Octomacrum spinum (Monogenoidea: Polyopisthocotylea: Octomacridae) from highland stoneroller, Campostoma spidaceum (Cypriniformes: Leuciscidae) from Arkansas and Oklahoma, USA, with a summary of the genus from North American and European fishes.

Octomacrum spinum Dansby & Shoemaker, 1973, is reported for the first time from 23 of 146 (16%) highland stonerollers, Campostoma spadiceum collected from central and western Arkansas and southeastern Oklahoma, USA. Analysis of molecular data revealed that the SSU rRNA gene of specimens of O. spinum from Arkansas was identical to a number of Octomacrum spp. and the LSU rRNA gene was 97.46% similar to Octomacrum europaeum. We also provide a summary of the species of Octomacrum reported from North American and European fishes.

A new species of Choleoeimeria (Apicomplexa: Eimeriidae) from the invasive curious skink, Carlia ailanpalai (Sauria: Scincidae) from Guam, U.S. Territory.

The curious skink, Carlia ailanpalai Zug, occurs in the main group of the Admiralty Islands of Papua New Guinea but has also successfully invaded Guam, the Marianas, Yap, and Kosrae. A single coccidian, Eimeria zugi McAllister, Duszynski, Fisher, & Austin, 2013 was described from C. ailanpalai from Papua New Guinea. No additional coccidians are known from this host. Fourteen C. ailanpalai were collected from Cocos Island (Islan Dåno), Guam, U.S. Territory, and their feces examined for coccidians. A single skink (7%) was found to be passing oöcysts of a new species of Choleoeimeria. Oöcysts of Choleoeimeria cocosensis n. sp. are ellipsoidal to ovoidal with a bi-layered wall, measure (L × W) 21.1 × 12.9 µm, and have a length/width (L/W) ratio of 1.6; a micropyle and an oocyst residuum were absent but fragmented polar granule(s) was present. Sporocysts are ovoidal and measure 8.6 × 6.3 µm, L/W 1.4; Stieda, sub-Stieda, and para-Stieda bodies were absent. Sporocyst residuum was typically a loose aggregate of various-sized granules between and across the sporozoites but sometimes a dense irregular mass between and across the sporozoites. Sporozoites were elongate, with a centrally located nucleus and a large spheroidal to subspheroidal posterior refractile body, but without an anterior refractile body. The new species can be differentiated from all other choleoeimerians from skinks by possessing one of the smallest oöcysts known from the host family. We also provide an updated summation of the choleoeimerians from skinks of the world. This article was registered in the Official Register of Zoological Nomenclature (ZooBank) as urn:lsid:zoobank.org:pub:6EFDF027-0A92-43C4-9AD0-E555252E7741.

A NOVEL SPECIES OF MYXOBOLUS (CNIDARIA: MYXOSPOREA: MYXOBOLIDAE) FROM THE GILL OF GREEN SUNFISH, LEPOMIS CYANELLUS (PERCIFORMES: CENTRARCHIDAE), FROM THE BLACK RIVER OF NORTHEASTERN ARKANSAS.

During March 2023, 7 green sunfish (Lepomis cyanellus) and 2 bluegill (Lepomis macrochirus) were collected from the Black River (White River drainage) in Lawrence County, Arkansas. In addition, during March 2023 and again in May-June 2023, 13 L. cyanellus and 6 L. macrochirus were taken from Butcherknife and Big Fork creeks (Ouachita River drainage), Polk County, Arkansas, 9 L. cyanellus were collected from the Caddo River, Montgomery County, Arkansas, and 5 green sunfish were taken from Clear Creek at Savoy, Washington County, Arkansas. All fish had their gill, gallbladder, fins, integument, musculature, and other major organs examined for myxozoans. The gill of 1 of 34 (3%) L. cyanellus was infected with a new myxozoan, Myxobolus fergusoni n. sp. Qualitative and quantitative morphological data were obtained from fresh myxospores, and molecular data consisted of a 1,933-base-pair sequence of the partial small subunit (SSU) ribosomal RNA (rRNA) gene. Phylogenetic analysis grouped M. fergusoni n. sp. with other centrarchid-infecting myxobolids from North America and placed this cluster in a larger clade comprising myxozoans that infect North American and European esocids, a North American aphredoderid, European percids, and a gasterosteid from Japan. Myxobolus fergusoni n. sp. infects the gill arches of L. cyanellus, similar to Myxobolus cartilaginis (Hoffman, Putz, and Dunbar, 1965), which was described from head cartilage, gill arches, and large fin rays of L. cyanellus. Another is Myxobolus mesentericusKudo, 1920, which was described from the viscera of green sunfish. A large polysporic plasmodium filled with myxospores was present in a basifilamental location associated with multiple gill filaments at their junction with the gill arch. The intact plasmodium replaced connective tissue within the arch but elicited only mild proliferation of overlying epithelium and a minimal host inflammatory response. This is the third time a myxozoan has been described from L. cyanellus, as well as being the first time it has been described from an Arkansas specimen.

