Fecal samples collected in April 2019 from 10 half-lidded ovals, Patera binneyana (Pilsbry, 1899) (Gastropoda), in McCurtain County, Oklahoma, U.S.A., were examined for coccidial parasites. Seven (70%) contained oocysts of Pfeifferinella gugleriWacha, 1980. Ovoidal octozoic oocysts without sporocysts measured (average L × W) 22.2 × 14.1 µm with an L:W ratio of 1.5. Oocysts possessed a subspheroidal to spheroidal oocyst residuum as well as a micropyle. This snail represents the fourth host to harbor this coccidian. We document a new host and geographic distribution record for P. gugleri.

During August 2019, 2 stump-tailed geckos, Gehyra mutilata were collected by hand from 2 sites within Peninsular Malaysia and examined for coccidia. Both were found to be passing oocysts of Eimeria cf. cicakiElse and Colley, 1975. Oocysts are subspheroidal to ellipsoidal, with a smooth bilayered wall, measure 19.4 ×16.1 µm, and have a length/width (L/W) ratio of 1.2; a micropyle and oocyst residuum are absent, but a single polar granule is present. Sporocysts are ellipsoidal and measure 7.3 × 6.7 µm, L/W 1.1; Stieda, sub-Stieda, and para-Stieda bodies are absent. The sporocyst residuum is composed of large dispersed granules lying between the sporozoites. The current isolate appears to be morphologically divergent from the specimens as originally described. Previously reported endogenous development shows this coccidian should be transferred to the genus AcroeimeriaPaperna and Landsberg, 1989. Here, we provide additional morphological information on the coccidian, as well as the first photomicrographs of the sporulated oocysts of the species.

The relatively recent surge in Aspidodera species descriptions suggests that several species are yet to be documented and properly described. We describe Aspidodera serrata n. sp. from the giant anteater Myrmecophaga tridactyla from the Cerrado biome (Savanna), Brazil. The new species is distinctive in the genus because of the attributes of the cephalic cordons, position of pore-like papillae and a thickening of body cuticle. Because no male specimens were recovered from the host, morphological characteristics that are identical in both sexes and specific for the genus were fundamental during the identification. We emphasize the relevance of hood features and scanning electron microscopy to base descriptions in Aspidodera. We provide a new key for the genus to assist in the efforts to identify the species present in multiple infections. This is the first report of a coinfection with 3 congeners in the same individual host involving Aspidodera. We urge researchers to preserve and document the metazoan parasites from tetrapod species considered vulnerable, because they can be valuable sources of information on the distribution of parasites in the wild.

Abandonment, irresponsible care, and overpopulation are the main causes of the large number of dogs roaming free in urban areas or living in shelters. These shelters provide temporary homes for dogs that have been lost, abused, or reported for biting, but also provide an environment that could enable the spread of gastrointestinal parasites. City municipal shelters receive dogs throughout the year, feed them, and provide veterinary care before offering them for adoption. This article reports on the intestinal parasite infections of municipal shelter dogs from San Carlos de Bariloche, Río Negro, Argentina, over 3 consecutive years. Fecal samples were collected from all shelter dogs during the winters of 2017, 2018, and 2019. The samples were examined using Sheather's flotation and Ziehl Neelsen stain techniques to detect parasite eggs and coccidia, respectively. Total prevalence values ranged from 32 to 45%, with a total of 6 parasite taxa found, including coinfections, with a maximum of 2 species. Some dogs seemed to become infected during their stay in the shelter, and despite periodic deworming, some dogs were still parasitized. Zoonotic parasites like Toxocara canis, Toxascaris leonina, and Dibothriocephalus latus were identified in this study. Thus, such shelter dogs may act as disseminators of transmission stages of zoonotic parasites. This work emphasizes the importance of raising awareness about the responsible care of companion animals to prevent the need for shelter care.

