SPECIATION OF PROTOPOLYSTOMA BYCHOWSKY, 1957 (MONOGENEA, POLYSTOMATIDAE) IN HOSTS OF THE GENUS XENOPUS (ANURA, PIPIDAE)

The taxonomy, geographical distribution and host range of the polystom atid genus Protopolystoma Bychowsky, 1957 are reviewed. P. xenoyodis ( Price, 1943) and five new species are recognised, which occur in clawe d toads (Xenopus spp.) throughout subsaharan Africa. Of the two clawed toad subgenera, Xenopus and Silurana, only the former is infected. Pr otopolystoma spp. are differentiated by morphological variation of the gut, large hamulus and penis armature. P. xenopodis is found in Xenop us laevis subspecies in South Africa, Transkei, Zimbabwe, Democratic R epublic of Congo (D.R.C.), Rwanda, Uganda, Kenya and Cameroon (X. l. p oweri and X. l. sudanensis are new host records). It also occurs in in troduced populations of X. l. laevis in the United States (southern Ca lifornia) and United Kingdom (South Wales). In subsaharan Africa the s pecies displays significant, but continuous, geographical variation of penis spine size between southern populations in X. l. laevis and tho se in more northerly host subspecies. Data on the natural host range o f this parasite were complemented by an experimental study of host-spe cificity in the southern form. This can produce patent infections in X . l. victorianus and X. gilli, but not X. wittei nor X. (Silurana) tro picalis. P. simplicis n. sp. is endemic to central and east African ar eas, infecting X. laevis subspecies in eastern D.R.C., Rwanda, Uganda and western Kenya, X. wittei-like hosts in eastern D.R.C., western Uga nda, Rwanda and Burundi, X. vestitus in western Uganda and Xenopus sp. at Nairobi, Kenya. P. ramulosus n. sp. occurs in X. fraseri-like toad s in eastern D.R.C. (Gabon and Cameroon are also possible literature r ecords), and P. fissilis n. sp. is found in X. fraseri- and X. wittei- like species in Cameroon and eastern D.R.C., and in southern Rwanda, r espectively. Two Protopolystoma taxa are found in X. muelleri populati ons now suspected to represent distinct species: P. occidentalis n. sp . occurs in X. muelleri (western form) in Ghana, Togo, Nigeria and Cam eroon, while P. orientalis n. sp. is found in X. muelleri (eastern for m) in South Africa, Zimbabwe and Tanzania. The allopatrically distribu ted species P. ramulosus, P. simplicis, P. occidentalis and P. orienta lis form a relatively homogenous grouping with some interspecific morp hological overlap. These taxa are distinguished from P. xenopodis by p enis spine morphology and from P. fissilis by hamulus root form and as pects of gut morphology. Unidentified Protopolystoma sp. have been rec orded in X. clivii in Ethiopia, X. fraseri aff. in Cameroon and Xenopu s sp. in Kenya and Tanzania. At some localities, single host species w ere infected by two representatives of Protopolystoma. P. fissilis was recorded in eastern D.R.C. with P. ramulosus, with Protopolystoma sp. in Cameroon in X. fraseri-like hosts and with P. simplicis in X. witt ei-like hosts in Rwanda. P. xenopodis co-occurred with P. simplicis in X. laevis subspecies through central and east Africa.