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DNA sequencing of the nuclear ribosomal DNA internal transcribed spacers (ITS) and mitochondrial rrnS and cox2 genes, and analysis of polymorphisms in restriction profiles in the ITS and rrnS, were used to characterise anisakid nematodes belonging to Contracaecum Railliet & Henry, 1912 infecting the brown pelican Pelecanus occidentalis (L.) in Galveston Bay, Texas and Sarasota Bay, Florida. Molecular data led to the detection of two new species: Contracaecum fagerholmi n. sp., which was also supported by clear morphological evidence, and Contracaecum rudolphii F, a new cryptic species within the Contracaecum rudolphii Hartwich, 1964 complex. Bayesian phylogenetic analysis demonstrated that C. fagerholmi and C. rudolphii F form two well-separated clusters, with C. fagerholmi being closely related to Contracaecum bioccai Mattiucci et al., 2008 and C. rudolphii F being included in the C. rudolphii complex. C. fagerholmi can be readily differentiated morphologically from all of its congeners, other than C. microcephalum (Rudolphii 1809) and the five currently recognised members of the C. rudolphii complex (C. rudolphii A, B, C, D and E). C. fagerholmi differs from C. microcephalum in the length of the spicules and the shape of the distal tip of the spicules, and from C. rudolphii (sensu lato) in the shape and size of the ventro-lateral and dorsal lips and by having interlabia which are not distally bifurcate. Further studies are needed to determine which morphological characteristics can be used to distinguish the cryptic species of the C. rudolphii complex in order to assign them with formal names. The recovery of a third species, C. bioccai, from the brown pelican confirms its occurrence in this host and extends its known geographical distribution.

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Species of the genus Lepidapecon are divided into various groups and subgroups based on vitelline distribution relative to the acetabulum and anterior extent of the excretory vesicle. Members of this genus predominantly parasitise gadiform fishes and are commonly collected from relatively deep waters. A recent study of deep-sea helminths from macrourids of the Gulf of Mexico and Caribbean Sea revealed six new species of this genus. L. mexicanensis n. sp., of the elongatum group, elongatum subgroup, differs from other species in this subgroup in proportions (as % of body length), lacking confluent vitelline fields between both the ovary and anterior testis and the testes, and in having a smaller egg and body size. L. nezumiatis n. sp., of the elongatum group, desclersae oesophagus than prepharynx. L. caribbaei n. sp. and L. longivesicula n. sp., of the garrardi group, congeri sub-subgroup, differs from both L. filiformis and L. desclersae in having intermediate egg and body sizes, and a longer group, differ from L. congeri in having a sucker-ratio of 1: < 1. L. caribbaei n. sp. and L. longivesicula n. sp. differ from each other in that L. caribbaei n. sp. has numerous long, barb-like, deeply imbedded spines, a less elongate body, an infundibuliform oral sucker, a similar-sized oesophagus and prepharynx, and a caecal bifurcation which is closer to the acetabulum than oral sucker, while L. longivesicula n. sp. has shorter, serrate or plate-like, lightly imbedded, widely to sporadically spaced spines, a more elongate body, a spherical to subspherical oral sucker, a longer oesophagus than prepharynx, and a caecal bifurcation which is closer to the oral sucker than acetabulum. L. desotoensis n. sp., of the 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, while it differs from L. abyssensis specifically in having a much longer oesophagus than prepharynx, lateral vitelline fields that are not confluent intertesticularly, and wider eggs. L. zaniophori n. sp., also of the rachion subgroup, differs from both L. cascadensis and L. genge in having a smaller egg size, a shorter prepharynx and oesophagus than pharynx, and vitelline fields that are intertesticular but only slightly encroach between the ovary and anterior testis. L. sammari and L. spiniferi are designated as incertae sedis, and L. quiloni and L. stromateusi are designated as species inquirendae. New parasite keys and host records for Coelorinchus coelorhincus. C. caribbaeus and Nezumia cyrano are offered. Support is given to Lepidapedon probably being the dominant digenean genus in deep water.

