Stephen S. Curran

A Review of Polylekithum Arnold 1934 and Its Familial Affinities Using Morphological and Molecular Data, with description of Polylekithum catahoulensis sp. nov.

The type material of Polylekithum ictaluri, P. halli, and Maculifer chandleri was examined from the United States National Parasite Museum, and we determined that the material was conspecific, making P. halli and M. chandleri junior subjective synonyms of P. ictaluri. Polylekithum catahoulensis sp. nov. was described from material collected from catfishes at the Catahoula Wildlife Refuge, LaSalle Parish, Louisiana, USA, and compared with P. ictaluri collected from catfishes in Reelfoot Lake, Obion County, Tennessee, USA, and the Pearl River, Hancock County, Mississippi, USA. Polylekithum catahoulensis had smaller eggs (77–88 μm long by 51–63 μm wide vs. 94–108 μm by 52–76 μm) and a longer forebody (35–41% of overall body length vs. 29–34%). Comparison of more than 2,400 bp long fragments of nuclear ribosomal DNA (complete ITS and partial 28S regions) strongly supported the status of P. catahoulensis as a new species. Molecular phylogenetic analysis of 28S rDNA gene sequences from Polylekithum as well as representative species from Allocreadiidae, Atractotrematidae, Brachycoeliidae, Callodistomidae, Dicrocoeliidae, Encyclometridae, Gorgoderidae, Haploporidae, Opecoelidae, Plagiorchiidae, and Telorchiidae rooted by Monorchiidae and Lissorchiidae demonstrated that of the families tested, Polylekithum was most closely related to Encyclometridae as a gorgoderoid and not to Allocreadiidae as previously reported. Morphological features of three South American allocreadiids, Allocreadium patagonicum, P. percai, and A. pichi were inconsistent with generic diagnoses of Allocreadium and Polylekithum, so we suggested they belonged in a single unnamed genus similar to Creptotrema. Polylekithum catlai from India was assessed from the description and failed to conform to the generic diagnosis of Polylekithum. Morphology of Caudouterina suggested a close relationship with Polylekithum and not Allocreadiidae.

Phylogenetic relationships of the Gorgoderidae (Platyhelminthes: Trematoda), including the proposal of a new subfamily (Degeneriinae n. subfam.)

Phylogenetic analyses of a range of gorgoderid trematodes based on ITS2 and partial 28S rDNA data lead us to propose the Degeneriinae n. subfam. for the genus Degeneria in recognition of its phylogenetic isolation and distinctive morphology and biology. The current concepts of the subfamilies Anaporrhutinae and Gorgoderinae were supported. Within the Gorgoderinae, the large genus Phyllodistomum is shown to be paraphyletic relative to Pseudophyllodistomum and Xystretrum. Notably, the clade of marine Phyllodistomum does not form a clade with the other marine genus, Xystretrum. Distinct clades within the Gorgoderinae correspond variously to identity of first intermediate host, form of cercaria and their marine or freshwater habitat. We are not yet in a position to propose separate genera for these clades.

Phylogenetic Affinities of Auriculostoma (Digenea: Allocreadiidae), with Descriptions of Two New Species From Peru

abstract:  Two new allocreadiid trematodes are described from the intestine of characid fishes from Rio Itaya, a tributary of the Amazon River near Iquitos, Peru. Auriculostoma foliaceum n. sp. is described from Bryconops cf. caudomaculatus (Günther, 1864) Backup, 2003, and Auriculostoma diagonale n. sp. from Stethaprion cf. erythrops Cope, 1870. Auriculostoma foliaceum n. sp. differs from its congeners by having a foliated lateral margin and lacking vitelline follicles in the forebody. Auriculostoma diagonale n. sp. differs from all of its congeners except Auriculostoma platense (Szidat, 1954) Scholz, Aguirre-Macedo, and Choudhury, 2004, by having oblique rather than tandem testes and differs from A. platense by having a much more elongated cirrus sac. Phylogenetic hypotheses based on analyses of 3 alignments of partial sequences of the 28S rDNA gene conducted in this study provide a framework for revaluating the classification of Allocreadiidae Looss, 1902. The present analyses show that (1) Paracreptotrematina limi Amin and Myer, 1982, does not belong in the Allocreadiidae; (2) Creptotrematina aguirrepequenoi Jiménez-Guzmán, 1973 (spelled here without diacritic mark), does not belong to Paracreptotrematina Amin and Myer, 1982, but remains in the Allocreadiidae; (3) Auriculostoma astyanace Scholz, Aguirre-Macedo, and Choudhury, 2004, is closely related to C. aguirrepequenoi and Wallinia chavarriae Choudhury, Hartvigsen-Daverdin, and Brooks, 2002; (4) Megalogonia Surber, 1928, is retained as an accepted genus in the Allocreadiidae; and (5) Margotrema Lamothe-Argumedo, 1970, is found to be nested among 3 species of Crepidostomum Braun, 1900.

