The Herpetological Journal

pp.3-6

Authors: J.C. Poynton

Abstract: The toad family Bufonidae is being studied as part of a review of Tanzanian amphibians. The current list includes 6 genera (one undescribed), and 28 described and undescribed species. This represents 40% of the bufonid genera and 31 % of the bufonid species known in sub-Saharan Africa. Two genera and fifteen species are considered to be endemic. Tanzania appears to have the richest bufonid fauna of any sub-Saharan country. Bufonid distribution conforms with the tendency in Tanzania towards marked differences between upland and lowland biotic communities. Separation of the Afromontane Nectophrynoides and the lowland Mertensophryne and Stephopaedes is particularly striking. Fifty-seven per cent of the bufonid species recorded in Tanzania appear to be associated with forest. Precise data concerning the rate and extent of forest disturbance and deforestation are lacking, and the potential for forest-associated bufonids to survive these perturbations is unknown. Effective conservation action requires more information and improved understanding of the many factors involved.

pp.7-12

Authors: Malcolm J. Largen

Abstract: Provisionally, 60 named species of amphibian are recognized in Ethiopia, of which 14 have been described since 1970. Six genera and 23 species are currently listed as endemic, the great majority of these being clearly associated with montane forest, grassland or moorland at altitudes above 1800 m. The Ethiopian Plateau has evidently provided a refuge for some taxa which have a relict distribution in the mountains of Africa and a major centre for occupation and adaptive radiation by others. Huge areas of Ethiopia remain to be explored biologically and it seems certain that future fieldwork will substantially increase the number of amphibian species recorded. Meanwhile, as destruction of natural habitats by an ever-growing human population becomes increasingly widespread, it is inevitably the threat to montane and forest endemics which gives greatest cause for concern.

pp.13-17

Authors: H. R. Kobel, B. Barandun And Ch. H. Thlébaud

Abstract: Based on morphological, biochemical and karyological characters, the genus Xenopus can be divided into two main groups (subgenera), Silurana and Xenopus, and the latter into five subgroups. The relationships among these five subgroups are less clear. Since all except one species are allopolyploid (tetra-, octo- and dodecaploid), they are, by definition, not monophyletic. In principle, sequence data would permit unravelling of these complex relationships, provided that all duplicated genes were conserved. However, that is not the case: redundant genetic information tends to become lost, interrupting phylogenetic lines of descent of the genes. Since the mitochondrial genome is inherited in a purely matrilinear manner, problems linked to polyploidy are seemingly avoided. However, this character is not monophyletic either. At least at the start of an allopolyploid speciation, mitochondria of both parental species can be present though one or the other type eventually becomes extinct. Which one is conserved is probably random. Nevertheless, it may be interesting to compare the phylogeny of mitochondria to species trees based on nuclear characters. We sequenced about 600 bp of mitochondrial 12s and 16s rRNA genes of the diploid X. tropical is, of most tetraploid species, and of the octoploid X. wittei. Trees obtained with Neighbor Joining, Maximum Likelihood and Maximum Parsimony methods essentially confirm the tropicalis, laevis and muelleri groups and subgroups, whereas thefraseri subgroup is less well defined. Mitochondria of X. clivii and X. largeni, members of the muelleri and the laevis subgroup respectively, show only a low bootstrap score when connected to any subgroup, thus forming a polytomy of several speci es. Divergence of the same sequence between Rana catesbeiana and R. temporaria, for which immunological and zoogeographic considerations suggest a possible age of roughly 30-40 Ma, was used for tentative calibration of the Xenopus mitochondrial tree. This calibration is necessary for comparison with other phylogenetic data on this genus.

pp.19-22

Authors: Joseph A. Jackson, Richard C. Tinsley And Stephen Kigoolo

Abstract: Three Xenopus taxa occur with sympatric or parapatric distributions in western Uganda. Two of these, X. wittei and X. vestitus, are polyploid relative to the third, X. laevis, and are considered to have arisen by allopolyploidization. This is a rare mechanism of speciation by which doubling of the genome in interspecific hybrids leads to the production of a self-maintaining hybrid lineage. As one of the parental lineages of both higher polyploid species may have been related to X. laevis, the co-occurrence of the three tax a might show the effects of hybrid host genomes on parasite specificity. Data are reported on the natural distribution of a monogenean fluke, Protopolystoma, occurring in these hosts at five sites in western Uganda. It is established that P. xenopodis, a common parasite of X. laevis, is absent from wild populations of X. vestitus and X. wittei in this area. Another Protopolystoma species infects all three hosts. The results of other recent host-specificity studies of parasites occurring in central African Xenopus species are also reviewed. Observed host-parasite relationships can be related to the genealogical origin of X. wittei and X. vestitus. Hybrid organisms might inherit susceptibility to parasites from both parents and thus be exposed to infection by a greater number of species. However, the available information suggests that allopolyploid clawed toads do not show such an effect and are resistant to some potential parasites from their presumed parental lineages. The possible use of parasites as "tags" for investigating the distribution and relationships of cryptic host species is also considered.

