Michael J. Andres

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.

New species of Plagioporus Stafford, 1904 (Digenea: Opecoelidae) from California, with an amendment of the genus and a phylogeny of freshwater plagioporines of the Holarctic

Plagioporus hageli n. sp. is described from the intestine of Oncorhynchus mykiss (Walbaum) collected from the River Yuba, California, USA. Of the accepted, nominal species of Plagioporus Stafford, 1904 from the Nearctic, the new species is morphologically similar to three intestinal species from the western USA parasitising diadromous fishes, including Plagioporus shawi (McIntosh, 1939), Plagioporus kolipinskii Tracey, Choudhury, Cheng & Ghosh, 2009 and Plagioporus siliculus Sinitsin, 1931, and is also similar to Plagioporus serotinus Stafford, 1904 from catostomids from eastern Canada. Plagioporus hageli n. sp. is distinguished from the former three species in lacking a dorsal vitelline field and from the latter species in having a consistent interruption in the distribution of the vitellarium at the level of the ventral sucker. The new species is also morphologically similar to an unnamed species of Plagioporus and a species misidentified as ‘Plagioporus angusticolle’ that were collected from California, but it is easily distinguished from both in its shorter body length. To estimate the placement of the new species within Plagioporus and within the Opecoelidae Ozaki, 1925, we conducted a Bayesian inference (BI) analysis of partial 28S rDNA sequence data that included sequences from Plagioporus hageli n. sp., five other species of Plagioporus, three species of Neoplagioporus Shimazu, 1990, including the type-species, Neoplagioporus zacconis (Yamaguti, 1934), two species of Urorchis Ozaki, 1927 (including the type-species, Urorchis goro Ozaki, 1927) and sequences of 42 opecoelid species obtained from GenBank. Our phylogenetic analysis revealed (i) plagioporines parasitising freshwater hosts form a monophyletic group; (ii) Plagiocirrus loboides Curran, Overstreet & Tkach, 2007 nested within the rest of the members of Plagioporus; (iii) the new species was closer to Plagiocirrus loboides than to Plagioporus shawi, the other salmonid parasite included in our analysis; (iv) P. shawi was the poorly supported sister to its congeners; (v) Neoplagioporus elongatus (Goto & Ozaki, 1930) Shimazu, 1990 was closer to the two species of Urorchis than to the other two species of Neoplagioporus; and (vi) the paraphyly of the Plagioporinae Manter, 1947 was reinforced. Based on 28S rDNA sequence data and our BI analysis, we propose Plagioporus loboides (Curran, Overstreet & Tkach, 2007) n. comb., and amend Plagioporus accordingly. This analysis represents the first phylogenetic study of the opecoelids that estimates the interrelationships of the Plagioporinae that includes a member of Plagioporus.

The Relative Importance of Terrestrial Versus Marine Sediment Sources to the Nueces-Corpus Christi Estuary, Texas: An Isotopic Approach

Determining sources of sediment to coastal systems is an important and complex problem that figures prominently in a myriad of geological, geomorphological, geochemical, and biological processes. Lithogenic (226Ra,228Ra,228Th,230Th,232Th) and fallout (137Cs,210Pb) isotopes were employed in conjunction with sedimentological methods to determine rates of sedimentation in the Nueces Delta and Nueces-Corpus Christi Estuary and to assess the relative importance of marine versus terrestrial sediment sources to the estuary. Similarity of lithogenic isotope ratios in surface sediments throughout the system precluded a numeric approach to discerning the importance of each of the two large scale sediment sources (terrestrial and marine). A stepwise, graphical examination of discrete lithogenic isotope activity concentrations shows more promise. Terrestrial, marine, and bay sediment means for226Ra versus232Th,226Ra versus230Th, and228Ra versus232Th show that terrestrial and marine sediment sources have different signatures, despite having similar grain size distributions (sands), and that sediment deposited in Nueces and Corpus Christi Bays are indistinguishable from the terrestrial component. Supporting evidence is provided by thorium isotopes,230Th versus232Th,228Th versus232Th, and228Th versus230Th. Nueces Delta sedimentation (0.09–0.53 g cm−2 yr−1) shows a subtle gradient, with rates generally lower in the west and progressively higher moving east, likely reflecting contrasts in land use and topography. Nueces Bay cores differ from those in Corpus Christi Bay in that sands comprise a larger percentage of their composition, and they are mixed over greater depth, most likely due to geographic and physiographic effects. Sediment accumulation rates consistently decrease over the first 20 km from the Nueces River and become constant after that, implying that the river is the most significant source of sediment to the estuary. The interpretation of sediment supply to this estuary as dominated by terrestrial inputs is based on three complimentary sets of data: sediment grain size distributions, discrete lithogenic isotope data (Ra versus Th and Th versus Th), and sediment accumulation rates for both Nueces and Corpus Christi Bays.