Large Scale Screening of Digeneans for Neorickettsia Endosymbionts Using Real-Time PCR Reveals New Neorickettsia Genotypes, Host Associations and Geographic Records

Digeneans are endoparasitic flatworms with complex life cycles including one or two intermediate hosts (first of which is always a mollusk) and a vertebrate definitive host. Digeneans may harbor intracellular endosymbiotic bacteria belonging to the genus Neorickettsia (order Rickettsiales, family Anaplasmataceae). Some Neorickettsia are able to invade cells of the digeneans vertebrate host and are known to cause diseases of wildlife and humans. In this study we report the results of screening 771 digenean samples for Neorickettsia collected from various vertebrates in terrestrial, freshwater, brackish, and marine habitats in the United States, China and Australia. Neorickettsia were detected using a newly designed real-time PCR protocol targeting a 152 bp fragment of the heat shock protein coding gene, GroEL, and verified with nested PCR and sequencing of a 1371 bp long region of 16S rRNA. Eight isolates of Neorickettsia have been obtained. Sequence comparison and phylogenetic analysis demonstrated that 7 of these isolates, provisionally named Neorickettsia sp. 1–7 (obtained from allocreadiid Crepidostomum affine, haploporids Saccocoelioides beauforti and Saccocoelioides lizae, faustulid Bacciger sprenti, deropegid Deropegus aspina, a lecithodendriid, and a pleurogenid) represent new genotypes and one (obtained from Metagonimoides oregonensis) was identical to a published sequence of Neorickettsia known as SF agent. All digenean species reported in this study represent new host records. Three of the 6 digenean families (Haploporidae, Pleurogenidae, and Faustulidae) are also reported for the first time as hosts of Neorickettsia. We have detected Neorickettsia in digeneans from China and Australia for the first time based on PCR and sequencing evidence. Our findings suggest that further surveys from broader geographic regions and wider selection of digenean taxa are likely to reveal new Neorickettsia lineages as well as new digenean host associations.

A new species of Intromugil (Digenea: Haploporidae) and redescription of Intromugil mugilicolus.

Abstract: Intromugil alachuaensis n. sp. is described based on specimens collected from the flathead grey mullet (Mugil cephalus) from the Santa Fe River in Florida. The new species is the fourth recognized species in the genus and the second from North America, with the other 2 being confined to South America. Intromugil mugilicolus from Louisiana and Mississippi is redescribed based on the holotype and newly collected material that was not flattened prior to fixation. Two generic features not previously reported are apparent in the new material from I. mugilicolus and I. alachuaensis n. sp.: an armed oral sucker and a series of sacs containing glandular material arranged in symmetrical rows in the hermaphroditic duct. Intromugil alachuaensis differs from I. mugilicolus by having an oral sucker longer than wide, body spines smaller and lanceolate rather than longer and hastate, and smaller vitelline follicles. Intromugil alachuaensis n. sp. differs from Intromugil simonei by having a large elongated pharynx rather than a smaller subspherical one, a proportionately larger and longer oral sucker, and a longer prepharynx (greater than 1 pharyngeal length). Intromugil alachuaensis n. sp. differs from Intromugil annakohnae by having a longer than wide pharynx, a relatively large oral sucker, less extensive vitellarium, and smaller body spines. Comparison of more than 2,400 base-pair-long sequences of nuclear rDNA (partial 18S, complete ITS1, complete 5.8S, complete ITS2, and partial 28S) from I. mugilicolus and I. alachuaensis n. sp. reveals 110 pairwise differences, including gaps, thus supporting our proposal of a new species. These represent the first published sequences from species in this genus.