pp.23-27

Authors: G. John Measey And Richard C. Tinsley

Abstract: Despite its prominence as the "standard laboratory amphibian", the ecology of the African clawed frog, Xenopus laevis, has been neglected. Feral populations have been documented in several countries with Mediterranean climates, but established populations are also known from the UK. Long term studies of individually-marked X. laevis in South Wales reveal large demographic fluctuations and the ability to migrate overland. Maximum longevity recorded from recapture of marked individuals was 14 years. Diet analysis demonstrates a major reliance on benthic invertebrates and zooplankton components of the pond fauna. Skeletochronological studies of growth rings in bone showed that lines of arrested growth are formed annually and allow calculation of age. Data on population age structure indicate successful recruitment is infrequent, with dominant cohorts originating in perhaps only four summers during the past 20 years.

pp.29-34

Authors: Ania M. Wieczorek , Alan Channing And Robert C . Drewes

Abstract: This paper reviews the problematic taxonomy of the superspecies Hyperolius viridiflavus (the senior synonym of H. marmoratus) (Anura: Hyperoliidae). The classifications proposed by various authors for the complex are summarized and compared. Significant differences in classification have resulted in the complex being divided into as few as three species (with numerous subspecies) or as many as 18 species (with a number of subspecies).The review shows that the taxonomy of this complex has not been resolved, as a consequence of dependence on the use of dorsal colour patterns as diagnostic characters. Colour pattern is polymorphic within taxa, and shows both geographical as well as non-geographical variation. Recent work has shown molecular techniques to be a valuable means of distinguishing tax a previously considered to be subspecies. It is proposed that the use of molecular techniques and phylogenetic analysis of these data is the most suitable means of resolving the taxonomy of the members of this complex.

pp.35-40

Authors: Michael W. Klemens

Abstract: Recent field work in the Udzungwa Mountains of Tanzania has resulted in the discovery of the hitherto unreported nuptial characters of male Arthroleptides martiensseni which are described and illustrated in this contribution. These newly described characters are compared with the nuptial characters of male Arthroleptides dutoiti, a supposedly extinct species from Mount Elgon (Kenya) as well as with members of the West African genus Petropedetes, which exhibit some remarkable morphological and ecological similarities with Arthroleptides martiensseni.

pp.41-46 

Authors: Christina M. Richards And William S. Moore

Abstract: A phylogenetic tree is presented for the Old World treefrog family Rhacophoridae and other ranoid frogs that that have an Africa-Madagascar-Asia distribution. The tree was inferred from parts of the mitochondrial ribosomal 12S and 16S genes and the tRNA^val gene sequences with the Microhylidae as outgroup. The tree indicates that the rhacophorids are a monophyletic group composed of a Madagascar clade and an Asian-African clade. When endemic Madagascar mantellids were added to the tree, they also were part of the Madagascar rhacophorid clade, but the support for this assignment is weak. Tomopterna labrosa, a ranid endemic to Madagascar, appears more closely related to the Madagascar rhacophorids than it does to the ran ids included in the analysis. Support for this relationship is strong enough to merit reinvestigation of the morphology and extension of the molecular data set.

pp.47-50

Authors: M. R. Warburg , Mira Rosenberg And K. E. Linsenmair

Abstract: The epidermis of Hyperolius nitidulus (Peters, 1 875) (Hyperoliidae) consists of three strata: stratum corneum, stratum granulosum and stratum germinativum. The stratum corneum of both H. nitidulus and Hemisus marmoratus (Peters, 1 854) (Hemisiidae), contains 1 -2 replacement layers. The granular cells of H. nitidulus are arranged in 2-3 rows. No granular cells typical of the stratum granulosum could be seen in H. marmoratus. This is a unique situation for any .amphibian. Very large germinative cells were observed in both anurans. In H. nitidulus a unique, long and slender 'pillar cell' is situated under the stratum corneum, extending through the stratum germinativum, and the basement membrane deep into the dermis. This cell contains abundant tonofilaments, and appears to function as a pillar supporting the frequently moulting stratum corneum.

pp.51-56

Authors: Brian A. Wilson , Gerhard Van Der Horst And Alan Channing

Abstract: Studies on anuran spermatozoa have been restricted to the use of testicular sperm. Although these studies have been effective in creating baseline data, the motility parameters of ejaculate spermatozoa could present a clearer picture of the reproductive physiology. Methods were devised to aspirate sperm from amplectant males and collect the ejaculate from males. Sperm motion was then studied quantitatively and the various sperm motion parameters compared. Further research is necessary to determine whether Wolffian duct and cloaca! secretions play a role in altering sperm motion characteristics of anuran testicular spermatozoa.

pp.57-64

Authors: Begoña Arano , Gustavo A. Llorente, Albert Montori , David Buckley And Pilar Herrero

Abstract: We have assessed the consistency of allozyme and morphometric data sets in discriminating water frogs at inter- and intraspecific level. Twenty allozyme loci and 14 morphometric characters were used in a study on Iberian and North African water frogs. The results from the morphometric analysis, using PCA, confirmed the interspecific differences between Rana perezi from the Iberian Peninsula and Rana saharica from North-west Africa previously detected by allozyme analysis. Allozyme and morphometric data were also consistent in discerning between Algerian and Moroccan populations of R. saharica, pointing to the presence of at least two subspecies in the Maghreb: R. saharica saharica from Algeria and R. saharica riodeoroi from Morocco. A possible paleobiogeographical scenario of the divergence between the two groups is discussed.