Accessibility / Report Error

Phyllodistomum vaili(Plagiorchiida: Gorgoderidae) infecting Parupeneus rubescens (Perciformes: Mullidae): morphology and phylogeny

Phyllodistomum vaili (Plagiorchiida: Gorgoderidae) infectando Parupeneus rubescens (Perciformes: Mullidae): morfologia e filogenia

Abstract

Knowledge of the Arabian Gulf fish’s parasite fauna is very poor. Until recently, only scattered reports from different locations are known for ecto- and endoparasites. Therefore, the present study aimed to investigate the digenean species that infects one of the most economically fish species in the Arabian Gulf, the rosy goatfish Parupeneus rubescens . One plagiorchiid species has been described, belonging to the Gorgoderidae family, and has been named as Phyllodistomum vaili Ho, Bray, Cutmore, Ward & Cribb, 2014 based on its morphological and morphometric characteristics. In order to accurately classify and characterize this plagiorchiid species, molecular analysis was carried out using both nuclear 18S and 28S rRNA gene regions and revealed that the present plagiorchiid species was associated with other species belonging to the Gorgoderidae family and deeply embedded in the Phyllodistomum genus, closely related to the previously described P. vaili (gb| KF013187.1, KF013173.1). The present study therefore revealed that the species Phyllodistomum is the first account as endoparasites from the rosy goatfish inhabiting the Arabian Gulf.

Keywords:
Rosy goatfish; Digenean parasites; Gorgoderidae; Plagiorchiida; Arabian Gulf

Resumo

O conhecimento da fauna de parasitas dos peixes do Golfo Árabe é escasso. Atualmente, apenas relatórios dispersos de diferentes locais são conhecidos para ecto e endoparasitas. Portanto, o presente estudo teve como objetivo investigar as especies digenéticas que infectam uma das espécies economicamente mais importantes do Golfo Arábico, o peixe-cabra rosado Parupeneus rubescens . Uma espécie de plagiorquídeo foi descrita, pertencente à família Gorgoderidae e foi denominada Phyllodistomum vaili Ho, Bray, Cutmore, Ward & Cribb, 2014, com base em suas propriedades morfológicas e morfométricas. A fim de classificar e caracterizar com precisão essa espécie de plagiorquídeo, a análise molecular foi realizada usando as regiões nucleares do gene 18S e 28S rRNA, revelando que a atual espécie de plagiorchídeo estava associada a outras espécies pertencentes à família Gorgoderidae e, profundamente incorporada ao gênero Phyllodistomum , intimamente relacionado ao P. vaili descrito anteriormente (gb | KF013187.1, KF013173.1). O presente estudo revelou, portanto, que a espécie Phyllodistomum vailli é o primeiro relato como endoparasita do peixe-cabra rosado que habita o Golfo Arábico.

Palavras-chave:
Peixe-cabra Rosado; Parasitas digenianos; Gorgoderidae; Plagiorchiida; Golfo Arábico

Introduction

The Gorgoderidae was erected by Looss in 1899 for infecting the urinary bladder of actinopterygians and tetrapods, while those in chondrichthyans are generally in the body cavity; some species are recorded from other sites such as swim bladder, gall bladder and intestine ( Campbell, 2008Campbell RA. Family Gorgoderidae Looss, 1899. In: Bray RA, Gibson DI, Jones A. Keys to the Trematoda, volume 3 . Wallingford: CAB International, Natural History Museum; 2008. p. 191-213. ). It was a distinctive family of trematodes characterized by non-spinous tegument, simple male terminal genitalia, highly restrained vitellarium and extensive uterus ( Campbell, 2008Campbell RA. Family Gorgoderidae Looss, 1899. In: Bray RA, Gibson DI, Jones A. Keys to the Trematoda, volume 3 . Wallingford: CAB International, Natural History Museum; 2008. p. 191-213. ). The molecular phylogenetic analysis of Trematoda by Olson et al. (2003)Olson PD, Cribb TH, Tkach VV, Bray RA, Littlewood DTJ. Phylogeny and classification of the Digenea (Platyhelminthes: trematoda). Int J Parasitol 2003; 33(7): 733-755. http://dx.doi.org/10.1016/S0020-7519(03)00049-3. PMid:12814653.
http://dx.doi.org/10.1016/S0020-7519(03)...
included species of four Gorgoderidae genera that were recovered as monophyletic. Within the Gorgoderoidea, Olson et al. (2003)Olson PD, Cribb TH, Tkach VV, Bray RA, Littlewood DTJ. Phylogeny and classification of the Digenea (Platyhelminthes: trematoda). Int J Parasitol 2003; 33(7): 733-755. http://dx.doi.org/10.1016/S0020-7519(03)00049-3. PMid:12814653.
http://dx.doi.org/10.1016/S0020-7519(03)...
recognized the Gorgoderidae, one of four superfamilies within the Xiphidiata crown suborder. Gorgoderoidea consisted of Callodistomidae, Dicrocoeliidae, Encyclometridae, Gorgoderidae, Haploporidae (with the Atractotrematidae nested within it), Orchipedidae, Paragonimidae and Troglotrematidae. Relationships within the Gorgoderidae are unclear, except for the assumption that the peculiar deep-sea genus Degeneria Campbell, 1977 was indeed a gorgoderid, and that it was probably basal within the family.

Following Olson et al. (2003)Olson PD, Cribb TH, Tkach VV, Bray RA, Littlewood DTJ. Phylogeny and classification of the Digenea (Platyhelminthes: trematoda). Int J Parasitol 2003; 33(7): 733-755. http://dx.doi.org/10.1016/S0020-7519(03)00049-3. PMid:12814653.
http://dx.doi.org/10.1016/S0020-7519(03)...
, Curran et al. (2006)Curran SS, Tkach VV, Overstreet RM. A review of Polylekithum Arnold, 1934 and its familial affinities using morphological and molecular data, with description of Polylekithum catahoulensis sp. nov. Acta Parasitol 2006; 51(4): 238-248. http://dx.doi.org/10.2478/s11686-006-0037-1.
http://dx.doi.org/10.2478/s11686-006-003...
extended the scope of related taxa studied and concluded that another family, the Allocreadiidae, should be integrated into the Gorgoderoidea, but that the Haploporidae and Atractotrematidae should be recognized in a separate Haploporoidea superfamily. In a study that paralleled some of that of Curran et al. (2006)Curran SS, Tkach VV, Overstreet RM. A review of Polylekithum Arnold, 1934 and its familial affinities using morphological and molecular data, with description of Polylekithum catahoulensis sp. nov. Acta Parasitol 2006; 51(4): 238-248. http://dx.doi.org/10.2478/s11686-006-0037-1.
http://dx.doi.org/10.2478/s11686-006-003...
, Choudhury et al. (2007)Choudhury A, Rosas Valdez R, Johnson RC, Hoffmann B, Pérez-Ponce de León G. The phylogenetic position of Allocreadiidae (Trematoda: Digenea) from partial sequences of the 18S and 28S ribosomal RNA genes. J Parasitol 2007; 93(1): 192-196. http://dx.doi.org/10.1645/GE-966R.1. PMid:17436963.
http://dx.doi.org/10.1645/GE-966R.1...
also concluded that the Allocreadiidae are closely associated with the Callodistomidae and Gorgoderidae. Bray & Blair (2008)Bray RA, Blair D. Superfamily Gorgoderoidea Looss, 1899. In: Bray RA, Gibson DI, Jones A. Keys to the Trematoda, volume 3 . Wallingford: CAB International, Natural History Museum; 2008. p. 187-190. based on their Gorgoderoidea conception in the study of Olson et al. (2003)Olson PD, Cribb TH, Tkach VV, Bray RA, Littlewood DTJ. Phylogeny and classification of the Digenea (Platyhelminthes: trematoda). Int J Parasitol 2003; 33(7): 733-755. http://dx.doi.org/10.1016/S0020-7519(03)00049-3. PMid:12814653.
http://dx.doi.org/10.1016/S0020-7519(03)...
, but added several families for “convenience” not included in that analysis.

Although understanding of the family’s overall phylogenetic status seems to be relatively stable, the relationships within it are little understood. The family has two subfamilies Gorgoderinae Looss, 1899 and Anaporrhutinae Looss, 1901, as actually conceived ( Campbell, 2008Campbell RA. Family Gorgoderidae Looss, 1899. In: Bray RA, Gibson DI, Jones A. Keys to the Trematoda, volume 3 . Wallingford: CAB International, Natural History Museum; 2008. p. 191-213. ). The Gorgoderinae contains twelve genera all of which lack a pharynx except for enigmatic and monotypic Phyllodistomoides Brooks, 1977. The subfamily includes the genus Phyllodistomum Braun, 1899, one of the two largest genera of fish trematodes ( Cribb et al., 2002Cribb TH, Chisholm LA, Bray RA. Diversity in the Monogenea and Digenea: Does lifestyle matter? Int J Parasitol 2002; 32(3): 321-328. http://dx.doi.org/10.1016/S0020-7519(01)00333-2. PMid:11835972.
http://dx.doi.org/10.1016/S0020-7519(01)...
). Species of this genus can be found in a wide range of marine and freshwater actinopterygians ( Cribb et al., 2002Cribb TH, Chisholm LA, Bray RA. Diversity in the Monogenea and Digenea: Does lifestyle matter? Int J Parasitol 2002; 32(3): 321-328. http://dx.doi.org/10.1016/S0020-7519(01)00333-2. PMid:11835972.
http://dx.doi.org/10.1016/S0020-7519(01)...
). The Anaporrhutinae, the second subfamily, contains eight genera, all of which have a pharynx. Two of the eight genera as subgenera ( Nagmia as Petalodistomum (Nagmia) and Staphylorchis as Anaporrhutum (Staphylorchis)) were recognized by Campbell (2008)Campbell RA. Family Gorgoderidae Looss, 1899. In: Bray RA, Gibson DI, Jones A. Keys to the Trematoda, volume 3 . Wallingford: CAB International, Natural History Museum; 2008. p. 191-213. . Species of the two genera, Bicornuata Pearse, 1949 and Plesiochorus Looss, 1901, parasitize the urinary and gall bladders of marine turtles and the monotypic Degeneria infects a deep-sea teleost ( Campbell, 1977Campbell RA. Degeneria halosauri (Bell 1887) gen. et comb. n. (Digenea: Gorgoderidae) from the deep-sea teleost Halosauropsis macrochir. J Parasitol 1977; 63(1): 76-79. http://dx.doi.org/10.2307/3280106. PMid:845742.
http://dx.doi.org/10.2307/3280106...
). The remaining five genera infect elasmobranchs, and are found mainly in the body cavity. Brooks & Macdonald (1986)Brooks DR, MacDonald CA. A new species of Phyllodistomum Braun, 1899 (Digenea: Gorgoderidae) in a Neotropical catfish, with discussion of the generic relationships of the Gorgoderidae. Can J Zool 1986; 64(6): 1326-1330. http://dx.doi.org/10.1139/z86-197.
http://dx.doi.org/10.1139/z86-197...
used 19 character series to create a morphology-based phylogenetic analysis of 14 gorgoderid genera. A basal division between the Gorgoderinae and the Anaporrhutinae is recognized in the study of Brooks & Macdonald (1986)Brooks DR, MacDonald CA. A new species of Phyllodistomum Braun, 1899 (Digenea: Gorgoderidae) in a Neotropical catfish, with discussion of the generic relationships of the Gorgoderidae. Can J Zool 1986; 64(6): 1326-1330. http://dx.doi.org/10.1139/z86-197.
http://dx.doi.org/10.1139/z86-197...
. A key finding was that autapomorphies were absent from Phyllodistomum .