Molecular Evidence for Two Cryptic Species of Homalometron (Digenea: Apocreadiidae) in Freshwater Fishes of the Southeastern United States

ABSTRACT: The identities of 2 freshwater adult digenean species from the southeastern United States belonging in the Apocreadiidae, and consistent with the genus Homalometron Stafford, 1904, are investigated. One species is from the intestine of Aplodinotus grunniens from the Pearl River bordering Louisiana and Mississippi, U.S.A., and the other is from the intestine of Lepomis microlophus in the Pascagoula River, Mississippi, U.S.A. Both species closely resemble Homalometron armatum (McCallum, 1895) Manter, 1947, and differentiation among the 3 forms by conventional morphological features is found to be ambiguous and unreliable. Ribosomal DNA, consisting of the partial 18S nuclear rDNA gene, internal transcribed spacer regions ( = ITS1 + 5.8S + ITS2), and partial 28S gene, is compared among the 3 forms, revealing considerable genetic differences. The 2 adult forms are consequently considered cryptic species in Homalometron. Additionally, metacercariae from snails collected from the same or similar habitats that support the 2 cryptic species are identified by matching their rDNA sequences with those from adults. The metacercariae from both forms are found to be present in south central Louisiana, U.S.A., and the metacercariae of the adult form from the Pearl River are found to occur in the Pascagoula River.

PHYLOGENETIC AFFINITIES OF PLAGIOCIRRUS VAN CLEAVE AND MUELLER, 1932 WITH THE DESCRIPTION OF A NEW SPECIES FROM THE PASCAGOULA RIVER, MISSISSIPPI

Plagiocirrus loboides n. sp. (Digenea: Opecoelidae) is described from Fundulus nottii, F. dispar blairae, F. chrysotus, and Notemigonus crysoleucas from the Pascagoula River in Mississippi. Plagiocirrus loboides differs from P. primus Van Cleave and Mueller, 1932, by having a longer postcecal space (14–25% of body length vs. about 7%); a more anterior vitellarium (extending at least to the middle of the ventral sucker vs. to its posterior margin); and larger eggs (51–71 μm long by 23–34 μm wide vs. 40–55 μm long by 30–35 μm wide). Plagiocirrus loboides differs from P. testeus Fritts, 1959, by having a long postcecal space (vs. <5% of body length); irregular, oblique, contiguous testes (vs. strongly lobed, well separated, tandem testes); and a more extensive vitellarium. Plagiocirrus loboides differs from both congeners by having an ovary comprised of 3 or 4 distinct lobes rather than having an entire ovary. Plagiocirrus wuyienensis Wang, 1981, from Hemimyzon zebroidus in Fujian Province, China, is herein considered a species inquirenda because it has a Y-shaped excretory bladder. Molecular phylogenetic analysis of 28S rDNA gene fragments from P. loboides and 17 digenean species demonstrates that Plagiocirrus belongs in Opecoelidae.

ATTACHMENT SITE SPECIFICITY AND THE TAPEWORM ASSEMBLAGE IN THE SPIRAL INTESTINE OF THE BLUE SHARK (PRIONACE GLAUCA)