From November 2016 to October 2020, 14 adult southern short-tailed shrews, Blarina carolinensis (Bachman), were collected from Arkansas (n = 10) and Oklahoma (n = 4) and examined for parasites. All were infected and/or infested with various endo- and ectoparasites, including 3 trematodes (Brachylaima thompsoni, Ectosiphonus rhomboideus, Panopistus pricei), a cestode (Cryptocotylepis anthocephalus), 2 nematodes (Longistriata caudabullata and larval Porrocaecum sp.), an acanthocephalan cystacanth (Centrorhynchus conspectus), 3 mites (Olistrophorus blarina, Echinonyssus blarinae, and Prowichmannia cf. spinifera), and a tick (Ixodes scapularis). In addition, an epifaunistic beetle (Leptinus americanus) was found on 1 of the B. carolinensis collected. We document a new host and 9 new distributional records, and the first records of helminth parasites from any shrew from Arkansas or Oklahoma.

Examination of spiral intestines from Himantura tutulBorsa, Durand, Shen, Arlyza, Solihin, and Berrebi, 2013 (=Himantura uarnak 3 sensu Naylor et al. [2012]), collected from Malaysian Borneo revealed the presence of a new species of tapeworm belonging to the genus Stillabothrium (Rhinebothriidea: Escherbothriidae). Stillabothrium borneoense n. sp. Herzog, Meininger, and Reyda is assigned to the genus based on its possession of a scolex with 4 bothridia divided into a distinct anterior region with facial loculi that are oriented horizontally and a distinct posterior region with facial loculi that are oriented vertically. The new species is distinguished from its congeners by features of the scolex and proglottids, including a vagina that recurves well anterior to the cirrus sac, as well as a unique locular arrangement not previously reported for members of this genus: 4 horizontally oriented loculi in the anterior region of the bothridia and 7 vertically oriented loculi in the posterior region of the bothridia. Stillabothrium borneoense n. sp. expands both known morphological variation and known host associations within the genus.

Between January 2013 and September 2016, 14 juvenile and adult Banded Pygmy Sunfish, Elassoma zonatum Jordan, were collected in southwestern Arkansas (n = 13) and southeastern Oklahoma (n = 1) and examined for parasites. Five (36%) were infected, including 3 (21%) harboring the monogenean, Gyrodactylus heterodactylus Rogers and Wellborn, 2 (14%) with Proteocephalus sp. plerocercoids, and 5 (36%) with larval nematodes, Spiroxys sp. We document a new host as well as a new geographic distributional record for parasites of E. zonatum.

Three species of frogs (Rhacophoridae) from Borneo, Malaysia were examined for helminths: Nyctixalus pictus (n = 4), Philautus hosii (n = 6), and Rhacophorus pardalis (n = 12). We found 3 species of Nematoda, Batrachostrongylus longispiculus, Cosmocerca ornata, and Seuratascaris numidica, 1 species of Cestoda, Cylindrotaenia sp., and 1 species of Acanthocephala, Pseudoacanthocephalus bufonis. No helminth species occurred in more than 1 frog species. The most abundant helminth (7) was C. ornata in R. pardalis. The 3 species of frogs are parasitized by helminths that also infect other species of anurans. Five new host records are reported. A table summarizing helminth records in anurans from Borneo is presented.

Sixty-eight lizards representing 4 species (Aspidoscelis mexicanus, Sceloporus horridus, Sceloporus ochoterenae, and Urosaurus bicarinatus) collected from the locality of Santiago Tamazola in the Mixteca Region of Oaxaca, Mexico were examined for gastrointestinal helminths. One species of Cestoda, Mesocestoides sp. (tetrathyridium larvae), and 2 species of Nematoda, Physaloptera retusa and Spauligodon garciaprietoi were found. Physaloptera retusa had the highest prevalence (85%) in S. horridus and was found parasitizing all 4 lizard species, and S. garciaprietoi had the most numerous helminth (n = 626) in A. mexicanus. The helminths are generalist and have indirect life cycles with the exception of S. garciaprietoi. We provided new host and distribution records for the 3 helminth species (Mesocestoides sp., P. retusa, and S. garciaprietoi) and present the first helminth reports for S. horridus, S. ochoterenae, and U. bicarinatus. Further, Mesocestoides sp. tetrathyridia is reported for the first time in Oaxaca State. This work contributes to the helminth fauna associated with lizards from Mexico.