The genus Phyllodistomum Braun, 1899 was erected for accommodating several trematode species from the urinary bladders of a variety of ectothermic vertebrates, marine and freshwater fish and, more rarely, amphibians ( Goodchild, 1943Goodchild CG. The life-history of Phyllodistomum solidum Rankin, 1937, with observations on the morphology, development and taxonomy of the Gorgoderinae (Trematoda). Biol Bull 1943; 84(1): 59-86. http://dx.doi.org/10.2307/1538050.
http://dx.doi.org/10.2307/1538050...
; Thomas, 1956Thomas JD. Life-history of Phyllodistomum simile Nybelin. Nature 1956; 178(4540): 1004. http://dx.doi.org/10.1038/1781004a0.
http://dx.doi.org/10.1038/1781004a0...
; Rai, 1964Rai SL. Observations on the life-history of Phyllodistomum srivastavai sp. nov. (Trematoda: gorgoderidae). Parasitology 1964; 54(1): 43-51. http://dx.doi.org/10.1017/S0031182000074308.
http://dx.doi.org/10.1017/S0031182000074...
; Schell, 1967Schell SC. The life history of Phyllodistomum staffordi Pearse, 1924 (Trematoda: gorgoderidae Looss, 1901). J Parasitol 1967; 53(3): 569-576. http://dx.doi.org/10.2307/3276717. PMid:6026845.
http://dx.doi.org/10.2307/3276717...
; Ubelaker & Olsen, 1972Ubelaker JE, Olsen AW. Life cycle of Phyllodistomum bufonis (Digenea: Gorgoderidae) from the boreal toad, Bufo boreas. Proc Helminthol Soc Wash 1972; 39: 94-100. ; Bakke & Bailey, 1987Bakke TA, Bailey RE. Phyllodistomum umblae (Fabricius) (Digenea, Gorgoderidae) from the British Columbia salmonids: A description based on light and scanning electron microscopy. Can J Zool 1987; 65(7): 1703-1712. http://dx.doi.org/10.1139/z87-263.
http://dx.doi.org/10.1139/z87-263...
). In the same year, Looss created the genus Spathidium unaware of Braun’s publication for the same trematode. Lewis (1935)Lewis FG. The trematode genus Phyllodistomum Braun. Trans Am Microsc Soc 1935; 54(2): 103-117. http://dx.doi.org/10.2307/3222118.
http://dx.doi.org/10.2307/3222118...
considered the genus Catoptroides to be a synonym of Phyllodistomum based on the full intergradation of generic characters. The genera Phyllochorus Dayal, 1938, Plesiodistomum Dayal, 1949 and Vitellarinus Zmeev, 1936 were considered synonyms of Phyllodistomum . The lack of a well-defined pattern of host specificity creates taxonomic ambiguity in the genus Phyllodistomum . In addition, considerable intra-specific variation was observed in most of these digeneans’ morphological and morphometric characteristics ( Gibson, 1996Gibson DI. Trematoda. In: Margolis L, Kabata Z. Guide to the parasites of fishes of Canada. Part IV . Ottawa: NRC CNRC; 1996. pp. 1-373. (Canadian Special Publication of Fisheries and Aquatic Sciences; vol. 124). ; Pérez-Ponce De León et al., 2015Pérez-Ponce de León G, Aquinoa AM, Mendoza-Garfias B. Two new species of Phyllodistomum Braun, 1899 (Digenea: Gorgoderidae), from freshwater fishes (Cyprinodontiformes: Goodeidae: Goodeinae) in central Mexico: An integrative taxonomy approach using morphology, ultrastructure and molecular phylogenetics. Zootaxa 2015; 4013(1): 87-99. http://dx.doi.org/10.11646/zootaxa.4013.1.6.
http://dx.doi.org/10.11646/zootaxa.4013....
). The numerous published keys for gorgoderid subfamilies, genera, Phyllodistomum subgenera, and Phyllodistomum species ( Holl, 1929Holl EJ. The phyllodistomes of North America. Trans Am Microsc Soc 1929; 48(1): 48-53. http://dx.doi.org/10.2307/3222458.
http://dx.doi.org/10.2307/3222458...
; Lewis, 1935Lewis FG. The trematode genus Phyllodistomum Braun. Trans Am Microsc Soc 1935; 54(2): 103-117. http://dx.doi.org/10.2307/3222118.
http://dx.doi.org/10.2307/3222118...
) were created on the basis of body shape differences, or the presence and absence of a groove separating the hind-body and fore-body, or the two suckers’ size ratios.

Clearly, more extensive work is needed to get a better idea of the Arabian Gulf fish’s parasitic infections in general and those off Saudi Arabia in particular. This study aimed to provide full data on parasitic trematodes and their indices in the rosy goatfish Parupeneus rubescens from the Arabian Gulf in Saudi Arabia.

Materials and Methods

Experimental animal's collection

A total of twenty specimens of the rosy goatfish Parupeneus rubescens (F: Mullidae) were collected from the boat landing sites at the coasts of the Arabian Gulf off Dammam City in Saudi Arabia during the time of the current study. Fish were immediately transported to the Laboratory of Parasitology Research, Zoology Department, College of Science, King Saud University, Riyadh, Saudi Arabia. All procedures that contribute to this work comply with the ethical standards authorized by Institutional Review Board (IRB) at King Saud University, Riyadh, Saudi Arabia. Within 48 h of sampling, all fish are dissected. Macro- and microscopic analysis of the collected fish specimens were performed externally and then necropsied and their internal organs under a stereo-dissecting microscope were examined for the presence of any parasite infection according to standard parasitological techniques of Vidal-Martínez et al. (2002)Vidal-Martínez V, Aguirre-Macedo ML, Scholz T, González-Solís D, Mendoza EF. Atlas de los helmintos parásitos de cíclidos en México. México: Instituto Politécnico Nacional; 2002. 182 p. . The site and number of parasite species was reported from each fish. Infection prevalence was estimated according to Bush et al. (1997)Bush AO, Lafferty KD, Lotz JM, Shostak AW. Parasitology meets ecology on its own terms: Margolis et al. revisited. J Parasitol 1997; 83(4): 575-583. http://dx.doi.org/10.2307/3284227. PMid:9267395.
http://dx.doi.org/10.2307/3284227...
.

Parasitological examination

According to Cribb & Bray (2010)Cribb TH, Bray RA. Gut wash, body soak, blender, and heat-fixation: approaches to the effective collection, fixation and preservation of trematodes of fishes. Syst Parasitol 2010; 76(1): 1-7. http://dx.doi.org/10.1007/s11230-010-9229-z. PMid:20401574.
http://dx.doi.org/10.1007/s11230-010-922...
, we recommend killing and fixing the recovered trematodes with heat as an effective method. As, we advocate pipetting worms into the hot vertebrate saline, at this time, worms typically extend and assume a highly uniform and reproducible form. Some worms were fixed in a buffered formalin solution (10%) and others fixed for molecular analysis in a high grade 96% absolute alcohol. Worms fixed for whole mounts were stained with Semichon's acetocarmine, dehydrated through a graded ethanol series, cleared in clove oil and mounted with Canada balsam in permanent preparations. A Leica DM 2500 microscope (NIS ELEMENTS software, ver. 3.8) was used to examine, record and then photograph the stained specimens and the relevant structural details. All measurements in the descriptions and tables are in millimeters and are shown as the range followed by the mean ± standard deviation in parentheses.

Molecular analysis

DNA extraction and Polymerase Chain Reaction (PCR)

According to the manufacturer's instructions, genomic DNA was extracted from ethanol-preserved samples using a DNeasy tissue kit © (Qiagen, Hilden, Germany). A NanoDrop ND-1000 spectophotometer (Thermo Fischer Scientific, Inc., Wilmington, DE, USA) was used to quantify the concentration and purification of genomic DNA and 20 ng of genomic DNA was used for the polymerase chain reaction (PCR). Following the manufacturer's protocol, the nuclear 18S and 28S rRNA genes were amplified using the GeneJET TM PCR Purification kit [Thermo (Fermentas)]. The 18S rRNA gene was amplified with the forward primer 18SU467F (5'-ATC CAA GGA AGG CAG CAG GC-3') and the reverse primer 18SL1170R (5'-GTG CCC TTC CGT CAA TTC CT-3') designed by Indaryanto et al. (2015)Indaryanto FR, Abdullah MF, Wardiatno Y, Tiuria R, Imai H. A description of Lecithocladium angustiovum (Digenea: Hemiuridae) in Short Mackerel, Rastrelliger brachysoma (Scombridae), of Indonesia. Trop Life Sci Res 2015; 26(1): 31-40. PMid:26868591. . While, the 28S rRNA gene was amplified using the forward primer JB10F (5'-GAT TAC CCG CTG AAC TTA AGC ATA-3') and the reverse primer JB9R (5'-GCT GCA TTC ACA AAC ACC CCG ACT C-3'), as designed by Lee et al. (2007)Lee SU, Chun HC, Huh S. Molecular phylogeny of parasitic Platyhelminthes based on sequences of partial 28S rDNA D1 and mitochondrial cytochrome c oxidase subunit I. Korean J Parasitol 2007; 45(3): 181-189. http://dx.doi.org/10.3347/kjp.2007.45.3.181. PMid:17876163.
http://dx.doi.org/10.3347/kjp.2007.45.3....
. The amplification procedure was based on the schematic diagrams of the thermocycle profiles of the PCR and the primer combinations used to amplify the two genetic markers ( Figure 1 ). All PCR products were verified on a 1% agarose gel in 1× Tris–acetate–EDTA (TAE) stained with 1% ethidium bromide and then visualized with UV trans-illuminator. PCR products of the intended size are excised, purified and cloned using a PureLink TM Quick Gel Extraction Kit (Qiagen, Hilden, Germany) following the manufacturer’s instructions.

Figure 1
Schematic illustrations of the PCR thermocycle profiles and primer combinations used for amplification of the two genetic markers (18S and 28S rRNA), designed in this study.

Sequence alignment and Phylogenetic analysis

Sequencing was performed using BigDye Terminator v3.1 Cycle Sequencing Kit (Applied Biosystems, Foster City, CA) on a 310 Automated DNA Sequencer (Applied Biosystems, Foster City, CA). Using ABI Editview (Perkin-Elmer) each sequence was manually edited for accuracy. A BLAST search was conducted on the NCBI database to classify associated sequences. These sequences are aligned directly with other gene region sequences available from GenBank TM using the multiple sequence alignment CLUSTAL-X ( Thompson et al., 1997Thompson JD, Gibson TJ, Plewniak F, Jeanmougin F, Higgins DG. The CLUSTAL-X windows interface: Flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Res 1997; 25(24): 4876-4882. http://dx.doi.org/10.1093/nar/25.24.4876. PMid:9396791.
http://dx.doi.org/10.1093/nar/25.24.4876...
). Such sequences are selected to represent all available digenean lineages, with an emphasis on the taxa presumed to be linked to the groups being examined. The alignment was manually adjusted using the BIOEDIT 4.8.9 alignment editor software ( Hall, 1999Hall TA. BioEdit: A user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucleic Acids Symp Ser 1999; 41: 95-98. ). A phylogenetic tree was constructed using MEGA ver. 7.0 by using Maximum Likelihood method based on the Kimura 2-parameter model. Branch support under appropriate substitution models was calculated with 1000 bootstrap replicates. Tree has been drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer phylogenetic tree.

