Dieffluvium nidulorum n. sp. is described from smallmouth buffalo, Ictiobus bubalus, collected from Menard Creek in the Big Thicket National Preserve, Texas, U.S.A. The new species is characterized by a scolex with 2 medial acetabula, 4 lateral loculi, and a terminal disc; a uterus that extends far anterior of the cirrus sac in 2 lateral loops; and a very large and muscular external seminal vesicle. Postovarian vitellaria may be present or absent. The new species is a member of the Caryophyllaeidae, and most closely resembles Dieffluvium unipapillatum, Rowardleus pennensis, and some species of Biacetabulum. We amend the genus Dieffluvium to reflect additional information provided by the discovery of the new species, and precisely differentiate its members from other similar taxa.

Three species (2 new) of Lamellodiscus (Diplectanidae) are reported from gill lamellae of porgies (Perciformes: Sparidae) from the Gulf of Mexico off Florida. Lamellodiscus occiduus n. sp. is described from the littlehead porgy Calamus proridens and knobbed porgy Calamus nodosus. Lamellodiscus vesperus n. sp. is described from the jolthead porgy Calamus bajonado. Lamellodiscus baeri is reported from the red porgy Pagrus pagrus. The new species of Lamellodiscus are the first of the genus to be described from the western Atlantic region (Gulf of Mexico). The Gulf of Mexico is a new locality record for L. baeri.

Faustula gangetica (Srivastava, 1935) Yamaguti, 1958 (Plagiorchiida: Faustulidae) from the Hilsa shad, Tenualosa ilisha (Hamilton) (Clupeiformes: Clupeidae), collected in the Arabian Gulf off Iraq between June and October 2014 is redescribed. We include details of the structures within the cirrus sac and provide further basic morphology for this species not previously available. Faustula ilishii (Srivastava, 1935) Yamaguti, 1958 is synonymized with F. gangetica. This is the first report of F. gangetica from the Hilsa shad in the Arabian Gulf.

Bluegill sunfish (Lepomis macrochirus) have two male morphotypes, α- and β-males, each differing in appearance and mating strategy. Alpha-males use nest-building tactics, whereas β-males use sneaker or satellite tactics. Lepomis macrochirus are important members of the aquatic community, and are often involved in parasitic life cycles. Among the most common parasites infecting L. macrochirus are strigeids, which include white grub (Posthodiplostomum minimum), black grub (Uvulifer ambloplitis), and yellow grub (Clinostomum marginatum). Previous studies found a higher abundance of strigeid parasites in α-males, even though β-males spend increased time in the littoral zone. One hypothesis is that α-males recruit the parasites during the spawn because of their nest-guarding behavior, which potentially increases their interactions with snail intermediate hosts. To test this hypothesis, L. macrochirus were collected between February and July in consecutive years from 2015 to 2017 from 13 lakes and ponds in northwestern Virginia. The fish were necropsied and all of the endo- and ectoparasites infecting the fish were identified and enumerated. The results supported the hypothesis and showed that α-males had greater infections postspawn, whereas β-males and females had no increase in infection from pre- to postspawn. Additionally, α-males recruited strigeid parasites at a greater rate than β-males, which negatively affected their body condition. The body condition of both α-males and females were negatively affected by P. minimum and U. ambloplitis, but β-males were not affected by either parasite. This shows that the differences in mating strategies between male morphotypes may result in greater strigeid infection in α-males compared with β-males. This may affect the fitness and reproductive output of α-males and be a contributing factor to the maintenance of β-males in the ecologically stable system, despite decreased reproductive success.

Microhabitat use of Allocreadium lobatum (Trematoda) in the intestine of creek chub (Semotilus atromaculatus) was studied using natural infections. Seventy-six creek chub harboring only A. lobatum in their intestine provided data on the position of 212 worms along the length of the intestine. Positions of worms within the intestine co-varied strongly with host size and therefore intestinal length; worm positions standardized by intestinal length eliminated this relationship. Analyses of standardized worm positions (worm location) revealed that microhabitat use did not vary with worm size, maturity, or number of eggs in the uterus. Individuals of A. lobatum occurred throughout the intestine, but were concentrated in the posterior 30% of the intestine, regardless of demographic properties of the worms themselves. Standardized niche breadths of parasite infrapopulations suggested strict microhabitat specificity, but nearest-neighbor analyses revealed very little aggregation of worms in infrapopulations beyond what is expected by chance. Overall, trematodes of this species appear to exhibit some microhabitat specificity when examined with snapshot, field-collected data, but there is no clear indication of what mechanism might produce the observed pattern. Use of the intestine by individuals of A. lobatum might be more dynamic than can be revealed by the present investigation or studies similar to it.

