Macrolecithus papilliger sp.nov. (Digenea: Allocreadiidae, Stossich, 1904) from Phoxinus phoxinus (L.). Morphology, histochemistry and egg capsule formation

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Abstract
Macrolecithus papilliger sp.nov. from the stomach and intestine of Phoxinus phoxinus (L.) is described and its systematic position discussed. The life span in the fish, in captivity during January, is 5–6 weeks. The sequence of events in release of oocytes from the ovary and egg capsule formation has been observed in living specimens. Mature oocytes, in the ovary, are enclosed in groups of eight in a transparent membrane which ruptures, releasing them singly into the ovicapt. The egg capsule is formed in two stages: a transparent membrane is secreted, probably by Mehlis's gland, around the oocyte and vitelline cells in the ootype; later this is reinforced by vitelline globules released from the vitelline cells. These coalesce on the inner side of the membrane. The operculum is formed in the ootype. Histochemical tests support the observations.I would like to express my gratitude to Mr S. Prudhoe, British Museum (Nat. Hist.), for helpful comments on this species and to Mr M. C. Bibby and Mrs M. Fisher for technical assistance.The work was supported by a grant from the Science Research Council, for which I am most grateful.