We propose Listrocephalos n. gen. (Monogenea: Capsalidae: Entobdellinae) for 2 new capsalid species that infect the skin of 2 species of diamond stingrays (Dasyatidae) in the Gulf of California. We also provide additional observations on 2 previously described capsalid species, which infect the external body surface of stingrays and are currently in Entobdella Blainville in Lamarck, 1818, and transfer them to the proposed new genus. The members of this genus, Listrocephalos corona (Hargis, 1955) n. comb. (type species), Listrocephalos guberleti (Caballero and Bravo-Hollis, 1962) n. comb., Listrocephalos kearni n. sp., and Listrocephalos whittingtoni n. sp., differ from other entobdellines by the combination of having an anterolateral adhesive pad comprising 2 ventral columns of raised ovoid structures, I pair of glands that flank the preoral depression, a discoid and aseptate haptor that lacks a marginal valve but has clover-shaped papillae dispersed radially over its entire ventral surface, minute and nonoverlapping median haptoral sclerites, a bizarre chamber yielding a duct that opens on the surface of the penis, separate genital pores, and a gland of Goto located between the testes and ovary. Listrocephalos kearni n. sp. infects Dasyatis brevis and is most easily distinguished from its congeners by the combination of lacking penis tubules and having a convoluted proximal portion of the vas deferens that occupies the space between the ootype and ovary. Listrocephalos whittingtoni n. sp. infects Dasyatis longa and is most easily distinguished from its congeners by the combination of having penis tubules and a vaginal pore that is located posterior to the level of the uterus. We report specimens of L. corona from the ventral body surface of Dasyatis say from a new locality, Mississippi Sound, as well as specimens of L. guberleti from the skin of 2 new hosts, Urobatis maculatus and Urobatis concentricus, and a new locality, Elkhorn Slough, California. We provide a diagnostic key and a table of records for Listrocephalos spp.

New morphological information on the deep-sea parasitic copepod Bobkabata kabatabobbus Hogans and Benz, 1990 (Lernaeosoleidae: Poecilostomatoida) is provided based on 2 newly discovered, complete specimens collected from a pallid sculpin, Cottunculus thomsoni (Gunther, 1882), captured in water 1,463 m deep in Welker Canyon off Rhode Island (western North Atlantic). The first antennae of both specimens were tiny, indistinctly segmented, and armed with spiniform setae. Terminal segments of the second antennae were robust hooks and were impossible to disengage from the host without severing them from their basal sockets. A simple orifice without any associated appendages may have represented the mouth. Both specimens were transformed adult females and each was embedded in the flesh of their scaleless host up to where the pregenital trunk began to broaden into its characteristic horseshoe shape. Whereas each copepod's bulbous cephalothorax appeared to be the primary attachment device, the powerfully hooked second antennae seemed positioned to facilitate the application of the presumed mouth to the host. A revised family diagnosis for Lernaeosoleidae Hogans and Benz, 1990 is provided that primarily differentiates Lernaeosoleidae from the closely allied Chondracanthidae H. Milne-Edwards, 1840 and other poecilostomatoids based on the absence of mandibles, first and second maxillae, maxillipeds, and thoracic legs 1-4 in lernaeosoleids.

Postoncomiracidia of Dionchus sp. are described from specimens collected from the skin of 2 blacktip sharks Carcharhinus limbatus, captured in the northern Gulf of Mexico. The parasites resemble nonciliated oncomiracidia hatched from eggs laid by Dionchus sp. on gills of a cobia Rachycentron canadum and adults of Dionchus remorae that were collected from gills of a common sharksucker Echeneis naucrates, captured in association with a third blacktip shark. The hamuli of the postoncomiracidia were morphologically similar to those of adult D. remorae. This is the first report of dionchids from an elasmobranch and from a location other than the gills. These findings support the idea that some dionchid oncomiracidia colonize the skin of sharks or other aquatic vertebrates that sponsor remoras, prior to transferring to other remoras and maturing.

Taeniacanthodes dojirii n. sp. (Copepoda: Poecilostomatoida: Taeniacanthidae) is described from adult female specimens collected from the body surface of Cortez electric rays Narcine entemedor (Torpediniformes, Narcinidae), captured at several locations in the Gulf of California. Taeniacanthodes dojirii is distinguished from its congeners, as well as from other members of Taeniacanthidae, by possessing unimerous fifth legs. A cladistic analysis of the 3 known species of Taeniacanthodes resulted in a single most parsimonious tree (tree length = 18 steps, consistency index = 1) demonstrating that T. gracilis and T. haakeri, both parasites of benthic teleosts, are more closely related to each other than to the new species.