Guineo-Congolian Rainforest Research Articles

Trophic Resource Use by Sympatric vs. Allopatric Pelomedusid Turtles in West African Forest Waterbodies.

Organisms that are similar in size, morphological characteristics, and adaptations, including vertebrates, often coexist by partitioning the available resources (food, space, and time). So, studies of the dynamics of these cases of coexistence are scientifically interesting. Here, we study a coexistence case of two species of freshwater turtles inhabiting the forest waterbodies of West Africa, focusing on the dietary habits of the two species. We found that both turtle species are omnivorous generalists, eating both vegetal and animal matter abundantly. However, there were clear interspecific differences, with the larger of the two species (P. cupulatta) eating more vertebrates (mainly fish but occasionally other vertebrates), whereas P. castaneus consumed more invertebrates. These patterns appeared consistently within the species and across sites, highlighting that the same patterns were likely in other conspecific populations from the Upper Guinean forest streams (Côte d'Ivoire and Liberia). Our study also showed that interspecific competition for food does not occur between these two species; instead, previous studies uncovered that a clear partitioning of the habitat niche occurs. We conclude that the food resource is likely unlimited in the study areas, as it is not the case in more arid environments (since food shortages may occur during the dry season). We anticipate that, within the Pelomedusidae communities throughout Africa, intense competition for food probably occurs in the Sahel and Sudanian vegetation zones, particularly during the dry months, but is unlikely within the Guinea and wet savannah region and even less likely in the Guineo-Congolian rainforest region.

A new species of the Curtonotum platyphallum species-group (Diptera: Curtonotidae) from Nouabalé-Ndoki National Park, Republic of Congo

A new species of Curtonotum Macquart is described and figured from Nouabalé-Ndoki National Park, Republic of Congo, based on the unique male holotype from disturbed Guineo-Congolian rainforest. The new species clearly belongs to the Curtonotum platyphallum species-group in sharing the synapomorphy of the basiphallus with an angulate ventrally expanded and concave process. Additional key couplets are provided to distinguish the new species from its congeners.

Diversity and Relative Abundance of Ungulates and Other Medium and Large Mammals in Flooded Forests in the Dahomey Gap (Togo).

"The Dahomey Gap" is a human-derived mostly savannah region that separates the Guineo-Congolian rainforest block into two major units: the Upper Guinean and the Lower Guinean Forest blocks. Several forest patches are distributed throughout this savannah-dominated habitat. The mammal communities in the Dahomey Gap region have been poorly studied. In this paper we analyse the species richness and abundance of, as well as conservation implications for, medium and large mammals (especially ungulates) inhabiting a complex of flooded forests near the Mono river in south-eastern Togo. We use several field methods to describe the species richness of mammals in this area, including camera-trapping, recce transects, Kilometric Index of Abundance (KIA) estimates, examination of hunters' catches and face-to-face hunter interviews. Overall, we directly recorded 19 species that coexist in these forests. Based on interviews, nine other species were confirmed as present in the study area. Only five species were common: Cephalophus rufilatus, Tragelaphus scriptus, Chlorocebus aethiops, Atilax paludinosus and Herpestes ichneumon. The area still contains various threatened species such as Tragelaphus spekii and Hippopotamus amphibius. We stress that to ensure the protection of the Dahomey Gap mammals, it is important to seriously consider protecting not only the forest patches but also the surroundings, mainly savannah landscapes.

Nuclear ribosomal phylogeny of Brachystegia: new markers for new insights about rain forests and Miombo woodlands evolution