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During a study of digeneans of shorebirds from the Texas gulf coast, 2 undescribed species of diplostomes were found in northern gannet, Morus bassanus. Bursatintinnabulus n. gen. (Diplostomidae) is established with reassignment of Bursacetabulus macrobursus Dronen et al., 1999, as type species, and the second species in the proposed genus is described, Bursatintinnabulus bassanus n. sp. Generic diagnosis of Bursacetabulus Dronen et al., 1999, is emended to include a conical hindbody, an inconspicuous pouchlike or conspicuous well-developed tribocytic organ, and digitiform vitellaria distributed mainly in the hindbody with processes extending into the tribocytic organ and ventrolaterally in the hindbody to the level of the testes. Bursacetabulus morus n. sp. is described as the second species in that genus. In Diplostominae, Bursacetabulus and Bursatintinnabulus n. gen. are most similar to Tylodelphys Diesing 1850, but can be distinguished by having smooth testes and vitellaria that extend ventrolaterally into the hindbody to the level of the posterior testis; and the absence of a genital cone, an acetabulum, and a prepharynx. Bursatintinnabulus n. gen. is different from Bursacetabulus and all other genera of Diplostominae by a well-developed, bell-like skirt surrounding the bursa.

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Ten (100%) lesser savanna cane rats, Thryonomys gregorianus, collected from the Lake Kivv area of the Democratic Republic of Congo, Africa were found to be infected with an undescribed anoplocephalid tapeworm, Thysanotaenia congolensis n. sp. Like other species of Thysanotaenia, T. congolensis n. sp. has the ovary and vitellarium centrally located, and the egg capsules and testes are intervascular. The new species differs from the 2 existing species, Thysanotaenia lemuris in lemurs and Thysanotaenia cubensis in humans, in being smaller (34-50 mm long) and in having a smaller scolex (260-410 microns in diameter), a shorter cirrus sac (115 microns long), and smaller eggs (40 microns in diameter). Anastomoses of the excretory system and formation of egg capsules in the new species are also described.

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During a study of digenean parasites of deep-sea fishes, 81% (17 of 21) of Monomitopus agassizzi (Ophidiidae) from the Gulf of Mexico were infected with Megenteron manteri n. sp. and 10% (2 of 21) were infected with what appears to be a new species of Steringophorus. M. manteri n. sp. differs from M. crassum in having a longer body (3,733-9,394 microns), shorter caeca and a uterus that extends posteriorly beyond the ends of the caeca. The species of Steringophorus differs from other species in the genus in having smaller eggs (19-23 microns long) and caeca that extend into the posterior half of the hindbody.

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Because of limited access to the endangered Attwater's prairie chicken (Tympanuchus cupido attwateri), we used a related species, the northern bobwhite (Colinus virginianus), as a surrogate for disease evaluation. Free-living northern bobwhites (n = 62) on the Attwater Prairie Chicken National Wildlife Refuge (near Eagle Lake, Texas, USA) were examined during spring and fall 1993 for helminthic endoparasites and specific antibodies against the infectious agents responsible for nine infectious diseases. Trichostrongylus cramae, Raillietina sp., and Strongyloides avium were collected from 97, 44, and 32% of northern bobwhites examined, respectively. Dispharynx nasuta and Syngamus trachea also were found. No gross lesions due to parasites were observed. Specific antibody to Pasteurella multocida was found in 3 of 53 plasma samples. It is possible that potentially pathogenic species such as P. multocida, T. cramae, and D. nasuta could threaten sympatric Attwater's prairie chickens.

