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Members of the order Trypanorhyncha are cestode parasites that are frequently found infecting the muscles of several marine fish species, affecting fish health and resulting in consumers' rejection. Seventy-five specimens of marine fish were freshly caught from boat landing sites at the Alexandria coast along the Mediterranean Sea in Egypt, including two Carangids, the greater amberjack Seriola dumerili and the gulley jack Pseudocarans dentex; two Serranids, the Haifa grouper Epinephelus haifensis and the mottled grouper Mycteroperca rubra. Forty-five fish were infected; the infection was recorded as blastocysts embedded in fish flesh. Blastocysts were isolated and ruptured; the generated plerocerci were described morphologically, where, four different species were recovered; Callitetrarhynchus gracilis, Callitetrarhynchus speciosus, Protogrillotia zerbiae, and Grillotia brayi. The taxonomic position of these parasites was justified by multiple-sequence alignment and a phylogenetic tree was constructed following maximum likelihood analysis of the 18s rRNA sequences of the recovered worms. The accession numbers MN625168, MN625169, MN611431and MN611432 were respectively assigned to the recovered parasites. The results obtained from the molecular analyses confirmed the morphological records of the recovered parasites. Since metacestodes are found in the musculature of infected fish specimens, it is necessary to remove these areas in the commercialization of fish.

Forty specimens of the Narrowstripe cardinal fish Apogon exostigma were examined for gastrointestinal helminthes, and 62.5% were infected with a new trypanorhynchid larval cestode parasite. The morphology of its larval stage was studied based on light and scanning electron microscopy. The data revealed plerocercoid larvae characterized by a pyriform body lined with prominent microtriches; the acraspedote scolex had four overlapping bothridia; four tentacles protruded through the pars bothridialis; the armature of the tentacles was homeocanthous, homeomorphous, and consisted of falcate compact rose-thorn-shaped tentacular hooks; four oval-shaped bulbs in pars bulbosa; and short appendix at terminal end of the body. Molecular analysis of the 18S rRNA sequences verified the taxonomy of this parasite and supported its morphology. We discovered that there was a close identity (up to 87%) with alternative species obtained for comparison from GenBank. The data also showed that there were high blast scores and low divergence values between this parasite and other Tentaculariidae species. The phyletic analysis showed that parasite sequences in conjunction with existing data places this trypanorhynchid species among the Tentaculariidae. This species is deeply embedded within genus Nybelinia with close relationships to Nybelinia queenslandensis as a putative sister taxon.

Proteocephalids are cestoda parasites that mostly infect freshwater fish. The present study was carried out to investigate the presence of proteocephalids infecting the electric catfish Malapterurus electricus from Lake Manzala, Kafr El-Sheikh Governorate, Egypt. Morphological characterization revealed the present parasite is a cestoda belonging to the genus Electrotaenia. Morphologically, the recovered worms were characterized by an elongated body measuring 100-127 (120 ± 2) mm long and 0.92-2.11 (2.76 ± 0.1) mm wide. The anterior part of the worm was obvious terminated at a spherical scolex measured 1.12-1.91 (1.72 ± 0.01) mm long and 1.12-1.65 (1.42 ± 0.01) mm wide with a rostellum-like apical organ equipped by 5-6 irregular rows of minute hooklets, as well as four uniloculate suckers with a diameter of 0.13-0.15 (0.14 ± 0.01) mm and covered with microtriches. A long unsegmented neck was observed followed by acraspedote and anapolytic strobila consisted of 85-120 proglottids divided into 50-58 immature, 12-19 mature, and up to 49 gravid proglottids. Molecular characterization based on 28S rRNA sequences was done to confirm the taxonomy of this parasite based on its morphology. It was observed that there was a close identity up to 72.0% with other protocephalid species obtained for comparison from the GenBank. Also, the data obtained revealed that there was high blast scores and low divergence between the present parasite and previously described Electrotaenia malapteruri (acc. no. JX477434). Phylogenetic analysis showed that the parasite sequence in conjunction with existing data investigates the placement of this protocephalid species within Proteocephalidea. It was shown that the present species is deeply embedded in the genus Electrotaenia with close relationships to other Electrotaenia malapteruri as a putative sister taxon., (Copyright © 2018 Elsevier B.V. All rights reserved.)

During the present investigation, a total of 220 fish specimens belonging to three different species, namely, little tunny Euthynnus alletteratus, African snook Lates niloticus, and striped red mullet Mullus surmuletus, were collected from January-November 2016 from the coasts off Abu Qir landing site, Alexandria City, south-eastern Mediterranean Sea, Egypt. The collected fish samples were dissected and examined for the presence of helminth parasites. Twenty-three out of 220 (10.45%) fish specimens were found to be naturally infected with four species of trematode parasites belonging to three different families of the order Plagiorchiida. The recovered parasite species were collected and identified by applying light microscopic examinations. The present study recorded two new parasite species, namely, Stephanostomum alletterani sp. nov. and Bathycreadium mulli sp. nov., belonging to the families Acanthocolpidae and Opecoelidae and infecting E. alletteratus and M. surmuletus, respectively and re-descriptions of the two remaining species, namely, Acanthostomum spiniceps and Aponurus mulli of the families Acanthostomatidae and Opecoelidae, respectively, to clarify the measurements of some body parts. Morphological and morphometric characterizations revealed some differences between the present species and other related species detected previously. Future studies are recommended to include advanced molecular characteristics for these species.