Results

Ten out of twenty (50%) specimens of the examined rosy goatfish Parupeneus rubescens were found to be naturally infected with the trematode parasite in the urinary bladder that identified as Phyllodistomum vaili Ho, Bray, Cutmore, Ward & Cribb, 2014.

Microscopic examination ( Figure 2 , Table 1 ).

Figure 2
Photomicrographs of the adult Phyllodistomum vaili infecting Parupeneus rubescens . (A) Whole mount preparation. (B,C) Forebody. (D) Middle region of the body. (E) Vitelline glands. (F) Testes. (G) Marginal undulations. (H) Eggs. (I) Posterior extremity. Note: ATE, anterior testis; AVC, antero-ventral chamber; E, esophagus; EG, eggs; EP, excretory pore; EV, excretory vesicle; GP, genital pore; IC, intestinal ceca; LVG, left vitelline gland; OS, oral sucker; PDC, postero-dorsal chamber; PTE, posterior testis; RVG, right vitelline gland; UT, uterus; VS, ventral sucker.
Table 1
Comparative measurements of the adult Phyllodistomum vaili under study with those described previously.

Body lanceolate, 1.38-2.10 (1.75±0.1) mm in length and 0.41-0.63 (0.52±0.01) mm as a maximum width at the anterior testis level. Forebody narrow and tapering, 0.50-0.87 (0.63±0.1) mm long. Hindbody with 4-5 weak marginal undulations on each side produced by distinct lateral muscular loops. Oral sucker opening subterminally, 0.11-0.18 (0.14±0.01) mm long and 0.10-0.18 (0.12±0.01) mm wide. Intestinal bifurcation midway between oral and ventral suckers. Ventral sucker of 0.10-0.16 (0.13±0.01) mm long and 0.08-0.14 (0.12±0.01) mm wide, usually slightly smaller than oral sucker, pre-equatorial, and rounded in shape. Absence of prepharynx and pharynx. Esophagus 0.13-0.31 (0.27±0.01) mm long. There are penetration glands at the end of the esophagus. Caeca simple, blind tubes ending from the posterior extremity at 0.11-0.49 (0.26±0.01) mm.

Testes slightly lobed, oblique, in mid-hindbody; anterior testis 0.09-0.17 (0.15±0.01) × 0.07-0.15 (0.13±0.01) mm in size; posterior one 0.06-0.19 (0.16±0.01) × 0.06-0.16 (0.13±0.01) mm in size. Cirrus sac absent. Seminal vesicle saccular, bipartite; postero-dorsal chamber large, dorsal to genital pore, anteriorly constricting to small antero-ventral chamber situated anterior to the genital pore. Prostatic chamber and surrounding cells ventrally to the posterodorsal chamber of seminal vesicle. Seminal ducts arising from two testes unite at slightly posterior to seminal vesicle into a common seminal duct and opens to seminal vesicle. Genital pore median, 0.18-0.28 (0.23±0.01) mm anterior to the ventral sucker.

Ovary subspherical, entire, postero-sinistral to the ventral sucker and anterior-sinistral to testes, 0.06-0.17 (0.11±0.01) mm long and 0.04-0.15 (0.09±0.001) mm wide. Oviduct extends into a distinct chamber prior to entering mehlis’ gland. Paired vitelline glands posterolateral to the ventral sucker; left lobe immediately posterior to and occasionally overlapped by ovary, 0.054-0.098 (0.081±0.001) × 0.051-0.083 (0.054±0.001) mm in size; right lobe 0.049-0.118 (0.086±0.001) × 0.035-0.087 (0.064±0.001) mm in size. Laurer’s canal short, running transversely, opening on the antiovarian side of the body dorsally close to the vitellarium. Median ootype, between vitellaria, anterior to vitelline ducts. Mehlis’ gland large. There was no seminal receptacle. Uterus almost entirely intracaecal in hindbody with extensive coils reaching just posterior to ends of intestinal caeca; uterine chamber distinct and prominent dorsal to ventral sucker and genital pore, packed with numerous eggs. Metraterm well developed, surrounded by small gland cells and opened at gonopore. Eggs elongate elliptical, not operculated, 0.032-0.059 (0.050±0.001) mm long and 0.015-0.027 (0.020±0.001) mm wide. Excretory vesicle tubular and extending anteriorly to the ovarian level. Excretory pore dorsally subterminal, close to the posterior end of the body. Table 1 shows the maximum and minimum values of the different body parts of this species in comparison to the previously described Phyllodistomum species, as well as the mean values.

Molecular analysis

For 28S rRNA gene region

A total of 237 bp with 56.5% GC content for 28S rRNA gene region of the present digenea species was analysed and deposited in GenBank under the accession number MK881623.1. Phylogenetic analysis was performed based on the alignment of partial and complete 28S rRNA sequences for 29 taxa using maximum likelihood method based on the Kimura 2-parameter model representing two plagiorchiid suborders (Xiphidiata and Lepocreadiata) ( Table 2 , Figure 3 ).

Table 2
Digenea species used in the 28S rRNA nuclear gene analysis of Phyllodistomum vaili specimens obtained in this study.
Figure 3
Molecular Phylogenetic analysis of 28S rRNA of Phyllodistomum vaili by Maximum Likelihood method based on the Kimura 2-parameter model. The tree with the highest log likelihood (-1497.51) is shown. The percentage of trees shown above the branches in which the related taxa clustered together. By applying the Maximum Parsimony method, initial tree(s) for the heuristic search are obtained automatically. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. Evolutionary analyses were conducted in MEGA7.

Comparison of nucleotide sequences and divergence showed that the 28S rRNA of this species revealed taxa sequence identities belonged to Xiphidiata as 99.50-85.77% with Plagiorchioidea, 88.66-86.55% with Allocreadioidea, and 86.13% with Haploporoidea. While, the sequence identities for nucleotide sequences within Plagiorchioidea were 99.50-86.46% with taxa under the Gorgoderidae family, 87.76% with Cephalogonimidae, 86.55% with Dicrocoeliidae, and 85.77% with Plagiorchiidae ( Table 2 ). Among Gorgoderidae, the maximum identity (99.50%) with lowest divergent value was recorded between the present digenea species and the previously described P. vaili (gb| KF013187.1, KF013173.1) followed by Phyllodistomum pacificum (98.73%, gb| MG845599.1), Phyllodistomum sp. (91.58%, gb| KF013179.1), Phyllodistomum sp. (91.09%, gb| KF013175.1), and Phyllodistomum hoggettae (90.10%, gb| KF013191.1) (Table 2 ).

This analysis ( Figure 3 ) demonstrated the basal position of Plagiorchiidae in which forming sister group to Brachycladiidae+ Dicrocoeliidae + Haploporidea + Atractotrematidae with weak nodal support. Also, Allocreadiidae forming sister group to Cephalogonimidae with high nodal support. In addition, Lepocreadiidae forming sister group to Gibsonivermidae within Lepocreadiata, while, Lepocreadiidae forming more related sister group with Haploporidea + Atractotrematidae with moderate nodal support. The ME tree showed the cluster containing all Phyllodistomum spp. was clearly divided into two distinct clades which was strongly supported by a high bootstrap value. For the present plagiorchiid species, the ME tree revealed a well-resolved distinct clade with other members of the digenea species belonging to the Gorgoderidae family and deeply embedded in the Phyllodistomum with close relationship to the previously described Phyllodistomum vaili (gb| KF013187.1, KF013173.1) and Phyllodistomum pacificum (98.73%, gb| MG845599.1) as a more related sister taxons.

For 18S rRNA gene region

A total of 666 bp with 47.14% GC content was analysed and the resulting sequences of the present digenea species were deposited in GenBank under the accession number MK883474.1. No identical sequences found in the DNA databases through the basic local alignment search tool (BLAST). Phylogenetic analysis was performed based on the comparison with 25 related species using a maximum likelihood method based on the Kimura 2-parameter model representing three orders of Plagiorchiida, Opisthorchida, and Echinostomida ( Table 3 , Figure 4 ).

Table 3
Digenea species used in the 18S rRNA nuclear gene analysis of Phyllodistomum vaili specimens obtained in this study.
Figure 4
Molecular Phylogenetic analysis of 18S rRNA of Phyllodistomum vaili by Maximum Likelihood method based on the Kimura 2-parameter model. This displayed the tree with the highest log likelihood (-3184.75). The percentage of trees shown above the branches in which the associated taxa clustered together. Initial tree(s) for the heuristic search are obtained automatically by applying the Maximum Parsimony method. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. In MEGA7, evolutionary analyses are performed.

Comparison of the nucleotide sequences and divergence revealed that the 18S rRNA of this species revealed sequence identities with taxa belonged to Plagiorchiida as 93.11-89.40% with Plagiorchioidea, 91.19-88.97% with Haploporoidea, 90.02-89.85% with Allocreadioidea, 89.85% with Troglotrematidea, and 88.79% with Monorchioidea ( Table 3 ). The maximum identity with lowest divergent values were recorded with other gorgoderid species, Gorgoderina lufengensis (93.11%, gb| MH285258.1) and Gorgodera sp. (92.81%, gb| AJ287518.1) ( Table 3 ).

The constructed dendrogram ( Figure 4 ) is divided into two clades, the major one clustering all Gorgoderidae species to forming sister group with Troglotrematidae + Callodistomidae + Orchipedidae. While, the minor clade was subdivided into lineages; the former clustered all species belonging to Haploporidae, Omphalometridae, Telorchiidae, Auridistomidae, Haematoloechidae, and Plagiorchiidae; the latter lineage demonstrated the basal position of Acanthocolpidae within Opisthorchida forming sister group to Lissorchiidae + Brachycladiidae with moderate nodal support. The ME tree showed a well-resolved distinct clade for the present plagiorchiid species with other members of the digenea species belonging to the Gorgoderidae family and deeply embedded in the Phyllodistomum genus with close relationship to Gorgoderina lufengensis (gb| MH285258.1) and Gorgodera sp. (gb| AJ287518.1) as a sister taxon associated with it.

