Multiple paternity in a viviparous toad with internal fertilisation

Anurans are renowned for a high diversity of reproductive modes, but less than 1% of species exhibit internal fertilisation followed by viviparity. In the live bearing West African Nimba toad (Nimbaphrynoides occidentalis), females produce yolk-poor eggs and internally nourish their young after fertilisation. Birth of fully developed juveniles takes place after nine months. In the present study, we used genetic markers (eight microsatellite loci) to assign the paternity of litters of 12 females comprising on average 9.7 juveniles. In nine out of twelve families (75%) a single sire was sufficient; in three families (25%) more than one sire was necessary to explain the observed genotypes in each family. These findings are backed up with field observations of male resource defence (underground cavities in which mating takes place) as well as coercive mating attempts, suggesting that the observed moderate level of multiple paternity in a species without distinct sperm storage organs is governed by a balance of female mate choice and male reproductive strategies

Figure 11 from: Sandberger-Loua L, Müller H, Rödel M-O (2017) A review of the reproductive biology of the only known matrotrophic viviparous anuran, the West African Nimba toad, Nimbaphrynoides occidentalis. Zoosystematics and Evolution 93(1): 105-133. https://doi.org/10.3897/zse.93.10489

Figure 11 - Male during the mating season, showing pronounced nuptial pads on the thumbs. © Joseph Doumbi

A review of the reproductive biology of the only known matrotrophic viviparous anuran, the West African Nimba toad, Nimbaphrynoides occidentalis

Amphibians, and anurans in particular, show the highest diversity of reproductive modes among tetrapods. Nevertheless, viviparity is scarce in anurans and its occurrence is even more often assumed rather than confirmed. Probably the best studied viviparous amphibian is the Nimba toad, Nimbaphrynoides occidentalis. During more than 40 years of research, the Nimba toad’s reproductive morphology, endocrine activity of the ovary as well as the pituitary gland, and to some extent the ecological impact (seasonality, humidity, food availability) on reproduction was examined. Due to the Nimba toad’s unique reproductive mode, summaries are usually included in reviews discussing amphibian reproduction and articles on reproductive biology often discuss the exceptional reproductive system of Nimba toads. However, to our knowledge a detailed synthesis, summarising all the different original studies on the toad’s reproduction, is so far missing. In this paper we review and summarise all available initial publications, which often have been published in French and/or are difficult to access. A short overview is given of the climatic and environmental conditions experienced by Nimba toads and the key findings supporting a “true” viviparous reproduction with matrotrophy (maternal provision of nutrition during the gestation) and pueriparity (birth of juveniles). Then foetal development (morphological, gonad and pituitary development), and the female (ovary, oviduct, pituitary and their endocrine interactions) and the male reproductive system (testes and pituitary) are reviewed. Finally, the reproductive cycle and its link to the Nimba mountains’ seasonality and ecological/ conservation implications are discussed

A review of the reproductive biology of the only known matrotrophic viviparous anuran, the West African Nimba toad, Nimbaphrynoides occidentalis

Amphibians, and anurans in particular, show the highest diversity of reproductive modes among tetrapods. Nevertheless, viviparity is scarce in anurans and its occurrence is even more often assumed rather than confirmed. Probably the best studied viviparous amphibian is the Nimba toad, Nimbaphrynoides occidentalis. During more than 40 years of research, the Nimba toad’s reproductive morphology, endocrine activity of the ovary as well as the pituitary gland, and to some extent the ecological impact (seasonality, humidity, food availability) on reproduction was examined. Due to the Nimba toad’s unique reproductive mode, summaries are usually included in reviews discussing amphibian reproduction and articles on reproductive biology often discuss the exceptional reproductive system of Nimba toads. However, to our knowledge a detailed synthesis, summarising all the different original studies on the toad’s reproduction, is so far missing. In this paper we review and summarise all available initial publications, which often have been published in French and/or are difficult to access. A short overview is given of the climatic and environmental conditions experienced by Nimba toads and the key findings supporting a “true” viviparous reproduction with matrotrophy (maternal provision of nutrition during the gestation) and pueriparity (birth of juveniles). Then foetal development (morphological, gonad and pituitary development), and the female (ovary, oviduct, pituitary and their endocrine interactions) and the male reproductive system (testes and pituitary) are reviewed. Finally, the reproductive cycle and its link to the Nimba mountains’ seasonality and ecological/ conservation implications are discussed