A new species of Podocotyloides (Digenea: Opecoelidae) from the grey conger eel, Conger esculentus, in the Caribbean Sea.

Abstract:  Podocotyloides brevis n. sp. (Digenea: Opecoelidae) is described from Conger esculentus Poey, 1861, from the Caribbean Sea, off the coast of Mayagüez, Puerto Rico. It can be separated from the other 13 accepted species in the genus by having a shorter cirrus sac, both in length and relative length. Podocotyloides brevis, with a cirrus sac length less than 10% of the body length, most closely resembles Podocotyloides dorabus Lokhande, 1990, which has a cirrus sac that is approximately 16% of the body length. It can be further differentiated from P. dorabus by having ovarian and testicular lengths greater than the oral sucker length. This is the first report of a member of this genus from the Caribbean Sea and from a host species collected as deep as 200 m. A key to the recognized members of Podocotyloides Yamaguti, 1934, is also presented.

Erection of the haploporid genus Litosaccus n. g. and its phylogenetic relationship within the Haploporidae Nicoll, 1914

Litosaccus n. g. is erected for Paralecithobotrys brisbanensis Martin, 1974 n. comb. for which an amended description is given. The new genus is morphologically similar to the haploporine Lecithobotrys Looss, 1902 but with a more elongate and cylindrical body; an infundibuliform oral sucker; a thin-walled hermaphroditic sac; a shallow genital atrium; and unequal, cylindrical and elongated caeca. It also resembles Pseudolecithobotrys Blasco-Costa, Gibson, Balbuena, Raga & Kostadinova, 2009, but the only member of that genus has a hermaphroditic sac that is twice the length of the ventral sucker, a hermaphroditic duct with intensely-staining cuboidal cells, an elongate testis, and single or paired caeca. A Bayesian inference analysis of partial 28S rDNA sequences of L. brisbanensis and 24 other haploporoids revealed that L. brisbanensis grouped with other haploporines and placed Intromugil Overstreet & Curran, 2005 in a clade with the chalcinotrematine Saccocoelioides Szidat, 1954 rather than the other seven tested waretrematine species. This analysis represents the first phylogenetic study of the Haploporidae Nicoll, 1914 that incorporates a haploporine from outside of the Mediterranean Sea.

Description of three species of Isorchis (Digenea: Atractotrematidae) from Australia.

Three species of Isorchis Durio and Manter, 1969 are described from Australian waters. Isorchis megas sp. nov. is described from the spotbanded scat, Selenotoca multifasciata (Richardson), off Western Australia (WA) and Northern Territory (NT); Isorchis currani sp. nov. is described from S. multifasciata off NT; and Isorchis anomalus sp. nov. is described from the milkfish, Chanos chanos Forsskål, off WA. Isorchis megas sp. nov. can be differentiated from the other species of Isorchis by possessing a single, large egg that is greater than 20% of the body length; having a shorter body (the largest specimen is less than 500 μm); and utilizing a scatophagid rather than a chanid host. Isorchis currani sp. nov. can be differentiated from species of Isorchis other than I. megas sp. nov. by utilizing a scatophagid rather than a chanid host; it is differentiated from I. megas sp. nov. in having eggs that are 11−15% of the body length. Isorchis anomalus sp. nov. can be differentiated from all other species of Isorchis in possessing an irregular shaped genital pore rather than one that is circular to oblong. A Bayesian inference analysis of partial 28S rDNA sequences of the three new species of Isorchis and 30 other haploporoids revealed 1) the monophyly of the Atractotrematidae Yamaguti, 1939, 2) the two species of Isorchis infecting S. multifasciata were each other’s closest relative, and 3) that Isorchis was most closely related to Pseudomegasolena Machida and Komiya, 1976 rather than Atractotrema Goto and Ozaki, 1929 although sequence data are not yet available for a member of Pseudisorchis Ahmad, 1985.

