Eight new Afrotropical Spinitectus spp. (Nematoda: Cystidicolidae) from freshwater fishes with a key to the members of the genus in the Region

Abstract

Seven new species of the genus Spinitectus Fourment, 1883, recovered from several species of freshwater fishes from West and Central Africa, are described. The eighth species, Spinitectus allaeri Campana-Rouget , 1961 recorded by Moravec (1974) in Egypt, is assigned to Spinitectus moraveci n. sp. The new and known species have been divided into three groups according to the number of spines in the first row behind the anterior end. The Spinitectus spp. in Group A have fewer than 20 spines in the first row and the group contains Spinitectus mormyri Campana-Rouget, 1961, Spinitectus thurstonae Ogden, 1967 and Spinitectus micropectus n. sp. Those in Group B have between 20 and 40 spines in the first row and comprise the species S. allaeri, Spinitectus menzalei Hugot, 1979, Spinitectus maleficius n. sp., Spinitectus macilentus n. sp., Spinitectus minusculus n. sp., Spinitectus macherius n. sp., Spinitectus mucronatus n. sp. and Spinitectus moraveci n. sp. Group C species have more than 45 spines in the first row and consist of Spinitectus polli Campana-Rouget, 1961 , Spinitectus petterae Boomker, 1993, Spinitectus zambezensis Boomker, 1993, and Spinitectus monstrosus n. sp. The species that are quite distinctive are S. mucronatus , which has characteristic spinulation and lateral floats on the eggs; S. monstrosus, which has characteristic spinulation and an exceptionally long left spicule; S. micro pectus, which has approximately 80 rows of large spines and six post-cloacal papillae and S. maleficius , that has approximately 20 rows of large spines and seven post-cloacal papillae. The remaining species can be differentiated by the number of spines in the first row, the number of post-cloacal papillae, the number of labial papillae and, in the females, the distance between the anus and the vulva and the position of the gravid uterine coils in relation to the anterior end. S. moraveci differs from S. allaeri in that the first six rows of spines are raised, giving the anterior end an inflated appearance, in the number of post-cloacal papillae, and in that the distance between the anus and the vulva is considerably shorter. There are distinct morphological similarities between the Spinitectus species recovered from Heterobranchus isopterus and/or Clarias vanderhorsti (Clariidae) in Liberia, Ivory Coast and Sierra Leone, those recovered from Mormyrus spp. (Mormyridae) in western Zaire, Angola and Cameroon, and those recovered from Mastacembelus spp. (Mastacembelidae) in eastern Zaire. The differences lie mainly in the spinulation and the position at which the excretory pore opens, and they may be the result of host influence or represent adaptive radiation in the various regions. The affinities of the different species are discussed and a key to the members of the genus in Africa is provided.