Populations of Campyloderes sp. (Kinorhyncha, Cyclorhagida): One global species with significant morphological variation?

Altogether, 103 adult and 23 juvenile specimens of Campyloderes from 33 locations both in the deep sea and on the continental shelf all over the world were studied by light microscopy (97 specimens) and scanning electron microscopy (28 specimens). Especially from the Faroe Island, the Central American East Pacific Ocean and from the area east and northeast of New Zealand, enough specimens are available to study the regional variation of characters. Specimens both from these regional areas and worldwide reveal a significant morphological variation, especially in the distribution of sensory spots, gland cell outlets, and papillae, whereas characters conventionally used for species identification, such as spine pattern do not vary much. Overlapping character patterns do not allow identification of different species and to discriminate the current populations from previously described species. We conclude that the morphological variation results from ongoing species formation processes. We also report observations that two adult life history stages may exist in Campyloderes. The character set in the ground pattern of Campyloderes is presented.