ABSTRACT The hawksbill turtle Eretmochelys imbricata is a critically endangered species with a worldwide distribution. Limited information is available about the naturally occurring intestinal parasites of this species and what impact these parasites may have on the health of the hawksbill turtle. Diaschistorchis pandus was identified postmortem in 5 hawksbill turtles from Grenada, West Indies, using morphologic characterization. Sanger sequencing was performed for conserved ribosomal regions ( 5.8S , ITS2 , 28S ) and the mitochondrial cytochrome c oxidase subunit 1 gene ( COI ). Phylogenetic analysis of the 28S rRNA gene sequence data shows D. pandus clustering with other trematodes in the family Pronocephalidae, corroborating morphological classification. No genetic sequences have been previously reported for this trematode species, which has limited the collection of objective epidemiological data about this parasite of marine turtles.

ABSTRACT The pirate perch Aphredoderus sayanus is a relatively small fish species found in rivers throughout much of the eastern United States. Due to their cryptic nature, relatively little is known regarding their parasite fauna. A survey of pirate perch from the upper Mississippi River revealed 2 novel myxozoans. Hennegoides flockae n. sp. was observed in heavily infected gills where the lamellae featured irregular expansion by bulbous myxozoan polysporic plasmodia, typically affecting the middle to distal half of the filaments. When severe, infection of sequential filaments was such that the filaments were fused, forming what appeared as multicystic/lobular parasitic aggregates subdivided by fine epithelial cords. The total myxospore length of Hennegoides flockae was 35.4–46.4 (41.3 ± 3.3) and the spore body, asymmetrically ovoid in valvular view, was 15.4–18.7 (17.0 ± 0.7) × 7.1–8.7 (7.9 ± 0.4). Henneguya marcquenskiae n. sp. was observed in the liver with plasmodia present randomly and infrequently in the hepatocellular parenchyma. The total myxospore length for Henneguya marcquenskiae was 39.5–55.9 (48.4 ± 4.2), with the spore body being lanceolate, 13.9–16.5 (15.4 ± 0.7) × 7.1–9.0 (8.3 ± 0.5). Phylogenetic analysis of the SSU rRNA gene placed both Hennegoides flockae and Henneguya marcquenskiae as sisters to each other in a clade containing other Myxozoans known to infect the gills of esocids, percids, and centrarchids. These parasites represent the first reports of Henneguya and Hennegoides from pirate perch, with the latter being the first report of this genus outside of the Asian continent.

ABSTRACT Levisunguis subaequalis Curran, Overstreet, Collins & Benz, 2014 , was recently described from the lungs of the definitive hosts, softshell turtles, Apalone ferox (Schneider, 1783), and Apalone spinifera aspera (Agassiz, 1857) as well as the viscera of an intermediate host, the western mosquitofish, Gambusia affinis (Baird and Girard, 1853). However, the original account lacked molecular data. Furthermore, histological examination of infected host tissues in the original account of L. subaequalis did not reveal any pathological changes in the intermediate host. The present work provides a robust morphological description of the nymph and novel molecular data from the 18S and 28S ribosomal gene regions and the cytochrome c oxidase subunit 1 ( COI ) mitochondrial gene. Phylogenetic analyses using Bayesian inference and maximum likelihood analysis with concatenated sequence data from these 3 regions, as well as each region individually, placed the turtle pentastomid L. subaequalis as a sister clade to the crocodilian pentastomids of the genus Sebekia Sambon, 1922. While only concatenated phylogenetic analyses agreed with the currently accepted classification of the Eupentastomida and phylogenetic signal assessment indicated that the concatenated data set yielded the most phylogenetic signal, data from more taxa are still needed for robust phylogenetic inferences to be made. The intensity of infection ranged from 2 to 171 nymphs per fish, compared with the highest previously reported intensity of 6. These high-intensity infections with L. subaequalis were characterized by the nymphs occupying 5–50% of the coelomic cavity of G. affinis . However, despite this heavy parasite infection, fish exhibited minimal pathology. Observed pathology was characterized by compression or effacement of organs adjacent to the nymphs, particularly liver, swim bladder, and intestines, as well as the formation of granulomas around shed pentastomid cuticles. Nonetheless, the morphological and molecular data provided in the present work will bolster future efforts to identify this pentastomid in other hosts where pathology may be present in addition to aiding in the advancement of the field of molecular pentastomid systematics.