We examined 35 golden grass skinks Heremites auratus (Linnaeus, 1758) (Squamata: Scincidae), obtained from various locations in Turkey, for helminth parasites. We found 1 species of Cestoda, Mesocestoides sp., and 7 species of Nematoda: Parapharyngodon dogieli, Parapharyngodon lilfordi, Parapharyngodon psammodromi, Pharyngodon mamillatus, Spauligodon eremiasi, Spauligodon sp., and Thubunaea baylisi.

Although there are several similarities in the life cycles of the azygiid trematodes Leuceruthrus micropteri and Proterometra macrostoma, their prevalence in their snail intermediate host and infection intensity in their centrarchid fish definitive hosts at North Elkhorn Creek, Kentucky, U.S.A., are markedly different. Here, we provide evidence for factors affecting their infection intensity in centrarchids based on (1) duration of cercarial swimming, (2) conditions and time required for release of the distome body from the cercarial tail chamber in the fish stomach, and (3) possible differences in the developmental rate of worms in a common definitive host. Cercariae of P. macrostoma swam considerably longer than those of L. micropteri; no cercariae of L. micropteri were observed swimming off of the bottom of beakers after 8 hr, whereas 67% of the P. macrostoma cercariae were still swimming after 13 hr at 20°C. Almost all of the P. macrostoma distomes were released from their cercarial tail chambers in vitro after 60 min at pHs 1.5, 2.0, and 2.5 with and without 0.5% pepsin. Similarly, nearly all L. micropteri cercariae were released from their cercarial tail chamber at pH 1.5 with and without pepsin; however, they did not emerge at pHs 2.0 or 2.5 without pepsin. Although the emergence of the L. micropteri distome was stimulated by the addition of pepsin in the higher pH values, it was markedly slower than that of P. macrostoma. By contrast, in experimental infections of largemouth bass Micropterus salmoides at 24.6°C, all distomes of L. micropteri and P. macrostoma completely emerged from their tail chambers and were attached to the stomach mucosa of their bass hosts after 20 min postinfection (PI). Additional experimental infections of largemouth bass showed no increase in body length or width for P. macrostoma distomes on day 12, 21, or 31 PI, but an increase was apparent in the body length and width for L. micropteri distomes on days 21 and 31 PI at 24.6°C. No egg and only anlagen of testes and ovary were observed in L. micropteri by day 31 PI, whereas P. macrostoma adults contained fully mature eggs with miracidia by this time.

Macroscopic examination of 622 Salado salamanders, Eurycea chisholmensis Chippindale, Price, Wiens and Hillis, 2000, collected between June 2018 and July 2020 from 3 springs in Williamson County, Texas, U.S.A., revealed the presence of encapsulated metacercariae of Clinostomum cf. marginatum (“yellow grub”) in 3 (0.5%) hosts. Two of these 3 salamanders were examined and released unharmed per permit requirements, but 1 was found dead, and it harbored 6 total metacercariae, 4 on the head region (including 1 behind the left eye), 1 near the left front leg, and 1 in the tail. Morphological identification of C. cf. marginatum was achieved by comparison to previous accounts. Molecular identification was accomplished by comparing sequence homology and phylogenetic analysis using an 828 base pair partial sequence of the internal transcribed spacer region. This is the first report of any parasite from E. chisholmensis, a federally threatened species.

