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

First report of a fish blood fluke from sub-Saharan Africa: Nomasanguinicola dentata (Paperna, 1964) Warren and Bullard, 2023 infecting African sharptooth catfish, Clarias gariepinus (Burchell, 1822) Teugles, 1982 in the Kavango River, Namibia, and a revised phylogeny for Sanguinicolidae Poche, 1926

We herein provide a supplemental description of Nomasanguinicola dentata (Paperna, 1964) Warren and Bullard, 2023 (Digenea: Sanguinicolidae) and provide a revised 28S phylogeny to test relationships among freshwater fish blood flukes. We examined the heart of three African sharptooth catfish, Clarias gariepinus (Burchell, 1822) Teugles, 1982 from the Kavango River (northeastern Namibia) that was infected with adults of N. dentata. This blood fluke differs from N. canthoensis by having a body 5.3-6.7 longer than wide (vs. 3.5-4.6), an anterior esophageal swelling 7-8% (vs. 14-24%) of total esophageal length, a posterior esophageal swelling 3-5% (vs. 8-10%) of total esophageal length, a pre-cecal (vs. wholly post-cecal) testis, and an ovary that does not extend laterally beyond the nerve cords. The 28S sequence for N. dentata differed from that of N. canthoensis by 144 bp (9% difference). The phylogenetic analysis recovered these species as sister taxa and Sanguinicolidae as monophyletic. This is the first report of a fish blood fluke from sub-Saharan Africa, and the first report of a species of Nomasanguinicola from Africa in ∼40 yrs.

SYSTEMATIC REVISION OF THE FISH BLOOD FLUKES WITH DIAGNOSES OF CHIMAEROHEMECIDAE YAMAGUTI, 1971, ACIPENSERICOLIDAE N. FAM., SANGUINICOLIDAE POCHE, 1926, ELOPICOLIDAE N. FAM., AND APOROCOTYLIDAE ODHNER, 1912

We herein morphologically diagnose the 5 natural groups of fish blood flukes and name them. Species of Chimaerohemecidae Yamaguti, 1971 infect chimeras, sharks, and rays (Chondrichthyes) and have C-shaped lateral tegumental spines and a non-sinusoidal testis or lack spines and have a sinusoidal testis. Species of Acipensericolidae n. fam. infect sturgeons and paddlefish (Acipenseriformes) and have a robust, bowl-shaped, pedunculate anterior sucker, lateral tegumental spines that are spike-like (not C shaped), an inverse U-shaped intestine (anterior ceca absent) with posterior ceca terminating near the excretory bladder, 6 testes (inter-cecal ovoid or oblong, lacking deep lobes; including 1 post-ovarian testis), a Laurer's canal, and a dextral common genital pore. Species of Sanguinicolidae Poche, 1926 infect primarily later-branching freshwater ray-finned fishes (Teleostei) and have a diminutive anterior sucker, a medial esophageal swelling (pouch), short, radial ceca of approximately equal length or short anterior ceca plus an elongate, dendritic posterior cecum, testis with appendix-like lateral lobes, no Laurer's canal, and separate or common genital pores. Species of Elopicolidae n. fam. infect ladyfishes, tarpons, and catadromous eels (Elopomorpha) and have a robust, bowl-shaped, pedunculate anterior sucker, lateral tegumental spines that are spike-like (can be lost in adult), short or indistinct anterior ceca, posterior ceca that terminate at level of the testis(es), a single testis or 2 testes, a Laurer's canal present or absent, and a sinistral common genital pore and atrium. Species of Aporocotylidae Odhner, 1912 primarily infect later-branching marine and estuarine ray-finned fishes (Teleostei) and have a spheroid anterior sucker with concentric rows of circumferential spines or the spheroid anterior sucker is lost in adults or adults have a diminutive anterior sucker, a sinuous esophagus lacking a pouch, an X- or H-shaped intestine having 4 ceca, long anterior ceca (or secondarily lost), smooth posterior ceca that extend posteriad in parallel with respective body margin and terminate near the posterior body end, testis(es) that lack appendix-like lateral lobes, no Laurer's canal, and a sinistral common genital pore or separate genital pores that are sinistral. Our 28S phylogeny recovered the fish blood flukes as monophyletic and each of the morphologically diagnosed families as monophyletic and sister to the remaining blood flukes infecting turtles and homeotherms. Acipensericolidae was recovered sister to the clade comprising Chimaerohemecidae + Sanguinicolidae and Elopicolidae + Aporocotylidae. The branching order and interrelationships of these families remains unsettled perhaps because of low taxon sampling among non-aporocotylids and extinction of intermediate taxa.

