title: Cryptic diversity of the 'cosmopolitan' harpacticoid copepod Nannopus palustris: genetic and morphological evidence.
abstract: Nannopus palustris Brady, 1880 is a free-living widely distributed harpacticoid copepod, which has been formerly assumed to be a single, cosmopolitan but highly variable species. We compared several geographically distant N. palustris populations in terms of their morphology and genetics. Populations from the White Sea (WS), the North Sea (NS), the Black Sea (BS) and two sympatric morphs from South Carolina, USA (SC notched and SC straight morphs), were considered. The NS, BS and to a lesser extent SC notched specimens were morphologically similar and partly coincided to the 'canonical' description of the species. By contrast, WS population showed remarkable anatomical and morphometric peculiarities that correspond to some earlier descriptions. Genetic analyses of mitochondrial (cytochrome b) and nuclear (28S rDNA) genes demonstrated the significant distinctness among WS, both SC and (NS+BS) populations, the latter two being genetically indistinguishable. Concordance between mitochondrial and nuclear gene trees and morphological data supports that N. palustris is in fact composed of several pseudo-sibling species, which are genetically and morphologically divergent. Neither correlation between genetic divergence and geographical distance nor significant intrapopulation diversity was found for these species. Taxonomic status, distribution and phylogenetic relationships of the species within the Nannopus genus need to be reconsidered. A further subdivision of species complexes might have important implications for the analysis of biodiversity of benthic copepods and consequently for the interpretation of their (species-specific) ecological function.
authors.affiliation: Odesa Branch, Kovalevsky Institute of Biology of Southern Seas, NASU, 37 Pushkinska Str., 65125, Odesa, Ukraine. garlitska@gmail.com
authors.forename: Lesya
authors.initials: L
authors.lastname: Garlitska
authors.forename: Tatyana
authors.initials: T
authors.lastname: Neretina
authors.forename: Dimitry
authors.initials: D
authors.lastname: Schepetov
authors.forename: Nikolai
authors.initials: N
authors.lastname: Mugue
authors.forename: Marleen
authors.initials: M
authors.lastname: De Troch
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Baguley
authors.forename: Andrey
authors.initials: A
authors.lastname: Azovsky
mesh_terms: D000818:Animals; D044822:Biodiversity; D059038:Black Sea; D033342:Copepoda / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D005843:Geography; D008297:Male; D008969:Molecular Sequence Data; D009659:North Sea; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012744:Sex Ratio; D013022:South Carolina