Natural infections of Allocreadium lobatum Wallin, 1909 (Trematoda), Proteocephalus sp. (Cestoda), Rhabdochona canadensis Moravec and Arai, 1971 (Nematoda), Paulisentis missouriensis Keppner, 1974 (Acanthocephala), and Schyzocotyle acheilognathi (Yamaguti, 1934) (Cestoda) in the intestine of creek chub (Semotilus atromaculatus) were analyzed to determine whether patterns of interspecific competition were evident. Data from nearly 2 decades of sampling from the same system were analyzed for patterns of co-occurrence and abundance consistent with negative interactions. Co-occurrence analyses (null models and logistic regression) did not detect negative associations among parasite species. Positive associations among species were more common in null model comparisons. Correlation analyses demonstrated some significant negative correlations between the abundances of pairs of parasite species in some samples, but the overwhelming majority of correlations were insignificant or positive. Previous work did not detect negative microhabitat interactions among the most common helminths studied herein, and together, these results suggest the parasite communities of creek chub in the study area are absent any substantial effect of antagonistic or other negative interspecific interactions. Differences in transmission rate, mode, and spatiotemporal variation are likely dominant processes explaining the patterns observed in the present investigation.

We herein document the metazoan parasite component communities of channel catfish (Ictalurus punctatus), blue catfish (Ictalurus furcatus), and their commercially cultured hybrid (female I. punctatus × male I. furcatus) communally stocked as parasite-free fingerlings into each of 3 experimental earthen ponds (each pond harbored channel catfish, blue catfish, and hybrid catfish). The fundamental objective of this work was to test the hypothesis that hybrid catfish exhibit less susceptibility to infection by metazoan parasites than do their parental species. Fingerlings of each catfish species from each pond were parasitologically examined monthly for 1 yr. A total of 112 channel catfish, 74 blue catfish, and 209 hybrid catfish were necropsied; collectively resulting in the detection of 14 metazoan parasite species. Channel catfish had the most diverse component community (12 species: 3 myxozoans, 2 monogenoids, 3 cestodes, 1 nematode, 1 unionid, and 2 copepods) followed by hybrid catfish (11 species: 3 myxozoans, 2 monogenoids, 2 cestodes, 1 nematode, 1 unionid, and 2 copepods) and blue catfish (6 species: 1 myxozoan, 2 monogenoids, 2 cestodes, and 1 copepod). These results do not support the assertion that hybrid catfish are demonstrably more resistant to parasitic infection than either parental species. New host–parasite records herein comprise Corallotaenia intermedia (Fritts, 1959) Freze, 1965, and Corallotaenia parafimbriata (Befus and Freeman, 1973) Scholz, de Chambrier, Mariaux, and Kucha, 2011 for channel catfish; Henneguya sp., C. parafimbriata, and Neoergasilus japonicus (Harada, 1930) Yin, 1956 for blue catfish; and Henneguya adiposaMinchew, 1977, Henneguya bulbosusRosser, Griffin, Quiniou, Khoo, and Pote, 2014, Ligictaluridus mirabilis (Mueller, 1937) Beverley-Burton, 1985, Ligictaluridus pricei (Mueller, 1936) Beverley-Burton, 1984, Essexiella fimbriata (Essex, 1928) Scholz, de Chambrier, Mariaux, and Kucha, 2011, C. parafimbriata, Spiroxys sp., Pyganodon sp., N. japonicus, and Achtheres sp. for hybrid catfish. To our knowledge, this is the most extensive parasitological study of this particular hybrid catfish, or any hybrid catfish, published to date.

Between April 2011 and November 2020, 175 individuals of western creek chubsucker Erimyzon claviformis (Girard) (Cypriniformes: Catostomidae) were collected and examined for parasites from 12 sites in the Ouachita, Red, St. Francis, and White river drainages in Arkansas (n = 138 individuals for endoparasites, 22 of same individuals for gill parasites) and from 4 sites in the Red River drainage in Oklahoma (n = 37 individuals for endoparasites, 14 of same individuals for gill parasites). Ninety-nine (57%) were infected with at least 1 parasite, including 2 (6%) of 36 with Piscinoodinium limneticum, 8 (22%) of 36 with 3 different Myxobolus spp., 4 (11%) of 36 with Octomacrum lanceatum, 40 (23%) of 175 with Plagioporus sinitsini, 30 (17%) of 175 with Lissorchis amniculensis, 38 (21%) of 175 with Calientiella etnieri, 3 (2%) of 175 with Isoglaridacris cf. agminis, 10 (6%) of 175 with larval Spiroxys sp., and 1 (0.6%) of 175 with a Neoechinorhynchus sp.; 31 individuals harbored multiple infections. We document several new host and distributional records. Moreover, this report represents only the second published report of the caryophyllid tapeworm C. etnieri since its description more than 46 yr ago.