An additional genus and two additional species of Forticulcitinae (Digenea: Haploporidae).

Forticulcita platana sp. n. and Forticulcita apiensis sp. n. are described from Mugil liza Valenciennes in Argentina, and from Mugil cephalus Linnaeus in Salt Springs, Florida, USA, respectively. Supplemental material relating to the hermaphroditic sac of Forticulcita gibsoni Blasco-Costa, Montero, Balbuena, Raga et Kostadinova, 2009 is provided from a specimen isolated from M. cephalus off Crete, Greece. Forticulcita platana can be distinguished from all species of Forticulcita Overstreet, 1982 except F. gibsoni, based on possessing small pads or gland cells along the hermaphroditic duct. It can be differentiated from that species in possessing a hermaphroditic sac that is one and a half to two times longer than wide rather than one that is approximately three times longer than wide, longer eggs (44-52 μm rather than 34-44 μm long) and a shorter post-testicular space (< 45% of the body length). Forticulcita apiensis can be differentiated from the other species of Forticulcita in possessing a testis that is shorter than or equal to the pharynx rather than one that is longer than the pharynx. Xiha gen. n. is erected for Dicrogaster fastigatus Thatcher et Sparks, 1958 as Xiha fastigata (Thatcher et Sparks, 1958) comb. n., and we tentatively consider Dicrogaster fragilis Fernández Bargiela, 1987 to be Xiha fragilis (Fernández Bargiela, 1987) comb. n. The new genus fits within the concept of Forticulcitinae Blasco-Costa, Balbuena, Kostadinova et Olson, 2009 in having a vitellarium comprised of a single elongate to subspherical mass. Xiha can be differentiated from Forticulcita in having spines lining the hermaphroditic duct, or intromittent organ. A Bayesian inference analysis of partial 28S rDNA sequences of the two New World species of Forticulcita, Xiha fastigata and previously published haploporids places Xiha fastigata within the Forticulcitinae and sister to Forticulcita. Amended diagnoses for the subfamily and for Dicrogaster Looss, 1902 are provided.

Change in rank of Megaperidae (Trematoda) to Megaperinae within the Apocreadiidae and description of Haintestinum amplum n. g., n. sp.

Haintestinum amplum n. g., n. sp. is described from the scrawled cowfish, Acanthostracion quadricornis, collected in the Eastern Gulf of Mexico off Florida, USA. The new species is relatively large and shares characters of the Apocreadiidae and Megaperidae but conforms to the diagnosis of neither. It belongs in a new genus possessing a pharynx with lobed anterior margin and intestine terminating in paired ani, like in megaperids, and, when compared with apocreadiids, it shares important anatomical features, including an I-shaped excretory vesicle, canicular seminal vesicle, eye-spot remnants, and pretesticular uterus and lacks a cirrus and cirrus sac. The H-shaped intestine and large funnel-shaped oral sucker without a U-shaped sphincter encircling half the anterior aperture are the most notable diagnostic characters of the new monotypic genus. Additionally, the phylogenetic position of the Megaperidae is investigated for the first time, using analysis of partial 28S rDNA gene sequences from H. amplum, two species in the Megapera, Thysanopharynx elongatus, and previously published 28S sequences of species from members of the Apocreadiata, Haploporoidae, Lepocreadiata, and Opisthorchiata. The resulting analysis demonstrated a close relationship among the new genus and the three species of megaperids, and the megaperids were most closely allied with Schistorchis zancli of the apocreadiids. Moreover, we now consider Megaperidae as the subfamily Megaperinae within the Apocreadiidae.

