First elucidation of a blood fluke (Electrovermis zappum n. gen., n. sp.) life cycle including a chondrichthyan or bivalve. (December 2019)

• Record Type: Journal Article
• Authors: Warren, Micah B.; Bullard, Stephen A.
• Is Part Of: International journal for parasitology. Volume 10(2019)
• Page Start: 170
• Page End: 183
• Publication Date: 2019-12
• Subjects: taxonomy -- Phylogenetics -- Histology -- Bivalvia -- Elasmobranchii -- Life cycle; Parasites -- Periodicals; Parasitology -- Periodicals; Animals -- Periodicals; Wildlife diseases -- Periodicals; Parasites -- Periodicals; Animals, Wild -- Periodicals; Animals; Parasites; Parasitology; Wildlife diseases; Periodicals; 591.7857
• DOI: 10.1016/j.ijppaw.2019.06.008
• Languages: English
• ISSNs: 2213-2244

Abstract

Abstract: We describe a new fish blood fluke (Digenea: Aporocotylidae: Electrovermis zappum n. gen., n. sp.) and its life cycle in the intertidal zone adjacent to Mobile Bay (north-central Gulf of Mexico). This is the first elucidated aporocotylid life cycle that includes a chondrichthyan definitive host or a bivalve intermediate host. The new species undergoes asexual reproduction within the gonad of the variable coquina clam before maturing in the heart of the lesser electric ray. These adults and cercariae had identical 28S, 18S, and ITS2 nucleotide sequences. The new genus is similar to Ogawaia Cutmor et al., 2018 by having an inverse U-shaped intestine, a looping testis, and a uterus having distinct ascending and descending segments. It differs by having a body that is ≥ 30 × longer than wide, a testis with >30 curves, an obvious cirrus sac enveloping an extremely elongate cirrus, an ovary anterior to the seminal vesicle, and a post-gonadal uterus. The new species further differs from the type species of Ogawaia ( Ogawaia glaucostegi Cutmore et al., 2018) by having a massive seminal vesicle (>10% of body length), a cirrus sac enveloping an extremely elongate cirrus, and a slightly sinuous uterus. Histology confirmed gametogenesis in an infected coquina clam but no discernible cellular response to infection was observed. We also i) characterize a second morphologically and genetically distinct cercaria (perhaps representing an innominate chondrichthyan aporocotylid) infecting the green jackknife clam in Mississippi Sound (north-central Gulf of Mexico), ii) compare all known aporocotylid cercariae infecting estuarine and marine mollusks and polychaetes and iii) provide a key to identify those cercariae. A phylogenetic analysis including nucleotide sequences from adult and cercarial specimens of the newly collected fish blood flukes further supports the notion that chondrichthyan aporocotylids are monophyletic and use bivalves as the first intermediate host; perhaps unlike any other blood fluke lineage. Graphical abstract: Image 1 Highlights: Description of a new genus and species of fish blood fluke (Digenea: Aporocotylidae). Description of an innominate cercaria infecting green jackknife clam ( Solen viridis ). Morphological comparisons and key to all estuarine and marine aporocotylid cercariae. The blood flukes of rays (Batoidea) are paraphyletic. Evidence of cophyly between these parasites and their fish hosts is lacking.