Dennis J. Richardson

The Common North American Turtle Leech, Placobdella parasitica, was reported in 2023 using the Northwestern Pond Turtle, Actinemys (Emys) marmorata, as a host in the Lower Rogue River, southwestern Oregon, USA. Molecular analysis and haplotype networks based on the mitochondrial cytochrome c oxidase subunit I (COI) gene sequence revealed that this introduced population has very low haplotype diversity and is likely the result of a single introduction of a gravid adult, an adult brooding eggs or hatchlings, or a small number of related individuals. While we determined that the precise source population was not represented in our sampling, there was strong similarity between the representatives from Oregon and those from near the Arkansas-Missouri border. Molecular evidence also supports this as a recent introduction, likely via human activity, and potential pathways of introduction are considered. Our results agreed with a previous study of morphological and molecular data of P. parasitica samples from throughout its native range in North America that found the species to be widely distributed, morphologically conservative, and molecularly variable. Using COI sequence data with Bayesian Inference, we evaluated species cohesiveness using species delimitation analyses (ABGD, mPTP, bPTP, and GMYC) that revealed 13 species entities that were clustered by geographic region. Identifying the source population and possible invasion pathways of this introduced population and assessing the dispersal capabilities of P. parasitica could slow and prevent further range expansion in the western USA. Introduced P. parasitica has not been recognized as a threat to the health of the Northwestern Pond Turtle or the Rogue River ecosystem so its presence has not been systematically monitored, but any introduced parasite is concerning given that the U.S. Fish and Wildlife Service has proposed this turtle species for Threatened status under the Endangered Species Act.

The paucity of information concerning the occurrence of strongyle nematodes in New England dairy goats prompted a survey of 241 dairy goats from throughout New England. Of the 241 goats examined using the McMaster technique, 104 (42.7%) were infected with strongyles with a mean intensity (+ SE) of 369.7 + 45.8 eggs per gram. Subsequent molecular examination of 50 random samples from these goats revealed a prevalence of 88% infection specifically with Haemonchus contortus. Haemonchus contortus is the most important internal parasite of sheep and goats, exerting a crushing economic burden on the livestock industry worldwide due to lowered milk production, poor weight gain, substandard wool quality, and sudden death of animals in all production stages. Nigerian Dwarf (ND) goats have become exceedingly popular in New England and constituted nearly half of the goats surveyed. Comparison of strongyle infections between ND goats and all other goats combined, revealed a 60.7% prevalence of strongyle infection in breeds other than ND goats, while the ND goat infection rate was 25.2%. Likewise, the intensity of infection in ND goats was roughly half that of other breeds combined. The generally accepted threshold of intensity for clinical/economic importance for H. contortus is 1,000 eggs per gram feces. ND goats exhibited a significantly lower prevalence of clinical/economically important infection (2 of 119; 1.7%) than goats of other breeds (9 of 122; 7.4%). This higher prevalence, lower mean intensity, and level of heavy infection exhibited by ND goats suggests the possibility that ND goats in this New England population may possess some level of innate resistance to infection with strongyle nematodes. Further studies are warranted to investigate possible resistance and its biological significance.

Recent collection within Arkansas greatly enlarges the knowledge concerning hosts and distributions of fish leeches within the state. The natural history of the 6 species of fish leeches known from Arkansas (Placobdella montifera, Placobdella pediculata, Cystobranchus klemmi, Cystobranchus verrilli, Myzobdella lugubris, and Myzobdella reducta) is reviewed and updated and molecular data are provided.

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.

Placobdella parasitica (Say, 1824) is one of the most commonly encountered turtle leeches in North America. Molecular analysis of individuals of P. parasitica representing various populations throughout its range in North America using the cytochrome c oxidase subunit I gene, revealed the presence of nine distinct groups: (1) P. parasitica sensu stricto containing members, including the neotype specimen, occurring broadly throughout the central United States westward from the Mississippi River to the Rocky Mountains and throughout southern Ontario, Canada, and the upper midwestern United States as far east as New York State; (2) West Virginia; (3) Mississippi/Alabama; (4) Northeast, including New York, Massachusetts, and Vermont; (5) New England, including Rhode Island, Massachusetts, and Connecticut; (6) North Carolina/West Virginia; (7) South Carolina; (8) Tennessee; and (9) Florida. Both neighbor-joining and maximum likelihood analyses recovered an east-west split along the Appalachian Mountains with groups 1–3 clustering together and groups 4–9 clustering separately, with the exception of group 8 (Tennessee) that placed with the eastern groups. Group 1 includes specimens from a broad geographic distribution, yet with relatively low genetic variation, a pattern observed in other glossiphoniid species in North America. The groups with members east of the Appalachian Mountains are more tightly clustered by locality. This leech species is known to parasitize several turtle species, including Chrysemys picta, the painted turtle that originated in the central Gulf Coast region and dispersed northward representing a recolonization after Pleistocene glaciation. The neighbor-joining tree and pairwise distance data could suggest that P. parasitica has a similar phylogeographic pattern and dispersal history with its turtle hosts. In view of the morphological uniformity among the various groups, P. parasitica is provisionally considered to be a widely distributed, molecularly variable species.