Fifteen Gehyra dubia and 15 Gehyra punctata from Australia were examined for helminths. One species of Cestoda and 6 species of Nematoda were found. Gehyra dubia harbored Oochoristica australiensis, Maxvachonia chabaudi, and Skrjabinodon smythi. Gehyra punctata harbored Parapharyngodon fitzroyi, Pharyngodon kartana, Physalopteroides filicauda, and Abbreviata sp. (larva in cyst). Both species of Gehyra are parasitized by generalist helminths that also infect other species of lizards.All findings represent new host records.

The wageneri species group of Gyrodactylus contains the following molecularly confirmed salmonid parasites in Asia: Gyrodactylus taimeni Ergens, 1971, Gyrodactylus magnus Konovalov, 1967, Gyrodactylus brachymystacis Ergens, 1978, and Gyrodactylus derjavini Mikhailov, 1975; in Europe it contains the following: Gyrodactylus derjavinoides Malmberg, Collins, Cunningham, and Jalali, 2007, Gyrodactylus truttae Gläser, 1974, Gyrodactylus teuchis Lautraite, Blanc, Thiery, Daniel, and Vigneulle, 1999, Gyrodactylus lavareti Malmberg, 1956, Gyrodactylus salvelini Kuusela, Ziętara, and Lumme, 2008 (presented herein as a junior synonym of Gyrodactylus salmonis ), and Gyrodactylus salaris Malmberg, 1957, with the lone confirmed North American exception being G. salmonis. The mitochondrial DNA (cox1, 1545 bp) of this group shows a star-like phylogenetic expansion that began 2.05 ± 0.4 million years ago (mya), estimated from the mean distance of the cox1 gene (d_MCL = 0.267) using a tentative, potentially high-end, divergence rate of 0.13/Myr. European G. salaris on Thymallus thymallus and Asian G. magnus on Thymallus arcticus have been separated for 1.95 Myr (d_MCL = 0.253). The nuclear ITS rDNA region (1,245 bp) of G. salmonis was nearly uniform among North American populations of Oncorhynchus mykiss, Oncorhynchus clarkii, Oncorhynchus nerka, Salvelinus fontinalis, and Salmo salar (and non-native Salmo trutta) as well as on Salvelinus alpinus (under the synonym G. salvelini) from Lake Inari, Finland. Gyrodactylus salmonis is distal in a monophyletic subclade labeled by an apomorphic 56 bp insertion in the ITS1, shared by the European parasites G. lavareti (host: Coregonus lavaretus), Gyrodactylus pomeraniae Kuusela, Ziętara, and Lumme, 2008 (host: Rutilus rutilus), and Gyrodactylus bliccensis Gläser, 1974 (host: Alburnus alburnus). This subphylogeny suggests that a particular host switch from cyprinids to salmonids may have occurred less than 1.8 mya in the Old World [d_MCL = 0.234 G. pomeraniae vs (G. salmonis, G. lavareti)] and possibly again among coregonine hosts and Salvelinus 1.2 mya (d_MCL = 0.156). Although hypothetical, a transition from coregonines to charr (notably the widely distributed and adaptable Salvelinus alpinus) potentially could have occurred in a proglacial refugium leading to circumpolar distribution of G. salmonis and a secondary transition to other North American hosts. The maximum cox1 genetic distance within G. salmonis on all hosts was d_MCL = 0.032, at the same level as in multihosted European G. salaris (d_MCL = 0.032), suggesting circa 250,000 yr of population expansion with these parasites since a temporal, coinciding bottleneck.