular flap, with some concentration on the tip of the chin in males. The dorsal and ventral skin surfaces also both have granular asperities. The hand length is longer than the forelimb length. Hyperolius davenporti has webbing and expanded fleshy discs on both the hands and the feet. In terms of the hands, webbing reaches the distal subarticular tubercle of the outer finger. When the hind limb is adpressed anteriorly along the body, the tibio-tarsal articulation reaches the eye. The shank is about equal in length to the thigh. The foot length is shorter than both the thigh and shank. Except the first toe, which only has webbing reaching the first tubercle, webbing on the toes reaches the base of the discs (Loader et al. 2015).

DIAGNOSIS:

Hyperolius davenporti can be differentiated from other species within the genus through a few unique characteristics. To begin with, H. davenporti is the only species in its genus with black dermal asperities on its ventrum. Individuals from the species also have evenly distributed asperities on their gular flaps, which it shares in common with H. burgessi and H. spinigularis (Loader et al. 2015, Barratt et al. 2017). The gular flap of H. davenporti can be distinguished from other species in that it is not narrow and equal in length anteriorly and posteriorly. Furthermore, the height of the gular flap is much larger than its width (Loader et al. 2015).

COLORATION:

Hyperolius davenporti generally has brown dorsal coloration with darker spots speckled along the back. Most preserved specimens also possess white stripes with dark edges that run along the sides of the body and converge on the tip of the snout. The ventral side is much lighter than the dorsal side, with shades of cream and beige. However, differences within the species have been noted, with certain individuals having the same pattern of coloration, but with shades of yellow. The asperities on the dorsum, gular region, and ventral surface are black (Loader et al. 2015).

VARIATION:

Sexual dimorphism exists in that females tend to have a much larger body size than their male counterparts. The black asperities are also less pronounced on the female dorsum and nonexistent on their ventral sides. During the breeding season, males can be differentiated from females by their more rounded and wider gular sacs (Loader et al. 2015).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Tanzania, United Republic of

View distribution map in BerkeleyMapper.

Hyperolius davenporti is found in Southern Tanzania, specifically in the Sakara Nyumo Forest Reserve in the Livingstone mountains. At 2,010 meters above sea level, this species has been documented to live in shallow ponds on the montane forest’s edge and has never been seen in open areas. The current estimated extent of occurrence is 28 square kilometers. It is currently unknown if H. davenporti exists in other habitats or regions. Additional sampling will be required to conclude whether or not this species is confined to this forest reserve or if it exists in other parts of the Livingstone mountains or Southern Highland region (Loader et al. 2015, IUCN 2016).

Life History, Abundance, Activity, and Special Behaviors
IUCN (2016) states that H. davenporti is an arboreal species that does not undergo migration, however, specimens were collected from shallow ponds in a swamp near the edge of the forest (Loader et al. 2015).

As of 2021, no mating or territorial calls have been reported in this species. However, the area was only surveyed for five days, which was not enough time to definitively conclude whether H. davenporti is non-calling like its congeners H. burgessi and H. spinigularis (Loader et al. 2015).

As of 2021, there are no detailed observations about H. davenporti’s life history, reproductive mode, and larval morphology. However, other species within Hyperolius have a lifespan of 1 to 4 years and low lifetime fecundity. In terms of breeding biology, Hyperolius species generally become sexually mature at a small size. Hyperolius davenporti is presumed to undergo indirect development with oviparity, production of larvae, and metamorphosis (Sinsch and Dehling 2017). Though there is not much information on H. davenporti’s reproductive mode, its closely related sister species, H. burgessi, breeds during annual rainy seasons, lays its eggs on flora suspended above ponds or swamps, and has a typical clutch size of 89 eggs (Loader et al. 2015). No information has been collected about H. davenporti’s adult or larval diet, activity, or predators.

Trends and Threats
Hyperolius davenporti population trend is currently in decline, likely due to habitat loss and other human activities. A few major factors that contribute to this diminishing population are biological resource use (e.g., logging and harvesting of wood), increased agriculture and aquaculture (e.g., the growth of annual and perennial non-timber crops), and urbanization (e.g., increase in residential housing and commercial buildings). This species occurs within the Sakara Nyumo Forest Reserve, which offers minimal protection to its forests (IUCN 2016).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Urbanization

Comments

PHYLOGENETIC RELATIONSHIPS:

Maximum Likelihood and Bayesian methods were utilized on one mitochondrial gene (NADH dehydrogenase subunit 2) and three nuclear genes (POMC, C-myc, and Rag-1). The resulting tree found H. davenporti was sister to H. burgessi (Loader et al. 2015). In 2017, Barratt et al. recalculated the phylogenetic relationships using the same genes as Loader et al. with H. mitchelli as the outgroup. Their Bayesian and Maximum Likelihood approaches supported the phylogeny constructed by Loader et al. in placing H. davenporti as sister to H. burgessi (Barratt et al. 2017).

Hyperolius davenporti is distributed allopatrically relative to its congeners (Loader et al. 2015) and is potentially a result of peripatric speciation events from its sister lineages (Lawson et al. 2015).

ETYMOLOGY:

The species is named after scientist Dr. Tim Davenport, who made significant contributions to the conservation of rainforests in Tanzania, specifically the forests of the Southern Highlands and the Livingstone Mountains (Loader et al. 2015).

References

Barratt, C. D., Lawson, L. P., Bittencourt-Silva, G.B., Doggart, N., Morgan-Brown, T., Nagel, P., Loader, S. P. (2017). “A new, narrowly distributed, and critically endangered species of spiny‐throated reed frog (Anura: Hyperoliidae) from a highly threatened coastal forest reserve in Tanzania.” Herpetological Journal 27, 13–24 [link]

IUCN SSC Amphibian Specialist Group. (2016). "Hyperolius davenporti." The IUCN Red List of Threatened Species 2016: e.T69119609A69119652. https://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T69119609A69119652.en. Downloaded on 17 February 2021.

Lawson, L.P., Bates, J.M., Menegon, M., Loader, S.P. (2015). “Divergence at the edges: peripatric isolation in the montane spiny throated reed frog complex.” BMC Evolutionary Biology, 15(128): 1-15. [link]

Loader, S.P., Lawson, L.P., Portik, D.M., Menegon, M. (2015). “Three new species of spiny throated reed frogs (Anura: Hyperoliidae) from evergreen forests of Tanzania.” BMC Research Notes, 8(167): 1-16. [link]

Sinsch, U., Dehling, J.M. (2017). “Tropical anurans mature early and die young: Evidence from eight Afromontane Hyperolius species and a meta-analysis.” PLoS One 12(2): e0171666. [link]

Stevens, R.A. (1971). ''A new treefrog from Malawi (Hyperoliinae, Amphibia).'' Zoologica Africana, 6, 313-320.

Species Account Citation: AmphibiaWeb 2021 Hyperolius davenporti <https://amphibiaweb.org/species/8351> University of California, Berkeley, CA, USA. Accessed Sep 17, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 17 Sep 2024.

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