The first report of Asian fish tapeworm (AFT), Schyzocotyle acheilognathi (Yamaguti, 1934) Brabec, Waeschenbach, Scholz, Littlewood and Kuchta, 2015, is provided for New York State. This finding resulted from a long-term fish parasite survey in various water bodies in Otsego County in central-east New York that took place during 2008–2018. In total, 1,637 individual fish representing 44 species were examined for AFT, with 4 (9%) of the 44 species of fish infected with S. acheilognathi. These 4 species were all cyprinids: Notemigonus crysoleucas (golden shiner), Notropis heterodon (blackchin shiner), Pimephales promelas (fathead minnow), and Semotilus atromaculatus (creek chub). Among these host species, the prevalence of Schyzocotyle acheilognathi was highest in Notemigonus crysoleucas, with 19 (15.7%) of 121 fishes infected. The infection in Notropis heterodon constitutes a new host record for S. acheilognathi. The observed occurrence of S. acheilognathi only in cyprinid species was generally consistent with previously reported infection patterns for this cestode, but we note that AFT was absent from multiple fish species in our survey that had elsewhere been reported as hosts. The source of AFT for water bodies in Otsego County, New York is unknown, but bait-bucket introduction of infected Notemigonus crysoleucas is considered a possible explanation. This study contributes to a growing body of molecular data for this highly invasive tapeworm by providing sequence data for 2 markers (large ribosomal subunit, 28S, and cytochrome c oxidase I) for 6 specimens.

Four species of Dactylogyrus were found on gills of goldfish (Carassius auratus) in Cuba. The collected monogeneans were fixed in ammonium picrate and glycerin solution and mounted in glycerin gelatin. The species were identified based on morphological characteristics and measurements, and the 4 dactylogyrids were identified as D. dulkeiti Bychowsky, 1936; D. baueri Gussev, 1955; D. formosus Kulwiec, 1927; and D. intermedius Weger, 1910, which are new records from goldfish in Cuba.

Although information on the fauna of helminths of the shortfin molly Poecilia mexicana in freshwater environments is extensive, to date, there have been no studies on helminths that parasitize this fish in brackish water bodies. To increase the knowledge about the host-parasite association in this kind of habitats, during April 2014, 80 fish specimens of P. mexicana from 2 localities in Veracruz, Mexico, were examined for helminths: Arroyo Moreno (AM) and Laguna Mandinga (LM). Arroyo Moreno is an anthropogenically polluted mangrove swamp, and LM is a saline environment with low marine influence. The helminth species record in both fish populations included 9 taxa: 7 digeneans, 1 cestode, and 1 nematode, with 6,261 individuals, most of them collected in fishes from AM (5,768). In general, a high proportion of allogenic larval stages was observed, which agreed with the pattern observed in helminth fauna of tropic freshwater fish. In addition, these parasite assemblages were dominated by digeneans, worms that generally are numerically dominant in many helminth communities of freshwater fishes in Mexico. The euryhaline nature of P. mexicana establishes it as an adequate system to study the effects of salinity gradients focused on helminth communities.

The life cycles of many species of Diplostomum (Digenea) have been elucidated; however, few studies include the details of egg development and hatching success. Here the eggs of 2 molecularly delineated sympatric species of Diplostomum were observed for differences in developmental parameters. These parameters included prepatent period, time required for first visible eyespot formation, hatching time, and hatching success. There was no significant difference in the mean prepatent period, total number of miracidia that developed eyespots, or number of days to hatch between the 2 species. There was a significant difference in the average time for first visible eyespots to appear and hatching success. These data highlight the need for further studies investigating sympatric species of Diplostomum to document and understand differences in life history traits during the various phases of their life cycles and their role in transmission success.

The genus Linguatula (Pentastomida) is cosmopolitan and includes 6 species that have a higher prevalence in subtropical, tropical, and temperate regions. Larvae (nymphs) of Linguatula spp. require an intermediate host (herbivorous), while the adult worms inhabit the respiratory tract of wild and domestic carnivores. During an ongoing project on conservation biology of Baird's tapir (Tapirus bairdii), 3 pentastome nymphs were found parasitizing the liver, mesentery, and small intestine of an adult male from the region of Calakmul, Campeche, Mexico. Based on morphological and molecular data, these specimens correspond to Linguatula recurvata. Here, we present the first record of a linguatulid parasitizing a Tapirus sp., and only the second of a pentastomid in tapirs. In addition, this work includes for the first time sequences of the mitochondrial cytochrome c oxidase subunit I of L. recurvata.