Parasites are one of the most serious limiting factors in aquaculture. The Electric catfish Malapterurus electricus was subjected to study the prevalence and mean intensity of parasitic infections throughout the whole year of 2015. Heavy metals accumulation in host fish and parasites were determined in relation to water quality and sediments of two different sites of Lake Manzala (Manzala and Bahr El-Baqar), Egypt. A total of 100 specimens of Electric catfish were collected and examined for the presence of helminth parasites. Two parasite species were recovered and morphologically identified. These were cestoda Electrotaenia malapteruri and nematode Dujardinnascaris malapteruri. Heavy metal analysis in water and sediments showed that measured heavy metals in Bahr El-Baqar were found in risky levels higher than permissible limits and Manzala site. Sediments were found to contain a higher level of metals than water samples. Heavy metals accumulation in recovered parasites and their host were also determined and showed significantly higher concentrations in parasites compared to their host tissues. According to bioconcentration factors, E. malapteruri showed that highest accumulation rate for all recorded elements up to 302. Essential elements like Cu and Fe were found in significantly higher concentrations in D. malapteruri, whereas E. malapteruri accumulated elements Cd, Pb, Ni, Mn, Zn and Ca to a significantly higher degree. Accordingly, the ratios (C[D.malapteruri]/C[E. malapteruri]) for most essential elements were higher than 0.5. Therefore, fish cestodes can be regarded as useful bio-indicators more than nematodes when evaluating the environmental pollution of aquatic ecosystems by heavy metals.

During a survey of myxosporean parasites infecting freshwater fishes from the River Nile at Giza Governorates, Egypt between March and September 2016, nine out of 30 specimens of the Nile carp Labeo niloticus (Cyprinidae) were found to be naturally infected with Myxobolus naffari (Myxobolidae). Small macroscopic plasmodia appeared embedded in the host gill tissue accompanied with fusion of the gill epithelia, and atrophy was observed at the site of infection. The host reaction was manifested by the encapsulation of the plasmodia with a thick layer of connective tissue. The plasmodia appeared as white, elongated rods between gill filaments with an intensity ranging from three to eight cysts/fish. The average dimensions of plasmodia were 1.2–2.0 (1.8 ± 0.2) mm long × 0.4–0.7 (0.6 ± 0.2) mm wide. The spores were oval, reaching 9.56–11.2 (10.2 ± 0.2) μm long and 6.5–7.7 (7.0 ± 0.4) μm wide with two equal-sized polar capsules regularly arranged at the anterior pole of each spore. They were 4.51–5.5 (5.1 ± 0.4) μm in length and 1.5–2.0 (1.7 ± 0.2) μm in width. Histological, semi-thin sections were taken through parasite plasmodia and transmission electron microscopic examination of ultrathin sections was performed to describe the developmental stages of the recorded parasite within the host fish.

The phylum Myxozoa comprises more than 2180 species, almost all of which are considered to be obligate parasites of aquatic fishes. In the present study, Henneguya collaris sp. nov. is the first described histozoic myxozoan species of the genus Henneguya infecting the kidney of the greenband parrotfish Scarus collana (Actinopterygii, Scaridae). One hundred and eighty specimens of fish were collected randomly during the period from September 2014 to October 2015 from boat landing sites and the market places at Hurghada City along the Red Sea in Egypt. Of these, 90 (50 %) specimens were infected. Light microscopic examination showed that the infection was detected as mature spores with two polar capsules regularly arranged at the anterior pole of each spore and extruded polar filaments free in the kidney tissue. The spore body was oval in shape, measured 7.1 ± 0.2 (6.2-8.4) μm in length and 6.3 ± 0.2 (5.8-7.0) μm in width, with a bifurcated caudal process of equal length, reaching 6.3 ± 0.2 (5.8-7.0) μm in length. Polar capsules were 3.4 ± 0.2 (3.0-4.2) μm in length and 1.9 ± 0.2 (1.6-2.4) μm in width with 6-8 (10) turns of polar filaments. Ultrastructural analysis showed that the spore development was asynchronous. Sporogenesis, capsulogensis, valvogenesis, and spore maturation of the present parasite were also described. The present species was compared morphologically with the spore characteristics of the most similar species of Henneguya spp. recorded previously from different geographical areas taking into account the stage and dimensions of the spore body, tails, and polar filament coils, including their number and the most important characteristic features that distinguish them from the present species. Considering the data obtained, the material described herein represents a new species and the name Henneguya collaris sp. nov. is proposed.

