Showing posts with label Upper Guinean Biodiversity Hotspot. Show all posts
Showing posts with label Upper Guinean Biodiversity Hotspot. Show all posts

Sunday, 27 March 2022

Conraua kamancamarai: A new species of Slippery Frog from the Fouta Djallon Highlands of west-central Guinea.

The Fouta Djallon Highlands of west-central Guinea form a series of plateaus, deep valleys, and steep slope-faces covered by a mixture of tropical and sub-tropical forests and grasslands. The area receives some of the highest rainfall in West Africa, but also has a wide range of micro-climates, providing a highly diverse environment with a high number of endemic species, which is relatively understudied by scientists. The floral uniqueness of the region has long been recognised, and there have been many calls to protect areas of pristine forest being encroached upon by agriculture and Cattle ranching, but the faunal uniqueness of the area has been very little studied.

In a paper published in the journal Zoosystematics and Evolution on 19 January 2022, Karla Neira-Salamea of the Museum für Naturkunde Berlin, Joseph Doumbia of ONG EnviSud Guinée, Annika Hillers of the Wild Chimpanzee Foundation, Laura Sandberger-Loua, also of the Museum für Naturkunde Berlin, N’Goran Kouamé of the Laboratoire de Biodiversité et Ecologie Tropicale at the Université Jean Lorougnon Guédé, Christian Brede of Lübeck in Germany, Marvin Schäfer, again of the Museum für Naturkunde Berlin, David Blackburn of the Department of Natural History at the Florida Museum of Natural History, and Michael Barej and Mark-Oliver Rödel, once again of the Museum für Naturkunde Berlin, describe a new species of Slippery Frog from the Fouta Djallon Highlands of west-central Guinea.

 
Hörè Binti landscape, Fouta Djallon, Guinea. Neira-Salamea et al. (2022).

Slippery Frogs, Conraua spp., are endemic to Africa, with seven species currently recognised, one from East Africa, three from Central Africa, and three from West Africa. However, a recent phylogenetic study of one of these species, Conraua alleni, should in fact be considered to be a species cluster (group of morphologically identical but genetically distinct species, known as 'cryptic species') rather than a distinct species. With this in mind, Neira-Salamea et al. carried out morphological and genetic tests on a group of Slippery Frogs held in the Museum für Naturkunde Berlin, which were collected during an expedition to the Fouta Djallon in 2011, establishing that Frogs from Hörè Binti, Pita and Chute de Ditinn and Dalaba in the Fouta Djallon are all members of a new, previously undescribed species.

The new species is named Conraua kamancamarai, in honour of the late Kaman Camara, a long term field assistant and friend of the team, who began working with Mark-Oliver Rödel in 2002 on a survey to the Simandou Range that was organised by Conservation International, and worked with the team full time from 2007 until his death after a short illness in 2020, investigating the amphibians of the Nimba Mountains and other Guinean areas. Neira-Salamea et al. note that 'Kaman had outstanding skills in detecting and catching Frogs, and, more importantly, an unswerving positive attitude'. Kaman was born and lived in a remote village at the western foothills of the Simandou Range. He never received any formal education. Still, he repeatedly rejected other better paying job offers from mining companies, preferring instead to work with his frog team whenever it was possible.

 
Kaman Camara in June 2007 on Mount Nimba, Guinea. Inset figure taken on a Rapid Assessment to south-eastern Guinea, organised by Conservation International and Kaman’s first experience with frog work, from left to right: Mark-Oliver Rödel, Mohamed Alhassane Bangoura and Kaman Camara. Neira-Salamea et al. (2022).

Specimens of Conraua kamancamarai have a slightly dorsoventrally flattened, short and rounded body; the snout is rounded in dorsal and lateral view, the upper lip slightly projects forward. They range from 74.3 to 81.7 mm in length. Dorsal colouration ranges from uniform dark brown to predominantly brown with dark mottling or predominantly brown with dark spots. Ventral colour pattern of all specimens similar: whitish with distinct brown blotches, however, these blotches are lighter in the subadult specimens.

Colouration of life Conraua kamancamarai from the Fouta Djallon and surrounding region, Guinea, illustrating variation in colour pattern and skin texture. (a) From Dubreka, River Bindinbandan; (b) From Dalaba, Chute de Ditinn; (c) From Hörè Binti; (d) From Dubreka, River Bindinbandan; (e) From Dalaba, Chute de Ditinn; (f) From Télimélé, locality Kourakoto, river Didounpouriguè; Frogs in lower row in typical calling position, sitting in shallow water; specimens either not collected or not assignable to a voucher specimen, whereas the Frogs from Hörè Binti and Chute de Ditinn can be assigned to Conraua kamancamarai without doubt; the other Frogs may represent an undescribed Conraua species. Neira-Salamea et al. (2022).