Discussion

PhyllodistomumBraun, 1899 is the most specious gorgoderid genus, with a common infection site of urinary bladder and/or ureters of marine and freshwater fish, more rarely amphibians ( Goodchild, 1943Goodchild CG. The life-history of Phyllodistomum solidum Rankin, 1937, with observations on the morphology, development and taxonomy of the Gorgoderinae (Trematoda). Biol Bull 1943; 84(1): 59-86. http://dx.doi.org/10.2307/1538050.
http://dx.doi.org/10.2307/1538050...
; Thomas, 1956Thomas JD. Life-history of Phyllodistomum simile Nybelin. Nature 1956; 178(4540): 1004. http://dx.doi.org/10.1038/1781004a0.
http://dx.doi.org/10.1038/1781004a0...
; Rai, 1964Rai SL. Observations on the life-history of Phyllodistomum srivastavai sp. nov. (Trematoda: gorgoderidae). Parasitology 1964; 54(1): 43-51. http://dx.doi.org/10.1017/S0031182000074308.
http://dx.doi.org/10.1017/S0031182000074...
; Schell, 1967Schell SC. The life history of Phyllodistomum staffordi Pearse, 1924 (Trematoda: gorgoderidae Looss, 1901). J Parasitol 1967; 53(3): 569-576. http://dx.doi.org/10.2307/3276717. PMid:6026845.
http://dx.doi.org/10.2307/3276717...
; Ubelaker & Olsen, 1972Ubelaker JE, Olsen AW. Life cycle of Phyllodistomum bufonis (Digenea: Gorgoderidae) from the boreal toad, Bufo boreas. Proc Helminthol Soc Wash 1972; 39: 94-100. ; Bakke & Bailey, 1987Bakke TA, Bailey RE. Phyllodistomum umblae (Fabricius) (Digenea, Gorgoderidae) from the British Columbia salmonids: A description based on light and scanning electron microscopy. Can J Zool 1987; 65(7): 1703-1712. http://dx.doi.org/10.1139/z87-263.
http://dx.doi.org/10.1139/z87-263...
; Cribb, 1987Cribb TH. A new species of Phyllodistomum (Digenea: Gorgoderidae) from Australian and New Zealand freshwater fishes with notes on the taxonomy of Phyllodistomum Braun, 1899. J Nat Hist 1987; 21(6): 1525-1538. http://dx.doi.org/10.1080/00222938700770951.
http://dx.doi.org/10.1080/00222938700770...
; Hoffman, 1999Hoffman GL. Parasites of north american freshwater fish . 2nd ed. Ithaca, New York: Comstock Publishing Associates, Cornell University Press; 1999. ; Mendoza-Garfias & Pérez-Ponce de León, 2005Mendoza-Garfias B, Pérez-Ponce De Léon G. Phyllodistomum centropomi sp. n. (Digenea: Gorgoderidae), a parasite of the fat snook, Centropomus parallelus (Osteichthyes: Centropomidae), in the Papaloapan River at Tlacotalpan, Veracruz State, Mexico. Zootaxa 2005; 1056(1): 43-51. http://dx.doi.org/10.11646/zootaxa.1056.1.3.
http://dx.doi.org/10.11646/zootaxa.1056....
; Campbell, 2008Campbell RA. Family Gorgoderidae Looss, 1899. In: Bray RA, Gibson DI, Jones A. Keys to the Trematoda, volume 3 . Wallingford: CAB International, Natural History Museum; 2008. p. 191-213. ). This genus has a worldwide distribution and is one of the most specious groups in the Digenea, describing about 120 species ( Cribb et al., 2002Cribb TH, Chisholm LA, Bray RA. Diversity in the Monogenea and Digenea: Does lifestyle matter? Int J Parasitol 2002; 32(3): 321-328. http://dx.doi.org/10.1016/S0020-7519(01)00333-2. PMid:11835972.
http://dx.doi.org/10.1016/S0020-7519(01)...
; Helt et al., 2003Helt J, Janovy J Jr, Ubelaker J. Phyllodistomum funduli n. sp. (Trematoda: Gorgoderidae) from Fundulus sciadicus Cope from Cedar Creek in western Nebraska. J Parasitol 2003; 89(2): 346-350. http://dx.doi.org/10.1645/0022-3395(2003)089[0346:PFNSTG]2.0.CO;2. PMid:12760652.
http://dx.doi.org/10.1645/0022-3395(2003...
).

In this study, Phyllodistomum vaili Ho, Bray, Cutmore, Ward & Cribb, 2014 found to be naturally infected the urinary bladder of the rosy goatfish P. rubescens inhabited the Arabian Gulf and this species represented by a moderate parasite prevalence (50.0%). Firstly, the type of host species and the geographical location for the recovered gorgoderid species is differed from all other species within this genus due to the lack of a well-defined pattern of host specificity. In addition, considerable intraspecific variation was observed in most of these digeneans’ morphological and morphometric characteristics, which were agreed with Bakke (1988)Bakke TA. Morphology of adult Phyllodistomum umblae (Fabricius) (Platyhelminthes, Gorgoderidae): The effect of preparation, killing and fixation procedures. Zool Scr 1988; 17(1): 1-13. http://dx.doi.org/10.1111/j.1463-6409.1988.tb00082.x.
http://dx.doi.org/10.1111/j.1463-6409.19...
and Gibson (1996)Gibson DI. Trematoda. In: Margolis L, Kabata Z. Guide to the parasites of fishes of Canada. Part IV . Ottawa: NRC CNRC; 1996. pp. 1-373. (Canadian Special Publication of Fisheries and Aquatic Sciences; vol. 124). . Secondly, the rate of parasitic infection is higher than that observed for P. funduli infecting Fundulus scaidicus from Cedar Creek in Western Nebraska (21-42.4%; Helt et al., 2003Helt J, Janovy J Jr, Ubelaker J. Phyllodistomum funduli n. sp. (Trematoda: Gorgoderidae) from Fundulus sciadicus Cope from Cedar Creek in western Nebraska. J Parasitol 2003; 89(2): 346-350. http://dx.doi.org/10.1645/0022-3395(2003)089[0346:PFNSTG]2.0.CO;2. PMid:12760652.
http://dx.doi.org/10.1645/0022-3395(2003...
); P. simile Nybelin, 1926 infecting Cirrhinus marginipinnis from Bhumipol Dam, Tak Province, Thailand (16.6%, Sey et al., 2004Sey O, Wongsawad C, Wongsawad P. Trematodes from fish in the Bhumipol Dam, Tak Province, Thailand. Southeast Asian J Trop Med Public Health 2004; 35(Suppl. 1): 284-287. ); P. pseudofolium Nybelin, 1926 and P. folium Olfers, 1816 infecting Gymnocephalus cernuus from Lithuania (19, 12%, respectively; Stunžėnas et al., 2017Stunžėnas V, Petkevičiūtė R, Poddubnaya LG, Stanevičiūtė G, Zhokhov AE. Host specificity, molecular phylogeny and morphological differences of Phyllodistomum pseudofolium Nybelin, 1926 and Phyllodistomum angulatum Linstow, 1907 (Trematoda: Gorgoderidae) with notes on Eurasian ruffe as final host for Phyllodistomum spp. Parasit Vectors 2017; 10(1): 286. http://dx.doi.org/10.1186/s13071-017-2210-9. PMid:28587614.
http://dx.doi.org/10.1186/s13071-017-221...
); P. punctati infecting Channa punctata from Ozhakkodi Wayanad, Kerala, India (7%, Jithila & Prasadan, 2018Jithila PJ, Prasadan PK. Prevalence, intensity, mean abundance and description of Phyllodistomum punctati n. sp. (Digenea: Gorgoderidae) from the urinary bladder of Channa punctata (Bloch) from the Western Ghats, India. Inter J Fish Aquat Stud 2018; 6(5): 1-5. ); and P. thunni Baudin-Laurencin & Richard, 1973 infecting Thunnus albacares from Gulf of Guinea (14.8%, Guidelli et al., 2018Guidelli G, Tavechio WLG, Ferreira BP. New host and geographic distribution of Phyllodistomum thunni (Trematoda, Gorgoderidae). Mar Biodivers Rec 2018; 11(9): 1-5. http://dx.doi.org/10.1186/s41200-018-0144-3.
http://dx.doi.org/10.1186/s41200-018-014...
). However, it is lower than P. inecoli infecting Heterandria bimaculata from Creek at Aqua Bendita, Xico, Veracruz, Mexico (96%, Razo-Mendivil et al., 2013Razo-Mendivil U, Pérez-Ponce de León G, Rubio-Godoy M. Integrative taxonomy identifies a new species of Phyllodistomum (Digenea: Gorgoderidae) from the two spot livebearer, Heterandria bimaculata (Teleostei: Poeciliidae), in Central Veracruz, Mexico. Parasitol Res 2013; 112(12): 4137-4150. http://dx.doi.org/10.1007/s00436-013-3605-y. PMid:24022129.
http://dx.doi.org/10.1007/s00436-013-360...
); P. hohhettae infecting Plectropomus leopardus from Lizard Island, Northern Great Barrier Reef (80%, Ho et al., 2014Ho HW, Bray RA, Cutmore SC, Ward S, Cribb TH. Two new species of Phyllodistomum Braun, 1899 (Trematoda: Gorgoderidae Looss, 1899) from Great Barrier Reef fishes. Zootaxa 2014; 3779(5): 551-562. http://dx.doi.org/10.11646/zootaxa.3779.5.5. PMid:24871750.
http://dx.doi.org/10.11646/zootaxa.3779....
); P. vaili infecting Mulloidichthys vanicolensis from Lizard Island, Northern Great Barrier Reef (100%, Ho et al., 2014Ho HW, Bray RA, Cutmore SC, Ward S, Cribb TH. Two new species of Phyllodistomum Braun, 1899 (Trematoda: Gorgoderidae Looss, 1899) from Great Barrier Reef fishes. Zootaxa 2014; 3779(5): 551-562. http://dx.doi.org/10.11646/zootaxa.3779.5.5. PMid:24871750.
http://dx.doi.org/10.11646/zootaxa.3779....
); and P. angulatum infecting S. lucioperca from Lithuania (100%; Stunžėnas et al., 2017Stunžėnas V, Petkevičiūtė R, Poddubnaya LG, Stanevičiūtė G, Zhokhov AE. Host specificity, molecular phylogeny and morphological differences of Phyllodistomum pseudofolium Nybelin, 1926 and Phyllodistomum angulatum Linstow, 1907 (Trematoda: Gorgoderidae) with notes on Eurasian ruffe as final host for Phyllodistomum spp. Parasit Vectors 2017; 10(1): 286. http://dx.doi.org/10.1186/s13071-017-2210-9. PMid:28587614.
http://dx.doi.org/10.1186/s13071-017-221...
).

According to Campbell (2008)Campbell RA. Family Gorgoderidae Looss, 1899. In: Bray RA, Gibson DI, Jones A. Keys to the Trematoda, volume 3 . Wallingford: CAB International, Natural History Museum; 2008. p. 191-213. , smooth tegument, thin body muscles, well-developed suckers, a wide hindbody where the gonads are located, pretesticular ovary, seminal vesicle, pars prostatica and undeveloped ejaculatory duct, genital pore close to the intestinal bifurcation, uterus extending to the hindbody, and small and non-operculated eggs are the characteristic features described members within the Gorgoderidae family. The specimen recovered here from P. rubescens was described as belonging to the genus Phyllodistomum according to Campbell (2008)Campbell RA. Family Gorgoderidae Looss, 1899. In: Bray RA, Gibson DI, Jones A. Keys to the Trematoda, volume 3 . Wallingford: CAB International, Natural History Museum; 2008. p. 191-213. due to the site of infection, more-or-less foliate hindbody, blind caeca, a slender excretory bladder, arrangement and appearance of vitellarium and gonads, adjusting to the morphological variability recognized for the genus by Ho et al. (2014)Ho HW, Bray RA, Cutmore SC, Ward S, Cribb TH. Two new species of Phyllodistomum Braun, 1899 (Trematoda: Gorgoderidae Looss, 1899) from Great Barrier Reef fishes. Zootaxa 2014; 3779(5): 551-562. http://dx.doi.org/10.11646/zootaxa.3779.5.5. PMid:24871750.
http://dx.doi.org/10.11646/zootaxa.3779....
. At morphological and morphometric levels, the present gorgoderid species resembles species of Phyllodistomum Braun, 1899 with reference to the previously described P. vaili Ho, Bray, Cutmore, Ward & Cribb, 2014 that are closely resemble to each other by having all the characteristic features with similar body proportions and infection-specific site. The current study of P. vaili represents the first account of an endoparasite from the rosy goatfish. Also, it compared with adult stages of other Phyllodistomum species that infect different types of host species with the same sites of infection.