Background and aims – Brachystegia is a species-rich tree genus found in tropical Africa and a typical element of Miombo woodlands, a widely distributed subtype of the Zambezian savanna. Plastid DNA was shown to be largely uninformative to assess species phylogenetic relationships due to widespread chloroplast capture among species. Here, we aim to assess the capacity of nuclear ribosomal DNA (rDNA) to clarify the phylogeny of Brachystegia species while accounting for intra-individual site polymorphisms (2ISPs), which are often present in rDNA and potentially phylogenetically informative. Material and methods – Genome skimming sequencing on 47 samples representing 27 of the 29 currently recognized Brachystegia species, allowed us to retrieve complete nuclear ribosomal cistrons encoding for 18S, 5.8S, and 25S rRNA genes (35S rDNA). We reconstructed the Brachystegia phylogeny using Maximum Likelihood methods based on the standard substitution model or integrating 2ISPs (GENOTYPE implementation in RAxML-NG). We additionally tested the effect of partitioning the data (one partition for rDNA genes and one for the ITS1+ITS2). We also conducted network inferences (Neighbor-Net splits graph), as a strict bifurcative approach might not properly model topological uncertainty at shallow phylogenetic depth. Key results – 2ISPs-aware and standard phylogenetic reconstructions are largely congruent. We identified several well-supported main clades clarifying the species relationships, including two clades of Miombo woodlands species. Miombo Group A includes species with ovoid to globose axillary dormant buds, while Miombo Group B species have flattened ones. Two morphologically close Brachystegia species (B. kennedyi and B. leonensis) found in Guineo-Congolian rain forests form also a robustly supported clade. 2ISPs coding allowed to identify an additional Guineo-Congolian clade (B. eurycoma and B. nigerica). Ribosomal DNA therefore proves more useful to explore the generic phylogeny than plastid DNA but the species relationships within and among the main clades remain poorly resolved, probably due to recent diversification and/or recurrent hybridization, so that the diversification of Brachystegia remains to be more properly characterised. Conclusion – Nuclear and plastid phylogenetic reconstructions of Brachystegia species are discordant. Even if not well-resolved, rDNA phylograms and networks are characterized by taxonomic sorting, while we observe a strictly geographic sorting in the plastid dataset. Most of the species’ relationships remain to be characterized using additional nuclear markers combined with in-depth morphological investigations.

Phylogenetic relationships and biogeography of the Hybomys division (Muridae: Murinae: Arvicanthini), rodents endemic to Africa's rainforests

The Hybomys division (Muridae: Murinae: Arvicanthini) consists of four genera (Hybomys, Typomys, Dephomys, and Stochomys) endemic to the Guineo-Congolian rainforests of central Africa. Based on sequences from two mitochondrial (Cytb, 12S rRNA) and two nuclear (Rbp3, Ghr) genes, we present a fossil-calibrated molecular phylogeny of the Hybomys division, based on wider taxon and geographic sampling than previously published phylogenies. Species of Typomys formed a clade that was sister to a clade containing Hybomys and the sister genera Dephomys and Stochomys. Hybomys basilii and Hybomys lunaris were recovered as monophyletic, whereas Hybomys univittatus was recovered as polyphyletic and likely consists of at least three species. The divergence between the East African taxon H. lunaris, and the West and Central African taxa of Hybomys is estimated at 3.1 Mya. Based on molecular phylogenies and genetic distances, we infer that forms of Hybomys from both the highlands and lowlands of the Cameroon Volcanic Line, except for H. basilii, should be considered a single species for which Hybomys rufocanus is the oldest available name. As proposed, H. rufocanus would include the named forms badius and eisentrauti as synonyms, as well as populations north of the River Sanaga previously recognized as H. univittatus. Material from nearest the type locality of H. univittatus is sister to H. rufocanus, whereas other specimens currently recognised as H. univittatus from south of the River Ogooue and in the Congo Basin are sister to this H. rufocanus + true H. univittatus clade. Dating estimates place the origin and early diversification of the Hybomys division in the late Miocene, slightly preceding the radiation of most arvicanthine genera that inhabit savannah biomes. The historical biogeography of the Hybomys division appears to be congruent with hypothesized forest refugia, savannah barriers, and aridification cycles of the Neogene and Pleistocene.

