Variation of cuticular characters in the Nematomorpha: studies on Gordionus violaceus (Baird, 1853) and G. wolterstorffii (Camerano, 1888) from Britain and Ireland.

Gordionus violaceus (Baird, 1853) and G. wolterstorffii (Camerano, 1888) are regarded as two species which are clearly separated by distinct cuticular patterns. A study of 59 specimens of these two species from Britain and Ireland revealed numerous transitional stages between the cuticular patterns that are regarded as being typical for each species. Variation was also found at the posterior end, but no character separates both species. Therefore, G. violaceus and G. wolterstorffii might represent one polymorphic species. Four specimens resembled G. violaceus but had a different cuticular pattern, including a second type of areole occurring in a pattern which has been named a megareolar pattern. This might represent a separate species, but a detailed determination relies upon further revisional work in the genera Gordionus, Parachordodes and Paragordionus.