In addition, the present P. vaili is somewhat similar to: P. mamaevi Parukhin, 1970, P. hoggettae Ho, Bray, Cutmore, Ward & Cribb, 2014, and P. marinae Bravo-Hollis & Manter, 1957 by having strong marginal undulations; P. crenilabri Dolgikh & Naidenova, 1968, P. hoggettae , P. lancea Mamaev, 1968, P. leilae Nagaty, 1956, P. lewisi Srivastava, 1938, P. mamaevi , P. marinae , P. pacificum Yamaguti, 1951, P. parukhini Yamaguti, 1971, P. pomacanthi Nahhas & Cable, 1964, P. sobolevi Parukhin, 1979, P. thalassomum Soheir & Ahmed, 2000, P. unicum Odhner, 1902, P. caudatum Steelman, 1938, P. carangis MacCallum, 1913, P. kanae Nakao, 2015 by having the uterus is strongly developed intracaecally within hindbody; P. borisbychowskyi Caballero & Caballero, 1969, P. centropomi Mendoza-Garfias & Pérez-Ponce de Leon, 2005, P. hoggettae , P. parukhini , P. unicum , P. cribbi Pérez-Ponce de León et al., 2015, P. magnificum Cribb, 1987 by having entire lobed vitelline follicles; P. cribbi having ovary is smaller than the testes; P. hyporhamphiCutmore & Cribb (2018)Cutmore SC, Cribb TH. Two species of Phyllodistomum Braun, 1899 (Trematoda: Gorgoderidae) from Moreton Bay, Australia. Syst Parasitol 2018; 95(4): 325-336. http://dx.doi.org/10.1007/s11230-018-9784-2. PMid:29417344.
http://dx.doi.org/10.1007/s11230-018-978...
having a ventral sucker that is much smaller than an oral sucker; bipartite and saccular seminal vesicle; P. pacificum using the same body shape, 4–5 weak marginal undulations, slightly smaller ventral sucker than oral sucker; P. pacificum and P. magnificum by a bipartite and saccular seminal vesicle with posterodorsal chamber larger than anteroventral one; P. simile Nybelin, 1926 by having aspinous tegument.

However, it differs from other species of Phyllodistomum , as; P. psettodi Parukhin, 1966 by having the forebody occupy over half the body length; P. borisbychowskyi , P. acceptum Looss, 1901, P. centropomi , P. lancea , P. mirandai Lamothe-Argumedo, 1969, P. tongaatense Bray, 1985, P. trinectes Corkum, 1961, P. scrippsi Brooks & Mayes, 1975, P. funduli , P. simile by having the uterus is highly developed extracaecally or in the forebody; P. acceptum , P. crenilabri , P. lancea , P. leilae , P. lewisi , P. mirandai , P. pomacanthi , P. scrippsi , P. sobolevi and P. tongaatense by having firmly to deeply indented vitelline lobes; P. sobolevi by having deeply lobed vitelline follicles; P. acceptum , P. borisbychowskyi , P. lancea , P. leilae , P. mamaevi , P. marinae , P. parukhini , P. scrippsi , P. sobolevi , P. thalassomum and P. unicum which all of them have reported minimum lengths of at least 5.4 mm; P. acceptum , P. borisbychowskyi , P. crenilabri , P. lancea , P. leilae , P. mirandai , P. pacificum , P. parukhini , P. pomacanthi , P. scrippsi , P. sobolevi , P. thalassomum , P. tongaatense and P. trinectes by lacking of marginal undulations in the hindbody; P. hoggettae , P. hyporhamphi , P. simile by having a spatulated body, number of marginal undulations (7-9), and ventral sucker that is clearly larger than an oral sucker for the former; both seminal vesicle chambers of similar size for the latter species.

It also has some distinctions with P. cribbi by having spatulated body, tegument with numerous tiny papillae, lack of cephalic glands, oral sucker with 8 papillae, ventral sucker with 6 papillae, seminal vesicle saccular and relatively short, ovary lobed (3-5 lobes); P. wallacei Pérez-Ponce de León et al., 2015 by having oral sucker bears 14 well-developed papillae, ventral sucker has six well-developed papillae; P. wallacei , P. inecoli Razo-Mendivil, Perez-Ponce de Leon, & Rubio-Godoy, 2013 and P. spinopapillatumPérez-Ponce de León et al. (2015)Pérez-Ponce de León G, Aquinoa AM, Mendoza-Garfias B. Two new species of Phyllodistomum Braun, 1899 (Digenea: Gorgoderidae), from freshwater fishes (Cyprinodontiformes: Goodeidae: Goodeinae) in central Mexico: An integrative taxonomy approach using morphology, ultrastructure and molecular phylogenetics. Zootaxa 2015; 4013(1): 87-99. http://dx.doi.org/10.11646/zootaxa.4013.1.6.
http://dx.doi.org/10.11646/zootaxa.4013....
by having spatuled to elongate body, presence of irregular number of dome-like papillae on the ventral surface; P. cribbi , P. wallacei , P. hyporhamphi , P. magnificum , P. biringoShimazu (2005)Shimazu T. Digeneans found in fresh- and brackish-water fishes of Lake Ogawara in Aomori Prefecture, Japan. Bull Natn Sci Mus 2005; 31(4): 137-150. , P. punctati by having uterus extensive in the hindbody and developed inter- and extracaecal; P. carangis by possession of broadly rounded posterior and anterior ends, tri-lobed vitelline masses.

Some differences have also been reported with P. magnificumCribb (1987)Cribb TH. A new species of Phyllodistomum (Digenea: Gorgoderidae) from Australian and New Zealand freshwater fishes with notes on the taxonomy of Phyllodistomum Braun, 1899. J Nat Hist 1987; 21(6): 1525-1538. http://dx.doi.org/10.1080/00222938700770951.
http://dx.doi.org/10.1080/00222938700770...
, P. punctati having a spatulated body without prominent undulations, a ventral sucker with six prominent papillae for the former, and terminal oral sucker for the latter; P. biringo , P. carassii Long and Wai, 1958, P. mogurndae Yamaguti, 1934 by having banji-shaped body, pyriform seminal vesicle; P. parasiluri Yamaguti, 1934 by having lanceolate-oblong shape of the body; P. carassii , P. mogurndae , P. parasiluri with uterus much folded in post-vitelline field of hindbody; P. folium Olfers, 1816 by having oral sucker is smaller than the ventral one; P. caudatum by having suckers of equal size, 6-lobed ovary; P. americanum Osborn, 1903, P. pseudofolium Nybelin, 1926 by having three undulations on each lateral side of the hindbody, both suckers have the same size with six papillae on the oral sucker and four around the ventral sucker, P. angulatum Linstow, 1907 by the presence of 14 sensory papillae are found around the oral sucker and 6 around the ventral one; P. funduli by having terminal oral sucker, sac-like seminal vesicle, no marginal undulations in the hindbody; P. etheostomae Fischthal, 1943 by having 2 marginal demarcation in the hindbody; P. kanae by having body pyriform in shape, hindbody foliates without crenulate margin, ventral sucker larger than oral sucker.

The combination of morphological and molecular data has become a common practice in the parasite classification and characterization ( Curran et al., 2013Curran SS, Tkach VV, Overstreet RM. A new species of Homalometron (Digenea: Apocreadiidae) from fishes in the northern Gulf of Mexico. J Parasitol 2013; 99(1): 93-101. http://dx.doi.org/10.1645/GE-3169.1. PMid:22924927.
http://dx.doi.org/10.1645/GE-3169.1...
; Tkach et al., 2013Tkach VV, Curran SS, Bell JA, Overstreet RM. A new species of Crepidostomum (Digenea: Allocreadiidae) from Hiodon tergisus in Mississippi, and molecular comparison with three congeners. J Parasitol 2013; 99(6): 114-1121. http://dx.doi.org/10.1645/13-279.1. PMid:23915018.
http://dx.doi.org/10.1645/13-279.1...
). Even though Phyllodistomum is one of the most diverse genera in the Digenea, from a molecular perspective, few species have been studied. As a result, few sequences of cox1, 28S rRNA genes and the ITS regions are available to classify different Phyllodistomum species molecularly ( Razo-Mendivil et al., 2013Razo-Mendivil U, Pérez-Ponce de León G, Rubio-Godoy M. Integrative taxonomy identifies a new species of Phyllodistomum (Digenea: Gorgoderidae) from the two spot livebearer, Heterandria bimaculata (Teleostei: Poeciliidae), in Central Veracruz, Mexico. Parasitol Res 2013; 112(12): 4137-4150. http://dx.doi.org/10.1007/s00436-013-3605-y. PMid:24022129.
http://dx.doi.org/10.1007/s00436-013-360...
). In this analysis, both nuclear 28S and 18S rRNA genes were used to determine the exact taxonomic position of the recovered gorgoderid species and genetic variations were found in the two molecular markers studied, this is consistent with Parker et al. (2010)Parker JH, Curran SS, Overstreet RM, Tkach VV. Examination of Homalometron elongatum Manter, 1947 and description of a new congener from Eucinostomus currani Zahuranec, 1980 in the Pacific Ocean off Costa Rica. Comp Parasitol 2010; 77(2): 154-163. http://dx.doi.org/10.1654/4451.1.
http://dx.doi.org/10.1654/4451.1...
, Razo-Mendivil and Pérez-Ponce De León (2011)Razo-Mendivil U, Pérez-Ponce de León G. Testing the evolutionary and biogeographical history of Glypthelmins (Digenea: Plagiorchiida), a parasite of anurans, through a simultaneous analysis of molecular and morphological data. Mol Phylogenet Evol 2011; 59(2): 341-351. http://dx.doi.org/10.1016/j.ympev.2011.02.018. PMid:21356320.
http://dx.doi.org/10.1016/j.ympev.2011.0...
, Snyder & Tkach (2011)Snyder SD, Tkach VV. Aptorchis kuchlingi n. sp. (Digenea: Plagiorchioidea) from the Oblong Turtle, Chelodina oblonga (Pleurodira: Chelidae), in Western Australia. Comp Parasitol 2011; 78(2): 280-285. http://dx.doi.org/10.1654/4401.1.
http://dx.doi.org/10.1654/4401.1...
, and Pulis et al. (2013)Pulis EE, Fayton TJ, Curran SS, Overstreet RM. A new species of Intromugil (Digenea: Haploporidae) and redescription of Intromugil mugilicolus. J Parasitol 2013; 99(3): 501-508. http://dx.doi.org/10.1645/12-106.1. PMid:23327447.
http://dx.doi.org/10.1645/12-106.1...
who reported that these genes are considered as the important genes used to differentiate and classify closely related digenean species. As following the molecular information obtained, the establishment of the recovered species described herein is clearly supported and improved.