Parallel diversification of the African tree toad genus Nectophryne (Bufonidae)

African amphibian diversity remains underestimated with many cryptic lineages awaiting formal description. An important hotspot of amphibian diversification is the Guineo-Congolian rainforest in Central Africa, its richness attributable to present day and ancestral range fragmentation through geological barriers, habitat expansion and contraction, and the presence of steep ecological gradients. The charismatic Nectophryne tree toads present an interesting case study for diversification in this region. The two formally described species comprising this genus show nearly identical geographic distributions extending across most of the Guineo-Congolian rainforest, but show little morphological disparity. Both species harbour extensive genetic diversity warranting taxonomic revisions, and interestingly, when comparing the subclades within each, the two species show remarkably parallel diversification histories, both in terms of timing of phylogenetic splits and their geographic distributions. This indicates that common processes may have shaped the evolutionary history of these lineages.

Haploporus (Basidiomycota, Polyporales) in sub-Saharan Africa: Poria eichelbaumii, a long-forgotten name, is reinstated in Haploporus and H. grandisporus sp. nov. is proposed

Poria eichelbaumii, a long-forgotten name, is transferred to Haploporus based on studies of the type specimen, comparison with new collections, and evidences from both morphology and phylogeny. The species is redescribed and illustrated. Haploporus grandisporus is described as new, on the basis of concordant morphological and phylogenetic species concepts. These two species form two very closely related clades within the Haploporus lineage in [28S-ITS]-based phylogenetic inferences. Haploporus eichelbaumii and H. grandisporus are distinguished by the size of their basidiospores (11.5–14.5 × 5.0–6.0 μm, average = 12.7 × 5.8 μm, vs 14–17.5 × 6.0–7.3 μm, average 15.4 × 6.6 μm), the size of their pores (2.5–3.5 / mm, vs 1.5–2.5 / mm), and, likely, divergent autecologies. Although both species occur in montane ecosystems of the eastern African rift, the data so far available suggest they occupy different habitats. Haploporus eichelbaumii has wider distribution, spanning over both branches of the eastern rift, at elevation ~ 1500–2500 masl, in various vegetation types, mostly on small-sized dead branches or twigs, and dead bamboo culms. It is known so far from Kenya, Tanzania, and Malawi to the East, and western Burundi, western Uganda, and Eastern Congo (DRC) in the Albertine mountain ranges. Haploporus grandisporus is known, hitherto, only from the Eastern slopes of Mount Elgon in Kenya, at the timberline, 2900–3200 masl, mostly on dead heather branches (Erica arborea, Ericaceae) in heather thickets. Haploporus nanosporus is currently the third known Haploporus species from tropical Africa, known from the western edge of the Guineo-Congolian rain forest in Gabon and Cameroon. This species is also redescribed and illustrated.

Amanita in the Guineo-Congolian rainforest: Epitypes and new species from the Dja Biosphere Reserve, Cameroon

ABSTRACT Four epitypes and three new species of Amanita (Amanitaceae, Agaricales, Agaricomycetes, Basidiomycota) are described from Guineo-Congolian rainforests of Cameroon. Amanita echinulata, A. fulvopulverulenta, A. robusta, and A. bingensis are epitypified based on collections that are the first since the species were described nearly a century ago. Morphological features of the epitypes are described and enumerated. Amanita minima, Amanita luteolamellata, and A. goossensfontanae are described as new and added to the known macromycota of tropical Africa. Habit, habitat, and known distribution are provided for each species. Sequence data for the internal transcribed spacer (ITS) locus are provided for types and other collections of all taxa, and a molecular phylogenetic analysis across the genus Amanita corroborates morphology-based infrageneric placement for each.

A new Cymothales Gerstaecker from the Gabonese rainforest (Neuroptera Myrmeleontidae).

Nine species of Cymothales, one of the most characteristic African antlion genera, are known from the Guineo-Congolian rainforests. A new species, Cymothales massaronei sp. nov. is described here from Gabon. Cymothales massaronei sp. nov. is characterized by the fifth tarsomere equal in length to the first tarsomere, but differs from all of the congenerswith this character in the shape and markings of wings, shape of antenna and body pattern.