Placodella michiganensis (Sawyer, 1972) was originally described from free-living individuals collected from Mill Creek, St. Joseph County, Michigan, USA. The acquisition of contemporary specimens from its type locality has facilitated redescription of P. michiganensis. Placobdella michiganensis does not have a confusing taxonomic history like many other members of the genus Placobdella as it has only been collected two other times since its description. Placodella michiganensis is distinguished from its congeners by its five rows of whitish single-tipped papillae, genital and pre-anal patches, five pre-anal papillae, and absence of a dark dorsal-medial line. Placobdella michiganensis is a morphologically distinct species with a 16.0% to 22.0% difference in cytochrome c oxidase subunit I sequence data among congeners.

Placobdella pediculataHemingway, 1908 was originally described from individuals that were attached to Aplodinotus grunniens (freshwater drum) in Lake Pepin, Minnesota, USA. Apparently, no type material was deposited. The acquisition of contemporary specimens from its type host in the type locality facilitated redescription of P. pediculata. Placobdella pediculata is different from its congeners in that its caudal sucker is extended from the body by a pedicel (peduncle), bears digitate processes near the rim of the caudal sucker, a smooth body surface, and its anal placement (few annuli anteriad of the caudal sucker). Molecular comparison of cytochrome c oxidase subunit I sequence data from P. pediculata revealed differences of 13.8% to 17.4% among congeners. Placobdella pediculata is a distinct species.

Single juvenile specimens of a species of Centrorhynchus were collected from the small intestines of 3 stray dogs in Qom, Qom Province, Iran, constituting the third report of a centrorhynchids from a dog. The proboscis morphology and armature, 24–28 longitudinal rows of 9–10 hooks, were most similar to juveniles of Centrorhynchus mysentri from the Indian bullfrog, Hoplobatrachus tigerinus, and adults of Centrorhynchus globirostris from the pheasant crow Centropus sinensis, which are described from India and Pakistan, respectively. The dogs may have become infected when eating infected frogs.

Confusion regarding the identification of Placobdella hollensis (Whitman, 1892) (Hirudinida: Glossiphoniidae) has led to an unclear understanding of the distribution of the species. Two specimens of P. hollensis were collected from Merchants Millpond State Park, Gates County, North Carolina, U.S.A., representing a new geographic distribution record. Specimens were confirmed as P. hollensis by morphological and molecular study. Specimens of P. hollensis from North Carolina, had accessory eyes, 2 thin paramedial dark lines, and 3 pairs of pre-anal papillae. Molecular comparison of cytochrome c oxidase subunit I sequence data revealed a 99.0 to 99.7% similarity to specimens of P. hollensis collected from its type locality (Barnstable County, Massachusetts, U.S.A.). From confirmed specimens of P. hollensis, this report supports the assertion that P. hollensis has an Atlantic coastal distribution.

To date, the only species of leech reported from the American Alligator, Alligator mississippiensis is Placobdella multilineata. Seven specimens of a previously undescribed species of Placobdella were collected from the feet and lower jaw of a single female alligator from the Pascagoula River Wildlife Management Area, George County, Mississippi. The new species was named Placobdella siddalli Richardson & Moser, sp. n., in honor of the contributions of Dr. Mark Siddall to our understanding of the biology of leeches. Placobdella siddalli Richardson & Moser is similar to other papillated members of the genus Placobdella, but differs from Placobdella ali Hughes & Siddall, 2007, Placobdella rugosa (Verrill, 1874), Placobdella multilineata Moore, 1953, and Placobdella papillifera (Verrill, 1872) in coloration, papillation, ventral striping, and in the possession of a relatively large caudal sucker. In addition, molecular comparison of 626 nucleotides of CO-I between the new species and other papillated leeches (P. ali, P. multilineata, Placobdella ornata, P. papillifera, P. rugosa) revealed interspecific differences of 14.0–18.0% (88–113 nucleotides).