Towards resolving the problematic status of the digenean genus Astiotrema Looss, 1900: Taxa excluded from Astiotrema (sensu stricto) with special reference to plagiorchioid genera closely related to the restricted concept of Astiotrema.

The restricted concept of Astiotrema Looss, 1900 has been revised to include only eight species and various representative synonyms. However, several remaining taxa of Astiotrema (sensu lato) still need more inspection and scrutiny to determine their correct taxonomic position. Following a comprehensive review, four new genera are erected to accommodate some taxa excluded from Astiotrema (sensu stricto), three of which are closely related to this restricted concept of Astiotrema. Plesioastiotrema n. gen. is erected to accommodate Plesioastiotrema monticellii (Stossich, 1904) n. comb. (syn. Astiotrema monticellii Stossich, 1904) as the type-species and Plesioastiotrema magniovum (Fischthal & Kuntz, 1965) n. comb. (syn. Astiotrema magniovum Fischthal & Kuntz, 1965). Homeoastiotrema n. gen. is established for its type-species, Homeoastiotrema turneri (Bray, Van Oosterhout, Blais & Cable, 2006) n. comb., to accommodate Astiotrema turneri Bray, Van Oosterhout, Blais & Cable, 2006. Ichthyastiotrema n. gen. is erected with its type-species, Ichthyastiotrema fotedari (Dhar, 1977) n. comb. (syn. Astiotrema fotedari Dhar, 1977). A distinct morphologically and taxonomically distant taxon from Astiotrema (sensu stricto) is proposed in its own genus, Alloastiotrema n. gen. with its type-species, Alloastiotrema birmanii (Khan, Gul-E-Lala, Ghazi, Khatoon, Waheed & Khan, 2021) n. comb., to accommodate Astiotrema birmanii Khan, Gul-E-Lala, Ghazi, Khatoon, Waheed & Khan, 2021 and positioned distant from Astiotrema (sensu stricto). Astiotrema erinaceum (Poirier, 1886) Stossich, 1904, Astiotrema trituri Grabda, 1959 and Astiotrema (Biguetrema) tananarivense Deblock & Capron, 1962 are adopted synonyms of Galactosomum erinaceum (Poirier, 1886) Bittner & Sprehn, 1928, Neoastiotrema trituri (Grabda, 1959) Tkach, 2008 and Laiogonimus tananarivensis (Deblock & Capron, 1962) Fischthal & Thomas, 1968, respectively. Astiotrema lazeri El-Naffar, Saoud & Hassan, 1984 and Astiotrema gangeticus Gupta & Singh, 1985 nec Harshey, 1932 are synonymized with Glossidium pedatum Looss, 1899 and Orientocreadium batrachoides Tubangui, 1931, respectively. Based on its contradiction to the diagnosis of members of the Orientocreadiidae Yamaguti, 1958, we declare Orientocreadium lucknowensis Nigam, Chandra, Johri & Saxena, 2015 as incertae sedis. Longigula Qiu, Zhang & Li, 1983 and Kalipharynx Boeger & Thatcher, 1983 are morphologically closest to Astiotrema (sensu stricto) compared to members of the Plagiorchiidae Lühe, 1901 based on both genera possessing a cirrus-pouch with a unipartite, saccular seminal vesicle. The problematic status of Pseudoparamacroderoides Gupta & Agrawal, 1968 (sensu lato), the closest related genus to Astiotrema (sensu stricto), is discussed through evaluating the differential characteristics among listed species to indicate the extent of their validity and identifying the genuine species within this genus to re-evaluate the confusing and overlapping species to help understand their relationships with closely related plagiorchioids. Accordingly, only three species are recognized within Pseudoparamacroderoides Gupta & Agrawal, 1968 (sensu stricto): Pseudoparamacroderoides dongthapensis Truong, Curran & Bullard in Truong, Curran, Dutton & Bullard, 2021; Pseudoparamacroderoides pseudobagri (Wang in Wang, Zhao, Chen & Tao, 1983) n. comb. (syns. Astiotrema pseudobagri [Wang in Wang, Zhao, Chen & Tao, 1983] Karar, Blend, Dronen & Adel, 2021; Gauhatiana pseudobagri Wang in Wang, Zhao, Chen & Tao, 1983); and Pseudoparamacroderoides seenghali Gupta & Agrawal, 1968 (Syn. Pseudoparamacroderoides vittati Kakaji, 1969 n. syn.). Pseudoparamacroderoides raychaudhurii Agarwal & Kumar, 1983 is re-evaluated as Alloglossidium raychaudhurii (Agarwal & Kumar, 1983) n. comb. Anomalomacroderoiditrema n. gen. is erected for the type-species, Anomalomacroderoiditrema keni (Agarwal & Agarwal, 1984) n. comb., to accommodate specimens of Pseudoparamacroderoides keni Agarwal & Agarwal, 1984. Although the morphological convergence of Gauhatiana Gupta, 1953 within the Plagiorchioidea Lühe, 1901 has been suggested, it is neither a plagiorchiid nor a macroderoidid and does not appear closely related to Astiotrema (sensu stricto); it evidently is a member of the Monorchiidae Odhner, 1911. Alloglyptus Byrd, 1950 is taxonomically positioned as a gorgoderoid in the Allocreadiidae Looss, 1902, neither a plagiorchioid taxon nor closely related to Astiotrema (sensu stricto). The ambiguity of the seminal receptacle in some taxa of Astiotrema is discussed.