REVISION OF SANGUINICOLA PLEHN, 1905 WITH REDESCRIPTION OF SANGUINICOLA VOLGENSIS (RAŠÍN, 1929) MCINTOSH, 1934, DESCRIPTION OF A NEW SPECIES, PROPOSAL OF A NEW GENUS, AND PHYLOGENETIC ANALYSIS

Sanguinicola Plehn, 1905 comprises 26 species that collectively infect fishes from 8 orders (Cypriniformes, Characiformes, Siluriformes, Esociformes, Salmoniformes, Labriformes, Centrarchiformes, and Perciformes). Its revision is warranted because several species assigned to the genus could represent new genera, nucleotide sequences are wanting, many species have incomplete descriptions, and types for most species are missing or of poor quality. Herein, we emend Sanguinicola based on morphology and the first nucleotide-based phylogenetic analysis that includes multiple sequences from morphologically identified adult specimens. We describe Sanguinicola plehnae Warren and Bullard n. sp. from the heart of northern pike, Esox lucius Linnaeus, 1758 from Russia; provide supplemental observations of Sanguinicola volgensis (Rašín, 1929) McIntosh, 1934 from the heart of sabrefish (type species), Pelecus cultratus (Linnaeus, 1758) Berg, 1949 from Russia; describe Sanguinicola cf. volgensis from the heart of ide, Leuciscus idus (Linnaeus, 1758) Berg, 1949 from Russia; and describe Pseudosanguinicola occidentalis (Van Cleave and Mueller, 1932) Warren and Bullard n. gen., n. comb. from the heart of walleye, Sander vitreus (Mitchill, 1818) Bailey, Latta, and Smith, 2004 from eastern North America. Sanguinicola plehnae differs from its congeners by having lateral tegumental spines that total 118-122, are small (3% of body width), and protrude 2-3 µm from the tegument (lacking associated conical protrusion) as well as by having a large testis (>40% of body length). Sanguinicola volgensis differs from its congeners by having posteriorly directed lateral tegumental spines encased in a tegumental conical protrusion as well as by having an ovoid egg. Specimens of S. cf. volgensis differ from those of S. volgensis by having a body that is 5-6× longer than wide (vs. 2-3× in S. volgensis) and <90 lateral tegumental spines (vs. >95). Pseudosanguinicola Warren and Bullard n. gen. differs from Sanguinicola by having densely transverse rows of lateral tegumental spines (vs. a single column of large spines). The phylogenetic analysis utilizing the large subunit ribosomal DNA (28S) failed to reject monophyly of Sanguinicola.

New collections of blood flukes (Aporocotylidae) from fishes of the tropical Indo-west Pacific, including a new genus, two new species and molecular evidence that Elaphrobates chaetodontis (Yamaguti, 1970) is widespread in the region

We report new collections of the Aporocotylidae from Australia, French Polynesia, and Japan. A new species of Cardicola Short, 1953 is described from Scomberomorus commerson (Lacépède) (Scombridae), off Lizard Island. Cardicola nolani n. sp. can be distinguished from its congeners based on the position of the oötype, the position of the male genital pore, and the absence of an oral sucker. A new species is described from Abalistes stellatus (Anonymous) (Balistidae), also from off Lizard Island. Phylogenetically the new species forms a strongly-supported clade with Cardicola yuelao Yong, Cutmore & Cribb, 2018, which also infects balistids. These two species are distinct from all other aporocotylids in the combination of exceptionally short anterior and long posterior caeca, a lanceolate body, a single testis, an entirely post-ovarian uterus and the position of the oötype; a new genus, Balistidicola, is proposed for them. Balistidicola corneri n. sp. and B. yuelao (Yong, Cutmore & Cribb, 2018) n. comb. are essentially morphologically cryptic, only distinguishable by the form of the spination (B. corneri has five spines per row and B. yuelao has six). Elaphrobates chaetodontis (Yamaguti, 1970) is reported from 21 species of butterflyfishes (Chaetodontidae) from nine locations in tropical Indo-west Pacific; cox1 sequence data demonstrate extensive geographical structuring in this species. Braya jexi Nolan & Cribb, 2006, Elaphrobates milleri (Nolan & Cribb, 2006), and P. corventum Overstreet & Køie, 1989 are each re-reported from their type-hosts, and Pearsonellum pygmaeus Nolan & Cribb, 2004 and Balistidicola yuelao are each reported from a new host.

