Six new species of Lepidapedon Stafford, 1904 (Digenea : Lepocreadiidae) from deep-sea macrourid fishes from the Gulf of Mexico and Caribbean Sea, with revised keys to the species of the genus

Species of the genus Lepidapedon are divided into various groups and subgro ups based on vitelline distribution relative to the acetabulum and anterior extent of the excretory vesicle. Members of this genus predominantly paras itise gadiform fishes and are commonly collected from relatively deep water s. A recent study of deep-sea helminths from macrourids of the Gulf of Mexi co and Caribbean Sea revealed six new species of this genus. L. mexicanensi s n. sp., of the elongatum group, elongatum subgroup, differs from other sp ecies in this subgroup in proportions (as % of body length), lacking conflu ent vitelline fields between both the ovary and anterior testis and the tes tes, and in having a smaller egg and body size. L. nezumiatis n. sp., of th e elongatum group, desclersae subgroup, differs from both L. filiformis and L. desclersae in having intermediate egg and body sizes, and a longer oeso phagus than prepharynx. L. caribbaei n. sp. and L. longivesicula n. sp., of the garrardi group, congeri subgroup, differ from L. congeri in having a s ucker-ratio of 1:< 1. L. caribbaei n. sp. and L. longivesicula n. sp. diffe r from each other in that L. caribbaei n. sp. has numerous long, barb-like, deeply imbedded spines, a less elongate body, an infundibuliform oral suck er, a similar-sized oesophagus and prepharynx, and a caecal bifurcation whi ch is closer to the acetabulum than oral sucker, while L. longivesicula n. sp. has shorter, serrate or plate-like, lightly imbedded, widely to sporadi cally spaced spines, a more elongate body, a spherical to subspherical oral sucker, a longer oesophagus than prepharynx, and a caecal bifurcation whic h is closer to the oral sucker than acetabulum. L. desotoensis n. sp., of t he rachion group, rachion subgroup, is distinct from both L. luteum and L. abyssensis in having a smaller size, lacking cervical glands or pharyngeal gland cells, and possessing dark-staining particles in the mesenchyme, whil e it differs from L. abyssensis specifically in having a much longer oesoph agus than prepharynx, lateral vitelline fields that are not confluent inter testicularly, and wider eggs. L. zaniophori n. sp., also of the rachion sub group, differs from both L. cascadensis and L. genge in having a smaller eg g size, a shorter prepharynx and oesophagus than pharynx, and vitelline fie lds that are intertesticular but only slightly encroach between the ovary a nd anterior testis. L. sammari and L. spiniferi are designated as incertae sedis, and L. quiloni and L. stromateusi are designated as species inquiren dae. New parasite keys and host records for Coelorinchus coelorhincus, C. c aribbaeus and Nezumia cyrano are offered. Support is given to Lepidapedon p robably being the dominant digenean genus in deep water.