A new species of Myxinidocotyle (Monogenea: Acanthocotylidae: Myxinidocotylinae) from captive sixgill hagfish, Eptatretus hexatrema (Chordata: Myxinidae), with amendment of the subfamily diagnosis

Abstract

Myxinidocotyle eptatreti n. sp. is described from the skin of the sixgill hagfish, Eptatretus hexatrema collected for exhibition at the Two Oceans Aquarium in Cape Town, South Africa. The new species is the first acanthocotylid described from South Africa and differs significantly from the only two known Myxinidocotyle species by the morphology of the sclerotised male copulatory tube and the presence of a diverticulated intestinal caecum. The subfamily diagnosis is amended to include a single seminal receptacle, found within the anterior concave portion of the ovary and excludes the vaginal seminis receptaculum which is considered the seminal vesicle. The vagina travels ventrally over the seminal vesicle and does not fuse with it bilaterally as originally proposed by Malmberg & Fernholm (1989). Myxinidocotyle spp. possess 8 or 9 testes. The proximal male accessory gland reservoirs are connected by an intricate network of fine ducts to the field of extensive male accessory gland cells extending along the length of the body proper. Observations on the locomotion and attachment of live worms in vitro are discussed and the presence of adhesive secretions is confirmed for the haptoral glands and anterior glands.