New host record, Sclerophrys regularis (Bufonidae), for Rhabdias africanus (Rhabdiasidae, Kuzmin, 2001) based on molecular and morphological evidence.

With diversity of hosts range, most identified nematode species still lack the crucial connection between morphological and molecular make-up, which is important for precisely classifying the specimens. The present study provides the complete description of Rhabdias africanus in the new host record, Sclerophrys regularis. Fifty toad specimens were collected, and a high prevalence of R. africanus infection (74%) was observed. Morphology and ultrastructure were observed using light and scanning electron microscopes. Morphological characteristics, including peculiarities of the head, the shape and position of the lips, and the number of labial papillae, were described. The length of the body, the esophageal length, the distance from an anterior end to the nerve ring, and the tail length were reduced in the studied samples relative to previously described specimens. Furthermore, some variable matrices that have not previously been described, e.g., ovarian part widening, the nerve ring and its location, and eggs with different stages of larvae, were included in the present study. Genus and species identification was confirmed by comparing partial 12S (619 bp) and ITS (878 bp) gene sequences to those of Rhabdias species deposited in GenBank. The studied species showed a 99.34% resemblance to R. africanus from South Africa. We assume our findings will aid in the molecular identification of adult and larval stages of this genus in amphibians. We strongly recommend further studies on the environmental factors that promote Rhabdias infection and transmission.

Larval cestodes infecting commercial fish of Alexandria coast along the Mediterranean Sea: morphology and phylogeny.

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.

Towards resolving the problematic status of the digenean genus Astiotrema Looss, 1900: An updated concept and revision of species composition for Astiotrema (sensu stricto).

Species of Astiotrema Looss, 1900 (sensu lato) infect a wide range of fishes, amphibians and reptilians. They also possess a considerably wide spectrum of morphological features. Several species were recognized for variable, confusing, overlapping and unspecialized morphological characters rather than for unique distinguishing features, causing continuing dispute around the validity of several species. Following comprehensive review, a revised restricted concept of Astiotrema is proposed including a morphologically strict definition. Both Tremiorchis Mehra Negi, 1926 and Astioglossimetra Bilqees, Khatoon Khan, 2002 are synonymized with Astiotrema (sensu stricto). Several nominal species are synonymized, others are excluded and characters for each recognized species are presented and explained. Only eight species are recognized: Astiotrema cyclemysi Siddiqi, 1965, Astiotrema emydis Ejsmont, 1930, Astiotrema fotedari Dhar, 1977, Astiotrema impletum (Looss, 1899) Looss, 1900, Astiotrema karachiensis (Bilqees, Khatoon Khan, 2002) n. comb., Astiotrema odhneri Bhalerao, 1936, Astiotrema ranarum (Mehra Negi, 1926) Fotedar, 1971 and Astiotrema reniferum (Looss, 1898) Looss, 1900. A key to the species of Astiotrema (sensu stricto) is presented, a comprehensive list of all host-locality records is included and host-parasite specificity is elucidated.

Light and scanning electron microscopy on Serrasentis sagittifer Linton, 1889 (Acanthocephala): Palaeacanthocephala: Rhadinorhynchidae) infecting the common sea bream in Egypt.

Serrasentis sagittifer is one of the most important acanthocephalan parasites parasitizing fish. This species attach to the intestinal wall via their armed proboscis which is anchored by rows of recurved spines. In the present study, Twenty two out of 50 fish specimens (44.0%) were found to be naturally infected by adult worms of Serrasentis Sagittifer Linton, 1889 (Acanthocephala: Rhadinorhynchidae) which were collected from the stomach and intestine of the common sea bream Pagrus pagrus (family: Sparidae) from locations along the Red Sea at Hurghada City, Egypt. The light and scanning microscopic study revealed that the adult worm possessed a proboscis which was long, cylindrical with a uniform width measured 0.81 ± 0.020 (0.77-0.84) mm in length and 0.48 ± 0.020 (0.33-0.69) mm in width. Claviform, armed with 25 (23-28) longitudinal rows of hooks which show a distinct dorsoventral asymmetry, with ventral hooks stouter, larger. Proboscis receptacle was 2.12 ± 0.30 (2.10-2.14) long, double-walled, with ganglion at mid-level; two unequal, long and thin lemnisci 2.9 ± 0.30(2.41-3.33) length, arised from the base of the neck, and extend up to the med-level of the trunk. The present species is compared morphologically and morphometrically with some of the previously recorded species isolated from different host species, which revealed that the present species should be classified as Serrasentis sagittifer with a new host record in Egypt.

A new species of the genus Heterobothrium (Monogenea: Diclidophoridae) parasitizing the gills of tiger puffer fish Tetraodon lineatus (Tetraodontidae). A light and scanning electron microscopic study.

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.