Freshwater cyclopids (Crustacea: Copepoda) first recorded in South America – arguments for and against their non-native status

Interpretation of occurrence records outside the known range of the species for many freshwater copepods remains difficult due to unresolved taxonomy and/or sparse occurrence data. We report for the first time the occurrence in South America of two cyclopid species with very different evolutionary histories. Mesocyclops granulatus Dussart and Fernando, 1988, a (sub)tropical Asian species with close relatives in the Old World tropics, was found in an artificial lake in the Pacific coastal plain of Ecuador. Acanthocyclops trajani Mirabdullayev and Defaye, 2002, a northern temperate species with Holarctic relatives, was encountered in a high mountain lake in the Andes, Titicaca. Morphology (female and male) is described for both species in detail, nomenclature issues are discussed, and morphological comparisons to the South American congeners and/or close relatives are provided. Morphology-based identification of A. trajani is confirmed by three molecular markers, the nuclear 18S ribosomal DNA and the mitochondrial 12S rRNA and COI genes. While the non-native status of M. granulatus in Ecuador is supported by the biogeographical, phylogenetic and ecological evidence, the origin of the Titicaca populations of A. trajani remains poorly understood. The global distribution of A. trajani and its putative close relatives, as well as the numerous historical occurrence records of some congeners that may be confused with A. trajani in South America, seem to indicate a relict native distribution of the species in the Andes. On the other hand, a phylogenetic tree based on the mitochondrial COI gene in A. trajani populations from Lake Titicaca, North America and Europe does not confirm either the native or non-native status of A. trajani in South America, which may be due to limited information available on the spatial distribution of the haplotype diversity.