Sixty specimens of the moontail bullseye Priacanthus hamrur were collected at Coasts of Suez Gulf, Red Sea (Egypt) during the four different seasons of the whole year 2014 and necropsied to study the infection with metazoan parasites. Twenty-one out of 60 examined fish specimens (infection rate of 33.33 %) were found to be naturally infected by the hemiurid digenean parasite Lecithochirium priacanthi. The large-sized fish reaching 15-30 (23.5 ± 4.8) cm were more intensively infected than the smaller ones. A definite seasonal effect was observed as winter was found to be the season of severe parasitic infections, while midsummer was the lowest one. The morphological and morphometric characterization of this parasite were examined by light and scanning electron microscopy. The adult worms had an elongated body measuring 1.93-2.54 (2.11 ± 0.20) mm in length and 0.61-0.72 (0.67 ± 0.02) mm in width. The body was characterized by the presence of a sub-terminal oral sucker with diameters reaching 0.12-0.16 (0.14 ± 0.02) mm. The ventral sucker measured 0.32-0.45 (0.38 ± 0.02) mm in diameter. The body was supplied by a short retracted portion with a blunt end that measured 0.48-0.61 (0.56 ± 0.02) mm in length and 0.28-0.35 (0.32 ± 0.02) mm in width. Morphological results of the present parasite were compared with other related species described previously from Perciformes. Molecular characterization based on small subunit ribosomal DNA was done to confirm the obtained morphological and morphometric results. A preliminary genetic comparison between SSU rDNA of this parasite and other species of Hemiuridae places the present specimen as a putative sister taxon to Lecithochirium grandiporum and Lecithochirium caesionis. The finding of L. priacanthi in Egyptian marine water fish represents a new geographical record for this parasite.

Myxosporidian parasites infecting fish are very dangerous parasites causing severe damage to a large number of economically important fishes especially in aquaculture. A survey of myxosporean parasites infecting four species of fishes from the River Nile in Egypt is conducted. One hundred and ninety-five out of 316 fish specimens with a percentage of 61.7% were found to be naturally infected with these parasites. Light microscopic examination of different tissues revealed the presence of 12 myxosporean species belonging to the family Myxobolidae. Four of the identified species are novel and the other eight species are redescribed. Myxidium sp.nov. a coelozoic species inhabiting the gallbladder of Labeo niloticus with its mature spores float free in bile was detected. These spores possess a fusiform, straight, or slightly crescentic shape with less pointed ends and two equal polar capsules. Three novel histozoic Myxobolus species infecting Oreochromis niloticus were identified. Myxobolus sp(1).nov. is a species inhabiting kidney tissue with ovoid spores exhibiting a small intercapsular appendix. Myxobolus sp(2).nov. and Myxobolus sp(3).nov. recovered from kidney and intestinal tissues. Spores of Myxobolus sp(2).nov. are elliptical in shape with an anterior end wider than posterior one. Their two polar capsules are ovoid to pyriform occupied nearly the first third of the spore body. Spores of Myxobolus sp(3).nov. are broader than long with nearly rounded or ovoid two polar capsules. Eight species of the recovered myxosporean parasites are redescribed, Myxobolus niloticus Fahmy et al., 1971 from pectoral, dorsal, and tail fins of L. niloticus, Henneguya suprabranchiae Landsberg, 1987, and Henneguya branchialis Ashmawy et al., 1989 are recovered from the gills and suprabranchial organ of the catfish Clarias gariepinus, respectively, Myxobolus naffari Abdel-Ghaffar et al., 1998 and Myxobolus imami Ali et al., 2002 are found in the kidney of Barbus bynni and L. niloticus, Myxobolus caudatus Ali et al. & Parasitol Res (2002) from Tail fin of B. bynni, Myxobolus fomenai Abdel-Ghaffar et al., 2008 from kidney and intestinal tissues of O. niloticus, Thelohanellus niloticus Abdel-Ghaffar et al., 2012 are observed in the gills of L. niloticus.

Three juvenile nematode parasites were collected naturally from 90 (75 %) out of 120 specimens of the marine greater lizard fish Saurida undosquamis captured from water coasts at Hurghada City along the Red Sea in Egypt during the period from September 2013 to April 2014. Worms were identified on the basis of light and scanning electron microscopy. Two of the recovered worms were isolated from the peritoneal cavity of the infected fish around the wall of the stomach as encapsulated larvae. The anisakid juvenile Anisakis sp. (Type II) was characterized by an anteroventrally triangular mouth, with a boring tooth; its postanal tail was rounded, without a terminal mucron or spine. The gnathostomatid Echinocephalus overstreeti was characterized by the presence of a cephalic bulb armed with six transverse rows of spines which were slightly more compact near the anterior end of bulb with maximal separation near the midbulb; the cephalic bulb terminated at a pseudolabia which situated dorsoventrally and reached its greatest width at the posterior one third of the body, The postanal tail terminated at a pointed mucron. The third juvenile species, Hysterothylacium patagonense (Anisakidae), was isolated from the intestine of the infected fish; they are characterized by a small-sized body with a conical tail provided by a nodulose apex, and the anterior end was equipped with three lips. A dorsal lip slightly smaller than the two subventrals left a deep postlabial groove and prominent lateral flanges in between, and the proximal part of each lip was smooth. The three described species were compared morphologically and morphometrically with some of the previously recorded species of the same genus. From this comparison, the similarity and variations between these species were described and concluded that the present study should be considered as a new host record in Egypt.

