Freshwater rhabdocoela (Platyhelminthes) from ephemeral rock pools from Botswana, with the description of four new species and one new genus

Abstract

Four new species of freshwater rhabdocoel flatworms from ephemeral rock pools in southeastern Botswana are described and discussed. Two of them, Syringoplana kolasai n. gen. n. sp. and Mesostoma thamagai n. sp. belong to the Typhloplanidae Graff, 1905. The unique construction of the excretory system is the main characteristic of S. kolasai. M. thamagai can be separated from other Mesostoma Ehrenberg, 1837 species by the presence of a bundle of eosinophilic glands at the transition from oviduct to seminal receptacle. The other two taxa, Gieysztoria isoldeae n. sp. and G. faubeli n. sp. belong to the Dalyelliidae Graff, 1905. G. isoldeae is characterised by the presence of four separate hollow spines in the male atrium, which are connected to two accessory glandular organs. G. faubeli can be separated from other Gieysztoria Ruebush and Hayes, 1939 species by the detailed construction of the stylet. Apart from these two species the occurrence of an unidentified Microdalyellia Gieysztor, 1938 species is mentioned.