Conraua kamancamarai occupies fast-flowing rocky streams with waterfalls within riverine forest in mountainous areas in the Fouta Djallon. Like other Frogs of the genus, Conraua kamancamarai is predominately nocturnal and aquatic. Despite their occurrence in fast flowing streams, adults show a preference for calmer river sections, where turbulent water is absent. Usually, Frogs are encountered at least partly submerged in shallow water, facing the riverbanks. When outside of the water, they remain within jumping distance to water. Disturbed Frogs seek shelter on the ground of pools, sometimes trying to burrow deeper into them and cover themselves with gravel or substrate. Mating has never been observed; however, single observations of clutches and jelly remnants of spawn indicate that oviposition sites are small puddles or depressions on the riverbanks near the spray water zone of cascades and waterfalls. Conraua Tadpoles usually were observed in silted calm ponds where up to 50 Tadpoles of about the same size have been encountered.

 
The type locality of Conraua kamancamarai near Konkouré Fetto, Fouta Djallon, Guinea. The Frogs live in clear, fast flowing streams, with riverine forest. Neira-Salamea et al. (2022).

The forest fragments where Conraua kamancamarai occurs are generally degraded by anthropogenic disturbance, particularly Peanut and Rice crops and Cattle grazing. The type locality is located between Konkouré and the largest city within the Fouta Djallon, Mamou, within a relatively short distance to the connection road and was surveyed on 20 June 2011. Along the national route one (N1), one of the largest roads connecting the East with the West of Guinea, houses are numerous, but already within a relatively short distance to the road, Human presence may be considerably scarcer. Slopes are either covered by an open, short, dry forest with signs of Cattle grazing and used for charcoal production or comparatively large fields for Peanuts or Rice crops. Only steep slopes surrounding rivers had sometimes larger trees and denser vegetation with higher humidity levels than the surroundings. The type locality is at a river within denser forest, with large boulders and some cascades, allowing for a diverse river site with fast and slow flowing parts and comparatively clear water. These forests are not protected and were in the past burned by the population as protest against government decisions in Conakry.

 
The surroundings of the type locality are heavily degraded by agriculture, Cattle grazing and charcoal production (inset figure). Neira-Salamea et al. (2022).

The classified forest (partly protected areas allowing forestry) of Hörè Binti is located within a mountainous area containing several freshwater sources. It was surveyed from 22–23 July 2010. Many fast-flowing streams with cascades have its source on the mountain. The habitat degradation due to anthropogenic alterations was dramatic and only very small forest fragments remained. The anthropogenic pressure consisted of cultivations/fields (mainly Peanut and Rice) and grazing Cattle. Only streams were surrounded by some remaining larger trees. The Ditinn/Dalaba site was within a small fragment of gallery forest with a stream, next to the waterfall of Ditinn. It was surveyed from 24–25 July 2010. Although there is a small village next to the forest, only minor anthropogenic alterations were detectable.

Because the full range of Conraua kamancamarai is unknown, Neira-Salamea et al. recoment that it be treated as 'Data Deficient' under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species. However, they also note that if the known populations do represent the entire range of the species, then it should be considered to be Endangered.

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Wednesday, 29 April 2015

Cryptic diversity in West African Torrent Frogs.


The West African Torrent Frog, Odontobatrachus natator, is found in fast moving streams and waterways in the forests of Guinea, Sierra Leone Liberia, and western Côte d’Ivoire, part of the Upper Guinean Biodiversity Hotspot. While it has been known to science for over a hundred years, a recent study has shown it to be sufficiently genetically isolated from all other Frogs to merit placing it in its own family, the Odontobatrachidae, this being the first family of Vertebrates discovered which is entirely restricted to West Africa.

In a paper published in the journal BMC Evolutionary Biology on 19 April 2015, Michael Barej and Johannes Penner of the Museum für Naturkunde Berlin at the Leibniz Institute for Evolution and Biodiversity Science, Andreas Schmitz of the Department of Herpetology and Ichthyology at the Natural HistoryMuseum of Geneva and Mark-Oliver Rödel, also of the Museum für Naturkunde Berlin at the Leibniz Institute for Evolution and Biodiversity Science examine the genetic diversity of West African Torrent Frogs in order to determine if they were truly all one widespread species or a cluster of morphologically indistinguishable cryptic species.

A West African Torrent Frog, Odontobatrachus natator. Barej et al. (2014).

Cryptic species are species which resemble one-another closely but which are reproductively isolated. These have been known about for a long time in groups such as calling Frogs and Songbirds, where morphologically identical populations can be separated on the basis of different mating calls, but the true extent of hidden diversity in many groups did not become apparent until genetic tools became available to study wild populations in the 1990s. The discovery of cryptic species can have profound implications for conservation efforts, as what was thought to be a single, widespread species with a large population can suddenly be found to be a cluster of species, each with very limited populations and ranges. Cryptic diversity seems to be particularly common among groups such as small Amphibians and Reptiles, but has been found even in large charismatic animals such as Elephants, Giraffes, Baboons and Hammerhead Sharks.

