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 Author Karar, Yasser F. M. Department of Zoology, Faculty of Sciences, New Valley University, Kharga, New Valley, Egypt. & Research Associate, Laboratory of Parasitology, Department of Ecology & Conservation Biology, College of Agriculture & Life Sciences, Texas A & M University, College Station, Texas 77843, U. S. A. Author Blend, Charles K. Corpus Christi Museum of Science & History, 1900 N. Chaparral St., Corpus Christi, Texas 78401, U. S. A. & Laboratory of Parasitology, Biodiversity Research & Teaching Collection, Department of Ecology & Conservation Biology, College of Agriculture & Life Sciences, Texas A & M University, College Station, Texas 77843, U. S. A. Author Dronen, Norman O. Laboratory of Parasitology, Biodiversity Research & Teaching Collection, Department of Ecology & Conservation Biology, College of Agriculture & Life Sciences, Texas A & M University, College Station, Texas 77843, U. S. A. & The Schubot Center for Avian Health, Department of Veterinary Pathobiology, College of Veterinary Medicine & Biomedical Sciences, Texas A & M University, College Station, Texas 77843, U. S. A Author Adel, Asmaa Department of Zoology, Faculty of Sciences, South Valley University, 83523 Qena, Egypt. text Zootaxa 2023 2023-05-12 5284 3 445 495 http://dx.doi.org/10.11646/zootaxa.5284.3.2 journal article 57315 10.11646/zootaxa.5284.3.2 ef345052-79d9-488e-8753-677b445f3d5f 1175-5326 7929507 DA6684D9-508D-47A3-ACD9-D36A201086C3 Pseudoparamacroderoides pseudobagri (Wang in Wang, Zhao, Chen & Tao, 1983 ) n. comb. ( Fig. 25 ) (Syns. Astiotrema pseudobagri [Wang in Wang, Zhao, Chen & Tao, 1983 ] Karar, Blend, Dronen & Adel, 2021 n. syn. ; Gauhatiana pseudobagri Wang in Wang, Zhao, Chen & Tao, 1983 n. syn. ) Record. 1. Wang et al . (1983) . As previously mentioned, Karar et al . (2021) re-assigned G . pseudobagri into Astiotrema as A . pseudobagri based on its lack of one of the key characteristics of Gauhatiana , vitellarium divided into two separate clusters on each side of the body. Furthermore, Karar et al . (2021) considered A . pseudobagri a junior subjective synonym of A . reniferum . Karar et al . (2021) did not specify the presence of an I-shaped excretory vesicle in the specimens of Wang et al . (1983) illustrated in the original description (see Wang et al . 1983 , fig. 4). As a result of the problematic state of the specimens of Kumari et al . (1972) (discussed earlier), in particular, the variation of the excretory vesicle shape from I-shaped to Y-shaped with intermediate phases, Karar et al . (2021) did not emphasize this feature as one of the variables subject to intraspecific variation. Furthermore, species of Astiotrema ( sensu stricto ) have been recorded within the intestine of a wide variety of host groups including some freshwater fishes. However, no freshwater bagrid catfish has been reported as a host for any taxa of Astiotrema except for the disputed reports of Kumari et al . (1972) and Wang et al . (1983) . The earlier specimens of A. reniferum of Kumari et al . (1972) we now recognize as P . seenghali . Our findings indicate the specimens of Wang et al . (1983) are neither a taxon of Astiotrema nor Gauhatiana but belong to Pseudoparamacroderoides based on their high similarity to the features within the generic diagnosis of the latter, particularly, in having an I-shaped excretory vesicle, a common host group (freshwater bagrid catfishes; i.e., the yellow catfish, Tachysurus fulvidraco ) and a shared geographical distribution (Southeast Asia; Hongze Lake, China ). FIGURES 24 & 25. Pseudoparamacroderoides dongthapensis Truong, Curran & Bullard in Truong, Curran, Dutton & Bullard, 2021 and Pseudoparamacroderoides pseudobagri (Wang in Wang, Zhao, Chen & Tao, 1983 ) n. comb. 24. P . dongthapensis , ventral view, redrawn Truong et al . (2021 , fig. 1). 25. P . pseudobagri (syn. Gauhatiana pseudobagri Wang in Wang, Zhao, Chen & Tao, 1983 ), ventral view, redrawn from Wang et al . (1983 , fig. 4). Abbreviations: AT, anterior testis; BS, body spines; Ce, cecum; CP, cirrus-pouch; ED, ejaculatory duct; Eg, egg; EP, excretory pore; Es, esophagus; EV, excretory vesicle; GP, genital pore; OS, oral sucker; Ov, ovary; Ph, pharynx; PP, pars prostatica; PT, posterior testis; SR, seminal receptacle; SV, seminal vesicle; Ut, uterus; VD, vitelline duct; VF, vitelline follicle; VS, ventral sucker. Scale bars: Fig. 24 = 500 µm; Fig. 25 = 500 µm. Specimens of Wang et al . (1983) can be easily differentiated from the two recognized taxa within Pseudoparamacroderoides ( P . dongthapensis and P . seenghali ) by the following features: i) an indistinct or absent esophagus vs a short to moderately long one in P . dongthapensis and P . seenghali ; ii) a forebody less than 1/4 of body length vs larger values in P . dongthapensis and P . seenghali ; iii) tandem testes vs oblique or nearly opposite testes; iv) a cirrus-pouch predominantly dorsal to ventral sucker and extending into hindbody about 1/2 the distance between ventral sucker and ovary vs a cirrus-pouch predominantly lateral to ventral sucker and that can extend into hindbody to ovary; v) a median ovary distinctly separated by a long distance from ventral sucker vs a submedian ovary, posterolateral to ventral sucker or abutting it; vi) a seminal receptacle anteromedian to ovary vs either dextral or sinistral, posteromedian or median to ovary in P . dongthapensis and P . seenghali ; vii) larger egg size (36–39 × 21–22 μm) vs (28–33 × 10–13 μm in P . dongthapensis and 25–31 × 10–12 μm in P . seenghali ); and viii) possessing a short I-shaped excretory vesicle, wholly post-testicular, limited to the posterior half of the post-testicular space vs a long I-shaped excretory vesicle (with or without anterior swelling), wholly post-ovarian, inter-testicular, and never post-testicular, extending either anterior to or beyond anterior testis or median to posterior testis (see Gupta & Agrawal 1968 ; Kakaji 1969 ; Kumari et al . 1972 ; Truong et al . 2021 ). Accordingly, we reassign the specimens of Wang et al . (1983) as a distinct species, Pseudoparamacroderoides pseudobagri (Wang in Wang, Zhao, Chen & Tao, 1983 ) n. comb. , within Pseudoparamacroderoides ; the third species we recognize within this genus.