DESCRIPTIONS AND PHYLOGENETIC AFFINITIES OF TWO NEW SPECIES OF RHABDIAS STILES AND HASSALL, 1905 (NEMATODA: RHABDIASIDAE) FROM NORTH AMERICAN FROGS: ARE WE STILL ONLY SCRATCHING THE SURFACE?

Two new species of lung-dwelling nematodes are described from North American frogs: Rhabdias aurorae n. sp. from Rana aurora and Rhabdias conni n. sp. from Rana clamitans and Rana catesbeiana from Arkansas; the latter species was also found in Oklahoma and Georgia. Rhabdias aurorae n. sp. differs from other Nearctic congeners in the combination of the following characteristics: buccal capsule 22-25 µm wide, elongated tail covered with inflated cuticle, esophagus with prominent dilatation in anterior part and 6 small circumoral lips. Rhabdias conni n. sp. is morphologically closest to Rhabdias ranae Walton, 1929 and Rhabdias joaquinensisIngles, 1936; it differs from them in the shape of lateral pseudolabia, the dimensions of the body, and the egg size. Both new species were found to be significantly different from the Nearctic congeners in the nucleotide sequences of nuclear ribosomal DNA (18S-ITS-28S region), 12S, and CO1 mitochondrial genes. The 2 new species differ from other currently sequenced Nearctic congeners by 1.1-2.7% of nucleotide positions in the nuclear rDNA region, 1.3-3.4% in the 12S gene, and 3.4-9.4% in CO1 gene. Molecular phylogenetic analysis based on nuclear ribosomal DNA sequences placed both new species into the clade consisting of Nearctic and Neotropical Rhabdias spp. The position of Rh. aurorae n. sp. within the clade is uncertain because of a polytomy, but Rh. conni n. sp. is nested within the "Rh. joaquinensis complex" related to Rh. ranae and Rhabdias tarichaeKuzmin, Tkach, and Snyder, 2003. The phylogenetic analysis based on nuclear ribosomal DNA sequences has revealed 3 evolutionary host-switching events from anuran to caudatan hosts among Rhabdias spp. that occurred in the Nearctic and Palearctic. The molecular phylogeny also suggests that Rhabdias may have originally evolved in what is now Africa.

A New Isosporan (Apicomplexa: Eimeriidae) from the Pacific Blue-Tailed Skink, Emoia caeruleocauda (Sauria: Scincidae: Eugongylinae), from Guam, U.S. Territory.

PURPOSE: Nothing is known about coccidians (Apicomplexa: Eimeriidae) from the Pacific blue-tailed skink, Emoia caeruleocauda. Here, we report mensural and morphometric data on a new species of Isospora from E. caeruleocauda from Guam, US Territory. METHODS: Feces from four E. caeruleocauda collected by hand in November 2023 were placed in individual vials containing 2.5% potassium dichromate. They were examined for sporulated oocysts after flotation in Sheather's sugar solution, measured, and photographed. RESULTS: A single (25%) E. caeruleocauda was found to be passing oocysts representing a new species of Isospora. Oocysts of Isospora guamensis n. sp. are ellipsoidal to ovoidal with a bi-layered wall, measure (L × W) 16.5 × 11.8 µm, and have a length/width (L/W) ratio of 1.4; a micropyle and an oocyst residuum were absent but a polar granule was present. Sporocysts are ovoidal and measure 9.4 × 6.5 µm, L/W 1.4; Stieda and sub-Stieda bodies were present but a para-Stieda body was absent. The sporocyst residuum is composed various-sized granules in a compact rounded or irregular mass, sometimes dispersed between the sporozoites. The new species can be differentiated from all other isosporans from skinks by possessing the smallest oocysts known from this host family. CONCLUSION: This is the first time an isosporan coccidian has been reported from E. caeruleocauda as well as the first report of a coccidian from a Guam-inhabiting skink.

