Piscianchitrema, Dronen & Karar & Blend, 2020

Dronen, Norman O., Karar, Yasser F. M. & Blend, Charles K., 2020, A new genus and species of Anchitrematidae Mehra, 1935 (Digenea: Gorgoderoidea) in a freshwater fish from the River Nile at Qena, Egypt with amendation of the family, Zootaxa 4780 (2), pp. 367-378 : 369

Genus Piscianchitrema n. gen.

Type species: Piscianchitrema nilense n. gen, n. sp.

Etymology: The generic designation is in recognition of the Anchitrema -like type of species being described from a fish host, “Pisci” (Latin).

Diagnosis: Body elongate-oval to lingulate, spinose. Forebody about one-third of body length. Thick, shelflike rim continuous around most of ventral aspect of periphery of distome, more laterally extensive in forebody, not joined posteriorly, somewhat reminiscent of incomplete scoop of species of Bianium Stunkard, 1930 (Lepocreadiidae) , but rim extends more posteriorly to near posterior extremity of body; rim of lateral aspect of forebody composed of large internal patches of lightly vacuolated, somewhat glandular cells that form pads similar to those described for species of Pelopscreadium Dronen, Blend, Khalifa, Mohamadain & Karar, 2016 . Oral sucker spherical to elongate-oval, subterminal. Ventral sucker spherical, pre-equatorial. Prepharynx absent; pharynx spherical to slightly oval; esophagus short; ceca long, extend close to posterior extremity; ani absent.

Testes two, irregular, side by side, largely extra-cecal, situated near midbody in space from ventral sucker to short distance posterior to midlevel of body. Cirrus apparatus of typical anchitrematid type (see Fig. 2 ); cirrus sac large, delicate, nearly round, medial, situated immediately anterior to ventral sucker; seminal vesicle tubular and convoluted, winds extensively throughout cirrus sac. Genital pore near midline of body, located about halfway between anterior and posterior margins of cirrus sac; distinct genital atrium present.

Ovary entire, post-testicular, situated near midlevel of body. Laurer’s canal present. Canalicular seminal receptacle not known, uterine seminal receptacle present. Uterus extensively folded, uterine loops largely fill post-ovarian space with descending and ascending uterine limbs; metraterm distinct, extensive, extends posteriorly from cirrus sac to near level of anterior margin of ovary. Vitellarium post-testicular in lateral fields, terminates short distance anterior to posterior extremity on both sides, largely extra-cecal. Eggs oval, operculate.

Excretory vesicle Y-shaped. Excretory pore terminal or slightly subterminal. In insectivorous-prone freshwater fish.

Remarks: The presence of the thick, continuous rim around the periphery of the distome along most of its extent, the lateral aspect of the forebody being composed of large internal patches of vacuolated, somewhat glandular cells that form pad-like structures that are strikingly similar to the “pelops” of species of Pelopscreadium , and the presence of a uterine seminal receptacle are characteristics that have not been found previously in species in the family, and along with having a freshwater fish host, we feel these differences warrant the erection of Piscianchitrema n. gen. This unusual morphology was obvious in all specimens both pre- and post-restaining and remounting.

Figures

FIGURES 1–3. Piscianchitrema nilense n. gen, n. sp. from a freshwater fish in Egypt. 1. Adult specimen, ventral view. 2. Terminal genitalia showing details of cirrus sac, ventral view. 3. Details of female genital complex, ventral view. Abbreviations: A, ventral sucker; C, cecum; E, newly-formed eggs; F, vitelline follicles; G, genital pore; M, Mehlis’ glands; O, oral sucker; Ov, ovary; P, prostatic cells; Ph, pharynx; R, uterine seminal receptacle; T, testes; U, uterus; V, seminal vesicle; Y, vitelline reservoir