Systematics and phylogeny of the Ancorabolidae (Copepoda : Harpacticoida).I. The Ancorabolus-lineage, with the description of three new genera.

The Ancorabolus-group is recognized within the sub-family Ancorabolinae (Ha rpacticoida, Ancorabolidae) comprising Ancorabolus, Arthropsyllus and three new genera: Breviconia gen. nov., Juxtaramia gen. nov and Uptionyx gen. no v. The common ancestry of these genera is supported by antennulary segmenta tion, rostral morphology, cephalothoracic sensillar patterns, presence of l ateral body processes, elongation of P1 endopod, segmentation of male P3 en dopod and P5 armature in both sexes. Two new species of Ancorabolus are described from Frierfjord/Langesundfjord in Norway. A. inermis sp. nov. and A. confusus sp. nov. occur sympatricall y in southern Scandinavia and can be readily differentiated by the pattern of body processes. Re-examination of Sars' (1909) material revealed that hi s widely adopted redescription of the type species A. mirabilis was based o n an amalgamate of these two species. All records of A. mirabilis from outs ide the Firth of Clyde (Scotland) which cannot be identified as A. inermis or A. confusus have to be regarded as unconfirmed. Norman's (1903) material of A. mirabilis collected in East Finmark (Norway) and erroneously designa ted as types, is radically divergent in cephalic process pattern, caudal ra mus configuration, antennary armature and P1 morphology. It is allocated to a new genus and species, Juxtaramia polaris. Both sexes of Arthropsyllus serratus are redescribed from new and existing material collected in southern Norway. Re-examination of Norman's (1911) ma terial from the Firth of Clyde did not provide any conclusive evidence to m aintain A. serratus spinifera as a valid subspecies. A. australis is transf erred as the type species of a new genus Breviconia, since it deviates sign ificantly from the revised diagnosis of Arthropsyllus. Laophontodes echinat us Brady, 1918 is regarded as species inquirenda in Breviconia. A new genus and species, Uptionyx verenae, is described from a hydrothermal vent of the Juan de Fuca Ridge, northeastern Pacific Ocean. Parsimony analysis of the Ancorabolus-group identifies Arthropsyllus as the most primitive offshoot and Juxtaramia-Ancorabolus as the terminal clade w ith both Uptionyx and Breviconia diverging from intermediate nodes. Evoluti on in the group is typified by progressive elaboration and ramification of integumental processes on the cephalothorax and free body somites, culminat ing in the complex body ornamentation of the most advanced genus Ancorabolu s. Distribution records of all five genera are compiled.