The phylogeny presented herein demonstrated the relationship between the three plagiorchiid suborders Xiphidiata, Lepocreadiata, and Monorchiata, this was agreed with Brooks et al. (2000)Brooks DR, Pérez-Ponce de León G, León-Régágnon V. Phylogenetic analysis of the Enenteridae (Digenea, Lepocreadiidae) and discussion of the evolution of the digenean fauna of kyphosid fishes. Zool Scr 2000; 29(3): 237-246. http://dx.doi.org/10.1046/j.1463-6409.2000.00042.x.
http://dx.doi.org/10.1046/j.1463-6409.20...
, Cribb et al. (2001)Cribb TH, Bray RA, Littlewood DTJ, Pichelin S, Herniou EA. The Digenea. In: Littlewood DTJ, Bray RA. Interrelationships of the Platyhelminthes. London: Taylor and Francis; 2001. p. 168-185. , and Olson et al. (2003)Olson PD, Cribb TH, Tkach VV, Bray RA, Littlewood DTJ. Phylogeny and classification of the Digenea (Platyhelminthes: trematoda). Int J Parasitol 2003; 33(7): 733-755. http://dx.doi.org/10.1016/S0020-7519(03)00049-3. PMid:12814653.
http://dx.doi.org/10.1016/S0020-7519(03)...
who reported that the relationship between these suborders, due to the presence of a uniformity, the cercarial penetration gland dorsally located to the oral sucker, which exhibited among members of Apocreadiata, Lepocreadiata, Monorchiata, Opisthorchioidea and Xiphidiata, which form a nested clade within the higher Plagiorchiida. Furthermore, Olson et al. (2003)Olson PD, Cribb TH, Tkach VV, Bray RA, Littlewood DTJ. Phylogeny and classification of the Digenea (Platyhelminthes: trematoda). Int J Parasitol 2003; 33(7): 733-755. http://dx.doi.org/10.1016/S0020-7519(03)00049-3. PMid:12814653.
http://dx.doi.org/10.1016/S0020-7519(03)...
stated that the crown clade of digenea is the Xiphidiata consisting of four superfamilies Microphalloidea Ward, 1901, Gorgoderoidea Looss, 1901, Allocreadioidea Looss, 1902, and Plagiorchioidea Lühe, 1901, and the union of these superfamilies is confirmed by the presence of a penetrating stylet in the cercariae, reflected in the name ‘Xiphidiata’, and this unique character absent in Haploporidae and some Acanthocolpidae. This consistent with our data that the last three superfamilies have shared.

Cutmore et al. (2013)Cutmore SC, Miller TL, Curran SS, Bennett MB, Cribb TH. Phylogenetic relationships of the Gorgoderidae (Platyhelminthes: Trematoda), including the proposal of a new subfamily (Degeneriinae n. subfam.). Parasitol Res 2013; 112(8): 3063-3074. http://dx.doi.org/10.1007/s00436-013-3481-5. PMid:23760874.
http://dx.doi.org/10.1007/s00436-013-348...
stated that Gorgoderoidea consisted of Gorgoderidae, Dicrocoeliidae, Callodistomidae, Encyclometridae, Haploporidae, Paragonimidae, Orchipedidae, and Troglotrematidae. The present phylogenetic analysis found that Opisthorchioidea to be Haploporoidea’s sister group. In addition, it was found that the clade clustered Haploporoidea + Opisthorchioidea is closely associated with Lepocreadioidea. Bakhoum et al. (2011Bakhoum AJS, Bâ CT, Shimalov VV, Torres J, Miquel J. Spermatological characters of the digenean Rubenstrema exasperatum (Rudolphi, 1819) (Plagiorchioidea, Omphalometridae). Parasitol Res 2011; 108(5): 1283-1293. http://dx.doi.org/10.1007/s00436-010-2178-2. PMid:21127907.
http://dx.doi.org/10.1007/s00436-010-217...
, 2015Bakhoum AJS, Quilichini Y, Justine JL, Bray RA, Miquel J, Feliu C, et al. First spermatological study in the Atractotrematidae (Digenea, Haploporoidea): the case of Atractotrema sigani , intestinal parasite of Siganus lineatus. Parasite 2015; 22: 26. http://dx.doi.org/10.1051/parasite/2015026. PMid:26475645.
http://dx.doi.org/10.1051/parasite/20150...
) agreed on this data. In addition, as described by Olson et al. (2003)Olson PD, Cribb TH, Tkach VV, Bray RA, Littlewood DTJ. Phylogeny and classification of the Digenea (Platyhelminthes: trematoda). Int J Parasitol 2003; 33(7): 733-755. http://dx.doi.org/10.1016/S0020-7519(03)00049-3. PMid:12814653.
http://dx.doi.org/10.1016/S0020-7519(03)...
, Haploporidae nested in the same clade with Atractotrematidae. The current study showed that Gorgoderidae species formed sister group with Troglotrematidae + Callodistomidae + Orchipedidae, consistent with Bray & Blair (2008)Bray RA, Blair D. Superfamily Gorgoderoidea Looss, 1899. In: Bray RA, Gibson DI, Jones A. Keys to the Trematoda, volume 3 . Wallingford: CAB International, Natural History Museum; 2008. p. 187-190. and Olson et al. (2003)Olson PD, Cribb TH, Tkach VV, Bray RA, Littlewood DTJ. Phylogeny and classification of the Digenea (Platyhelminthes: trematoda). Int J Parasitol 2003; 33(7): 733-755. http://dx.doi.org/10.1016/S0020-7519(03)00049-3. PMid:12814653.
http://dx.doi.org/10.1016/S0020-7519(03)...
which reported that Callodistomidae + Gorgoderidae forming sister lineage with Orchipedidae and Dicrocoelidae + Encyclometridae. Choudhury et al. (2007)Choudhury A, Rosas Valdez R, Johnson RC, Hoffmann B, Pérez-Ponce de León G. The phylogenetic position of Allocreadiidae (Trematoda: Digenea) from partial sequences of the 18S and 28S ribosomal RNA genes. J Parasitol 2007; 93(1): 192-196. http://dx.doi.org/10.1645/GE-966R.1. PMid:17436963.
http://dx.doi.org/10.1645/GE-966R.1...
and Olson et al. (2003)Olson PD, Cribb TH, Tkach VV, Bray RA, Littlewood DTJ. Phylogeny and classification of the Digenea (Platyhelminthes: trematoda). Int J Parasitol 2003; 33(7): 733-755. http://dx.doi.org/10.1016/S0020-7519(03)00049-3. PMid:12814653.
http://dx.doi.org/10.1016/S0020-7519(03)...
reported that Acanthocolpidae, as defined herein, is probably reflected by the position of Stephanostomum as a sister-group to the Brachycladiidae within the Allocreadioidea. The Cephalogonimidae closely related in the present study to Plagiorchiidae, which is consistent with Mehra (1937)Mehra HR. Certain new and already known distomes of the family Lepodermatidae Odhner (Trematoda), with a discussion on the classification of the family. Z Parasitenkd 1937; 9(4): 429-469. http://dx.doi.org/10.1007/BF02120292.
http://dx.doi.org/10.1007/BF02120292...
, Prudhoe & Bray (1982)Prudhoe S, Bray RA. Platyhelminth parasites of the Amphibia . London: British Museum (Natural History); Oxford University Press; 1982. , and Brooks et al. (1985)Brooks DR, O’Grady RT, Glen DR. Phylogenetic analysis of the Digenea (Platyhelminthes: Cercomeria) with comments on their adaptive radiation. Can J Zool 1985; 63(2): 411-443. http://dx.doi.org/10.1139/z85-062.
http://dx.doi.org/10.1139/z85-062...
. Furthermore, as described by Fernández et al. (1998aFernández M, Aznar FJ, Latorre A, Raga JA. Molecular phylogeny of the families Campulidae and Nasitrematidae (Trematoda) based on mtDNA sequence comparison. Int J Parasitol 1998a; 28(5): 767-775. http://dx.doi.org/10.1016/s0020-7519(98)00027-7. PMid:9650057.
http://dx.doi.org/10.1016/s0020-7519(98)...
, bFernández M, Littlewood DTJ, Latorre A, Raga JA, Rollinson D. Phylogenetic relationships of the family Campulidae (Trematoda) based on 18S rRNA sequences. Parasitology 1998b; 117(4): 383-391. http://dx.doi.org/10.1017/S0031182098003126. PMid:9820860.
http://dx.doi.org/10.1017/S0031182098003...
), and Cribb et al. (2001)Cribb TH, Bray RA, Littlewood DTJ, Pichelin S, Herniou EA. The Digenea. In: Littlewood DTJ, Bray RA. Interrelationships of the Platyhelminthes. London: Taylor and Francis; 2001. p. 168-185. , there is a sister taxon relationship between Brachycladiidae and Acanthocolpidae.

Molecular phylogenetic analyses of Gorgoderidae members have recently shown that Phyllodistomum is paraphyletic ( Razo-Mendivil et al., 2013Razo-Mendivil U, Pérez-Ponce de León G, Rubio-Godoy M. Integrative taxonomy identifies a new species of Phyllodistomum (Digenea: Gorgoderidae) from the two spot livebearer, Heterandria bimaculata (Teleostei: Poeciliidae), in Central Veracruz, Mexico. Parasitol Res 2013; 112(12): 4137-4150. http://dx.doi.org/10.1007/s00436-013-3605-y. PMid:24022129.
http://dx.doi.org/10.1007/s00436-013-360...
; Cutmore et al., 2013Cutmore SC, Miller TL, Curran SS, Bennett MB, Cribb TH. Phylogenetic relationships of the Gorgoderidae (Platyhelminthes: Trematoda), including the proposal of a new subfamily (Degeneriinae n. subfam.). Parasitol Res 2013; 112(8): 3063-3074. http://dx.doi.org/10.1007/s00436-013-3481-5. PMid:23760874.
http://dx.doi.org/10.1007/s00436-013-348...
; Petkevičiūtė et al., 2015Petkevičiūtė R, Stunžėnas V, Stanevičiūtė G, Zhokhov AE. European Phyllodistomum (Digenea, Gorgoderidae) and phylogenetic affinities of Cercaria duplicata based on rDNA and karyotypes. Zool Scr 2015; 44(2): 191-202. http://dx.doi.org/10.1111/zsc.12080.
http://dx.doi.org/10.1111/zsc.12080...
), as described herein. The phylogenetic trees from 18S rRNA and 28S rRNA data sets were analysed separately in the present study. Both trees clearly showed that the recovered species represent independent lineage, and is part of a paraphyletic group, with 28S rRNA presenting the current species as the sister taxon to a clade containing at least eleven species of Phyllodistomum , Gorgodera, and Gorgoderina infecting fish. This data is consistent with that obtained by Cutmore et al. (2013)Cutmore SC, Miller TL, Curran SS, Bennett MB, Cribb TH. Phylogenetic relationships of the Gorgoderidae (Platyhelminthes: Trematoda), including the proposal of a new subfamily (Degeneriinae n. subfam.). Parasitol Res 2013; 112(8): 3063-3074. http://dx.doi.org/10.1007/s00436-013-3481-5. PMid:23760874.
http://dx.doi.org/10.1007/s00436-013-348...
, Nakao (2015)Nakao M. Phyllodistomum kanae sp. nov. (Trematoda: Gorgoderidae), a bladder fluke from the Ezo salamander Hynobius retardatus. Parasitol Int 2015; 64(5): 314-318. http://dx.doi.org/10.1016/j.parint.2015.04.003. PMid:25892565.
http://dx.doi.org/10.1016/j.parint.2015....
, and Pérez-Ponce de León et al. (2015)Pérez-Ponce de León G, Aquinoa AM, Mendoza-Garfias B. Two new species of Phyllodistomum Braun, 1899 (Digenea: Gorgoderidae), from freshwater fishes (Cyprinodontiformes: Goodeidae: Goodeinae) in central Mexico: An integrative taxonomy approach using morphology, ultrastructure and molecular phylogenetics. Zootaxa 2015; 4013(1): 87-99. http://dx.doi.org/10.11646/zootaxa.4013.1.6.
http://dx.doi.org/10.11646/zootaxa.4013....
who reported that this clade appeared to be related to species in which cystocercous cercariae develop in bivalves with family Sphaeriidae. While the present species nested as the sister taxon of Gorgoderina and Gorgodera species, which are parasites of the amphibian urinary bladder, in the tree of the current species with 18S rRNA phylogeny, which agreed with Mata-López & León-Règagnon (2006)Mata-López R, León-Règagnon V. Comparative study of the tegumental surface of several species of Gorgoderina Looss, 1902 (Digenea: Gorgoderidae), as revealed by scanning electron microscopy. Comp Parasitol 2006; 73(1): 24-34. http://dx.doi.org/10.1654/4186.1.
http://dx.doi.org/10.1654/4186.1...
and Campbell (2008)Campbell RA. Family Gorgoderidae Looss, 1899. In: Bray RA, Gibson DI, Jones A. Keys to the Trematoda, volume 3 . Wallingford: CAB International, Natural History Museum; 2008. p. 191-213. who stated that the broad and foliate hindbody of Phyllodistomum is a key morphological character that distinguishes this genus from Gorgoderina and Gorgodera , and furthermore Gorgodera has more testes than Phyllodistomum and Gorgoderina . The above-mentioned molecular phylogenies, however, indicate a probability that the hindbody shape and number of testes are homoplasious traits.

