Abstract
The Bulinus africanus species group (Planorbidae) of freshwater snails has been reported to be represented in Zambia by two species, B. africanus (Krauss) and B. globosus (Morelet), both named as intermediate hosts for Schistosoma haematobium. Uncertainty in identification of these snails from morphology led to the present investigation, combining morphometry (shell and copulatory organ) with enzyme analysis. Observations of both kinds were made usually on the same individual snails, from collecting sites mostly in the Lusaka area or at Lake Kariba. Particular attention was given to the proportional relationship between the penis sheath and the preputium of the copulatory organ, a character used previously to distinguish B. africanus from B. globosus in south-eastern Africa. The enzyme profile MDH-1, AcP-2, PGD-1 and PGM-2 was common to all snails examined from 25 populations; GPI and HBDH were polymorphic. The enzyme data indicate that the samples represent a single species. Shell characters varied continuously. The copulatory organ was generally of the form known for B. globosus. Although the copulatory organ of a few individuals had proportions overlapping the range reported for B. africanus, the present variation was continuous and was not bimodal. It is concluded that all these specimens are conspecific and may be identified as B. globosus. Previous identifications of B. africanus from Zambia appear to need substantiation and it seems that if this species is present at all in the sampled areas, it must be uncommon. It is relevant in regard to possible strain differences within S. haematobium in Zambia, that our observations indicate that only a single species of intermediate host is involved in transmission.
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References
Brown, D. S., 1966. On certain morphological features of Bulinus africanus and B. globosus and the distribution of these species in southeastern Africa. Ann. Natal Mus. 18: 401–415.
Brown, D. S., 1980. Freshwater snails of Africa and their medical importance. Taylor & Francis, London, 487 pp.
Brown, D. S., 1994. Freshwater snails of Africa and their medical importance. Taylor & Francis, London, 608 pp.
Brown, D. S., G. Oberholzer & J. A. van Eeden, 1971. The Bulinus natalensis/tropicus complex in southeastern Africa: 1, Shell, mantle, copulatory organ and chromosome number. Malacologia 11: 141–170.
Connolly, M., 1939. A monographic survey of the South African non-marine Mollusca. Ann. S. Afr. Mus. 33: 1–660.
Doumenge, J. P., K. E. Mott, C. Cheung, D. Villenave, O. Chapuis, M. F. Perrin & G. Reaud-Thomas, 1987. Atlas of the global distribution of schistosomiasis. CNRS/World Health Organisation, Talence, 400 pp.
Hamilton-Attwell, V. L. & J. A. Van Eeden, 1981. Electrophoresis of the perivitelline fluid of molluscan eggs: 5. A comparison between Bulinus africanus and B. globosus. Wetensk. Bydr. potchefstroom. Univ., B, Natuurwet. 77: 1–15.
Hira, P R., 1969. Transmission of schistosomiasis in Lake Kariba, Zambia. Nature, London 224: 670–672.
Hira, P. R., 1970a. Schistosomiasis at Lake Kariba, Zambia. 1, Prevalence and potential intermediate snail hosts at Siavonga. Trop. Geogr. Med. 22: 323–334.
Hira, P. R., 1970b. Schistosomiasis at Lake Kariba, Zambia. 2, Transmission of Schistosoma haematobium and S. mansoni at Siavonga. Trop. Geogr. Med. 22: 335–344.
Hira, P. R., 1972. Studies on schistosomiasis on the western shores of Lake Bangweulu, Zambia. E. Afr. Med. J. 49: 526–530.
Hira, P. R., 1974. Schistosoma haematobium in Lusaka, Zambia. Trop. Geogr. Med. 26: 160–169.
Hira, P. R., 1975. Seasonal population densities of snails transmitting urinary and intestinal schistosomiasis in Lusaka, Zambia. Trop. Geogr. Med. 27: 83–92.
Jelnes, J. E., 1979. Taxonomical studies on Bulinus using isoenzyme electrophoresis with special reference to the africanus group on Kano plain, Kenya. Malacologia 18: 147–149.
Jelnes, J. E., 1991. Morphometry versus classical and experimental taxonomy: a dilemma posed by studies on West African Bulinus. J. moll. Stud. 57: 297–299.