A new slippery frog (Amphibia, Conrauidae, Conraua Nieden, 1908) from the Fouta Djallon Highlands, west-central Guinea

We describe a new species of the genus Conraua from the Fouta Djallon Highlands in Guinea. The species is recognised as distinct from nominotypical C. alleni, based on morphological evidence and is supported by a recent species delimitation analysis, based on DNA sequence data. The new species is distinguished from its congeners by the unique combination of the following characters: medium body size, robust limbs, only one instead of two palmar tubercles, the first finger webbed to below the first subarticular tubercle, presence of a lateral line system, indistinct tympanum, two subarticular tubercles on fingers III and IV, venter in adults white with dark brown spots or dark brown with grey or whitish spots. The new species differs from all congeners by more than 6% in the DNA sequence of mitochondrial ribosomal 16S. We discuss isolation in Pliocene and Pleistocene forest refugia as a potential driver of speciation in the C. alleni complex. We also emphasise the importance of conserving the remaining forest fragments in the Fouta Djallon Region for the preservation of both its unique biodiversity and its valuable water sources for local people

Life in the spray zone - overlooked diversity in West African torrent-frogs (Anura, Odontobatrachidae, Odontobatrachus)

West African torrent-frogs of the genus Odontobatrachus currently belong to a single species: Odontobatrachus natator (Boulenger, 1905). Recently, molecular results and biogeographic separation led to the recognition of five Operational Taxonomic Units (OTUs) thus identifying a species-complex. Based on these insights, morphological analyses on more than 150 adult specimens, covering the entire distribution of the family and all OTUs, were carried out. Despite strong morphological congruence, combinations of morphological characters made the differentiation of OTUs successful and allowed the recognition of five distinct species: Odontobatrachus natator, and four species new to science: Odontobatrachus arndti sp. n., O. fouta sp. n., O. smithi sp. n. and O. ziama sp. n. All species occur in parapatry: Odontobatrachus natator is known from western Guinea to eastern Liberia, O. ziama sp. n. from eastern Guinea, O. smithi sp. n. and O. fouta sp. n. from western Guinea, O. arndti sp. n. from the border triangle Guinea-Liberia-Cote d'Ivoire. In addition, for the first time the advertisement call of a West African torrent-frog (O. arndti sp. n.) is described

West Africa - A Safe Haven for Frogs? A Sub-Continental Assessment of the Chytrid Fungus (Batrachochytrium dendrobatidis)

A putative driver of global amphibian decline is the panzootic chytrid fungus Batrachochytrium dendrobatidis (Bd). While Bd has been documented across continental Africa, its distribution in West Africa remains ambiguous. We tested 793 West African amphibians (one caecilian and 61 anuran species) for the presence of Bd. The samples originated from seven West African countries - Bénin, Burkina Faso, Côte d'Ivoire, Ghana, Guinea, Liberia, Sierra Leone - and were collected from a variety of habitats, ranging from lowland rainforests to montane forests, montane grasslands to humid and dry lowland savannahs. The species investigated comprised various life-history strategies, but we focused particularly on aquatic and riparian species. We used diagnostic PCR to screen 656 specimen swabs and histology to analyse 137 specimen toe tips. All samples tested negative for Bd, including a widespread habitat generalist Hoplobatrachus occipitalis which is intensively traded on the West African food market and thus could be a potential dispersal agent for Bd. Continental fine-grained (30 arc seconds) environmental niche models suggest that Bd should have a broad distribution across West Africa that includes most of the regions and habitats that we surveyed. The surprising apparent absence of Bd in West Africa indicates that the Dahomey Gap may have acted as a natural barrier. Herein we highlight the importance of this Bd-free region of the African continent - especially for the long-term conservation of several threatened species depending on fast flowing forest streams (Conraua alleni (“Vulnerable”) and Petropedetes natator (“Near Threatened”)) as well as the “Critically Endangered” viviparous toad endemic to the montane grasslands of Mount Nimba (Nimbaphrynoides occidentalis)