Spirorchis spp. (Digenea: Schistosomatoidea) infecting map turtles (Cryptodira: Emydidae: Graptemys spp.) in southeastern North America: A new species, molecular phylogenies, and key to species

Other Schistosomatoidea and Diplostomoidea

Trematodes of the order Diplostomida are well known as serious pathogens of man, and both farm and wild animals; members of the genus Schistosoma (Schistosomatidae) are responsible for human schistosomosis (schistosomiasis) affecting more than 200 million people in tropical and subtropical countries, and infections of mammals and birds by animal schistosomes are of great veterinary importance. The order Diplostomida is also rich in species parasitizing other major taxa of vertebrates. The "Aporocotylidae" sensu lato are pathogenic in fish, "Spirorchiidae" sensu lato in reptiles. All these flukes have two-host life cycles, with asexually reproducing larvae usually in mollusks and occasionally in annelids, and adults usually live in the blood vessels of their vertebrate hosts. Pathology is frequently associated with inflammatory reactions to eggs trapped in various tissues/organs. On the other hand, the representatives of Diplostomidae and Strigeidae have three- or four-host life cycles in which vertebrates often serve not only as definitive but also as intermediate or paratenic hosts. Pathology is usually associated with migration of metacercariae and mesocercariae within the host tissues. The impact of these trematode infections on both farm and wild animals may be significant.

Fatal spirorchiidosis in European pond turtles (Emys orbicularis) in Switzerland

Infections with intravascular digenean trematodes of the Spirorchiidae family (spirorchiidoses) are of great conservation concern both in marine and freshwater turtles due to their pathogenic potential. Between 2014 and 2021, Spirorchis sp. infections associated with granulomatous inflammation and sudden death were detected in European pond turtles (Emys orbicularis) from three conservation breeding facilities in Switzerland. Blood fluke eggs associated with lesions were found in the intestine, spleen, testis, skeletal musculature, heart, kidneys, stomach, pancreas, liver, lung, and meninges from nine pond turtles submitted for necropsy and in the intestinal content from five of these animals. Two novel polymerase chain reactions (PCRs) targeting the 28S ribosomal RNA gene and the ITS2 region and subsequent sequencing revealed 100% nucleotide identity with a Spirorchis sp. previously isolated from an Escambia map turtle (Graptemys ernsti) in the USA. Our findings suggest a spill-over event secondary to direct or indirect contact with invasive North American turtle species in Switzerland. We describe the clinical, haematological, ultrasonographical, endoscopical, parasitological, pathological, and molecular findings associated with spirorchiid blood fluke infections of the Spirorchis genus in E. orbicularis, as well as the biosecurity measures that were developed to prevent the spread of this parasite among breeding and highly endangered free-ranging E. orbicularis populations in Switzerland.

Redescription of the Type Species of Cardicola Short, 1953 (Digenea: Aporocotylidae) and Description of a New Congener Infecting Yellowedge Grouper, Hyporthodus flavolimbatus (Perciformes: Serranidae), from the Gulf of Mexico

Cardicola Short, 1953 is the most speciose aporocotylid genus (35 species) and includes marine and estuarine species of fish blood flukes that infect "higher ray-finned fishes" (Euteleostei). Several clades within Cardicola are recovered in phylogenetic analyses of the large subunit ribosomal DNA (28S), but morphological synapomorphies for those nucleotide-based clades remain elusive. The type species, Cardicola cardiocola (Manter, 1947) Short, 1953, has not been recollected in 73 yr and the original description was incomplete; making a genus revision challenging because of the ambiguous systematic position of its type species. Herein, we redescribe C. cardiocola by using the holotype (USNM 1337732) and new specimens collected from the type host, jolthead porgy, Calamus bajonado (Sparidae), from nearby the type locality. It differs from its congeners by the combination of having a body that is 5 times longer than wide, an anterior sucker with concentric rows of spines, 2-6 tegumental body spines per row, an esophageal gland that is 22-43% of the esophageal length, a testis that is 3-5 times longer than wide and that fills the intercecal space, a vitelline duct connecting to the anterior aspect of the oötype, an ascending uterus that lacks any coil, a descending uterus yielding a single coil, an obvious cirrus sac separated by constriction from the seminal vesicle, a tegumental protrusion surrounding the terminal end of cirrus sac, and a male genital pore that is posterior to the remainder of the genitalia. We also describe a new congener infecting the heart of yellowedge grouper, Hyporthodus flavolimbatus (Serranidae), from the Gulf of Mexico. It differs from its congeners by the combination of having an anterior sucker that does not extend beyond the anterior body margin, 2-5 tegumental body spines per row, posterior ceca that are 9 times length of the anterior ceca and that lack any coil, a testis that is 3 times longer than wide and that does not fill the intercecal space, an ovary that is >60% of the body width, a vitelline duct that connects to the anterior aspect of the oötype, a uterus that is >10% of the body width and that extends posterior to all genitalia, and a rounded posterior body margin. It is the first species of Cardicola to be described from a grouper (Serranidae). The 28S and internal transcribed spacer 2 phylogenetic analyses recovered the new species as a distinct lineage within the clade of Cardicola spp.