Morphological and molecular data establishes Clinostomum dolichorchum n. sp. (Digenea: Clinostomidae) in the great blue heron Ardea herodias L. and American bullfrog Rana catesbeiana Shaw.

Clinostomum is a cosmopolitan genus of trematodes that infect piscivorous birds, freshwater molluscs, freshwater fish and amphibians. Herein, a novel species of Clinostomum is described based on morphological and molecular data from an adult in the oral cavity of the great blue heron Ardea herodias and metacercariae collected from the gills and skin of American bullfrog tadpoles Rana catesbeiana. The novel species shares similar qualitative and quantitative morphological features with a congener, Clinostomum marginatum, which has overlap in host and geographic distribution. The most notable morphological difference when compared to C. marginatum is the greater posterior testis length of the novel species. Molecular data resolved similarities with morphological comparisons to nominal species and supports the establishment of a novel species. Molecular data include partial small ribosomal subunit (18S rRNA gene), ribosomal internal transcribed spacer regions (ITS1, 5.8S rRNA gene, and ITS2), partial large ribosomal subunit (28S rRNA gene), cytochrome c oxidase subunit 1 gene (cox1), and nicotinamide adenine dinucleotide dehydrogenase subunit 1 gene (nad1) sequences. Phylogenetic analyses place the novel species in a sister clade to C. marginatum. Morphological and molecular data, combined with phylogenetic analyses support the establishment of Clinostomum dolichorchum n. sp.

CHARACTERIZATION OF EIMERIA LANCASTERENSIS AND EIMERIA ONTARIOENSIS (APICOMPLEXA: EIMERIIDAE) FOUND IN EASTERN GRAY SQUIRRELS, SCIURUS CAROLINENSIS (RODENTIA: SCIURIDAE), FROM ARKANSAS AND OKLAHOMA.

We report the morphological characteristics of oocysts of Eimeria lancasterensisJoseph, 1969, collected from 6 of 6 (100%) eastern gray squirrels, Sciurus carolinensis, collected in Arkansas (n = 3) and Oklahoma (n = 3), and Eimeria ontarioensisLee and Dorney, 1971, recovered from an individual of S. carolinensis from Arkansas. Oocysts of E. lancasterensis were ovoidal to ellipsoidal, measuring (L × W) 24.0 × 14.6 (18-29 × 12-16) µm; shape index (L/W) was 1.6 (1.3-1.8). A micropyle and an oocyst residuum were absent, but up to 2 polar granules were present. Oocysts of E. ontarioensis were piriform and measured 40.6 × 26.0 (37-44 × 23-28); L/W was 1.6 (1.5-1.7). These oocysts possessed a distinct micropyle and rarely a polar granule but lacked an oocyst residuum. The DNA was isolated from both eimerians, and the 18S rDNA genetic markers were PCR-amplified, cloned, sequenced, and analyzed. To our knowledge, this study represents the first time 18S DNA sequence data have been generated from E. lancasterensis and E. ontarioensis found in North American sciurid hosts, as well as new geographic distribution records for these coccidians. In addition, we also include a tabular summary of these 2 species of Eimeria from Sciurus spp. worldwide, with information on their hosts, distribution, and taxonomically important morphological characteristics, including key measurements of oocysts and sporocysts.

A NEW SPECIES OF THELOHANELLUS (CNIDARIA: MYXOSPOREA: MYXOBOLIDAE) FROM THE GILL OF QUILLBACK, CARPIODES CYPRINUS (CYPRINIFORMES: CATOSTOMIDAE), FROM THE ARKANSAS RIVER DRAINAGE OF OKLAHOMA.

During May 2022 and again in March 2023, 5 quillbacks, Carpiodes cyprinus, were collected from the Verdigris River, Wagoner County, Oklahoma (n = 1), and the Black River, Lawrence County, Arkansas (n = 4), and their gill, gallbladder, fins, integument, musculature, and other major organs were macroscopically examined for myxozoans. Gill lamellae from the single quillback from the Verdigris River was infected with a new myxozoan, Thelohanellus oklahomaensis n. sp. Qualitative and quantitative morphological data were obtained from fresh and formalin-fixed preserved myxospores, and molecular data consisted of a 1,767 base pair sequence of the partial small subunit (SSU) ribosomal RNA gene. Phylogenetic analysis grouped T. oklahomaensis n. sp. with myxozoans known to infect North American catostomids and Eurasian cyprinids. Histological examination localized plasmodia to an intralamellar developmental site and revealed a possible vestige of a second polar capsule. Although plasmodia markedly expanded lamellae, there were no associated epithelial or inflammatory changes. Thelohanellus oklahomaensis n. sp. is the only member of the genus known to infect the gills of C. cyprinus.

