Haley R. Dutton

Amyloodinium ocellatum causes epizootics in marine fish hatcheries. Frozen, wild fish, often used as food in aquaculture, could introduce the disease. We investigated the parasite's ability to survive, reproduce and infect a host after freezing. Infected gills were frozen at −20°C for either 0, 24, 36, 48, or 72 h. Parasite viability was assessed first by placing thawed infected gills into tanks with naïve fish. Gills of the exposed fish were examined on day 0 and on days 4 and 7 post‐exposure. Tomonts from infected gills in all freeze durations produced infections. However, dinospore production decreased and infections took longer to establish in fish exposed to tomonts from the 72 h treatment. Second, eight tomonts from each freeze duration were placed in 5 mL of 25 ppt artificial seawater at 22°C in individual wells of a 12‐well plate and monitored for hatching. Ninety seven percent of tomonts from all treatments hatched. Tomonts frozen for up to 72 h survived, reproduced and infected fish, but dinospore production decreased as freeze duration increased. Extrapolation from the rate of reduction in dinospore production over the freeze durations tested suggests that a freeze duration of 237 h could inactivate all tomonts.

From July 2021 through June 2024, we necropsied 35 American alligators from Louisiana, Alabama, and South Carolina (including the Gulf of America and Atlantic Ocean river basins). A new polystomatid, Latergater dupreezi n. gen., n. sp. is described based on specimens collected from the eye of 1 wild-caught American alligator measuring 1,450 mm in total length and captured from a salt marsh habitat within the Rockefeller Wildlife Refuge (Grand Chenier, Louisiana) on 19 July 2021. The new species resembles species of Polystomoidinae Yamaguti, 1963 and Oculotrematinae Yamaguti, 1963. It is readily differentiated from species of Polystomoidinae by the combination of having circular haptoral suckers with skeletal elements but that lack marked separation between suckers; ceca having anterior, medial, and lateral diverticula; a compact testis that occupies a small proportion of the intercecal space (vs. a broad testis that spans the intercecal space); a sinistral and intercecal ovary (vs. an ovary that is ventral to the sinistral cecum) having a proximal oviduct extending mediad and then posteriad (vs. proximal oviduct extending anteriad); a small uterus (occupying a minute portion of the intercecal space), medial, and located close to the cecal bifurcation; and vaginal pores that open laterally at the level of or slightly posterior to the level of the testis. It differs from species of Oculotrematinae by having vaginae and lacking hamuli. No other nominal polystome has this combination of features; therefore, the erection of a new genus for the new species is warranted. We lack a nucleotide sequence for the new species because we used the only specimen we collected as a heat-killed, formalin-fixed, stained wholemount (holotype) for a taxonomic study that prioritized morphology. Without a nucleotide sequence (and phylogenetic analysis), we herein refrain from emending an existing subfamily or proposing a new subfamily to accommodate the new genus. This is the first record of a polystome infecting a crocodilian and the first definitive record of an ectoparasitic polystome infecting a host captured in saltwater.

We propose and describe Alobophora sandrae Cajiao-Mora & Bullard n. gen., n. sp. (Digenea: Caballerotrematidae) for specimens we collected from arapaima, Arapaima gigas sensu lato (Osteoglossiformes: Arapaimidae) in the Amazon River near Leticia, Colombia. Alobophora differs from Caballerotrema Prudhoe, 1960 by lacking head collar projections and by having clustered corner spines and a narrow head collar (4–5× wider than pharynx), whereas Caballerotrema has head collar projections, lacks clustered corner spines, and has a broad head collar (7–8× wider than pharynx). We reassign Caballerotrema annulatum (Diesing, 1850) Ostrowski de Núñez & Sattmann, 2002 to the new genus, as Alobophora annulata (Diesing, 1850) Cajiao-Mora and Bullard n. comb., and provide a supplemental description of Caballerotrema brasiliense Prudhoe, 1960 based on specimens we collected from arapaima. We also examined the holotype and a paratype of Caballerotrema piscicola (Stunkard, 1960) Kostadinova & Gibson, 2001 and concluded that C. piscicola is a junior subjective synonym of C. brasiliense. Our 28S phylogeny recovered A. sandrae sister to A. annulata, with that clade sister to a clade comprising C. brasiliense and an innominate species of Caballerotrema. Caballerotrematidae was recovered sister to Echinostomatidae. We also provide a dichotomous key to caballerotrematids based on head collar projections, corner spine arrangement, proportional pharynx and head collar breadth, testes shape and arrangement, body surface spine shape and distribution, vitellarium distribution, and abundance of prostatic cells.

We examined several American alligators, Alligator mississippiensis (Daudin, 1802) (Crocodilia: Alligatoridae) from Louisiana, Alabama, and South Carolina in August 2022. The intestine of one alligator from Alabama was infected by Dracovermis occidentalis Brooks and Overstreet, 1978 (Platyhelminthes: Digenea: Liolopidae Odhner, 1912), a seldom collected and incompletely described trematode that lacks a representative nucleotide sequence. Liolopidae comprises 5 genera and 15 species: Liolope spp. infect giant salamanders; Helicotrema spp. infect turtles and lizards; Harmotrema spp. infect snakes; Paraharmotrema spp. infect turtles; and Dracovermis spp. infect crocodilians. Based on our study of the newly collected specimens and the holotype of D. occidentalis, we redescribe D. occidentalis, correct errors in its original description, and provide an updated phylogeny for Liolopidae that, for the first time, includes Dracovermis Brooks and Overstreet, 1978. Our specimens were identified as D. occidentalis by having testes in the posterior 1/3 of the body, a pretesticular cirrus sac, a spined and eversible cirrus, a bipartite seminal vesicle, and a post-acetabular vitellarium. A phylogenetic analysis of the D1–D3 domains of the nuclear large subunit ribosomal DNA (28S) recovered Liolopidae as monophyletic; however, low taxon sampling in the group precludes hypothesis-testing about liolopid-vertebrate cophyly. This is the first collection for morphological study of the type species for Dracovermis since the genus was proposed 46 years ago, the first record of a liolopid from Alabama, and the first phylogenetic analysis that includes Dracovermis.