Ocular diplostomiasis is caused by trematode species in the family Diplostomidae, specifically those in the genera Austrodiplostomum , Diplostomum , and Tylodelphys . Diplostomid trematodes are globally distributed parasites of fish. Heavy infections of diplostomids that parasitize the eyes of fish can result in acute mortality while chronic infections are often characterized by impaired vision or blindness. In the southeastern United States, commercial catfish production is threatened by piscivorous birds and the many trematode species that parasitize them. The life cycles typically involve a piscivorous avian definitive host, a mollusk first intermediate host, and a fish second intermediate host. A survey of parasites infecting the snail host Biomphalaria havanensis (= B. obstructa ) in catfish production ponds was undertaken. Snails were collected from 2 separate ponds during the summer of 2014 and observed for the release of trematode cercariae. A total of 1,740 snails were collected. Three distinct longifurcate pharyngeate cercariae were observed and these cercariae were characterized morphologically and molecularly. Sequencing of ∼4,200 base pairs (bp) of the nuclear ribosomal genes and ∼450 bp of the mitochondrial cytochrome c oxidase gene revealed 3 genetically distinct species. One morphotype shared 99–100% sequence identity with metacercariae from the aqueous and vitreous humors of gizzard shad Dorosoma cepedianum and channel catfish Ictalurus punctatus as well as an adult trematode, Austrodiplostomum ostrowskiae , a parasite of the double-crested cormorant Nannopterum auritus . The remaining 2 cercariae morphotypes shared 99–100% sequence identity with an unidentified Tylodelphys sp. and Austrodiplostomum sp. metacercaria from the brain and eyes of several freshwater fish. Herein we molecularly link the cercaria, metacercaria, and adult stage of the life cycle of A. ostrowskiae , identifying the snail host for this parasite, in addition to providing notes on 2 cercariae representing 2 other diplostomids.

The channel catfish Ictalurus punctatus is a known host for 10 species of Henneguya , but few other myxozoan genera are described from this species. Unicauda is a genus of myxozoan parasites within the family Myxobolidae that consists of 10 valid species from freshwater fish. Herein, we describe a novel species of Unicauda from the intestinal tract of farm-raised channel catfish in Mississippi. Myxospores were consistent with the genus Unicauda but exhibited a unique branching at the terminal end of the caudal process that has not previously been reported. Myxospores measured 90.39 ± 14.97 μm (mean ± SD; range = 70.88–126.02 μm) in total length. The spherical spore body measured 7.31 ± 0.26 μm (6.75–7.84 μm) in length and 7.01 ± 0.63 μm (6.1–8.01 μm) in width. The 2 polar capsules measured 3.45 ± 0.33 μm (3.02–4.03 μm) in length and 2.65 ± 0.32 μm (2.18–3.11 μm) in width. The single caudal process measured 82.98 ± 14.97 μm (63.39–118.63 μm) in length from the base of the spore body to the end of the most terminal projection. Terminal projections measured 26.83 ± 8.8 μm (12.34–42.29 μm) in length and 0.95 ± 0.23 μm (0.52–1.6 μm) in width. The 18S rRNA gene sequence obtained did not match any published sequences. Given the uniqueness of the myxospore morphology, histological presentation, and gene sequence data, we describe this as an unreported species, Unicauda fimbrethilae n. sp.

The actinospore diversity of infected Dero digitata was surveyed (May 2011) from a channel catfish ( Ictalurus punctatus ) production pond in the Mississippi Delta region for the elucidation of unknown myxozoan life cycles. At present, only 2 myxozoan life cycles have been molecularly confirmed in channel catfish, linking the actinospore stage from an aquatic oligochaete ( D. digitata ) and the myxospore stage from the catfish. In this study D. digitata (n = 2,592) were isolated from oligochaetes collected from the bottom sediment of a channel catfish production pond. After 1 wk of daily observation, a total of 6 genetically different actinospore types were observed. The collective groups were classified as 2 aurantiactinomyxons, 2 helioactinomyxons, 1 raabeia, and 1 triactinomyxon. Overall prevalence of myxozoan infections in the isolated oligochaetes was 4.4%. Actinospores were photographed and measured for morphological characterization. Four previously undescribed actinospore types were identified and characterized molecularly and morphologically. Phylogenetic analysis revealed the raabeia and one of the helioactinomyxon (type 1) actinospores were closely related to the group of myxozoans known to parasitize ictalurids in North America. To date, no myxospores have been linked to the newly sequenced actinospores reported in this survey. The morphological and molecular data generated from this study will assist in the identification of myxospore counterparts for these actinospore stages and aid in the elucidation of unknown myxozoan life cycles in closed production systems.