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Because conservation biologists have postulated that infectious diseases may have potentiated the endangerment of the Attwater's prairie chicken (Tympanuchus cupido attwateri), free-living prairie chickens were surveyed from all remaining populations for helminthic endoparasites and antibody against the etiological agents of nine infectious diseases. Samples from 4 of 27 adult males were positive for anti-Pasteurella multocida antibody. All other serologic tests were negative (n = 19). We identified Dispharynx nasuta, a parasite previously associated with disease in other grouse from North America, in one of three adult Attwater's prairie chickens examined. Evidence of Trichostrongylus cramae was found for eight of nine suitable samples, which represents the first report of this parasite in prairie grouse. The mean intensity of T. cramae in Attwater's prairie chicken was 1,019.3 (Range = 3-1,906; n = 3). Further work is needed to determine whether P. multocida, T. cramae, or D. nasuta are detrimental to Attwater's prairie chicken populations. If so, conservation biologists could reduce the prevalence and incidence of these parasites and potentially gain more time to address the habitat conditions thought to be the ultimate cause of population declines.

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During a study of Digenea of shorebirds from Galveston, Texas, 30% (30 of 99) of willets, Catoptrophorus semipalmatus (Charadriiformes), were found to be infected with 55-405 Endocotyle bushi per infected host. Although the specimens from Texas generally agree with E. bushi from Florida, specimens from Texas are less elongated, have a more triangular to heart-shaped ovary, have slightly larger eggs, and have a smaller seminal vesicle.

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Ten Canada geese (Branta canadensis), 24 snow geese (Chen caerulescens) and 22 white-fronted geese (Anser albifrons) from coastal Texas (USA) were examined for helminths. Three cestode, seven nematode, and three trematode species were collected. Gizzard nematodes (Amidostomum anseris, A. spatulatum and Epomidiostomum crami) infected 53 of 54 birds. Gross lesions were not attributed to helminth infections and the host population does not appear to be impaired by them.

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Syncoelicotyloides zaniophori n. sp. (Monogenea: Microcotylidae) is described from the gills of the macrourid fish Coryphaenoides zaniophorus caught in the DeSoto Canyon area in the northeastern part of the Gulf of Mexico. This new species is differentiated from Syncoelicotyloides macruri Mamaev and Brashovjan, 1989 by its body size, number of testes, length of copulatory organ spines, morphology of immature portion of germarium, size and morphology of egg, and host.

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The annual prevalence of Leishmania mexicana in Neotoma micropus from 16 southern Texas localities was determined by screening 192 N. micropus using in vitro culture. Eight woodrats also were screened using the polymerase chain reaction (PCR). Forty-six Sigmodon hispidus from four localities were also tested. Seasonal transmission was investigated through trap-recapture studies at three localities and analysis of infections in juveniles. Fourteen N. micropus from four localities were culture-positive for L. mexicana, indicating an annual non-zero prevalence at these localities of 5.6-27%. Four additional infections at two foci were detected only by the PCR. Transmission occurred in the fall in each case in which season of transmission could be determined. No S. hispidus were positive. These data support the hypothesis that N. micropus is a reservoir of L. mexicana in Texas.

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During a study of digenean parasites of deep sea fishes from the Gulf of Mexico, 38% (5 of 13) of Coelorhynchus coelorhynchus Risso, 1810, (Macrouridae) were infected with a total of 33 specimens (6.6/infected fish) of an undescribed species of Fellodistomidae representing a new genus and subfamily. Other macrourids collected at the same time (Bathygadus macrops Goode and Bean, 1886, Malacocephalus occidentalis Goode and Bean, 1885, and Nezumia aequalis Günther, 1878) were not infected with Echinobreviceca coelorhynchae n. gen., n. sp. The new species is most similar to members of the subfamily Baccigerinae, but differs in having an I-shaped excretory vesicle, a densely spined tegument, a pretesticular ovary, and a blind seminal receptacle. Echinobrevicecinae n. subf. is separated from other subfamilies in the family by having an I-shaped excretory vesicle. Echinobreviceca n. gen. is established as the type and only genus in the new subfamily, and E. coelorhynchae n. sp. as the only known species in the genus.