Two New Eimerians from American Alligator, Alligator mississippiensis (Crocodilia: Alligatoridae), from Georgia, USA.

PURPOSE: Little is known about the coccidian parasites of the American alligator, Alligator mississippiensis (Daudin). To date, only two species of Eimeria Schneider, 1875 have been previously reported from A. mississippiensis. Here, we report from mensural and morphometric data on two new species of Eimeria from A. mississippiensis from Georgia, USA. METHODS: Fresh feces were collected in June 2023 from a single captive juvenile male A. mississippiensis. Multiple samples were placed in individual zip-lock bags and aqueous potassium dichromate was added. They were examined for sporulated oocysts after flotation in Sheather's sugar solution, measured, and photographed. RESULTS: Samples contained oocysts representing two new species of Eimeria. Oocysts of Eimeria tellezae n. sp. are subspheroidal to ellipsoidal with a pitted bi-layered wall, measure (L × W) 34.5 × 31.5 µm, and have a length/width (L/W) ratio of 1.1; a micropyle and polar granule were absent but an oöcyst residuum was present. Sporocysts are ellipsoidal and measure 17.2 × 7.7 µm, L/W 2.2; a nipple-like Stieda body bearing one to several filaments was present but sub-Stieda and para-Stieda bodies were absent. The sporocyst residuum is composed of various-sized granules in a compact rounded or irregular mass, sometimes dispersed between the sporozoites. Oocysts of Eimeria daudini n. sp. are ellipsoidal with a pitted bi-layered wall, measure (L × W) 32.5 × 20.2 µm, and have a length/width (L/W) ratio of 1.6; a micropyle and polar granule were absent but an oöcyst residuum was present. Sporocysts are ellipsoidal and measure 15.4 × 7.4 µm, L/W 2.1; a nipple-like Stieda body bearing one to several filaments was present but sub-Stieda and para-Stieda bodies were absent. The sporocyst residuum is composed of various-sized granules in a compact rounded or irregular mass, sometimes dispersed between the sporozoites. Both new species can readily be distinguished from previously described eimerians from crocodilians, including those from A. mississippiensis. CONCLUSION: We document two new species of Eimeria from the American alligator. Currently, four species of Eimeria are known from A. mississippiensis examined from both east and west of the Mississippi River, USA.

Discovering high species diversity of Ophiotaenia tapeworms (Cestoda: Proteocephalidae) of watersnakes (Colubridae) in North America.

Tapeworms of the genus Ophiotaenia La Rue, 1911 parasitize herptiles (= amphibians and 'reptiles') throughout the world, with about 100 species recognised as valid. In the present work, the North American species found in watersnakes (Colubridae) are reviewed. An examination of the holotype of Ophiotaenia perspicua La Rue, 1911, the type species of the genus, and other specimens from Nerodia rhombifer (Hallowell) revealed that two species were used for the species description. The 'true' O. perspicua has a small scolex and small, round suckers. This species is redescribed based on new material from Oklahoma, USA. The other species from N. rhombifer, Ophiotaenia laruei n. sp., has a larger scolex and larger, almost triangular suckers. Examination of the types of O. variabilis (Brooks, 1978) from N. rhombifer and N. cyclopion (Duméril, Bibron et Duméril) from Louisiana, USA has revealed that it is a mixture of two or more species. Because of poor quality of these specimens, it is not possible to adequately characterise O. variabilis, which is considered a species inquirenda. In addition, two new species are described from Nerodia fasciata confluens (Blanchard). Ophiotaenia currani n. sp. from Mississippi, USA is characterised by elongate, narrow proglottids, few testes, and a relatively long cirrus sac. Ophiotaenia tkachi n. sp. from Louisiana, USA is characterised by relatively short and wide proglottids, more testes, and an unusual terminal part of the vagina with folds. Morphologically similar tapeworms of N. fasciata confluens, N. erythrogaster (Förster), N. sipedon (Linnaeus), and Agkistrodon piscivorus (Lacépède) (Viperidae) from Arkansas and Oklahoma, USA, which are genetically nearly identical, are considered to be conspecific with O. tkachi n. sp. The present data suggest a high, previously undescribed species diversity of proteocephalid tapeworms in watersnakes in North America, and generally strict host specificity of these tapeworms.