Hysterothylacium aduncum (Nematoda, Anisakidae) was isolated from the intestine of the common sole Solea solea (Family, Soleidae) collected from coasts along Alexandria City at the Mediterranean Sea in Egypt, during the period from May to September 2013. Light and scanning electron microscopy revealed that this nematode parasite belongs to the family Anisakidae in the genus Hysterothylacium. The type species is named H. aduncum, based on the presence of three interlocked lips with the interlabium in between, the presence of cephalic papillae, and large numbers of caudal papillae in males. Body measurements showed that the male worms were smaller than females measuring 13.9-18 mm (16.2 ± 0.2) in length and 0.26-0.34 mm (0.30 ± 0.01) in width. Females measured 20.5-24.5 mm (22.7 ± 0.2) in length and 0.41-0.52 mm (0.45 ± 0.01) in width. The morphological characteristics of this species was confirmed by molecular analysis of 18S rDNA for these parasites followed by comparison between sequence data for them with those obtained from the Genbank showing that H. aduncum is deeply embedded in the genus Hysterothylacium with a sequence similarity between 95.5-94.3 % with close relationships to other H. aduncum specimens and Hysterothylacium sp.. Furthermore, it was shown that this parasitic nematode is able to accumulate larger concentrations of heavy metals such as Fe, Cu, Cd, and Ni within its tissues than of its host fish and thus it can be used as a useful bio-indicator of water pollution.

A total of 80 specimens of the European eel Anguilla anguilla were collected during the period from February 2013 to March 2014 at the coast of the Gulf of Suez (Red Sea, Egypt). A new species of parasitic nematodes was recovered and described as Cucullanus egyptae. It was found in the eel's intestine with a prevalence of 68.7%. The morphology of the recovered parasite was studied by light and scanning electron microscopy. The adult worms had a wide cephalic extremity with a slit-like oral aperture being surrounded by a cuticular ring and delimited internally by a row of small teeth in addition to four sub-median cephalic papillae and one pair of lateral amphids. Body measurements showed that the male worms were smaller than females measuring 7.5-8.9 mm (8.3 ± 0.2) in length and 1.6-1.9 mm (1.8 ± 0.1) in width. Females measured 12.9-13.5 mm (13.1 ± 0.2) in length and 2.9-3.2 mm (3.1 ± 0.1) in width. The posterior end of the males is provided with ten pairs of caudal papillae and two long spicules which are slightly sclerotized, equal in size measuring 0.59-0.65 mm (0.62 ± 0.01) in length. Comparing the present worms with other species of the genus Cucullanus, several similarities were observed. However, peculiar new characteristics such as the precloacal sucker (especially the spicula length), the arrangement and the distribution of the post-cloacal papillae, and the position of the excretory pore make it reasonable to describe a new species. The sequence data of the small subunit (SSU) ribosomal DNA (rDNA) obtained from the present nematode supported its taxonomic position within the genus Cucullanus. The new species is closely related to the first clade of Spirurina and even more closely related to Cucullanus dodsworthi as a sister taxon with a high percentage of identity. The sequence of the recorded SSU rDNA of this parasite is deposited in the GenBank with the accession no. KF681520. It is proposed to name the new species C. egyptae as the first representative of Cucullanidae in Egypt with a new host record.

Seventy specimens of the gilthead sea bream Sparus aurata of the Red Sea were collected during the period from March to November 2013; they were dissected and examined for parasitic acanthocephalans. Only 40 (57.14%) specimens were found to be naturally infected with Serrasentis sagittifer belonging to family Rhadinorhynchidae. The infection was recorded in the intestine, pyloric ceca, and the external surfaces of some internal organs of the infected fish. Seasonally, the prevalence of infection was increased to 77.14% during summer season and decreased to 37.14% during winter. Light and scanning electron microscopic investigation revealed that the adult worm was elongated (with broad anterior and narrow posterior ends) and measured 6.9-8.6 (7.6 ± 0.2) × 0.57-0.73 (0.63 ± 0.02) mm for male and 10.2-12.1 (11.5 ± 0.2) × 0.71-0.82 (0.76 ± 0.02) mm for female. Proboscis was long and cylindrical with a length of 0.97-1.6 mm (1.2 ± 0.2) for male and 1.12-1.17 mm (1.14 ± 0.02) for female. It was covered with numerous uniform spines arranged longitudinally as 9-11 rows each equipped by 15-18 spines. Spines were triangular, arrow-shaped, strong, and covered with cuticular theca; they decreased in size from the apex to the base of the proboscis. The proboscis is followed by a short spineless neck region followed by the body proper which is supported by multiple combs of spines (16-20) on its ventral surface. Molecular analysis of 18S rDNA sequence for the parasite demonstrated a close identity (>83%) between the present acanthocephalan and other previously described species within class Palaeacanthocephala with 98% identity with the previously recorded S. sagittifer (acc. no. JX014227) which is supported by the morphological data and the presence of trunk spines arranged within rows (comb-like) and the presence of four cement glands in the males. So, according to the records of morphological and molecular analyses, the present parasite is classified as S. sagittifer belonging to class Palaeacanthocephala and family Rhadinorhynchidae with a new host record from the gilthead sea bream S. aurata of the Red Sea.