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Buticulotrema stenauchenus n. gen., n. sp. (Opecoelidae: Opecoelinae) is described from the macrourid fishes Malacocephalus occidentalis Goode and Bean, 1885, and Nezumia aequalis Günther, 1878, collected in June 1971 from the DeSoto Canyon area of the Gulf of Mexico at a depth of 495 m. Eight of 25 (32%) M. occidentalis and 1 of 8 (13%) N. aequalis examined were infected with the new opecoelid. Specimens of Bathygadus macrops Goode and Bean, 1886, and Coelorhynchus coelorhynchus Risso, 1810, collected at the same time were not infected with B. stenauchenus. The new genus most closely resembles Genitocotyle Park, 1937, but differs in that it lacks an accessory sucker behind the genital pore, contains a blind rather than canalicular seminal receptacle, and has a slightly pedunculate acetabulum, a pharynx that is longer than wide, and a distinctive, long-necked, bottle-shaped body. Buticulotrema stenauchenus is also similar to Pseudopecoelus von Wicklen, 1946, but the latter lacks a blind seminal receptacle.

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An investigation of the chemotherapeutic effects of 2 anthelmintics, albendazole (ABZ, methyl 5-[propylthio]benzimidazole-2- carbamate) and mebendazole (MBZ, methyl 5-[benzoyl]benzimidazole-2-carbamate), on Hymenolepis microstoma and Hymenolepis diminuta in experimentally infected mice and rats is reported. Single (50 mg/kg) or multiple daily oral doses (50 mg kg-1 day-1 for 3 consecutive days) of MBZ had no effect on H. microstoma; at necropsy, the drug treated mice harbored appreciable numbers of the parasite in the bile duct and biliary passages. ABZ was also inactive when given as a single oral 50 mg/kg dose on day 27 PI. Better results were obtained when ABZ was administered at a dosage of 50 mg kg-1 day-1 for 3 consecutive days; the reduction in worm burden obtained with this treatment regimen was 50%. These results are in marked contrast to those obtained with the same anthelmintics against enteral H. diminuta in rats which succumbed at lower dosages. A review was made of the published reports on the pharmacokinetic behavior of these benzimidazole carbamate anthelmintics and a hypothesis for the inactivity of MBZ against H. microstoma is proposed.

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Trematodes found in 10 Numenius americanus from the Galveston area included Pelmatostomum americanum sp. n. (Echinostomatidae) from the intestine; Paratrema numenii gen. et sp. n. (Philophthalmidae) from the Bursa Fabricii and lower intestine; and the following previously known species, all representing new host records: Maritrema arenaria and Probolocorphye glandulosa (Microphallidae); Lyperosomum oswaldoi and L. sinuosum (Dicrocoeliidae); Cyclocoelum obscurum (Cyclocoelidae); Himasthla rhigedana (Echinostomatidae); and Parorchis acanthus (Philophthalmidae). New taxa are diagnosed and H. rhigedana is redescribed.

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Textrema hopkinsi gen. et sp. n. is described from Micropterus salmoides from central Texas. Textrema is most similar to the genus Multigonotylus but differs in having a single gomotyl. The new genus is placed in the family Cryptogonimidae.

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Mother and daughter sporocysts and xiphidiocercariae of Haematoloechus coloradensis develop in the snail, Physa virgata. Cercariae penerate and encyst in dragonfly nymphs, Tramea sp., Libellula sp., Anax sp., and in damselfly nymphs, Enallagma spp. Upon ingestion by the vertebrate host, metacercariae excyst and migrate into the lungs where they mature. Haematoloechus coloradensis is specific for its definitive host, R. pipiens, but shows some development in Ambystoma tigrinum. Although H. coloradensis is specific for its snail host, all odonate species tested served equally well as the second intermediate host.

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