Description
Hyperolius ruvuensis is a spiny-throated reed frog with unique dermal asperities described from two male and two female specimens. Adult male specimens measured 16.8 and 18.7 mm in snout to vent length and females measured 24.2 and 25.4 mm. The snout is short and rounded. The distance from the snout to the nostril is half that of the distance between the nostrils and less than a third of the distance between the eyes. The distance between the nostrils is greater than the distance between the nostril to the eye. The pupils are horizontal. The gular flap is raised, has two lobes, and is wider than long. The asperities are on the gular flap are clump on the posterior center of each lobe. The forelimb length is about the same length as the hand length in males and slightly shorter than the hand in females. The hand has webbing that is more extensive on the outer finger, reaching the distal subarticular tubercle, but reduced on the other fingers. The tips expand into rounded fleshy discs The tibia and thigh are about the same length, with the foot being about 1 mm shorter than either. When the hind limb is adpressed along the body, the tibio-tarsal articulation reaches the eye. The toes have expanded fleshy discs and extensive webbing. The skin on the dorsum is granular with asperites and granules. The ventrum is strongly granular and has prominent asperites near the lips, gular flap, abdomen, and femoral regions (Barratt et al. 2017).

DIAGNOSIS:

The members of the Hyperolius genus have relatively similar size and body shape but can be differentiated based on characters of their gular flap. The presences of dermal asperites on the gular flap differentiates H. ruvuensis from H. tanneri. The distribution of asperities into two circular raised platforms on each lobe of the flap differentiates H. ruvuensis from H. minutissimus and H. ukwiva, which are anteriorly distributed, and from H. burgessi, H. davenporti and H. spinigularis, which are evenly distributed. The bilobed and rounded gular flap in H. ruvuensis distinguishes it from the rounded gular flaps of H. burgessi, H. davenporti and H. minutissimus, but is similar to H. spinigularis and H. ukwiva (Barratt et al. 2017).

COLORATION:

In life, the head and dorsum are brown with a white cream colored modeling. The ventrum is white. Males have black asperities dotting both the gular flap and stomach. The black asperities on the gular flap are clump on the posterior center of each lobe. The forelimbs and hindlimbs are modeled with orange flashes on thighs and feet. The feet have white heels. When preserved, the coloration and pattern are similar, however, the colors are more muted and the flashes of orange on the limbs are absent (Barratt et al. 2017).

VARIATION:

Coloration can vary slightly as some specimens only exhibit a cream white modeling on the dorsum or back of the individual whereas the modeling pattern in other specimens extends further down the side of the animal. Sexual dimorphism is present with females being much larger than males and lack a gular flap and asperities on the ventrum (Barratt et al. 2017).

Distribution and Habitat

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

View distribution map in BerkeleyMapper.

Hyperolius ruvuensis is endemic to the south Ruvu coastal forest in Tanzania. The area where H. ruvuensis is distributed is very small, only around 10 km². The Ruvu forest contains areas of woodland, thicket, and swamp. Hyperolius Ruvuensis can be found in and around reeds and bushes in the swampy areas of the Ruvu Forest at an elevation of 230 meters above sea level. Specimens were found near small but permanent bodies of water with thick forest nearby (Tanzania Forest Conservation Group 2021, IUCN 2016).

Life History, Abundance, Activity, and Special Behaviors
The species is most likely to be endemic to the Ruvu South Forest Preserve in Tanzania where they live in reeds and bushes of swampy open grasslands with permanent ponds (Barratt et al. 2017).

Trends and Threats
Hyperolius ruvuensis is only found in a 10 km² range in the protected area of the Ruvu South Forest Reserve. However, the Ruvu South Forest Reserve has recently suffered from drastic deforestation for timber and fuel production. Additionally, the areas surrounding the reserve have been extensively affected by charcoal burning, which is evident through the rapid degradation of these areas, from grassland swamps to woodland. As of 2021, the Ruvu Forest is managed by the Tanzania Forest Conservation Group, however, illegal production of charcoal is constantly applying pressure to the forest. As one of the last remaining coastal forests in its area, the Ruvu South Forest is vital to several endemic species (IUCN 2016, Barratt et al. 2017, Tanzania Forest Conservation Group 2021).

Further support in conserving the reserve by the government is essential. Additionally, more research is needed to accurately determine the impact habitat loss and changes through charcoal burning has on the populations of H. ruvuensis and their spatial distribution (IUCN 2016, Barratt et al. 2017, Tanzania Forest Conservation Group 2021).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Habitat fragmentation

Comments

PHYLOGENETIC RELATIONSHIPS:

Bayesian and Maximum Likelihood analyses conducted on ND2 mtDNA and c-Myc, POMC, and Rag-1 nDNA indicate that H. ruvuensis is sister to the clade composed of H. burgessi, H. davenport, and H. spinigularis. The next most closely related species is is H. tanneri. Morphological Principal Components analysis did not significantly distinguish H. ruvuensis from other members of the H. spinigularis complex (Barratt et al. 2017).

ETYMOLOGY:

The species epithet, “ruvuensis” is a reference to the Ruvu jungle in which the species is found. The name literally translates to “Originating in Ruvu.” Therefore, H. ruvuensis means the Ruvu Reed Frog (Barratt et al. 2017).

OTHER INTERESTING INFORMATION:

Hyperolius ruvuensis is the evolutionary product of climate change. The paleoclimate of Africa where many species in the genus Hyperolius are found was once an interconnected forest, which fragmented as climate changed. This left many Hyperolius isolated, leading to the speciation of the genus and current Hyperolius distribution of species in small, isolated patches of west African forest (Barratt et al. 2017).

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 ruvuensis." The IUCN Red List of Threatened Species 2016: e.T69119695A69123103. https://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T69119695A69123103.en. Downloaded on 18 February 2021.

Tanzania Forest Conservation Group. “Conservation of Ruvu South Forest through education, advocacy, tree planting and Elimination of Poverty (CREATE) project” Accessed February 18, 2021 at http://www.tfcg.org/what-we-do/conserve/ruvu-south/ [link]

Species Account Citation: AmphibiaWeb 2021 Hyperolius ruvuensis: Ruvu spiny reed frog <https://amphibiaweb.org/species/8594> 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.

AmphibiaWeb's policy on data use.