The morphology of the adult stage of Acanthostomum spiniceps recovered from the African snook, Lates niloticus (Perciformes: Latidae) of the river Nile, Egypt was studied with both light and scanning electron microscopy.The most important morphological features differentiating this species are the number of circumoral spines, body shape, ratio of body length to width, sucker sizes, and the presence or absence of spines on the ventral sucker. Sixteen out of forty fish (40%) was found to be naturally infected with this digenetic trematode belonging to family: Acanthostominae. The infection was recorded in the intestinal wall of the host fish. Body was elongate, 1.203-2.074 mm long, maximum width 0.311-0.534 mm. Oral sucker was terminal, funnel-shaped, 0.201-0.353 mm long and 0.245-0.310 mm wide. Simple peribuccal spines 0.042-0.066 mm long. Ventral sucker was circular, 0.110-0.140 mm long, 0.120-0.204 mm wide, situated approximately at 1/3 of body length. Ratio of oral and ventral suckers was 1: 0.5. Testes tandem or slightly diagonal, located near posterior end of body being of irregular rounded shape. Size of anterior testis was 0.130-0.220 mm long, 0.314-0.358 mm wide, that of posterior testis was 0.180-0.274 mm long, 0.390-0.327 mm wide. Ovary transversely oval, smaller than testes, measured 0.102-0.166 mm long, 0.100-0.164 mm wide, situated just anterior to anterior testis. By comparison with some of the previously described species of this genus, the present one showed all morphological characters and the most morphologically similar species was A. spiniceps.

A new species of Microsporidia found in the marine teleost Sparus aurata collected from Hurghada coasts along the Red Sea, Egypt was described based on light and ultrastructural studies. Twenty three (30.6%) out of 75 of the examined fish were parasitized with a microsporidian parasite. Numerous macroscopic whitish cysts embedded in the peritoneal cavity were observed to infect many organs of the body including muscles, connective tissues, and the intestinal epithelium. The infection was developed as tumor-like masses of often up to 5 mm in diameter inducing an enormous hypertrophy to the infected organs. Fresh spores appeared mostly ovoid to pyriform in shape reaching a size of 1.7 ± 0.5 (1.5-2.5) μm × 1.3 ± 0.4 (1-2) μm; they possessed a large vacuole at the posterior end. These spores were located within a sporophorous vesicle which was bound by a thick amorphous wall. The ultrastructural features support the placement of the present species within the genus Microsporidium. The developmental stages were enclosed within a xenoma structure that was bounded by a double-layered cyst wall. The life cycle of the microsporidian pathogen described herein included four stages: proliferation (merogony), sporogony, sporoblast, spores, and liberation. Mature spores appeared electron dense, uninucleate, and were ellipsoidal in shape. At the anterior end of the spore, the anchoring disk was found in a central position. There was a definite number (5-11) of turns of the polar tube. A 538-bp region of the SSU rDNA gene of the studied species was sequenced (GenBank accession number: KF0220444). Multiple sequence alignment calculated a high degree of similarity (>92%) with six microsporidian species. The most closely related sequence was provided by the GenBank entry AF151529 for Microsporidium prosopium isolated from Hyperoplus lanceolatus differing in 67 nucleotide positions in its SSU rDNA with the highest percentage of identity (97.2%) and the lowest divergence value (0.20). Variations in the morphology of the spores and developmental stages between the two species revealed that the two species are different. The site of infection in the host and description of the onset of parasite development are strong criteria for the placement of the microsporidian parasite of the fish S. aurata within the genus Microsporidium as a new species, and we propose to name it Microsporidium aurata nov. sp.

