Revision of the Megaperidae Manter, 1934 n. comb. (Syn. Apocreadiidae Skrjabin, 1942) including a reorganization of the Schistorchiinae Yamaguti, 1942

Abstract

Modified and/or new keys to the four subfamilies now recognized within the Megaperidae Manter, 1934 n. comb. (Syn. Apocreadiidae Skrjabin, 1942) as well as the genera within each subfamily are presented. Two new genera, Paraschistorchis n. gen. and Plesioschistorchis n. gen., both within the Schistorchiinae Yamaguti, 1942, are erected and keys are provided to the species considered in both new genera-distinguished by possessing caeca that end either in separate ani or blindly. Plesioschistorchis callyodontis (Yamaguti, 1942) n. comb. and Plesioschistorchis haridis (Nagaty, 1957) n. comb. are re-described from new material collected from the common parrotfish, Scarus psittacus Forsskål (Perciformes: Scaridae), inhabiting the Red Sea off Egypt; S. psittacus represents a new host record for both species. The taxonomic status of Schistorchis sensu stricto Lühe, 1906 is examined and revised, a key to the four species we consider in this genus offered, and the monotypic genus Megacreadium Nagaty, 1956 declared a junior synonym of Schistorchis. Members of Schistorchis sensu stricto possess a unique "complex" (i.e. highly cellular/glandular) instead of "simple" (i.e. entirely muscular) type of oral sucker that is quite large in relation to body size; an elongate, somewhat sub-rectangular-shaped body; 5+ testes arranged in at least two rows; caeca that open via separate ani; a long post-testicular region; a median genital pore either at the anterior margin of or just anterior to the ventral sucker; and species of Schistorchis sensu stricto parasitize the intestine of marine fish within the Order Tetraodontiformes Berg. With the revision of this genus, we re-describe Schistorchis carneus Lühe, 1906 from the lower and mid-intestine of the white-spotted puffer, Arothron hispidus (Linnaeus) (Tetraodontiformes: Tetraodontidae), collected in the Red Sea off Egypt. Finally, a plea is made for further study of the Megaperidae n. comb. focusing, in particular, on the following: (1) obtaining new type/voucher materials of Plesioschistorchis manteri (Gupta & Tandon, 1984) n. comb. and Schistorchis paruchini Kurochkin, 1974; (2) elucidating the life histories (i.e. intermediate hosts) of members of the Postporinae Yamaguti, 1958 and Schistorchiinae; and (3) generating DNA sequence data for more species of megaperids to help future workers produce increasingly accurate taxonomic classifications that better reflect phylogenetic relationships within this ecologically diverse group of digeneans.

Testing the higher-level phylogenetic classification of Digenea (Platyhelminthes, Trematoda) based on nuclear rDNA sequences before entering the age of the ‘next-generation’ Tree of Life

“…Superfamily Gorgoderoidea Looss, 1901Superfamily Microphalloidea Ward, 1901Superfamily Plagiorchioidea Lühe, 1901 *The suborder Apocreadiata, and the superfamily Apocreadioidea require further scrutiny. In a recent revision of the Megaperidae Manter, 1934 based on morphological characters, the family was recognized as valid, although the family Apocreadiidae was considered a synonym of the latter (Blend et al, 2017).…”

Integrated characterisation of nine species of the Schistorchiinae (Trematoda: Apocreadiidae) from Indo-Pacific fishes: two new species, a new genus, and a resurrected but ‘cryptic’ genus

“…Members of the Apocreadiidae Skrjabin, 1942 parasitise a wide range of marine and freshwater fishes, with the family comprising four subfamilies (the Apocreadiinae Skrjabin, 1942; Megaperinae Manter, 1934; Postporinae Yamaguti, 1958; and Schistorchiinae Yamaguti, 1942) and 23 genera (Blend et al, 2017 ). The family name is presently controversial.…”

Apharyngogyliauchen callyodontis Yamaguti, 1942 (Digenea) from a New Host, the Common Parrotfish, Scarus psittacus (Scaridae) with Special Reference to its Morphological Intra-SpecificVariations

“…The present study reports A. callyodontis from another a scarid fish, Scarus psittacus from the same geographic locality (Northern Red Sea off Egypt) [See table.1]. To our knowledge, only two digenean parasites are known to infect Scarus psittacus; both Plesioschistorchis callyodontis (Yamaguti, 1942) and Plesioschistorchis haridis (Nagaty, 1957) were reported by Blend et al (2017) from off Northern Red Sea, off Sharm El-Naga, Makadi Bay and El-Halaka Fish Market, southern Hurghada, Egypt (respectively).…”

“…Wang (1977) recognized Gyliauchen thalassamae from the Sixbar wrasse, Thalassoma Hardwicke], off China Sea and characterized it from the other Gyliauchen spp. by its long ceca and absence of the oesophageal bulb (= "pharynx" of Wang [1977]) and on the basis of the later feature, Hall & Cribb (2005) investigations reassigned G. thalassamae Wang, 1977 inside Apharyngogyliauchen as Apharyngogyliauchen thalassamae (Wang, 1977) Hall & Cribb, 2005 As part of an on-going study of the Digenea parasitizing the Red Sea fishes (see Khalifa et al, 2015;Dronen et al 2016;Blend et al 2017;Khalifa et al, 2018), A. callyodontis Yamaguti, 1942 was redescribed and its comparative metric account by several authors is also given and discussed.…”