TAPEWORMS (CESTODA: OPHIOTAENIA) FROM THE NORTHERN COTTONMOUTH (AGKISTRODON PISCIVORUS).

The northern cottonmouth, Agkistrodon piscivorus (Lacépède, 1789) (Viperidae: Crotalinae), occurs in the southeastern United States and is one of the few semiaquatic vipers in the world. Three proteocephalid tapeworms of the genus OphiotaeniaLa Rue, 1911 (Cestoda), have been described from this venomous snake. A critical evaluation of type specimens and tapeworms recently collected from A. piscivorus has revealed that only 2 species, Ophiotaenia marenzelleri (Barrois, 1898) and Ophiotaenia grandisLa Rue, 1911 (new synonym Ophiotaenia agkistrodontis [Harwood, 1933]), are specific parasites of this crotaline viper; both species are redescribed here. Ophiotaenia grandis was originally described from a mixture of 2 species: 'true' O. grandis, which is indistinguishable from O. agkistrodontis described 22 yr later and thus considered to be a junior synonym of O. grandis, and O. marenzelleri. Ophiotaenia marenzelleri, also reported from the pygmy rattlesnake, Sistrurus miliarius (Linnaeus, 1766), is a larger tapeworm with a massive scolex, a large cirrus sac, a very large, annular vaginal sphincter near the equatorial gonopore, and an oval, 3-layered embryophore surrounded by a nearly square hyaline outer membrane. Ophiotaenia grandis is much smaller and more slender and has a narrower scolex, a smaller cirrus sac and vaginal sphincter, a 2-layered embryophore, and a distinctly pre-equatorial gonopore. In addition to O. marenzelleri and O. grandis, other Ophiotaenia species typical of semiaquatic snakes (Colubridae: Natricinae) may be present in the northern cottonmouth, which serves only as a postcyclic or occasional host. There is also a tabular summary of 18 species of Ophiotaenia from semiaquatic snakes worldwide, with information on their hosts, distribution, and taxonomically important characters, including key measurements.

Amended diagnosis, mitochondrial genome, and phylogenetic position of Sphyranura euryceae (Neodermata, Monogenea, Polystomatidae), a parasite of the Oklahoma salamander.

Polystomatidae is a monogenean family whose representatives infect mainly (semi)-aquatic tetrapods. Species of Sphyranura Wright, 1879 exhibit ectoparasitism on salamander hosts, with molecular work supporting their inclusion within Polystomatidae, at an early diverging, yet unresolved, position in the clade of otherwise endoparasitic polystomatid parasites of batrachian hosts. Records of representatives of Sphyranura are scarce with genetic data only available for S. oligorchis Alvey, 1933. Based on detailed morphological examination and comparison with type material, we identified worms belonging to Sphyranura infecting Oklahoma salamander (Eurycea tynerensis) as S. euryceae Hughes & Moore, 1943. Along with an amended diagnosis of Sphyranura, we provide the first molecular data for S. euryceae in the form of a mitochondrial genome and nuclear (18S, 28S rRNA) markers. Close morphological similarity between the two species of Sphyranura is reflected in low genetic divergence. Mitochondrial level comparison reveals instances of tRNA gene rearrangements in polystomatids. Although the phylogenetic reconstruction supports Sphyranura as early branching in the lineage of polystomatid monogeneans infecting batrachians, certain nodes remain unresolved.