A new order of fishes as hosts of blood flukes (Aporocotylidae); description of a new genus and three new species infecting squirrelfishes (Holocentriformes, Holocentridae) on the Great Barrier Reef

A new genus and three new species of blood flukes (Aporocotylidae) are described from squirrelfishes (Holocentridae) from the Great Barrier Reef. Holocentricola rufus n. gen., n. sp. is described from Sargocentron rubrum (Forsskål), from off Heron Island, southern Great Barrier Reef, and Lizard Island, northern Great Barrier Reef, Australia. Holocentricola exilis n. sp. and Holocentricola coronatus n. sp. are described from off Lizard Island, H. exilis from Neoniphon sammara (Forsskål) and H. coronatus from Sargocentron diadema (Lacepède). Species of the new genus are distinct from those of all other aporocotylid genera in having a retort-shaped cirrus-sac with a distinct thickening at a marginal male genital pore. The new genus is further distinct in the combination of a lanceolate body, X-shaped caeca, posterior caeca that are longer than anterior caeca, a single, post-caecal testis that is not deeply lobed, a post-caecal, post-testis ovary that is not distinctly bi-lobed, and a post-ovarian uterus. The three new species can be morphologically delineated based on the size and row structure of the marginal spines, as well by total length, oesophagus and caecal lengths, and the position of the male genital pore, testes and ovary relative to the posterior extremity. The three species of Holocentricola are genetically distinct from each other based on cox1 mtDNA and ITS2 rDNA data, and in phylogenetic analyses of 28S rDNA form a well-supported clade sister to species of Neoparacardicola Yamaguti, 1970. This is the first report of aporocotylids from fishes of the family Holocentridae and the order Holocentriformes.

Molecular phylogenetic analysis of the problematic genus Cardicola (Digenea: Aporocotylidae) indicates massive polyphyly, dramatic morphological radiation and host-switching

Novel multi-locus sequence data were used to assess the molecular phylogenetic relationships of fish blood flukes showing similarity to the genus Cardicola Short, 1953 (Trematoda: Aporocotylidae). Analyses of three ribosomal (ITS2, 28S & 18S) subregions and one mitochondrial (cox1) DNA subregion shows that the hitherto-monophyletic clade formed by species of Cardicola Short, 1953 also includes species of three other genera - Braya Nolan & Cribb, 2006, Elaphrobates Bullard & Overstreet, 2003 and Rhaphidotrema Yong & Cribb, 2011 - as well as a new, morphologically distinct species discovered from the heart of the yellowfin tripodfish, Tripodichthys angustifrons (Tetraodontiformes: Triacanthidae). In the context of conflicting morphological, molecular and ecological data, we argue that the recognition of seven genera produces a more satisfactory taxonomy for these parasites than considering them all as species of Cardicola. We thus recognise Cardicola (as an explicitly polyphyletic taxon) together with Braya, Elaphrobates, Rhaphidotrema and three new genera. We propose Allocardicola n. gen. for A. johnpagei n. sp. from T. angustifrons, Chanicola n. gen. for three species of Cardicola that infect the chanid Chanos chanos, and Spirocaecum n. gen. for six species of Cardicola that infect siganid fishes. We interpret the pattern of diversification seen in the clade of these seven genera as one of multiple host-switching events followed by diversification among closely-related hosts and differing levels of morphological divergence.

Cardicola mediterraneus n. sp. (Trematoda, Aporocotylidae): a new species infecting the gilthead seabream, Sparus aurata L., from the Western Mediterranean Sea

The genus Cardicola Short, 1953 has the highest number of species within the family Aporocotylidae (Trematoda: Digenea). Five Cardicola species have been reported to date in the Mediterranean Sea, one of them in the gilthead seabream Sparus aurata L. Analyses of infected S. aurata recovered from cultured fish off Sardinia (Italy) and from wild and cultured fish off the Levantine coast (Southeastern Spain) have revealed the presence of two species identified as Cardicola aurata Holzer, Montero, Repullés, Nolan, Sitjà-Bobadilla, Álvarez-Pellitero, Zarza and Raga, 2008 and Cardicola mediterraneus n. sp.. New morphological and molecular data are provided for both species. Features of C. aurata specimens differ slightly from those of the original description of the species, the most important differences being the longer extension of the metraterm and the central and posterior position of the female genital pore. Cardicola mediterraneus n. sp. can be easily distinguished from other Cardicola species by two unique specific characters: (i) the very unequal posterior caeca length and (ii) the shape of the testis, deeply notched at the anterior extremity. Cardicola spp. from sparids occupy a basal phylogenetic position respect the other congeneric species. The genus Cardicola has a complex taxonomy and shows high intrageneric differences for both 28S and ITS2 rDNAs, similar to the intergeneric differences among other aporocotylid genera, suggesting that it could be split. The presence of two Cardicola species could hamper treatment design and application; thus, data discriminating species herein reported can improve the infection management in fish farms.