Sara Vanessa Brant

Museums serve as tangible links to the past, providing the context needed to understand and estimate change over time. In the ever-changing global landscape, documenting the world's parasites, a critical component of biodiversity, has become essential. Parasitism, a lifestyle rather than a taxonomic category, spans a remarkable range of organisms, from protozoans and metazoans to fungi and plants. Although scientists broadly agree on the need to voucher parasites in museums, practical guidance on how to do so across the diversity of parasite taxa remains limited. Voucher specimens are preserved specimens and associated data that are deposited and catalogued in accessible, recognized, permanent museum collections. Vouchers are fundamental for making studies repeatable and verifiable, providing firm reference points for investigations. All parasitological studies can contribute vouchers of parasites and their natural or experimental hosts. Here we review (1) the nature of a voucher and its role within parasitology; (2) the proportion of specimens represented in the Journal of Parasitology (2011–2021) publications that have been vouchered; (3) a survey of the membership of the American Society of Parasitologists for perceived roadblocks to vouchering; (4) suggested practices for increasing specimen vouchering; and (5) a field-to-museum vouchering case study from the Museum of Southwestern Biology, Division of Parasites, Albuquerque, New Mexico.

The collection and preservation of parasites come with many challenges. One of the most significant is the proper identification, preservation, and availability of their hosts. Vouchering parasites and their hosts is essential for understanding host–parasite evolutionary and ecological interactions, extension and revalidation of past research, and for building biodiversity infrastructure to support future science as new questions arise and new tools are developed. Exact host identification is an important component of understanding parasite transmission due to the trophic breadth of host use by different parasites; thus, vouchering the host ensures they are available for revision. The University of New Mexico's Museum of Southwestern Biology offers a model for integration of a parasite division with a suite of vertebrate and invertebrate host divisions. Here, we outline suggested practices for the preservation of host specimens examined for parasites, offering taxon-specific guidelines derived from the experience of museum personnel. These guidelines are designed to help researchers incorporate host preservation into existing protocols with minimal additional effort. Adopting even simple vouchering practices can ensure that parasite and host data remain permanently linked, verifiable, and available for future research. Building spatially and taxonomically broad and temporally deep archives of hosts and parasites provides unparalleled infrastructure for parasite discovery and natural history, assessing environmental change, and understanding host–reservoir dynamics.

Psilochasmus Lühe, 1909 is a small genus of psilostomid digeneans parasitic in birds and characterized by the presence of a retractable tail-like structure at the posterior end of the body. Despite its low diversity, the taxonomic history of the genus is tumultuous, with opinions varying from recognizing only a single species to 11 nominal species. In this study, newly generated and previously available sequences of nuclear ribosomal DNA operon (ITS1+5.8S+ITS2; 28S) and partial NADH dehydrogenase (nad1) mtDNA gene sequences of Psilochasmus spp. from Europe (Palearctic), North America (Nearctic) and South America (Neotropics) were used to assess the diversity of Psilochasmus spp. and explore the phylogenetic interrelationships among members of genus and to distinguish between species. Based on combined morphological and molecular data, descriptions of two new Psilochasmus species from Europe and North America, Psilochasmus slavaukrainiisp. nov. and Psilochasmus urbenisp. nov., are provided, as well as the first morphological description of P. oxyurus specimens linked to DNA sequence data. In addition, a key to the identification of Psilochasmus spp. recognized as a result of this study has been constructed.

Metacercariae of the genus Posthodiplostomum are often recorded in freshwater fish hosts. While the diversity and taxonomy of this genus are receiving increasing attention in molecular phylogenetic studies, available data remain geographically biased. Most molecular studies of Posthodiplostomum and morphologically similar (neascus) worms originate in North America and Europe and Asia (more than 60% of DNA sequences are from USA and Canada), with few data currently available from the Neotropics, where high host diversity suggests high and under-sampled parasite diversity. In this study, we report molecular and morphological data from metacercariae of Posthodiplostomum in fish in Puerto Rico, where only a single species has been previously reported. Partial sequences of cytochrome c oxidase subunit 1 from metacercariae from Dajaus monticola (native to Puerto Rico) and the introduced fishes Poecilia reticulata, Parachromis managuensis, Lepomis macrochirus and Micropterus salmoides revealed 7 genetically distinct species-level lineages, of which 4 were novel. We report novel molecular life-cycle linkages in Posthodiplostomum macrocotyle (metacercariae in muscle of the cichlid Pa. managuensis), a species previously known only from adults in birds from South America; and in Posthodiplostomum sp. 23 (metacercariae in poeciliids), which has recently been found in Ardea herodias in Georgia, USA. We also report the first molecular data from Posthodiplostomum sp. 8 in M. salmoides in the Caribbean. Metacercariae of most species were morphologically distinguished and all displayed narrow specificity for fish hosts, with no indication of parasite sharing among introduced and native fishes.