During a 2021 parasitological survey of birds in the Nyae Nyae-Khaudum Dispersal Area (Kavango-Zambezi Transfrontier Conservation Area, Namibia), we collected 9 specimens of Dendritobilharzia pulverulenta (Braun, 1901) Skrjabin, 1924 infecting the blood (heart lumen) of a white-backed duck, Thalassornis leuconotus (Eyton, 1838) (Anseriformes: Anatidae), and a fulvous whistling duck, Dendrocygna bicolor (Vieillot, 1816) (Anatidae). These flukes were fixed for morphology and preserved for DNA extraction. We assigned our specimens to Dendritobilharzia Skrjabin and Zakharow, 1920 because they were strongly dorso-ventrally flattened in both sexes and had an intestinal cyclocoel with a zig-zag common cecum with lateral dendritic ramifications, numerous testes posterior to the cyclocoel and flanking the dendritic ramifications, and a tightly compacted convoluted ovary as well as lacking an oral sucker, ventral sucker, and gynaecophoric canal. Further, our specimens were morphologically identical to previously published descriptions of D. pulverulenta. Sequences of the 28S from our specimens were nearly identical to those identified as D. pulverulenta from North America (New Mexico), and our 28S phylogenetic analysis recovered D. pulverulenta within a polytomy of other Gigantobilharziinae spp. The CO1 phylogenetic analysis recovered a monophyletic Dendritobilharzia and, with low taxon sampling, a monophyletic Gigantobilharzia. This is the first record of a species of Dendritobilharzia infecting these ducks as well as the first record of an adult Dendritobilharzia from sub-Saharan Africa. The original description of adult D. pulverulenta (type locality: northern Sudan) was based on 2 males only, and hence the present study is the first description of female D. pulverulenta from Africa (the continent of the type locality). We reassign 2 Gigantobilharziinae spp. based on morphology and nucleotide evidence: Gigantobilharzia ensenadense (Lorenti, Brant, Gilardoni, Diaz, and Cremonte, 2022) Dutton and Bullard, n. comb., and Gigantobilharzia patagonense (Lorenti, Brant, Gilardoni, Diaz, and Cremonte, 2022) Dutton and Bullard, n. comb. We also comment on several avian schistosome sequences whose identities need confirmation or that likely have been misidentified.

While surveying the parasites of birds associated with western Alabama aquaculture ponds, we collected several specimens of Anativermis normdroneni n. gen., n. sp. (Digenea: Cyclocoelidae) from the nasopharyngeal cavity of a Canada goose, Branta canadensis (Linnaeus, 1758) (Anseriformes: Anatidae). These flukes were heat killed and fixed in neutral buffered formalin for morphology or preserved in 95% ethanol for DNA extraction. Anativermis resembles Morishitium (Witenberg, 1928) by having testes that are spheroid with smooth margins and located in the posterior quarter of the body, an anterior testis that is lateral to the midline and abuts the respective cecum, a posterior testis that is medial (testes diagonal) and abuts the cyclocoel, a genital pore that is immediately postpharyngeal, and a vitellarium that is discontinuous posteriorly. The new genus differs from Morishitium and is unique among all other cyclocoelid genera by having the combination of a body that is broadest in the anterior body half, a posterior body end that is more sharply tapered than the anterior body end, an ovary that nearly abuts the posterior testis, a vitellarium that is asymmetrical and distributes from the area immediately posterior to the cecal bifurcation posteriad to approximately the level of the ovary, and uterine loops extending dorsolateral to the ceca and filling the space between the ceca and the respective body margin for nearly the entire body length. The new genus was recovered as a distinct lineage in separate 28S, 18S, and ITS2 phylogenetic analyses. This is the first report of a cyclocoelid infecting the Canada goose and of a cyclocoelid from Alabama.

Introduction Pseudocapillaria (Ichthyocapillaria) bumpi n. sp. (Nematoda: Capillariidae) is described from specimens infecting the digestive tract of the West African lungfish, Protopterus annectens (Owen) (Lepidosireniformes: Protopteridae). Methods Nematodes were collected in Karingani Game Reserve, Southern Mozambique and studied using light microscopy; obtained sequences of the 18S ribosomal (18S rRNA) gene used for phylogenetic studies. Results The new species is assigned to Pseudocapillaria Freitas, 1959 by having a stichosome consisting of a single row of stichocytes and ventrolateral lobes on the male tail as well as by lacking spines on the specular sheath, caudal alae, a membranous caudal bursa, and a lateral expansion of the caudal end. It is also assigned to the sub-genus Ichthyocapillaria Moravec, 1982 by having a membrane between the ventrolateral lobes and by lacking a vulvar appendage. Pseudocapillaria (I.) bumpi n. sp. differs from its nominal congeners by having a comparatively large body size with relatively long spicule, bearing the thin membrane non-extending further than ventrolateral lobes in males and relatively smaller eggs without protruding polar plugs. It is the 20th species of the genus, the first from the Afrotropical Realm, and the first from any lungfish species. Phylogenetic analyses suggested that P. (I.) bumpi is deeply nested in a clade that associates species of the genera Pearsonema, Aonchotheca and Baruscapillaria.