A review of the taxonomy of five Ontario genera of freshwater cyclopoid Copepoda (Crustacea)

Abstract

Examination of material of five cyclopoid copepod genera found in Ontario fresh waters and a comparison with species of these genera from other parts of the world closely related to Ontario species has given some very interesting results. The widespread Ectocyclops phaleratus was the species previously recorded from Ontario. However, the Ontario material fits the description of E. polyspinosus Harada, 1931, known from Taiwan. There is considerable confusion in the nomenclature of North American species of Eucyclops. In Ontario Eucyclops serrulatus is found. This widespread and variable species needs revision on the basis of worldwide material. Hence, only a provisional identification can be made now. The species previously called E. speratus in Ontario is a hitherto underscribed species, E. neomacruroides, closely related to, but we think distinct from, E. macruroides and E. speratus. The third species is Eucyclops macruroides denticulatus and the fourth is the very distinctive E. prionophorus. In the genus Tropocyclops, besides the widely occurring Tropocyclops prasinus prasinus, T. extensus was found. This latter species has been consistently identified as T. prasinus mexicanus since 1959. Four species of the genus Acanthocyclops occur in Ontario. Acanthocyclops robustus is very common; A. vernalis is rare and so are A. venustoides and A. carolinianus. We are unable to resolve the status of A. venustoides bispinosus, as only late copepodid stages of this species, and no mature adults, are available. Mesocyclops americanus, long called M. leuckarti, is now a well-documented species, much rarer than the somewhat atypical (for the genus) M. edax, well known in North America. Our proposed designations for North American species are summarized. There is a need to collect material year round from all available biotopes to document the species composition of Ontario Copepoda. Our work is also a first step in clarifying the status of North American Copepoda, comparing material from North America and elsewhere.