Molecular evidence of new freshwater turtle blood flukes (Digenea: Spirorchiidae) in the intermediate snail host Biomphalaria occidentalis Paraense, 1981 in an urban aquatic ecosystem in Brazil

In this study, two potentially new species of turtle blood flukes (TBFs) (Digenea: Spirorchiidae) have been recorded from South Brazil. The spirorchiid parasites infect the vascular system of turtles, thereby compromising their health. The life cycle of these parasites is not well studied. The larval stage of cercaria is found in intermediate gastropod hosts, with some species presenting similar morphological characteristics, which can result in misinterpretations when using only morphological taxonomy for species identification. In this study, we recorded a single morphotype belonging to the family Spirorchiidae in Biomphalaria occidentalis in an urban aquatic ecosystem in Brazil. However, molecular data (28S rDNA and cytochrome oxidase subunit I) confirmed the presence of two species of Spirorchiidae in the sampled environment; both phylogenetically close to genera previously studied in freshwater turtles from the Peruvian Amazon. In this study, species characterization was possible because of molecular tools. We recommend using more than one molecular marker in future studies focusing on TBFs, which need attention about their evolutionary history and ecology to understand their distribution in South America.

A new species and emendation of the seldom reported Enterohaematotrema Mehra, 1940 (Digenea: Schistosomatoidea), including a revised phylogenetic hypothesis for turtle blood flukes

Enterohaematotrema Mehra, 1940 is emended herein based upon a review of the literature and a description of a new species (Enterohaematotrema triettruongi n. sp.) infecting yellow-headed temple turtles, Heosemys annandalii (Boulenger) (Cryptodira: Geoemydidae), in the Mekong River, Vietnam. The new species differs from the published descriptions of its congeners Enterohaematotrema palaeorticum Mehra, 1940 and Enterohaematotrema hepaticum (Simha, 1958) Simha & Chattopadhyaya, 1980 by having two distinctive oesophageal glands, a short and eversible cirrus (vs protrusive with 3 distinct processes), a dorsal common genital pore that is sinistral (vs ventral and medial), a transverse (vs longitudinal) external seminal vesicle, an oviducal seminal receptacle that is sinistral (vs dextral), and a vitellarium distributing from the caecal bifurcation (anterior to the ventral sucker) to the caecal tips (vs vitellarium not extending anteriad beyond ventral sucker in E. palaeorticum or vitellarium wholly posterior to the terminal genitalia in E. hepaticum). A phylogenetic analysis of the D1-D3 domains of the nuclear large subunit ribosomal DNA (28S) recovered Enterohaematotrema and Platt Roberts & Bullard, 2016 as sister taxa that share a recent common ancestor with the clade comprising Ruavermis Dutton & Bullard, 2020 and Coeuritrema Mehra, 1933. These flukes collectively comprise a monophyletic group of southeast Asian turtle blood flukes. This analysis also indicated that the massive, longitudinal metraterm of species of Enterohaematotrema and Uterotrema Platt & Pichelin, 1994 represents homoplasy (convergent evolution). The present study comprises the first morphological study of original specimens of any species of Enterohematotrema in more than 50 years and is the first molecular phylogenetic placement of the genus among the various turtle blood fluke lineages.