Hence, this study represents the consistency of Phyllodistomum classification. The current study reflects a combination of morphometric data and morphological analysis in conjunction with the molecular data used to accurately identify and determine the exact taxonomic status of the recovered gorgoderid species. In addition, for this parasite species in Saudi Arabia, P. rubescens was considered a new host with new locality records.

Acknowledgements

This study was supported by Researchers Supporting Project (RSP-2019/25), King Saud University, Riyadh, Saudi Arabia. The authors declare that they have no conflict of interest regarding the content of this article.

  • Financial support: Researchers Supporting Project (RSP-2019/25), King Saud University, Riyadh, Saudi Arabia.
  • How to cite:Abdel-Gaber R, Al Quraishy S, Dkhil MAM, Abu Hawsah M, Alghamdi M, Althomali A, Bakr L, Maher S, El-Mallah A. Phyllodistomum vaili (Plagiorchiida: Gorgoderidae) infecting Parupeneus rubescens (Perciformes: Mullidae): morphology and phylogeny. Braz J Vet Parasitol 2020; 29(1): e020019. http://doi.org/10.1590/S1984-29612020005

References

  • Bakke TA, Bailey RE. Phyllodistomum umblae (Fabricius) (Digenea, Gorgoderidae) from the British Columbia salmonids: A description based on light and scanning electron microscopy. Can J Zool 1987; 65(7): 1703-1712. http://dx.doi.org/10.1139/z87-263
    » http://dx.doi.org/10.1139/z87-263
  • Bakke TA. Morphology of adult Phyllodistomum umblae (Fabricius) (Platyhelminthes, Gorgoderidae): The effect of preparation, killing and fixation procedures. Zool Scr 1988; 17(1): 1-13. http://dx.doi.org/10.1111/j.1463-6409.1988.tb00082.x
    » http://dx.doi.org/10.1111/j.1463-6409.1988.tb00082.x
  • Bakhoum AJS, Bâ CT, Shimalov VV, Torres J, Miquel J. Spermatological characters of the digenean Rubenstrema exasperatum (Rudolphi, 1819) (Plagiorchioidea, Omphalometridae). Parasitol Res 2011; 108(5): 1283-1293. http://dx.doi.org/10.1007/s00436-010-2178-2 PMid:21127907.
    » http://dx.doi.org/10.1007/s00436-010-2178-2
  • Bakhoum AJS, Quilichini Y, Justine JL, Bray RA, Miquel J, Feliu C, et al. First spermatological study in the Atractotrematidae (Digenea, Haploporoidea): the case of Atractotrema sigani , intestinal parasite of Siganus lineatus. Parasite 2015; 22: 26. http://dx.doi.org/10.1051/parasite/2015026 PMid:26475645.
    » http://dx.doi.org/10.1051/parasite/2015026
  • Bray RA, Blair D. Superfamily Gorgoderoidea Looss, 1899. In: Bray RA, Gibson DI, Jones A. Keys to the Trematoda, volume 3 . Wallingford: CAB International, Natural History Museum; 2008. p. 187-190.
  • Brooks DR, MacDonald CA. A new species of Phyllodistomum Braun, 1899 (Digenea: Gorgoderidae) in a Neotropical catfish, with discussion of the generic relationships of the Gorgoderidae. Can J Zool 1986; 64(6): 1326-1330. http://dx.doi.org/10.1139/z86-197
    » http://dx.doi.org/10.1139/z86-197
  • Brooks DR, O’Grady RT, Glen DR. Phylogenetic analysis of the Digenea (Platyhelminthes: Cercomeria) with comments on their adaptive radiation. Can J Zool 1985; 63(2): 411-443. http://dx.doi.org/10.1139/z85-062
    » http://dx.doi.org/10.1139/z85-062
  • Brooks DR, Pérez-Ponce de León G, León-Régágnon V. Phylogenetic analysis of the Enenteridae (Digenea, Lepocreadiidae) and discussion of the evolution of the digenean fauna of kyphosid fishes. Zool Scr 2000; 29(3): 237-246. http://dx.doi.org/10.1046/j.1463-6409.2000.00042.x
    » http://dx.doi.org/10.1046/j.1463-6409.2000.00042.x
  • Bush AO, Lafferty KD, Lotz JM, Shostak AW. Parasitology meets ecology on its own terms: Margolis et al. revisited. J Parasitol 1997; 83(4): 575-583. http://dx.doi.org/10.2307/3284227 PMid:9267395.
    » http://dx.doi.org/10.2307/3284227
  • Campbell RA. Degeneria halosauri (Bell 1887) gen. et comb. n. (Digenea: Gorgoderidae) from the deep-sea teleost Halosauropsis macrochir. J Parasitol 1977; 63(1): 76-79. http://dx.doi.org/10.2307/3280106 PMid:845742.
    » http://dx.doi.org/10.2307/3280106
  • Campbell RA. Family Gorgoderidae Looss, 1899. In: Bray RA, Gibson DI, Jones A. Keys to the Trematoda, volume 3 . Wallingford: CAB International, Natural History Museum; 2008. p. 191-213.
  • Choudhury A, Rosas Valdez R, Johnson RC, Hoffmann B, Pérez-Ponce de León G. The phylogenetic position of Allocreadiidae (Trematoda: Digenea) from partial sequences of the 18S and 28S ribosomal RNA genes. J Parasitol 2007; 93(1): 192-196. http://dx.doi.org/10.1645/GE-966R.1 PMid:17436963.
    » http://dx.doi.org/10.1645/GE-966R.1
  • Cribb TH, Bray RA, Littlewood DTJ, Pichelin S, Herniou EA. The Digenea. In: Littlewood DTJ, Bray RA. Interrelationships of the Platyhelminthes. London: Taylor and Francis; 2001. p. 168-185.
  • Cribb TH, Bray RA. Gut wash, body soak, blender, and heat-fixation: approaches to the effective collection, fixation and preservation of trematodes of fishes. Syst Parasitol 2010; 76(1): 1-7. http://dx.doi.org/10.1007/s11230-010-9229-z PMid:20401574.
    » http://dx.doi.org/10.1007/s11230-010-9229-z
  • Cribb TH, Chisholm LA, Bray RA. Diversity in the Monogenea and Digenea: Does lifestyle matter? Int J Parasitol 2002; 32(3): 321-328. http://dx.doi.org/10.1016/S0020-7519(01)00333-2 PMid:11835972.
    » http://dx.doi.org/10.1016/S0020-7519(01)00333-2
  • Cribb TH. A new species of Phyllodistomum (Digenea: Gorgoderidae) from Australian and New Zealand freshwater fishes with notes on the taxonomy of Phyllodistomum Braun, 1899. J Nat Hist 1987; 21(6): 1525-1538. http://dx.doi.org/10.1080/00222938700770951
    » http://dx.doi.org/10.1080/00222938700770951
  • Curran SS, Tkach VV, Overstreet RM. A review of Polylekithum Arnold, 1934 and its familial affinities using morphological and molecular data, with description of Polylekithum catahoulensis sp. nov. Acta Parasitol 2006; 51(4): 238-248. http://dx.doi.org/10.2478/s11686-006-0037-1
    » http://dx.doi.org/10.2478/s11686-006-0037-1
  • Curran SS, Tkach VV, Overstreet RM. A new species of Homalometron (Digenea: Apocreadiidae) from fishes in the northern Gulf of Mexico. J Parasitol 2013; 99(1): 93-101. http://dx.doi.org/10.1645/GE-3169.1 PMid:22924927.
    » http://dx.doi.org/10.1645/GE-3169.1
  • Cutmore SC, Cribb TH. Two species of Phyllodistomum Braun, 1899 (Trematoda: Gorgoderidae) from Moreton Bay, Australia. Syst Parasitol 2018; 95(4): 325-336. http://dx.doi.org/10.1007/s11230-018-9784-2 PMid:29417344.
    » http://dx.doi.org/10.1007/s11230-018-9784-2
  • Cutmore SC, Miller TL, Curran SS, Bennett MB, Cribb TH. Phylogenetic relationships of the Gorgoderidae (Platyhelminthes: Trematoda), including the proposal of a new subfamily (Degeneriinae n. subfam.). Parasitol Res 2013; 112(8): 3063-3074. http://dx.doi.org/10.1007/s00436-013-3481-5 PMid:23760874.
    » http://dx.doi.org/10.1007/s00436-013-3481-5
  • Fernández M, Aznar FJ, Latorre A, Raga JA. Molecular phylogeny of the families Campulidae and Nasitrematidae (Trematoda) based on mtDNA sequence comparison. Int J Parasitol 1998a; 28(5): 767-775. http://dx.doi.org/10.1016/s0020-7519(98)00027-7 PMid:9650057.
    » http://dx.doi.org/10.1016/s0020-7519(98)00027-7
  • Fernández M, Littlewood DTJ, Latorre A, Raga JA, Rollinson D. Phylogenetic relationships of the family Campulidae (Trematoda) based on 18S rRNA sequences. Parasitology 1998b; 117(4): 383-391. http://dx.doi.org/10.1017/S0031182098003126 PMid:9820860.
    » http://dx.doi.org/10.1017/S0031182098003126
  • Gibson DI. Trematoda. In: Margolis L, Kabata Z. Guide to the parasites of fishes of Canada. Part IV . Ottawa: NRC CNRC; 1996. pp. 1-373. (Canadian Special Publication of Fisheries and Aquatic Sciences; vol. 124).
  • Goodchild CG. The life-history of Phyllodistomum solidum Rankin, 1937, with observations on the morphology, development and taxonomy of the Gorgoderinae (Trematoda). Biol Bull 1943; 84(1): 59-86. http://dx.doi.org/10.2307/1538050
    » http://dx.doi.org/10.2307/1538050
  • Guidelli G, Tavechio WLG, Ferreira BP. New host and geographic distribution of Phyllodistomum thunni (Trematoda, Gorgoderidae). Mar Biodivers Rec 2018; 11(9): 1-5. http://dx.doi.org/10.1186/s41200-018-0144-3
    » http://dx.doi.org/10.1186/s41200-018-0144-3
  • Hall TA. BioEdit: A user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucleic Acids Symp Ser 1999; 41: 95-98.
  • Helt J, Janovy J Jr, Ubelaker J. Phyllodistomum funduli n. sp. (Trematoda: Gorgoderidae) from Fundulus sciadicus Cope from Cedar Creek in western Nebraska. J Parasitol 2003; 89(2): 346-350. http://dx.doi.org/10.1645/0022-3395(2003)089[0346:PFNSTG]2.0.CO;2 PMid:12760652.
