Phthinomita, Nolan & Cribb, 2006

Nolan, Matthew J. & Cribb, Thomas H., 2006, An exceptionally rich complex of Sanguinicolidae von Graff, 1907 (Platyhelminthes: Trematoda) from Siganidae, Labridae and Mullidae (Teleostei: Perciformes) from the Indo-west Pacific Region, Zootaxa 1218 (1), pp. 1-80 : 32-33

Phthinomita n. g.

Diagnosis

Body thread­like, elongate, cylindrical to ovoid, of consistent width through mid section, curving dorsally posteriorly, notched at level of male genital pore. Tegumental spines in incomplete lateral transverse rows, along entire length of body; 2–9 spines per row, covered in mucus or tegument. Tegumental papillae surround genital pores. Oral sucker vestigial, delimited posteriorly by constriction of body wall, internally separated from body proper by thin septum; sucker bearing 5–7 concentric rows of fine spines. Mouth opening ventro­subterminally, surrounded by vestigial oral sucker, opening between last spine row and body constriction. Oesophagus straight. Intestine H­shaped; anterior caeca short, unequal; posterior caeca longer than anterior pair, sinuous, unequal; right posterior caecum longer than left posterior caecum. Testes two; anterior testis originating posterior to, or in posterior half of, intercaecal field, rectangular or somewhat helical, margins irregular; posterior testis poorly developed (rudimentary), ovoid to elliptical, posterior to terminal genitalia, at posterior extremity of body. Vas deferens passing posteriorly from anterior testis; duct from posterior testis passing antero­ventrally. Auxiliary external seminal vesicle absent. Cirrus­sac present, antero­dorsally directed. Internal seminal vesicle spherical to ovoid; ejaculatory duct antero­dorsally directed. Male pore opening on dorsal surface, medial. Ovary triangular to ovoid, posterior to, abutting or slightly overlapping posterior margin of anterior testis. Oviduct originating at posterior margin of ovary, passing posteriorly, dextral to cirrus­sac and vas deferens, joining with vitelline reservoir, entering oötype posteriorly. Oviducal seminal receptacle absent. Oötype elliptical to ovoid, antero­ventrally directed, posterior to cirrus­sac, anterior to posterior testis, dorsal to vitelline duct. Mehlis’ gland prominent; gland cells extensive, extending posteriorly to posterior end of body, extending anteriorly to cirrus­sac. Laurer’s canal absent. Canalicular seminal receptacle absent. Uterus extending anteriorly from oötype, ventral to cirrus­sac and vas deferens, dorsal to vitelline duct and vitelline reservoir, posterior to, abutting or overlapping posterior margin of ovary passes posteriorly, expanding to form uterine chamber, narrowing posteriorly before opening at female genital pore. Uterine chamber originates at point where proximal portion of uterus (that passing anteriorly from oötype) passes posteriorly toward female pore, sinistral to ovary and oviduct, dorsal to proximal portion of uterus, vas deferens, vitelline duct and vitelline reservoir, extending from ovary to anterior margin of cirrus­sac, not muscular or surrounded by gland tissue. Metraterm absent. Female genital pore opening on dorsal surface, antero­dextral to male pore. Vitellarium follicular; vitelline follicles tightly compacted, clumped in round or square clusters, anteriorly ventral and sinistral to oesophagus, intestine and anterior testis, extending posteriorly past posterior margin of ovary, ventral to vas deferens, ovary and uterus. Vitelline duct forming posterior to posterior margin of ovary, passing posteriorly ventral to vas deferens, cirrus­sac, uterus and Mehlis’ gland. Excretory vesicle elliptical; two discernable anteriorly directed arms seen at anterior margin. Excretory pore terminal. Parasites of the intertrabecular spaces of ventricle, atrium and bulbus arteriosus (heart) of Indo­Pacific marine fishes ( Labridae , Mullidae and Siganidae ).

Etymology

Generic name from “ Phthino ” (Gr. waste away, wave, decline, perish) and “ Mitos ” (Gr. thread), for the rudimentary second posterior testis and the general appearance of these worms.

Type species Phthinomita symplocos n. sp. from Siganus lineatus (Valenciennes) off Lizard Island.