Title: Diagnostic modifié, génome mitochondrial et position phylogénétique de Sphyranura euryceae (Neodermata, Monogenea, Polystomatidae), un parasite de la salamandre de l'Oklahoma. Abstract: Les Polystomatidae sont une famille de monogènes dont les représentants infectent principalement les tétrapodes (semi)-aquatiques. Les espèces de Sphyranura Wright, 1879 présentent un ectoparasitisme sur les hôtes salamandres, et des travaux moléculaires soutiennent leur inclusion dans les Polystomatidae, à une position divergente précoce mais non résolue dans le clade des Polystomatidae endoparasites d'hôtes batraciens. Les signalements des représentants de Sphyranura sont rares et les données génétiques ne sont disponibles que pour S. oligorchis Alvey, 1933. Sur la base d'un examen morphologique détaillé et d'une comparaison avec le matériel type, nous avons identifié les vers appartenant à Sphyranura infectant la salamandre de l'Oklahoma (Eurycea tynerensis) comme S. euryceae Hughes & Moore, 1943. Parallèlement à un diagnostic modifié de Sphyranura, nous fournissons les premières données moléculaires pour S. euryceae sous la forme d'un génome mitochondrial et de marqueurs nucléaires (ARNr 18S, 28S). La similitude morphologique étroite entre les deux espèces de Sphyranura se traduit par une faible divergence génétique. La comparaison au niveau mitochondrial révèle des cas de réarrangements des gènes des ARNt chez les Polystomatidae. Bien que la reconstruction phylogénétique soutienne Sphyranura comme un rameau précoce dans la lignée des monogènes Polystomatidae infectant les batraciens, certains nœuds restent non résolus.

A global survey of tapeworms (Cestoda: Proteocephalidae) of 'true' frogs (Amphibia: Ranidae), including a tabulated list of all proteocephalids parasitising amphibians.

Proteocephalid tapeworms of frogs of the family Ranidae ('true' frogs) are reviewed with emphasis on their species diversity, host specificity and geographical distribution. New molecular data (nuclear lsrDNA and mitochondrial COI sequences) are presented for tapeworms of four species of ranid frogs in North America, including the poorly known Ophiotaenia saphena Osler, 1931 of Rana clamitans Latreille and R. catesbeiana (Shaw), which is redescribed using new material from Arkansas, USA. Tapeworms of R. sphenocephala (Cope) and R. pipiens Schreber, the latter previously identified as O. saphena, represent another, putative new species, but are not formally described due to insufficient available material. Proteocephalus papuensis Bursey, Goldberg et Kraus, 2008 from Sylvirana supragrisea (Menzies) is transferred to Ophiotaenia La Rue, 1911 as a new combination. After a critical review of the literature, only nine nominal species of Ophiotaenia are recognised as valid, which is in contrast to the large number of ranid frogs (> 440 spp.). The reasons for this striking disparity are briefly discussed, and a key based on morphology is presented for the identification of all species of Ophiotaenia from the Ranidae. Molecular data are available for only two taxa from North America that form a monophyletic group. The relationships among tapeworms of ranid frogs occurring in other zoogeographical regions are not yet known. The taxonomic status of Batrachotaenia Rudin, 1917, which was erected to accommodate proteocephalids from amphibians, is also discussed. To facilitate future studies, a tabulated summary of all 32 species of proteocephalids belonging to three genera reported from amphibians (frogs and salamanders) is presented, with information on their hosts, distribution, and taxonomically important characters, including key measurements.

A NEW EIMERIAN (APICOMPLEXA: EIMERIIDAE) FROM EASTERN MOLE, SCALOPUS AQUATICUS (MAMMALIA: EULIPOTYPHLA: TALPIDAE), IN CENTRAL ARKANSAS, WITH ADDITIONAL INFORMATION ON CYCLOSPORA YATESI MCALLISTER, MOTRIUK-SMITH, AND KERR.

The eastern mole, Scalopus aquaticus (L.), is a common inhabitant of loamy soils in Canada, the eastern United States, and Mexico. Seven coccidian parasites have been previously reported from S. aquaticus, including 3 cyclosporans and 4 eimerians from hosts taken in Arkansas and Texas. A single S. aquaticus, collected in February 2022 in central Arkansas, was found to be passing oocysts of 2 coccidians, a new species of Eimeria, and Cyclospora yatesiMcAllister, Motriuk-Smith, and Kerr, 2018. Oocysts of Eimeria brotheri n. sp. are ellipsoidal (sometimes ovoidal) with a smooth bilayered wall, measure 14.0 × 9.9 µm, and have a length/width (L/W) ratio of 1.5; both micropyle and oocyst residua are absent, but a single polar granule is present. Sporocysts are ellipsoidal and measure 8.1 × 4.6 µm, L/W 1.8; a flattened to knoblike Stieda body as well as a rounded sub-Stieda body are present. The sporocyst residuum is composed of an irregular mass of large granules. Additional metrical and morphological information is provided on oocysts of C. yatesi. This study demonstrates that although several coccidians were previously documented from this host, additional S. aquaticus should be examined for coccidians from Arkansas as well as other parts of its range.