Four previously unrecognized trypanorhynchids are described based on fish specimens from Sparidae and Mullidae host fish of the Red Sea. From September 2010 to June 2011, 66 specimens of the sea bream Pagrus pagrus (F: Sparidae) and 43 of the red mullet Mullus barbatus (F: Mullidae) were purchased from markets in the Suez and Hurghada cities of the Red Sea. The fishes were measured, and their organs investigated for helminth infections. Forty-one (37.6 %) out of the 109 fish specimens investigated were parasitized with Trypanorhyncha metacestodes, identified as Callitetrarhynchus speciouses Linton 1897, Pseudogrillotia sp. Dollfus 1969, Kotorella pronosoma Stossich 1901 from P. pagrus, and Nybelinia bisulcata Linton 1889 from M. barbatus in the mesentery and peritoneal cavity, with prevalences of 16.5, 11.0, 6.0, and 12.0 %. All of these larval stages were encapsulated larvae in blastocysts. C. speciouses is characterized by an elongated scolex, two bothria, a long postbulbosa, and four elongated bulbs. Pseudogrillotia sp. possesses a scolex with two lateral patelliform bothridia; posterior margins are free, not notched. A long sheath was observed, which was irregularly coiled when tentacles invaginated. N. bisulcata possesses an acraspedote scolex with four bothridia, which are broad, bean-shaped. The tentacles are spirally coiled, supplied with hooks with abruptly turned points. The four tentacles sheaths rose from scolex as two anterior (front) and two posterior (back) which overlap at the apices of bulbs. K. pronosoma is characterized by a short body with a craspedote scolex and four bothridia. The tentacles are short and emerge pairwise. The presence of Trypanorhyncha metacestodes in the muscles does not represent a risk of infection for humans. They have a negative effect on fish esthetics. The repugnant aspect and the prohibition for commercial use by sanitary inspectors, however, cause consumer rejection. Parasites of the order Trypanorhyncha have been recorded in these host fishes for the first time.

In the present study, the morphology and morphometric characterization of Dujardinnascaris mujibii (Heterocheilidae) and Hysterothylacium aduncum (Anisakidae), new nematode parasites infecting the sea bream Pagrus pagrus (Osteichthyes, Sparidae), were described for the first time from the Gulf of Suez and Hurghada City of the Red Sea, Egypt. Ninety-eight (70 %) and 62 (44.2 %) out of 140 of the examined fish were naturally infected with these nematodes, respectively. The infection was investigated macroscopically by the occurrence of these parasites in the flesh, stomach, intestines, as well as their body cavities as adult and larval stages. D. mujibii is characterized by an elongated body with a length of 36.4 ± 3 (23-38) mm (female) and 20 ± 3.0 (17-24) mm (males); the head is provided with three prominent lips each with four teeth like structures and the apical lip is embossed with a regular zigzag pattern as revealed by SEM. Interlabia were present, with prominent grooves. Juvenile stage is smaller than adults and provided with a spiny mucron. H. aduncum was small, measured 22.5 ± 2.0 (20.0-24.3) mm in length (female) and 16.3 ± 2.0 (14.5-17.4) mm (male). The head region bears three large lips which were clearly separated from each other, with the apical one having two rounded ends and the space between the two adjacent lips occupied by very prominent interlabia. The present study represents new host and locality records from P. pagrus fish in Egypt.

In the present study, the morphology and morphometric characterization of Thelohanellus niloticus sp. nov., a new myxozoan belonging to genus Thelohanellus Kudo, 1933 (Myxosporea, Bivalvulida) infecting the gills of Labeo niloticus (Osteichthyes, Cyprinidae), were described for the first time from the River Nile at El-Minia Governorate, Egypt. Forty-one out of 78 (52.6 %) of the examined fish were infected. The infection was observed as irregular, milky whitish, cyst-like plasmodia (up to 0.8 mm in diameter) attached to the gill filaments of the host fish. These plasmodia contained tear-shaped myxospores with slightly tapering anterior and rounded posterior ends. Each spore has a single pyriform polar capsule. Spores measured about 23.3 ± 0.3 (20.4-27.1) μm long and 13.4 ± 0.4 (11.5-14.2) μm wide. The polar capsule was 11.7 ± 0.3 (9.2-12.5) μm long and 4.7 ± 0.3 (3.5-6.2) μm wide, containing a polar filament coiled perpendicular to the longitudinal axis of the spore body making eight turns. Occasionally, an oblong, irregular-shaped mass of protoplasm with a slightly oval nucleus (1.4 μm in diameter) and a small iodinophilous vacuole measured 0.85 ± 0.2 μm (0.73-1.2 μm) were observed in the spore. Due to the lack of the second polar capsule characterizing Myxobolus sp., the present parasite is placed within the genus Thelohanellus. Based on morphological differences (compared with other members of Thelohanellus Kudo, 1933) and the host specificity, this species is described as a new one of the genus Thelohanellus recorded for the first time in Egypt.