Joubert, P. H., S. J. Pretorius, K. N. De Kock & J. A. Van Eeden, 1984. The effect of constant low temperatures on the survival of Bulinus africanus, B. globosus and Biomphalaria pfeifferi. S. Afr. J. Zool. 19: 314–316.
Joubert, P. H., S. J. Pretorius, K. N. De Kock & J. A. Van Eeden, 1986. Survival of Bulinus africanus, B. globosus and Biomphalaria pfeifferi at constant high temperatures. S. Afr. J. Zool. 21: 85–88.
Joubert, P. H., F. J. Kruger & S. J. Pretorius, 1990. Susceptibility of South African Bulinus africanus populations to infection with Schistosoma haematobium. Trans. r. Soc. trop. Med. Hyg. 84: 100–102.
Joubert, P. H., S. J. Pretorius & F. J. Kruger, 1991. Further studies on the susceptibility of Bulinus africanus to infection with Schistosoma haematobium. Ann. trop. Med. Parasit. 85: 253–258.
Kristensen, T. K. & A. G. Christensen, 1991. Morphometry versus electrophoresis in Bulinus taxonomy — a reply. J. Moll. Stud. 57: 299–300.
Kristensen, T. K., F. Frandsen & A. G. Christensen, 1987. Bulinusafricanus-group snails in East and South East Africa, differentiated by use of biometric multivariate analysis on morphological characters (Pulmonata: Planorbidae). Revue Zool. Afr. 101: 55–67.
Langand, J., V. Barral, B. Delay & J. Jourdane, 1993. Detection of genetic diversity within snail intermediate hosts of the genus Bulinus by using Random Amplified Polymorphic DNA markers (RAPDs). Acta Tropica, 55: 205–215.
Machena, C. & N. Kautsky, 1988. A quantitative survey of benthic vegetation and fauna in Lake Kariba, a tropical man-made lake. Freshwat. Biol. 19: 1–14.
Mandahl-Barth, G., 1957. Intermediate hosts of Schistosoma. African Biomphalaria and Bulinus: 2. Bulinus. Bull. Wld Hlth Org. 17: 1–65.
Mandahl-Barth, G., 1960. Intermediate hosts of Schistosoma in Africa. Some recent information. Bull. Wld Hlth Org. 22: 565–573.
Mandahl-Barth, G.,1965. The species of Bulinus, intermediate hosts of Schistosoma. Bull. Wld Hlth Org. 33: 33–44.
Mandahl-Barth, G., 1968. Freshwater molluscs. Expl. hydrobiol. Bangweulu-Luapula 12: 1–68.
Mandahl-Barth, G., 1973. Descriptions of new species of African freshwater molluscs. Proc. malac. Soc. Load. 40: 277–286.
Mungomba, L. M., S. K. Chandiwana & H. Madsen, 1993. Schistosomiasis around Siavonga, on the shores of Lake Kariba, Zambia. Ann. trop. Med. Parasit. 87: 365–371.
Rollinson, D. & R. A. Kane, 1991. Restriction enzyme analysis of DNA from species of Bulinus (Basommatophora: Planorbidae) using a cloned ribosomal RNA probe. J. moll. Stud. 57: 93–98.
Rollinson, D. & V. R. Southgate, 1979. Enzyme analyses of Bulinus africanus group snails from Tanzania. Trans. r. Soc. trop. Med. Hyg. 73: 667–672.
Strahan, K., R. A. Kane & D. Rollinson, 1991. Development of cloned DNA probes for the identification of snail intermediate hosts within the genus Bulinus. Acta Tropica 48: 117–126.
Wright, C. A. & D. Rollinson, 1979. Analysis of enzymes in the Bulinus africanus group (Molluscs: Planorbidae) by isoelectric focusing. J. nat. Hist. 13: 263–273.
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Brown, D.S., Rollinson, D. Aquatic snails of the Bulinus africanus group in Zambia identified according to morphometry and enzymes. Hydrobiologia 324, 163–177 (1996). https://doi.org/10.1007/BF00018178
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DOI: https://doi.org/10.1007/BF00018178