A new Myxobolus (Cnidaria: Myxosporea: Myxobolidae) from the gills of the southern striped shiner, Luxilus chrysocephalus isolepis (Cypriniformes: Leuciscidae), from southwestern Arkansas, USA.

The southern striped shiner, Luxilus chrysocephalus isolepis (Hubbs & Brown) is a relatively large minnow belonging to the true minnow family Leuciscidae Bonaparte. Between May 2020 and January 2022, 55 L. c. isolepis were collected from watersheds in Montgomery (n = 6), Polk (n = 17) and Sevier (n = 32) counties, Arkansas, USA, and their gills, gallbladders, urinary bladders, fins, integument, other major organs, and musculature were examined for myxozoans. Gills of 11 (34%) individual southern striped shiners from Sevier County were infected with a new myxozoan, Myxobolus carlhubbsi n. sp. A qualitative and quantitative morphological description was based on formalin-fixed preserved myxospores, and molecular data consisted of a 1,970 base pair sequence of the partial small subunit rRNA gene from ethanol-preserved specimens. Histologically, plasmodia filled and expanded interlamellar troughs. Hyperplastic epithelial and goblet cells filled interlamellar troughs adjacent to plasmodia, but inflammatory response was limited to scattered lymphocytes. Phylogenetic analysis revealed that M. carlhubbsi n. sp. is a member of a clade of species with pyriform myxospores parasitizing North American Pogonichthyinae Girard and North American and Eurasian Leuciscinae Bonaparte. This is the first report of a myxozoan from L. c. isolepis. This article was registered in the Official Register of Zoological Nomenclature (ZooBank) as urn:lsid:zoobank.org:pub:D10D71C2-2C75-4A1C-80ED-B98FF36CB509.

Redescription of Isospora vanriperorum Levine, 1982 (Apicomplexa: Eimeriidae) from the Northern Cardinal, Cardinalis cardinalis (L.) (Passeriformes: Cardinalidae), in North Texas, USA.

Little is known about the coccidian parasites of North American birds of the family Cardinalidae. A single isosporan, Isospora vanriperorum was previously described over 40 years ago from the northern cardinal, Cardinalis cardinalis from Hawaii. Since then, it was also reported in the green-winged saltator, Saltator similis from Brazil but the identification was invalidated recently. Feces were collected in July 2022 from two C. cardinalis found dead in Lamar County, Texas, USA. One sample contained oöcysts representing I. vanriperorum. Oöcysts are spheroidal to subspheroidal with a smooth uni-layered wall, measure (L × W) 23.8 × 22.4 µm and have a length/width (L/W) ratio of 1.04; a micropyle and oöcyst residuum are absent but polar granule(s) are present. Sporocysts are ovoidal and measure 15.5 × 10.5 µm, L/W 1.5; a knob-like Stieda body and a rounded sub-Stieda body are present. The sporocyst residuum is more often composed of various-sized granules dispersed between and across the sporozoites; it is less often in a compact rounded mass. This isosporan has now been reported from the northern cardinal for the second time but most importantly, from the mainland USA for the first time.

A new isosporan (Apicomplexa: Eimeriidae) from barn swallow, Hirundo rustica (Aves: Passeriformes: Hirundinidae: Hirundininae), in Oklahoma, USA.

Compared to other commonly examined passerine birds for coccidian (Apicomplexa) parasites, little is available on the coccidia of birds of the family Hirundinidae, including barn swallows (Hirundo rustica). Feces was collected in May 2022 from two nesting H. rustica in McCurtain County, Oklahoma, USA; the samples contained oöcysts representing a new species of Isospora. Oöcysts of Isospora zimmermani n. sp. are subspheroidal to ovoidal with a smooth bi-layered wall, measure (L × W) 22.8 × 20.8 µm, and have a length/width (L/W) ratio of 1.1; a micropyle and oöcyst residuum were absent but polar granule(s) are present. Sporocysts are ellipsoidal to ovoidal and measure 15.2 × 9.6 µm, L/W 1.6; a knob-like Stieda body and a rounded sub-Stieda body are present. The sporocyst residuum is composed of compact spheroid with a dense, irregular mass of finer granules lying between and dispersed among the sporozoites. The new species represents only the second isosporan reported from H. rustica but the first from the USA, and fourth species documented from the avian family Hirundinidae. This article was registered in the Official Register of Zoological Nomenclature (ZooBank) as urn:lsid:zoobank.org:pub:1F1E71C3-56E8-4EA7-A9B0-1E585FAA9DE0.