The spore morphology and molecular systematic of a new microsporidian which was isolated from the common sea bream Pagrus pagrus (F: Sparidae Linnaeus, 1758) from the Red Sea, Egypt have been studied. Fifty-six out of 300 (18.7%) of this fish were infected with microsporidian parasites. The infection was appeared as whitish, ellipsoid, round, or elongated nodules embedded in the epithelial lining of the peritoneum and also in the intestinal epithelium. Light microscopic study revealed that nodules were encapsulated by a fibrous layer encircling numerous mature spores measuring 1.7 ± 0.6 (1.5-2.7 μm) × 1.5 ± 0.3 μm (1.2-1.8 μm) in size. Ultrastructure of spores was characteristic for the genus Pleistophora: dimorphic, uninucleate spores (each spore possesses three to five polar filament coils) and a posterior vacuole. Also, the early recognizable stages of the parasite within nodules include uninucleated, binucleated, and multinucleated meronts followed by detachment of the plasmalemma of the sporont producing sporoblasts which mature to spores that consist of a spore coat and spore contents. Also, we analyzed the small subunit ribosomal gene (SSUrDNA) using PCR and sequencing specimens from the marine populations of P. pagrus fish from the Red Sea. From blast searches, sequence analysis, and phylogenetic analysis, we did not find corresponding GenBank entries to our species. Comparison of the nucleotide sequences showed that the sequence of our microsporidium was most similar to five Pleistophora species with degrees of identity (>91.5%). It was most similar (97.8% identity) to that of Pleistophora hyphessobryconis (account no. GU126672) differing in 19 nucleotide positions and with lower divergence value, Pleistophora ovariae (96.2% identity, account no. AJ252955), Pleistophora hippoglossoideos (91.9% identity, account no. AJ252953), Pleistophora mulleri (91.9% identity, account no. EF119339), and Pleistophora typicalis (91.9% identity, account no. AJ252956). So, they likely represent new species named Pleistophora pagri sp. n. with accession number JF797622 and a GC content of 53%.

In the present study, out of 200, 120 (60%) Plectropomus maculates fish were found to be naturally infected with Kudoa sp. The infection was intensive and appeared as clusters of ovoid to ellipsoidal plasmodia being restricted to the cardiac muscles. More than 100 plasmodia were counted per infected heart and measured 1.53 ± 0.2 (1.2-2.5) × 0.65 ± 0.2 (0.63-0.80) mm. On the basis of spore morphology, the parasite was identified as Kudoa sp. The spore measures 4.8 ± 0.3 (4.7-6.8) × .0 ± 0.3 (4.6-6.5) μm. The four polar capsules were pyrifom in shape measuring 1.4 ± 0.2 (1.3-3.5) × 1.2 ± 0.2 (1.1-2.2) μm. Transmission electron microscopy showed that the plasmodia were bordered by a single membrane which invaginates into pinocytotic canals. Adjacent to the plasmodial wall, the generative cells and the early pansporoblasts were located peripherally. The developmental stages characterizing sporogenesis, capsulogenisis, and valvogenesis of the present parasites were ultrastructurally studied.

Forty-three out of 120 (35.8%) Clarias garipenus fish were found to be naturally infected with Henneguya suprabanchiae. The infection appeared as clusters of ovoid to ellipsoidal plasmodia being embedded within the hyaline cartilage of the suprabranchial organ of the fish. Histological studies indicate tissue distortion at the sites of infection. The continuous growth of the plasmodium led to deformation of the filament structure as well as disorganization and displacement of the gill lamellae. Also, a severe atrophy occurred in the hyaline cartilage of the gills and also in the gill lamellae. Based on the structure and measurements of fresh spores by light microscopy, this parasite was identified as H. suprabranchiae. Spores are oval in shape, and they measure 13 (11-14) × 3 (2-5) μm length by width. It has two polar capsules inside, each measures 3 (2.5-5) × 1 (1.5-4) μm length by width. Each polar capsule has a spirally coiled (7-9 turns) polar filament. The ultrastructural analysis showed that the plasmodia were surrounded by single-unit membrane. The generative cells and the early developmental stages were arranged at the periphery of the plasmodia, while immature and mature spores were centrally arranged. The developmental stages characterizing sporogenesis, capsulogenisis, and valvogenesis of the present parasite were ultrastructurally studied. The small subunit 18 S rDNA (SSU rDNA) gene sequences from different isolates was sequenced and compared with the sequence of the same gene from the Henneguya sp. isolated from GenBank. The phylogenetic position of the present Henneguya sp. within the genus was determined using sequence analysis of all related taxa available in GenBank, and the phylogenetic tree derived from this study is elucidated and compared with the current taxonomy of the available myxosporeans. Comparison of the nucleotide sequences and divergence showed that the SSU rDNA gene of this Henneguya species revealed 92.2% sequence identity with Henneguya exilis (acc. no. AF021881) differing in 30 nucleotides with lower divergence value.