Two New Species of Homalometron (Digenea: Apocreadiidae) from Nearctic Freshwater Fundulids, Elucidation of the Life Cycle of H. cupuloris, and Molecular Phylogenetic Analysis of Some Congeners

Abstract:  Two species of digeneans belonging in Homalometron are described from Nearctic freshwater fundulid fishes: Homalometron robisoni n. sp. is described from the Blackstripe Topminnow, Fundulus notatus, from Oklahoma and Homalometron frocioneae n. sp. is described from the Banded Killifish, Fundulus diaphanus, from New York. Homalometron robisoni n. sp. differs from all congeners by having vitelline follicles that extend into the forebody, a feature that necessitates altering the generic diagnosis for the genus. Homalometron frocioneae n. sp. may be distinguished from North and Middle American congeners by the position of the intestinal bifurcation (relatively more posterior in the forebody than in other species) and tegumental spine coverage on the body (spines are absent from the posterior body extremity and on most of the dorsal surface). Comparison of ribosomal DNA (ITS 1 and 2 regions, 5.8S gene, and partial fragment of 28S gene) from the 2 new species and some congeners from the Western Hemisphere provided evidence for the validity of the 2 new species and affirmed a close relationship between H. robisoni n. sp. and Homalometron pallidum. Comparison of ribosomal DNA from newly collected Homalometron spp. and larval stages of an apocreadiid from brackish water hydrobiid snails (cercariae in rediae in Littoridinops palustris and metacercariae in L. palustris and Amnicola limosa) from a tidal river in Mississippi revealed that larval stages represented Homalometron cupuloris. A phylogeny based on Bayesian inference analysis using partial 28S rDNA gene fragments from 14 species of Homalometron (all from the Western Hemisphere) and 1 megaperine and rooted by a second megaperine was conducted and produced a strongly supported phylogram that estimates the interrelationships among species. The estimated phylogeny suggests that ecological factors such as salinity and food web interactions between species of Homalometron, intermediate hosts, and fishes drive coevolutionary forces influencing speciation within Homalometron.

Two New Species of Saccocoelioides (Digenea: Haploporidae) with Phylogenetic Analysis of the Family, Including Species of Saccocoelioides from North, Middle, and South America

Abstract Two cryptic species of haploporid digeneans belonging in Saccocoelioides are described from Costa Rica: one from a poeciliid fish, Poecilia gillii, and the other from a characid fish, Astyanax aeneus. Traditional morphological features are examined and found to be largely inefficient for differentiating among the new species and 20 New World congeners. Comparison of ribosomal DNA sequences among the 2 new species, 2 North American, 4 Middle American, and 3 South American species of Saccocoelioides, including the type-species Saccocoelioides nanii from Argentina and Saccocoelioides sogandaresi from Texas, is effective in differentiating among these species. A Bayesian inference analysis is conducted using a concatenated alignment of the same 2 ribosomal gene regions from 35 species belonging in the Haploporoidea and rooted by the atractotrematid Isorchis anomalus. The analysis provides stronger support for a close relationship between species in Saccocoelioides and Intromugil; thus, Intromugil is transferred from the Waretrematinae to the Chalcinotrematinae. Additionally, interrelationships among 11 species of Saccocoelioides are resolved and reveal a distinct genetic rift suggesting the presence of 2 distinct lineages within the genus, 1 containing the type-species and the other containing a group of species that more closely resemble other genera in the subfamily. Taxonomy of Saccocoelioides is discussed, and observations made during the present study justify taking several taxonomic actions: new combinations are proposed for Saccocoelioides tilapiae n. comb., formerly in the now-defunct Culuwiya, and Saccocoelioides ruedasueltensis n. comb., formerly in Chalcinotrema; Saccocoelioides guaporense nomen novem is proposed for Lecithobotrioides elongatus; Saccocoelioides papernai is considered a junior subjective synonym of Saccocoelioides overstreeti; Saccocoelioides godoyi is considered a junior subjective synonym of Saccocoelioides szidati; Saccocoelioides magnorchis and Saccocoelioides saccodontis are considered species inquirendae; and Saccocoelioides adelae is considered a nomen nudum. Four new hosts are reported for Saccocoelioides cichlidorum: Amphilophus lyonsi, Amatitlania nigrofasciatus, Amatitlania septemfasciatus, and Hypsophrys nicaraguensis. Molecular data call into question some existing species identifications in Saccocoelioides and reveal that molecular tools combined with traditional taxonomy are required for accurately identifying species in the genus. Twenty-two species of Saccocoelioides are formally accepted, but it is noted that as new molecular data become available, some of these species may be transferred to other genera in the subfamily.