The parasite assemblage in the scroll-type spiral intestine of 24 specimens of the blue shark Prionace glauca collected off of Montauk, Long Island, New York was investigated. When opened with a longitudinal incision to the right of the ventral blood vessels, the internal mucosal spiral of the spiral intestine of the blue shark could be unrolled into a flat sheet of double-sided mucosal tissue. Attachment sites and parasite assemblages were studied on both sides of the sheet in 12 sharks and on either the inside or the outside of the sheet in 12 additional sharks. Assemblages within host individuals were composed of up to 4 species of tetraphyllidean cestodes including the onchobothriid Platybothrium auriculatum, and the phyllobothriids, Prosobothrium armigerum. Paraorygmatobothrium prionacis, and Anthobothrium laciniatum. Each individual shark hosted 1-4 tapeworm species (mean = 3.7 +/- 0.65). The 12 sharks in which both sides of the mucosal scroll were examined hosted 156-2,382 (mean = 929.1 +/- 818) individual tapeworms. The assemblage consisted of 4 core species. Sharks were not found to host all of the possible combinations of species in their assemblages; the most common combination (17 out of 24 individuals) was the occurrence of all 4 parasite species. A chi-square test revealed no evidence that the 4 species did not occur independently. Regression revealed a significant relationship between shark total length and spiral intestine area. Analysis of covariance (ANCOVA) revealed a significant difference between the surface areas of the 2 sides of the mucosal sheet when shark total length was taken into account.(ABSTRACT TRUNCATED AT 250 WORDS)

Examination of Homalometron elongatum Manter, 1947 and Description of a New Congener from Eucinostomus currani Zahuranec, 1980 in the Pacific Ocean off Costa Rica

Abstract Homalometron elongatum is reexamined using heat-killed material that was not subjected to pressure during fixation from Gerres cinereus collected from San Juan Harbor, Puerto Rico, U.S.A. The new material is compared with some paratype specimens and differs by having a much less variable forebody length, and a median rather than submedian genital pore. Tegumental spines reportedly cover the anterior end of the body but we observed tegumental spines covering the entire body surface in both the paratype and new material. Homalometron lesliorum n. sp. is described from Eucinostomus currani from the Pacific coasts of Costa Rica and Nicaragua. The new species has 3 pairs of oral papillae surrounding the mouth and thus resembles 3 other congeners: H. elongatum, Homalometron carapevae, and Homalometron papilliferum. Homalometron lesliorum n. sp. is distinguished from the 3 species by having the anterior extent of the vitelline follicles at or above the base of the ventral sucker, compared with posterior to the ventral sucker at the level of the seminal vesicle (H. elongatum) or further posterior at the posterior margin of the ovary (H. carapevae and H. papilliferum). The 4 species are further differentiated from one another by sucker width ratio, tegumental spine size and distribution, egg size, host preference, and biogeography. Comparison of nuclear ribosomal DNA (3′ end of 18S, internal transcribed spacer [ITS]1, ITS2, and 5′ end of 28S) between H. elongatum and H. lesliorum n. sp. revealed 1 variable base (n  =  162) at the 3′ end of 18S, 12 variable bases (n  =  476) at ITS1, 10 variable bases (n  =  310) at ITS2, and 11 variable bases (n  =  1,325) at the 5′ end fragment of 28S. Nuclear ribosomal DNA from Homalometron pallidum and Homalometron armatum are included for further comparison with H. elongatum and H. lesliorum n. sp.

Molecular characterization of two opecoelid trematodes from fishes in the Gulf of Mexico, with a description of a new species of Helicometra

The plagioporine opecoelids Helicometra fasciata (Rudolphi, 1819) Odhner, 1902, and Macvicaria crassigula (Linton, 1910) Bartoli, Bray, and Gibson, 1989 have been reported from fishes in expansive geographic regions, disjointed from their type localities. New material of M. crassigula was collected from near its type locality as well as specimens resembling Helicometrafasciata sensu lato from three triglids in the Gulf of Mexico. Comparisons of the ribosomal DNA (rDNA) sequences, comprising the partial 18S rDNA, internal transcribed spacer region (= ITS1, 5.8S, and ITS2), and partial 28S rDNA gene, from M. crassigula and Helicometra fasciata sensu lato in the Gulf of Mexico were made with sequences deposited in GenBank from those species from the Mediterranean Sea. Results reveal that M. crassigula sensu stricto from the Gulf of Mexico is distinct from the two cryptic species of M. crassigula sensu lato from the Mediterranean Sea and Helicometra fasciata sensu lato in this study differs from H. fasciata sequences from the Mediterranean Sea, thus Helicometra manteri sp. nov. is described.