A review of the genus Helicometra Odhner, 1902 (Digenea: Opecoelidae: Plagioporinae) with a key to species including Helicometra overstreeti n. sp from the cusk-eel Luciobrotula corethromycter Cohen, 1964 (Ophidiiformes: Ophidiidae) from the Gulf of Mexico
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2014, Senckenberg Gesellschaft fr Naturforschung and Springer-Verlag Berlin Heidelberg. Helicometra Odhner, 1902 (Digenea: Opecoelidae) is one of the largest genera within Plagioporinae Manter, 1947. All 34 nominal species possess a single polar filament on the egg, a unique, conspicuous helical uterus, and they parasitize the intestinal tract of 75 families, 172 genera, and 296 species of mostly marine piscine hosts from shallow to deep waters and from equatorial to polar latitudes. This study describes a new species of Helicometra from the cusk-eel Luciobrotula corethromycter Cohen, 1964 (Ophidiiformes: Ophidiidae) collected from 1,280m depth in the northwestern Gulf of Mexico, and it represents the first report of a parasite from the genus Luciobrotula Smith and Radcliffe in Radcliffe, 1913. A key is presented for Helicometra, all species of which are placed into one of four groups based on oral sucker shape, cirrus-sac length, and vitelline follicle distribution. Analyses and conclusions are given for trends observed in zoogeography, life history, and host families (definitive and intermediate) of Helicometra as well as the presence of this parasite in the deep sea and in Ophidiidae Rafinesque, 1810. A prospective life cycle for the new species includes a gastropod as first intermediate host, a caridean shrimp as second intermediate host, and an ophidiid cusk-eel as a definitive host. We provide a comprehensive historical faunal review of all species of Helicometra with information presented on taxonomic status (synonymies, validity of species), definitive and intermediate hosts, infection sites, geographic localities, and museum accession numbers for deposited specimens.