Schistosomatidae Stiles and Hassall 1898 is a medically significant family of digenetic trematodes (Trematoda: Digenea), members of which infect mammals or birds as definitive hosts and aquatic or amphibious gastropods as intermediate hosts. Currently, there are 17 named genera, for many of which evolutionary interrelationships remain unresolved. The lack of a resolved phylogeny has encumbered our understanding of schistosomatid evolution, specifically patterns of host-use and the role of host-switching in diversification. Here, we used targeted sequence capture of ultra-conserved elements (UCEs) from representatives of 13 of the 17 named genera and 11 undescribed lineages that are presumed to represent either novel genera or species to generate a phylogenomic dataset for the estimation of schistosomatid interrelationships. This study represents the largest phylogenetic effort within the Schistosomatidae in both the number of loci and breadth of taxon sampling. We present a near-comprehensive family-level phylogeny providing resolution to several clades of long-standing uncertainty within Schistosomatidae, including resolution for the placement of the North American mammalian schistosomes, implying a second separate capture of mammalian hosts. Additionally, we present evidence for the placement of Macrobilharzia at the base of the Schistosoma + Bivitellobilharzia radiation. Patterns of definitive and intermediate host use and a strong role for intermediate host-switching are discussed relative to schistosomatid diversification.

Although most studies of digenetic trematodes of the family Schistosomatidae dwell on representatives causing human schistosomiasis, the majority of the 130 identified species of schistosomes infect birds or non-human mammals. The cercariae of many of these species can cause swimmer’s itch when they penetrate human skin. Recent years have witnessed a dramatic increase in our understanding of schistosome diversity, now encompassing 17 genera with eight more lineages awaiting description. Collectively, schistosomes exploit 16 families of caenogastropod or heterobranch gastropod intermediate hosts. Basal lineages today are found in marine gastropods and birds, but subsequent diversification has largely taken place in freshwater, with some reversions to marine habitats. It seems increasingly likely that schistosomes have on two separate occasions colonized mammals. Swimmer’s itch is a complex zoonotic disease manifested through several different routes of transmission involving a diversity of different host species. Swimmer’s itch also exemplifies the value of adopting the One Health perspective in understanding disease transmission and abundance because the schistosomes involved have complex life cycles that interface with numerous species and abiotic components of their aquatic environments. Given the progress made in revealing their diversity and biology, and the wealth of questions posed by itch-causing schistosomes, they provide excellent models for implementation of long-term interdisciplinary studies focused on issues pertinent to disease ecology, the One Health paradigm, and the impacts of climate change, biological invasions and other environmental perturbations.

Gigantobilharzia Odhner, 1910 (Schistosomatidae) includes species that parasitize several orders of birds and families of gastropods from both freshwater and marine environments worldwide. Due to their delicate bodies, most of the species descriptions are incomplete, and lumped in the genus Gigantobilharzia, in some cases despite major morphological variability. Only three of those species have molecular sequence data but then lack a robust morphological description, making species differentiation very difficult. For this reason, several authors consider that many of the species of Gigantobilharzia should be reassigned to new genera. The aim of this paper is to describe two new genera and two new species of schistosomes using morphological and molecular characterization. We described Marinabilharzia patagonense n. g., n. sp. parasitizing Larus dominicanus from north Patagonian coast, and Riverabilharzia ensenadense n. g., n. sp. parasitizing L. dominicanus, Chroicocephalus maculipennis and Chroicocephalus cirrocephalus from freshwater Río de La Plata, in South America, Argentina. We then analysed and discussed the combinations of characters defining species of Gigantobilharzia and, based on that and on the available molecular data, we propose at least four possible new genera.

In response to annual outbreaks of human cercarial dermatitis (HCD) in Lake Wanaka, New Zealand, ducks and snails were collected and screened for avian schistosomes. During the survey from 2009 to 2017, four species ofTrichobilharziawere recovered. Specimens were examined both morphologically and genetically.Trichobilharzia querquedulae, a species known from four continents, was found in the visceral veins of the duckSpatula rhynchotisbut the snail host remains unknown.Cercaria longicauda[i.e.Trichobilharzia longicauda(Macfarlane, 1944) Davis, 2006], considered the major aetiological agent of HCD in Lake Wanaka, was discovered, and redescribed from adults in the visceral veins of the duckAythya novaeseelandiaeand cercariae from the snailAustropeplea tomentosa.Recovered from the nasal mucosa ofAy. novaeseelandiaeis a new species ofTrichobilharziathat was also found to cycle naturally throughAu. tomentosa. Cercariae of a fourth species ofTrichobilharziawere found inAu. tomentosabut the species remains unidentified.

The Journal of Parasitology publishes on basic or applied aspects of general, veterinary, or medical parasitology, and epidemiology.

The Journal of Parasitology publishes on basic or applied aspects of general, veterinary, or medical parasitology, and epidemiology.