Miocene Diversification in the Savannahs Precedes Tetraploid Rainforest Radiation in the African Tree Genus Afzelia (Detarioideae, Fabaceae).

The dating of diversification events, including transitions between biomes, is key to elucidate the processes that underlie the assembly and evolution of tropical biodiversity. Afzelia is a widespread genus of tropical trees, threatened by exploitation for its valuable timber, that presents an interesting system to investigate diversification events in Africa. Africa hosts diploid Afzelia species in the savannahs north and south of the Guineo-Congolian rainforest and autotetraploid species confined to the rainforest. Species delimitation and phylogenetic relationships among the diploid and tetraploid species remained unresolved in previous studies using small amounts of DNA sequence data. We used genotyping-by-sequencing in the five widespread Afzelia species in Africa, the savannah species A. africana and A. quanzensis and the rainforest species A. bipindensis, A. pachyloba, and A. bella. Maximum likelihood and coalescent approaches resolved all species as monophyletic and placed the savannah and rainforest taxa into two separate clades corresponding to contrasted ploidy levels. Our data are thus compatible with a single biome shift in Afzelia in Africa, although we were unable to conclude on its direction. SNAPP calibrated species trees show that the savannah diploids started to diversify early, at 12 (9.09–14.89) Ma, which contrasts with a recent and rapid diversification of the rainforest tetraploid clade, starting at 4.22 (3.12 – 5.36) Ma. This finding of older diversification in a tropical savannah clade vs. its sister rainforest clade is exceptional; it stands in opposition to the predominant observation of young ages for savannahs lineages in tropical regions during the relatively recent expansion of the savannah biome.

Kakameganula, a new name for the preoccupied Kakamega Dawidowicz & Wesołowska, 2016 (Araneae: Salticidae)

Dawidowicz Wesołowska (2016) proposed the jumping spider genus Kakamega for the type species Kakamega holmi Dawidowicz Wesołowska, 2016, probably endemic to the Kakamega Forest of Kenya, a remnant of the Guineo-Congolian tropical rainforest.

Hymenochaetaceae (Basidiomycota, Hymenochaetales) from the Guineo-Congolian phytochorion: Phylloporia rinoreae sp. nov., an additional undescribed species from the Forest Global Earth Observatory Plot in Gabon

Background and aims – The aim of this study is the continuation of an ongoing survey of Hymenochaetaceae (Basidiomycota, Hymenochaetales) from the lower Guinean sub-region in Central Africa. In this frame, a new species of Phylloporia is described from Gabon, based on morphological, ecological and phylogenetic data. Methods – The species is described using morphological methods, and ecological data. DNA-based phylogenetic analysis are also used to search for affinities.Key results – A new species of Phylloporia, P. rinoreae, is described based on specimens collected on living twigs of a shrubby Rinorea species (Violaceae), occurring in the Guineo-Congolian rain forest. Phylogenetic inferences using DNA sequence data from partial nuc 28S (region including the D1/D2/D3 domains) resolved this species as a distinct clade within the Phylloporia lineage. An identification key to the species reported from the Guineo-Congolian phytochorion is provided.Conclusion – Phylloporia rinoreae is the seventh species of the genus described from and so far only known from Gabon in the Lower Guinean phytogeographical sub-region.

Pleistocene refugia and genetic diversity patterns in West Africa: Insights from the liana Chasmanthera dependens (Menispermaceae).

Processes shaping the African Guineo-Congolian rain forest, especially in the West African part, are not well understood. Recent molecular studies, based mainly on forest tree species, confirmed the previously proposed division of the western African Guineo-Congolian rain forest into Upper Guinea (UG) and Lower Guinea (LG) separated by the Dahomey Gap (DG). Here we studied nine populations in the area of the DG and the borders of LG and UG of the widespread liana species, Chasmanthera dependens (Menispermaceae) by amplified fragment length polymorphism (AFLP), a chloroplast DNA sequence marker, and modelled the distribution based on current as well as paleoclimatic data (Holocene Climate Optimum, ca. 6 kyr BP and Last Glacial Maximum, ca. 22 kyr BP). Current population genetic structure and geographical pattern of cpDNA was related to present as well as historical modelled distributions. Results from this study show that past historical factors played an important role in shaping the distribution of C. dependens across West Africa. The Cameroon Volcanic Line seems to represent a barrier for gene flow in the present as well as in the past. Distribution modelling proposed refugia in the Dahomey Gap, supported also by higher genetic diversity. This is in contrast with the phylogeographic patterns observed in several rainforest tree species and could be explained by either diverging or more relaxed ecological requirements of this liana species.