    » http://dx.doi.org/10.1645/0022-3395(2003)089[0346:PFNSTG]2.0.CO;2
  • Ho HW, Bray RA, Cutmore SC, Ward S, Cribb TH. Two new species of Phyllodistomum Braun, 1899 (Trematoda: Gorgoderidae Looss, 1899) from Great Barrier Reef fishes. Zootaxa 2014; 3779(5): 551-562. http://dx.doi.org/10.11646/zootaxa.3779.5.5 PMid:24871750.
    » http://dx.doi.org/10.11646/zootaxa.3779.5.5
  • Hoffman GL. Parasites of north american freshwater fish . 2nd ed. Ithaca, New York: Comstock Publishing Associates, Cornell University Press; 1999.
  • Holl EJ. The phyllodistomes of North America. Trans Am Microsc Soc 1929; 48(1): 48-53. http://dx.doi.org/10.2307/3222458
    » http://dx.doi.org/10.2307/3222458
  • Indaryanto FR, Abdullah MF, Wardiatno Y, Tiuria R, Imai H. A description of Lecithocladium angustiovum (Digenea: Hemiuridae) in Short Mackerel, Rastrelliger brachysoma (Scombridae), of Indonesia. Trop Life Sci Res 2015; 26(1): 31-40. PMid:26868591.
  • Jithila PJ, Prasadan PK. Prevalence, intensity, mean abundance and description of Phyllodistomum punctati n. sp. (Digenea: Gorgoderidae) from the urinary bladder of Channa punctata (Bloch) from the Western Ghats, India. Inter J Fish Aquat Stud 2018; 6(5): 1-5.
  • Lee SU, Chun HC, Huh S. Molecular phylogeny of parasitic Platyhelminthes based on sequences of partial 28S rDNA D1 and mitochondrial cytochrome c oxidase subunit I. Korean J Parasitol 2007; 45(3): 181-189. http://dx.doi.org/10.3347/kjp.2007.45.3.181 PMid:17876163.
    » http://dx.doi.org/10.3347/kjp.2007.45.3.181
  • Lewis FG. The trematode genus Phyllodistomum Braun. Trans Am Microsc Soc 1935; 54(2): 103-117. http://dx.doi.org/10.2307/3222118
    » http://dx.doi.org/10.2307/3222118
  • Mata-López R, León-Règagnon V. Comparative study of the tegumental surface of several species of Gorgoderina Looss, 1902 (Digenea: Gorgoderidae), as revealed by scanning electron microscopy. Comp Parasitol 2006; 73(1): 24-34. http://dx.doi.org/10.1654/4186.1
    » http://dx.doi.org/10.1654/4186.1
  • Mehra HR. Certain new and already known distomes of the family Lepodermatidae Odhner (Trematoda), with a discussion on the classification of the family. Z Parasitenkd 1937; 9(4): 429-469. http://dx.doi.org/10.1007/BF02120292
    » http://dx.doi.org/10.1007/BF02120292
  • Mendoza-Garfias B, Pérez-Ponce De Léon G. Phyllodistomum centropomi sp. n. (Digenea: Gorgoderidae), a parasite of the fat snook, Centropomus parallelus (Osteichthyes: Centropomidae), in the Papaloapan River at Tlacotalpan, Veracruz State, Mexico. Zootaxa 2005; 1056(1): 43-51. http://dx.doi.org/10.11646/zootaxa.1056.1.3
    » http://dx.doi.org/10.11646/zootaxa.1056.1.3
  • Nakao M. Phyllodistomum kanae sp. nov. (Trematoda: Gorgoderidae), a bladder fluke from the Ezo salamander Hynobius retardatus. Parasitol Int 2015; 64(5): 314-318. http://dx.doi.org/10.1016/j.parint.2015.04.003 PMid:25892565.
    » http://dx.doi.org/10.1016/j.parint.2015.04.003
  • Olson PD, Cribb TH, Tkach VV, Bray RA, Littlewood DTJ. Phylogeny and classification of the Digenea (Platyhelminthes: trematoda). Int J Parasitol 2003; 33(7): 733-755. http://dx.doi.org/10.1016/S0020-7519(03)00049-3 PMid:12814653.
    » http://dx.doi.org/10.1016/S0020-7519(03)00049-3
  • Parker JH, Curran SS, Overstreet RM, Tkach VV. Examination of Homalometron elongatum Manter, 1947 and description of a new congener from Eucinostomus currani Zahuranec, 1980 in the Pacific Ocean off Costa Rica. Comp Parasitol 2010; 77(2): 154-163. http://dx.doi.org/10.1654/4451.1
    » http://dx.doi.org/10.1654/4451.1
  • Pérez-Ponce de León G, Aquinoa AM, Mendoza-Garfias B. Two new species of Phyllodistomum Braun, 1899 (Digenea: Gorgoderidae), from freshwater fishes (Cyprinodontiformes: Goodeidae: Goodeinae) in central Mexico: An integrative taxonomy approach using morphology, ultrastructure and molecular phylogenetics. Zootaxa 2015; 4013(1): 87-99. http://dx.doi.org/10.11646/zootaxa.4013.1.6
    » http://dx.doi.org/10.11646/zootaxa.4013.1.6
  • Petkevičiūtė R, Stunžėnas V, Stanevičiūtė G, Zhokhov AE. European Phyllodistomum (Digenea, Gorgoderidae) and phylogenetic affinities of Cercaria duplicata based on rDNA and karyotypes. Zool Scr 2015; 44(2): 191-202. http://dx.doi.org/10.1111/zsc.12080
    » http://dx.doi.org/10.1111/zsc.12080
  • Prudhoe S, Bray RA. Platyhelminth parasites of the Amphibia . London: British Museum (Natural History); Oxford University Press; 1982.
  • Pulis EE, Fayton TJ, Curran SS, Overstreet RM. A new species of Intromugil (Digenea: Haploporidae) and redescription of Intromugil mugilicolus. J Parasitol 2013; 99(3): 501-508. http://dx.doi.org/10.1645/12-106.1 PMid:23327447.
    » http://dx.doi.org/10.1645/12-106.1
  • Rai SL. Observations on the life-history of Phyllodistomum srivastavai sp. nov. (Trematoda: gorgoderidae). Parasitology 1964; 54(1): 43-51. http://dx.doi.org/10.1017/S0031182000074308
    » http://dx.doi.org/10.1017/S0031182000074308
  • Razo-Mendivil U, Pérez-Ponce de León G, Rubio-Godoy M. Integrative taxonomy identifies a new species of Phyllodistomum (Digenea: Gorgoderidae) from the two spot livebearer, Heterandria bimaculata (Teleostei: Poeciliidae), in Central Veracruz, Mexico. Parasitol Res 2013; 112(12): 4137-4150. http://dx.doi.org/10.1007/s00436-013-3605-y PMid:24022129.
    » http://dx.doi.org/10.1007/s00436-013-3605-y
  • Razo-Mendivil U, Pérez-Ponce de León G. Testing the evolutionary and biogeographical history of Glypthelmins (Digenea: Plagiorchiida), a parasite of anurans, through a simultaneous analysis of molecular and morphological data. Mol Phylogenet Evol 2011; 59(2): 341-351. http://dx.doi.org/10.1016/j.ympev.2011.02.018 PMid:21356320.
    » http://dx.doi.org/10.1016/j.ympev.2011.02.018
  • Schell SC. The life history of Phyllodistomum staffordi Pearse, 1924 (Trematoda: gorgoderidae Looss, 1901). J Parasitol 1967; 53(3): 569-576. http://dx.doi.org/10.2307/3276717 PMid:6026845.
    » http://dx.doi.org/10.2307/3276717
  • Sey O, Wongsawad C, Wongsawad P. Trematodes from fish in the Bhumipol Dam, Tak Province, Thailand. Southeast Asian J Trop Med Public Health 2004; 35(Suppl. 1): 284-287.
  • Shimazu T. Digeneans found in fresh- and brackish-water fishes of Lake Ogawara in Aomori Prefecture, Japan. Bull Natn Sci Mus 2005; 31(4): 137-150.
  • Snyder SD, Tkach VV. Aptorchis kuchlingi n. sp. (Digenea: Plagiorchioidea) from the Oblong Turtle, Chelodina oblonga (Pleurodira: Chelidae), in Western Australia. Comp Parasitol 2011; 78(2): 280-285. http://dx.doi.org/10.1654/4401.1
    » http://dx.doi.org/10.1654/4401.1
  • Stunžėnas V, Petkevičiūtė R, Poddubnaya LG, Stanevičiūtė G, Zhokhov AE. Host specificity, molecular phylogeny and morphological differences of Phyllodistomum pseudofolium Nybelin, 1926 and Phyllodistomum angulatum Linstow, 1907 (Trematoda: Gorgoderidae) with notes on Eurasian ruffe as final host for Phyllodistomum spp. Parasit Vectors 2017; 10(1): 286. http://dx.doi.org/10.1186/s13071-017-2210-9 PMid:28587614.
    » http://dx.doi.org/10.1186/s13071-017-2210-9
  • Thomas JD. Life-history of Phyllodistomum simile Nybelin. Nature 1956; 178(4540): 1004. http://dx.doi.org/10.1038/1781004a0
    » http://dx.doi.org/10.1038/1781004a0
  • Thompson JD, Gibson TJ, Plewniak F, Jeanmougin F, Higgins DG. The CLUSTAL-X windows interface: Flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Res 1997; 25(24): 4876-4882. http://dx.doi.org/10.1093/nar/25.24.4876 PMid:9396791.
    » http://dx.doi.org/10.1093/nar/25.24.4876
  • Tkach VV, Curran SS, Bell JA, Overstreet RM. A new species of Crepidostomum (Digenea: Allocreadiidae) from Hiodon tergisus in Mississippi, and molecular comparison with three congeners. J Parasitol 2013; 99(6): 114-1121. http://dx.doi.org/10.1645/13-279.1 PMid:23915018.
    » http://dx.doi.org/10.1645/13-279.1
  • Ubelaker JE, Olsen AW. Life cycle of Phyllodistomum bufonis (Digenea: Gorgoderidae) from the boreal toad, Bufo boreas. Proc Helminthol Soc Wash 1972; 39: 94-100.
  • Vidal-Martínez V, Aguirre-Macedo ML, Scholz T, González-Solís D, Mendoza EF. Atlas de los helmintos parásitos de cíclidos en México. México: Instituto Politécnico Nacional; 2002. 182 p.

Publication Dates

  • Publication in this collection
    30 Mar 2020
  • Date of issue
    2020

History

  • Received
    29 Oct 2019
  • Accepted
    17 Jan 2020
Colégio Brasileiro de Parasitologia Veterinária FCAV/UNESP - Departamento de Patologia Veterinária, Via de acesso Prof. Paulo Donato Castellane s/n, Zona Rural, , 14884-900 Jaboticabal - SP, Brasil, Fone: (16) 3209-7100 RAMAL 7934 - Jaboticabal - SP - Brazil
E-mail: cbpv_rbpv.fcav@unesp.br