Pseudomurraytrema fergusoni n. sp. (Monogenea: Dactylogyridae) from gills of Pealip Redhorse, Moxostoma pisolabrum (Catostomidae) from Arkansas, USA, with a description of gill pathology.

Pseudomurraytrema fergusoni n. sp. is described from the Pealip Redhorse, Moxostoma pisolabrum from the Black River (White River drainage), Lawrence County, Arkansas, USA. This represents the second monogenean described from M. pisolabrum as well as the second species of Pseudomurraytrema reported from an Arkansas catostomid. The description includes partial 18S rRNA and 28S rRNA gene sequences (732 bp and 851 bp, respectively), helping fill a void in sequence data from North American monogeneans, particularly those in the genus Pseudomurraytrema. In addition, histopathologic changes associated with the infection resulted in severe localized pathologic lesions in gills of the host, suggesting compromise of respiratory surfaces within affected areas adjacent to the worms.

A New Isospora (Apicomplexa: Eimeriidae) from the Dark-Eyed Junco, Junco hyemalis (L.) (Passeriformes: Passerellidae), in West-Central Arkansas, USA.

PURPOSE: Many passeriform birds are excellent hosts of coccidian parasites but little is known of the coccidians infecting members of the family Passerellidae, particularly from the dark-eyed junco, Junco hyemalis (Linnaeus, 1758). Here, we report from morphometric and mensural data a new species of Isospora from J. hyemalis in Arkansas, USA. METHODS: During November 2020, seven adult J. hyemalis were taken with a mist net from Polk County, Arkansas, USA, and their faecal samples examined for coccidian parasites. Samples were placed in individual vials containing aqueous potassium dichromate. They were examined for coccidia after flotation in Sheather's sugar solution, measured, and photographed. RESULTS: A single J. hyemalis (14%) was found to be passing a new species of Isospora. Oöcysts of Isospora pittmani n. sp. were spheroidal to subspheroidal with a smooth bi-layered wall, measured (L × W) 24.8 × 23.8 µm, and had a length/width (L/W) ratio of 1.04; a micropyle and oöcyst residuum was absent but typically one to up to four polar granule(s) was present. Sporocysts are ovoidal to ellipsoidal and measured 15.0 × 10.0 µm, L/W 1.5; a flattened Stieda body was present as well as a barely discernible sub-Stieda body but para-Stieda bodies were absent. The sporocyst residuum was composed of various-sized granules dispersed between and across the sporozoites. A spheroidal to ellipsoidal posterior refractile body and spheroidal anterior refractile body occasionally seen, but a nucleus was not observed. Only two previous isosporans have been reported from passerellid birds and the new species can readily be distinguished from them. CONCLUSION: This is the first coccidian reported from J. hyemalis and, more importantly, the first isosporan known from any member of the family Passerellidae in North America.

A NEW SPECIES OF MYXOBOLUS (CNIDARIA: MYXOSPOREA: MYXOBOLIDAE) FROM THE FINS OF THE WESTERN CREEK CHUBSUCKER, ERIMYZON CLAVIFORMIS (CYPRINIFORMES: CATOSTOMIDAE), FROM ARKANSAS.

Between November 2018 and December 2021, 35 juvenile and adult Western Creek Chubsuckers, Erimyzon claviformis, were collected from 5 sites in western and southern Arkansas (Ouachita and Red River drainages), and their gills, gallbladders, fins, integument, other major organs, and musculature were examined for myxozoans. The fins of 12 (34%) individuals were infected with a novel species, Myxobolus stuartae n. sp. Qualitative and quantitative morphological data were obtained from formalin-fixed preserved myxospores. Molecular data from ethanol-preserved specimens consisted of a 2,028 base pair sequence of small subunit (SSU) ribosomal DNA (rDNA) from a specimen collected in Nevada County. Three other specimens from Polk County yielded partial SSU rDNA sequences that were identical to the first sequence. Phylogenetic analyses placed M. stuartae n. sp. as sister to Myxobolus bibullatus (Kudo, 1934), both clustering with other catostomid-infecting myxobolids. This is the first fin-infecting myxozoan reported from E. claviformis.