Mallomonas cronbergiae (Chrysophyceae, Stramenopiles), A New Species from the Guineo-Congolian Rainforest in Cameroon

AbstractA new species of Mallomonas Perty, M. cronbergiae J. Piątek sp. nov., was found in a tropical shallow stream pool in the Guineo-Congolian rainforest in Cameroon. It belongs to the series Ouradiotae and is similar to the three other Mallomonas taxa from this series, namely M. ouradion Harris & Bradley, M. parvula Dürrschmidt and M. parvula var. nichollsii Wujek & Bland, but differs in some morphological characters that clearly differentiate M. cronbergiae as a distinct species. The new species has a different size of scales, characteristic 3–7 pores at the posterior rim, an anterior flange ornamented with papillae, and a shield thickly ornamented with papillae (14–16 per scale width). The species is described and illustrated with the use of light and scanning electron microscopy.

Mallomonas Camerunensis Sp. Nov. (Chrysophyceae, Stramenopiles) From A Shallow Puddle In The Guineo-Congolian Rainforest (Cameroon)

AbstractA new silica-scaled chrysophyte species, Mallomonas camerunensis J. Piątek, is described and illustrated from a shallow puddle in the Guineo-Congolian rainforest in Cameroon. This species belongs to section Papillosae and series Papillosa. It is similar to other Mallomonas species placed in Papillosa, such as M. binocularis Siver, M. calceolus D. E. Bradley, M. delanciana Siver, M. kalinae Řezáčová, M. papillosa K. Harris & D. E. Bradley, M. paxillata (D. E. Bradley) L. Ş. Péterfi & Momeu, M. rasilis Dürrschm. and M. tropica Dürrschm. & Croome, but differs from them in several morphological characters warranting recognition as a distinct species. The dome of M. camerunensis is clearly delimited and ornamented with papillae and ribs. The scales lack an anterior submarginal rib, while the posterior rim and V-rib are smooth and unornamented. The shield is thickly ornamented with papillae (18–22 papillae per scale width). The species is described and illustrated using light microscopy and scanning electron microscopy.

Two new Phrynobatrachus species (Amphibia: Anura: Phrynobatrachidae)from the Republic of the Congo.

We describe two new species of puddle frogs, genus Phrynobatrachus, from the south-western Republic of the Congo. One of them, P. horsti sp. nov., occurs also in neighbouring Gabon and is morphologically most similar to the Cameroonian P. ruthbeateae. It differs from the latter species by smaller males with longer thighs and shanks. The new species comprises various colour morphs but always has less conspicuous black borders between flanks and belly than P. ruthbeateae. The distinct and large black axillary blotch of P. ruthbeateae is either much smaller in P. horsti sp. nov., or broken into numerous irregularly shaped smaller dots. Similarly, a black transversal line at the anterior ventral border of thighs and the black face mask is less distinct and irregularly delimitated in P. horsti sp. nov. when compared to P. ruthbeateae. The mean genetic difference in the sampled region of the 16S rRNA gene between P. horsti sp. nov. and 40 other western African congeners range from 3.66-18.10%. The second new species, P. mayokoensis sp. nov., differs from all other known congeners by the combination of a compact and warty body, the absence of a spiny eyelid tubercle and pedal webbing, a conspicuous black triangle on throat and anterior part of the belly, and a distinct large red blotch on the anterior-proximal surface of the thighs. It exhibited a mean genetic difference in the 16S rRNA to 40 other western African congeners ranging from 1.34-16.98%. The genetically most similar sequence stems from a GenBank entry of a Gabonese frog, determined as P. ogoensis. A comparison of the new species with P. ogoensis syntypes confirmed their specific distinctiveness, most convincingly underlined by the absence of pedal webbing in the new species and the pronounced pedal webbing in P. ogoensis. The GenBank entry thus most likely is based on a misidentification and P. mayokoensis sp. nov. may also occur in neighbouring Gabon. The discovery of the two new frog species is further evidence of the huge gap in our knowledge concerning the species richness in the Guineo-Congolian rainforests.