Barejet al. found that the population of Odontobatrachus natator contains six distinct genetic lineages, and though they do not go so far as to name them as new species from this preliminary study, they do indicate that further studies are likely to result in the group being divided into a number of separate species.

Tree resulting from partitioned Bayes and ML analyses of mitochondrial genes 16S, 12S, cytb and nuclear genes RAG1, SIA and BDNF (outgroups not shown). Barej et al. (2015).

The most widespread of these is found in western Guinea, across Sierra Leone and as far to the east as eastern Guinea and eastern Liberia. This includes the area from which the species was first described (Sierra Leone, unspecified), and will therefore retain the name Odontobatrachus natator however the group is subdivided in future. This population is considered to be of ‘Least Concern’ under the terms of the International Union for the Conservation of Nature’s Red List of ThreatenedSpecies.

The most closely related outgroup to this (and therefore the group least likely to subsequently be described as a separate species) was a population found only on the Freetown Peninsula in Sierra Leone. This population is referred to as Odontobatrachus natator (Freetown Peninsula), and while closely related to the larger population, does appear to be separate on the basis of the genes studies and is separated from the main population by a wide area of unsuitable habitat, which may have allowed reproductive isolation to develop. If this population is recognized as a separate species then it would be recognized as ‘Critically Endangered’ under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species, due to the limited geographical range it inhabits.

Environmental niche modelling map of genetically confirmed records of the Operational Taxonomic Units Odontobatrachus natatorand Odontobatrachus natator (Freetown Peninsula). Barej et al. (2015).

In addition four other distinctive genetic lineages are identified, and provisionally named as ‘Operation Taxonomic Units’ (OTUs) 1 to 4. These can be further groups as (OTU 1 and OUT 4) which are most closely related to one-another and the sister group to (Odontobatrachus natatorand Odontobatrachus natator (Freetown Peninsula)), and (OUT 2 and OUT 3) which are more closely related to one-another, and form an outgroup to all the other populations.

OTU 1 is found in the Simandou Range and the Massif du Ziama in south-eastern Guinea, and environmental niche modelling suggests that it may also occur westwards into parts of Sierra Leone. This population is considered to be ‘Vulnerable’ under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

Environmental niche modelling map of genetically confirmed records of Operational Taxonomic Unit 1. Barej et al. (2015).

OTU 2 was found in western Guinea, though Environmental Niche Modelling suggested that it may also be found as far east as central Sierra Leone, though Barej et al. deem this unlikely. This population is considered to be ‘Vulnerable’ under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

Environmental niche modelling map of genetically confirmed records of Operational Taxonomic Unit 2. Barej et al. (2015).

OTU 3 was also found in wesertn Guinea, though Environmental Niche Modelling suggests that it may be found as far east as central Sierra Leone and as far west as parts of Guinea Bissau, though againBarejet al. deem this unlikely.This population is considered to be ‘Endangered’ under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

Environmental niche modelling map of genetically confirmed records of Operational Taxonomic Unit 3. Barej et al. (2015).

OTU 4 was found in the Nimba Mountains of southeaster Guinea and the surrounding area, as well as in northeastern Liberia and the Mont Sangbé National Park in western Côte d’Ivoire. Environmental niche modelling suggested that this population could extend across much of eatern Guinea and northern Liberia, and even into eastern Sierra Leone. This population is considered to be ‘Endangered’ under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

Environmental niche modelling map of genetically confirmed records of Operational Taxonomic Unit 4. Barej et al. (2015).

Although this is only a preliminary study, the degree of genetic separation between the populations suggests that they may have diverged during the Plio-Pleistocene. This is consistent with palaeoclimatic models of West Africa, which suggest while the region was not directly affected by glaciation during the Pleistocene, glacial intervals at higher latitudes led to a cooler drier climate in which forests withdrew and grasslands expanded. During such periods forest species would have been restricted to isolated refugia, where populations cut off from one-another geographically could become permanently separated by genetic drift.

See also….

Robber Frogs of the genus Eleutherodactylus are found from Texas to Guatemala and Belize and across the islands of the Caribbean. The genus was formerly the most specious of any genus of Vertebrate Animals (i.e. it contained more species than any other Vertebrate...

In the late 1960s and early 1970s a series of anthropological excavations were carried out at Minatogawa Fissure on southern Okinawa Island, producing a number of Late Pleistocene Human...


Fanged Frogs, Limnonectes spp., are unique among Frogs in that the males are typically larger than the females, and frequently fight for territories, the females then mating with the males perceived as having the...

 

 

 

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