Towards a revision of Ameira Boeck, 1865 (Harpacticoida, Ameiridae): reinstatement of Psammameira Noodt, 1952

Both sexes of Ameira hyalina (Noodt, 1952) and A. parasimulans Lang, 1965 are redescribed. The genus Psammameira Noodt, 1952 previously regarded as a junior subjective synonym of Ameira. is reinstated to accommodate these two species and a revised diagnosis for the genus is presented. Examination of the type material of Psammameira reducta Wells, 1967 and P. gradis (Nicholls, 1939) revealed that they should be removed from the genus. The possible relationships of two species of doubtful affinity, A. esigun T. Scott, 1894 and A. simulans T. Scott, 1912 are reconsidered. The phylogenetic position of Psammameira within the Ameiridae is briefly discussed.     

Studies on the Cylindropsyllidae (Copepoda, Harpacticoida). 1. The status of Leptastacus laticaudatus Nicholls

Leptastacus laticaudatus Nicholls, 1935, commonly found interstitially in fine sands of European boreal waters, is redescribed and figured. As a result, the subspecies names L. laticaudatus laticaudatus and L. laticaudatus intermedius Kunz, 1938 are nullified. Some variable characters, i.e. caudal rami and structure of the fifth leg, are discussed and the distribution of the species is summarized. The most closely allied species L. macronyx (T. Scott, 1892) and L. spatuliseta Mielke, 1982 constitute, together with L. laticaudatus , the 'macronyx -group'. L. laticaudatus intermedius sensu Apostolov, 1973 is considered species inquirenda . An amended diagnosis of the genus Leptastacus T. Scott, 1906 is presented.     

A new genus of Canuellidae (Copepoda, Harpacticoida) associated with Atlantic bathyal sea-urchins

Both sexes of Echinosunaristes bathyalis gen. ct sp. n. are described from the rectum of a deepwater spatangoid sea-urchin Palaeopneustes sp. taken off San Salvador Island, Bahamas. The new genus displays strong sexual dimorphism in body form, size, antennules and caudal rami. E. bathyalis can also be readily distinguished from the other members of the family by the specialized geniculation mechanism of the male antennule, the atypical reductions in the mouthparts and the unusual facies of the swimming legs. On the basis of the structure of the genital field in both sexes, Echinosunaristes is placed in the Sunaristes lineage which groups species that arc primarily associated with crustacean hosts. A ncw genus Intersunaristes is established to accommodate Sunaristes curticaudata Thompson & A. Scott, 1903 and S. dardani Humes & Ho, 1969. Canuella paenelanitica Fiers, 1992 is formally transferred to the genus Elanella Por, 1984. Records of Canuellidae associated with other invertebrates arc compiled and a key to the 17 genera of the family is presented.     

Small subunit rDNA and Bayesian inference reveal Pectenophilus ornatus (Copepoda incertae sedis) as highly transformed Mytilicolidae, and support assignment of Chondracanthidae and Xarifiidae to Lichomolgoidea (Cyclopoida)

Phylogenetic analysis of newly obtained data from the complete small subunit rDNA (18S) nuclear gene of a wide range of copepods placed the enigmatic Pectenophilus ornatus firmly in the Cyclopoida. Both maximum parsimony tree reconstruction, and Bayesian analysis operating under the GTR + I + Γ model of nucleotide substitution, gave identical solutions and placed P. ornatus at the base of the poecilostome families, in apposition to the mytilicolid taxa. The recently suggested assignment to the Siphonostomatoida on the basis of a tubular mouth cone in the pygmy male was rejected not only by the molecular data but also by new morphological observations. Scanning electron microscopy revealed that the appendage previously interpreted as the mandible was in reality the maxilla, the presumptive ‘labium’ only an intermaxillary outgrowth of the ventral cephalic sclerite bearing the widely separated paragnaths, and that there was no basal fusion between the labrum and the ‘posterior lip’ as in genuine siphonostomatoids. Absence of mandibles and their functional replacement by the anteriorly displaced maxillae is a unique and robust apomorphy for the Mytilicolidae and placed unequivocally P. ornatus in that family. The morphology of male Pectenophilus probably evolved as a result of global progenesis, involving early sexual maturation at the metanauplius stage and the complete cessation of somite and limb development. The molecular data were also employed to examine the relationships of two other highly modified parasitic families, the Xarifiidae (inhabiting hard corals) and the Chondracanthidae (parasitic on marine demersal fishes). Our analyses rejected the previously proposed relationship between Xarifiidae and Vahiniidae and strongly supported an Anchimolgidae + (Rhynchomolgidae + Xarifiidae) clade as sister group to the Sabelliphilidae within a monophyletic Lichomolgoidea. The obtained topology suggests that the common ancestor of this clade had already established a symbiotic relationship with scleractinian corals and that host switching occurred only secondarily in the Rhynchomolgidae, involving predominantly other cnidarian and occasionally noncnidarian hosts. Reassessment of the morphology of Parangium provided new evidence for a relationship with the xarifiids, rendering its current position in the Serpulidicolidae extremely unlikely. Both parsimony and Bayesian analyses revealed an unexpected but strongly supported relationship between the Chondracanthidae and Pseudanthessiidae. This result contrasts with earlier views advocating affinity to the Synapticolidae or Lichomolgidae, but was congruent with the previously unnoticed morphological similarity in antennary armature patterns in the first copepodid stage. The morphological grounds used to establish the Lernaeosoleidae were shown to be secondarily derived characters shared with one or several chondracanthid genera. Particularly the similarity between the Lernaeosoleidae and Markevitchielinus demonstrated that the former evolved from a mesoparasitic ancestor within the Chondracanthidae and consequently should sink as a synonym of the latter. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87 , 403–425.