Hymenochaetaceae from the Guineo-Congolian rainforest: three new species of Phylloporia based on morphological, DNA sequences and ecological data

Four species are added to Phylloporia. Three species, originating from the western edge of the Guineo-Congolian rainforest in Gabon (central Africa), are described as new. Phylloporia afrospathulata sp. nov. forms seasonal, stipitate, solitary basidiomata emerging from soil, more likely connected to buried roots, and has broadly ellipsoid basidiospores. Phylloporia inonotoides sp. nov. forms seasonal sessile, soft basidiomata, solitary at the base of small-stemmed trees including Crotonogyne manniana (Euphorbiaceae) and Garcinia cf. smeathmannii (Clusiaceae). It has a homogeneous context, large pores (2–3 mm), and oblong-ellipsoid to suballantoid basidiospores. Phylloporia fulva sp. nov. forms sessile, conchate, mostly pendant, gregarious basidiomata emerging from the trunk of an unidentified small-stemmed tree and has small, subglobose basidiospores. This species is compared to Polyporus pullus and Phylloporia pulla comb. nov. and proposed based on the study of the type specimen. Phylogenetic inferences using partial nuc 28S DNA sequence data (region including the D1/D2/D3 domains) and the most exhaustive dataset available to date resolved these new morphospecies as three distinct terminal lineages. No sequence data of P. pulla currently is available. The 28S-based phylogenic inferences poorly resolved the interspecific relationships within the Phylloporia clade.

Some Nocturnal and Crepuscular Mammals of Kakamega Forest: Photographic Evidence

Kakamega Forest is a small remnant of Guineo-Congolian rainforest in Kenya. Along with direct observation, we used an automatic camera to sample the nocturnal and crepuscular mammalian fauna within 1.5 km of the Kakamega Forest Station near Isecheno. We detected 11 indigenous species belonging to 10 genera, as well as domestic cats and dogs. We directly observed pottos and African palm civets. Additionally, we photographed giant pouched rats, African civets, white-tailed mongooses, a marsh mongoose, a tree pangolin, servaline genets, blotched genets, side-striped jackals, and what appears to be an African wildcat. We found both whitetailed and black-tailed morphs of the white-tailed mongooses. Similarly, we recorded side-striped jackals with and without white-tipped tails. Our findings offer insight about the seldom studied nocturnal and crepuscular mammals of Kakamega Forest, including which species are persisting there, their various morphs, and some bait preferences, thus adding to and reaffirming previous reports.

Sexual size dimorphism and morphological divergence in the yellow-whiskered Greenbul (Andropadus latirostris) in the Guineo-Congolian rainforest of Africa

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Morphological variability of new chrysophyte stomatocyst forming a single-cyst assemblage in a low-conductivity tropical lake in the Guineo-Congolian rainforest

Morphological variation of the chrysophyte stomatocyst found in surface sediments of a small, shallow lake in the Guineo-Congolian rainforest in eastern Cameroon, is described, illustrated and discussed. Neither living cells nor scales of chrysophytes were observed in the lake. The stomatocyst cannot be assigned to any known cyst and is described as new to science (stomatocyst #49) using International Statospore Working Group (ISWG) guidelines. This is the third report of stomatocysts in Africa, and the second from the tropical part of this continent. Some basic ecological information on the sampling site is provided and compared with similar data from other sampling sites of chrysophytes in Africa.