In the present study, the morphology and morphometric characterization of Heterobothrium lineatus, a monogenean gill parasite infecting the gills and wall of the bronchial cavity of the tiger pufferfish Tetraodon lineatus, were described by means of light and scanning electron microscopy for the first time from the River Nile at Qena Governorate, South Valley, Egypt. In wet mount preparation, the adult worms exhibited an elongated body with anterior pointed and posterior broad ends. The adult worm measured 1.15-1.76 mm (1.53 ± 0.2) in length and 0.30-0.42 mm (0.35 ± 0.02) in width. Light and scanning electron microscopic observations showed the presence of two buccal organs situated anteriorly around the mouth opening. The opisthohaptor was subdivided into four pairs of clamps but had no isthmus separating it from the body proper. The present Heterobothrium species differs from all other described species in the genus, by its lower dimensions of the worm measurements and the presence of a copulatory organ armed with 12-15 genital hooks. Furthermore, it is easily distinguished from Heterobothrium tetrodonis and Heterobothrium okamotoi by the absence of a distinct isthmus, and resembles Heterobothrium lamothei described from the gills of Sphoeroides testodineus in Mexico in its general appearance and the presence of rectangular haptor with the fourth pair of clamps smaller than the previous ones.

One hundred three out of 225 (45.8%) of the Red Sea fish Saurida tumbil were infected with microsporidian parasites. The infection was recorded as tumor-like masses (whitish macroscopic cysts) or xenomas often up to 2 cm in diameter and embedded in the peritoneal cavity. Generally, the infection was increased during winter 63.8% (86 out of 135) and fall to 18.9% (17 out of 90) in summer. Light microscopic study revealed that xenomas were encapsulated by a fibrous layer encircling numerous sporophorous vesicles filled with mature spores measuring 1.7 ± 0.6 (1.5-2.7 μm) × 1.5 ± 0.3 μm (1.2-1.8 μm) in size. Ultrastructural microscopic study showed the presence of smooth membranes of the sarcoplasmic reticulum forming a thick, amorphous coat surrounding various developmental stages of the parasite. The various recognizable stages of the parasite were uninuclear, binucleated, and multinucleated meronts followed by detachment of the plasmalemma of the sporont from the sporophorous vesicle producing sporoblasts. Mature spores consist of a spore coat and spore contents. The spore contents consist of the uninucleated sporoplasm and a posterior vacuole located at the posterior end. The polar tube consists of a straight shaft and a coiled region (26-32 coils) arranged in many rows along the inside periphery of the spore. The polaroplast consisted of an anterior region of closely and loosely packed membranes. Molecular analysis based on the small subunit rDNA gene was performed to determine the phylogenetic position of the present species. The percentage identity between this species and a range of other microsporidia predominantly from aquatic hosts demonstrated a high degree of similarity (>92%) with eight Pleistophora species. Comparison of the nucleotide sequences and divergence showed that the sequence of the present microsporidium was most similar to that of Pleistophora anguillarum (99.8% identity) differing in 13 nucleotide positions. So, the present species was recorded and phylogenetically positioned as a new species of Pleistophora.

Out of 600 marine fish from the Red Sea belonging to three different species that were collected and examined for microsporidian parasites, 87 (14.5%) fish were found to be infected. The infection was recorded as cysts or xenomas embedded in the gut epithelium and the peritoneal cavity of the three fish species. The highest percent of infection with microsporidian parasites was recorded in Saurida tumbil 19.5% (39/200) followed by Pagrus pagrus 15% (45/300) and the lowest percent of infection was recorded in Epinephelus chlorostigma 3% (three out of 100). After rupture of the cysts, the spores were released and examined by light microscopy. Each spore was elongated to ellipsoidal in shape and possessed a posterior vacuole which is characteristic to phylum Microspora. They measure 1.6 ± 0.5 μm (1.5-2.4 μm) × 1.3 ± 0.1 μm (1.3-2.0 μm) in Saurida tumbil and Pagrus pagrus, respectively. The spores of Pleistophora sp recorded from E. chlorostigma were ovoid to pyriform in shape and measure 1.9 ± 0.5 μm (1.8-2.7 μm) × 1.6 ± 0.4 μm (1.5-2.4 μm).

The life cycle of a new microsporidian of the genus Pleistophora is described. This parasite infects the epithelial cells of the gut and the peritoneal cavity of the Red Sea fish, Epinephelus chlorostignei. All stages develop within a special structure, the sporophorocyst, which is covered by a thick dense wall. This wall grows along with the growth of the parasites inside. Meronts are uni- to binucleate, which divide and constantly give rise to sporonts. During transition to sporonts, the cell border of the meronts increases its thickness, temporarily featuring thick irregular projections. Eventually, a uniform thick sporont wall is formed; then, the sporont cells detach themselves from the wall (future wall of the sporophorous vesicle, SPV) and start a series of divisions to produce sporoblasts. The SPV wall is compact, has no pores, and consists of two layers. Mature spores measure about 2.0 x 1.8 microm. They possess a polar filament with 20-28 coils, a posterior vacuole, and a polaroplast made up of an outer part of dense and closely spaced lamellae encircling an inner part of widely spaced lamellae. All morphological and ultrastructural features indicate that the described microsporidian parasite belongs to the genus Pleistophora.