We have encountered azygiid cercariae shed from the snail, Pleurocera semicarinata, at North Elkhorn Creek, Scott County, Kentucky, since 2004. Samples of these cercariae were frozen, and their DNA analyzed. The resulting alignment total length of 394 base pairs from partial 5.8S and 28S genes and the complete ribosomal internal transcribed spacer 2 (ITS2) confirmed our identification of the North Elkhorn Creek cercaria as Leuceruthrus micropteri. There was a 100% match to adult L. micropteri obtained from largemouth bass at Wheeler Reservoir, Alabama. Prevalence of infections by L. micropteri in snails was low at North Elkhorn Creek during 2004 (1.8% [7/400]) and 2017 (0.9% [4/432]). Quantitative data were obtained regarding cercarial emergence (daily and long-term patterns), site of infection of rediae, and functional morphology of the distome and tail stem. Most (96.1%) cercariae were released during the 12-hr light phase of a 12-hr light:12-hr dark cycle, and the average number of cercariae released per 7 snails per day over 21 d ranged between 0 and 2.3. Individual snails most frequently shed between 0 and 2 (range 0–6) cercariae per day. Snails shed cercariae for an average of 12.6 ± 3.1 d of the 21-d sampling period. Histology revealed rediae in the bottom whorl of the snail within the perintestinal sinus separated from the mantle cavity and gills by a thin mantle membrane. Envelopment of the distome body by the tail stem in vitro required less than 2 min. The lip of the tail chamber moved forward over the distome body until the latter was completely enclosed.

Three species of dicroglossid frogs from Malaysia were examined for helminths: Limnonectes ibanorum (n = 5), Limnonectes ingeri (n = 5), and Limnonectes leporinus (n = 6). We found 7 species of Nematoda (Amphibiocapillaria bufonis, Cosmocerca ornata, Falcaustra dubia, Orneoascaris sandoshami, Oswaldocruzia sp., Physaloptera sp., Cosmocercinae gen., sp. 1 of Moravec and Sey 1990); 1 species of Cestoda (pleurocercoid); 1 species of Acanthocephala (Pseudoacanthocephalus bufonis); and 1 species of Digenea (Diplodiscus amphichrus). Cosmocerca ornata was the only helminth infecting the 3 dicroglossid species. The most numerous helminth (n = 36) was Cosmocercinae gen. sp. in L. ibanorum. The 3 species of Limnonectes are parasitized by generalist helminths that also infect other species of frogs. Twelve new host records are reported.

Twenty-three salvaged specimens of Coluber constrictor constrictor Linnaeus (Northern Black Racer) from North Carolina, U.S.A., were examined for gastrointestinal helminths. Eighteen species of helminths (4 trematodes, 2 cestodes, 10 nematodes, and 2 acanthocephalans) are reported, representing 6 new host records and 6 new geographic distribution records. At 52% prevalence, immature physalopterids were the most prevalent helminth, followed by another nematode, Abbreviata terrapenis, at 43%. Specimens of the cestode Oochoristica sp. were the most prevalent (48%) platyhelminth, and macracanthorhynchid cystacanths were the most prevalent (17%) acanthocephalan.

The Appalachian leech Placobdella biannulata is a presumed host generalist for an array of amphibian species. One species commonly parasitized by this leech is the salamander Desmognathus quadramaculatus because of its semiaquatic nature and relatively large size. We tested the null hypothesis that this leech species exhibits equal prevalence in large species of Desmognathus with the same level of aquatic tendency. We compared leech prevalence between D. quadramaculatus and sympatric Desmognathus folkertsi, which has the same extent of aquatic tendency. While smaller than D. quadramaculatus, D. folkertsi is still among the largest members of the genus. We found leech parasitism on 38/182 (21%) D. quadramaculatus from 2 different streams. Only 3 D. folkertsi out of 179 (<2%) from the same streams were parasitized. We concluded that the leech P. biannulata is more host specific than previously believed.

A total of 196 yellow perch, Perca flavescens (Percidae), from 3 locations (100 from Strawberry Light in September 2015, 73 from Clinton River Cutoff in November 2017, and 23 from New Baltimore in November 2017) in Lake St. Clair, Michigan, U.S.A., were examined for the digenetic trematode Phyllodistomum superbumStafford, 1904 (Gorgoderidae Looss, 1901). The prevalence, mean intensity, and mean abundance of P. superbum in yellow perch were highest at Strawberry Light (30%, 1.5, and 0.45, respectively) and lowest at Clinton River Cutoff (7%, 1.2, and 0.08, respectively). The maximum intensity of P. superbum varied from 2 to 5 worms per infected fish. Individuals of P. superbum infected the urinary bladder and ureters of perch. Lake St. Clair is a new locality record for P. superbum.