Macvicaria mekistomorphe Aken' Ova, Cribb & Bray 2008

Based on 4 gravid, whole-mount specimens from Sillago maculata. Measurements are of 4 gravid, unfl attened whole-mount worms. Body elongate oval; width recorded from area of gonads although greatest in region of the ventral sucker, 1440-1904 (1724) × 287-382 (346); width to length ratio 1:4.7-5.2 (5.0). Tegument with irregularly dispersed papillate structures. Oral sucker ventrally subterminal, sub-spherical, 109-154 (130) × 122-160(141). Ventral sucker larger than oral sucker, transversely oval, borne on slight eminence, in anterior third of body, 160-218 (189) × 192-237 (211); sucker width ratio 1:1.4- 1.6 (1.5). Forebody relatively short, 371-467 (414) long, 24.5-25.8 (24.9)% bodylength. Prepharynx, indistinct, short, may be entirely dorsal or posterior to oral sucker. Pharynx well developed, sub-spherical, 77-102 (90) × 83-128 (107); pharynx to oral sucker width ratio 1:1.2-1.5 (1.3). Oesophagus short, thick walled. Intestinal bifurcation 55-104 (81) anterior to ventral sucker. Caeca terminate blindly close to posterior extremity. Testes 2, entire, usually separate, occasionally contiguous (n=1), tandem, in posterior half of body, anterior 134-173 (154) × 128-154 (141); posterior 154-192 (170) × 125-173 (142). Post-testicular area 339-512 (426) long, 21.0-26.9 (24.5)% bodylength. Cirrus-sac well developed, claviform, extends from point sinistral to oesophagus, overlapping ventral sucker dorsally usually to point just anterior to or level with its posterior margin, occasionally to ventral sucker aperture (n=1), 272-305 (294) × 71-78 (75). Internal seminal vesicle tubular; anterior portion narrower than posterior, loops once, occupies most of broad posterior portion of cirrus-sac. Pars prostatica distinct, narrow, surrounded by gland cells. Ejaculatory duct well developed, surrounded by numerous gland cells. Genital atrium distinct, small. Genital pore antero-sinistral to caecal bifurcation, may be level with posterior margin of pharynx, or on outer margin of left caecum and more or less level with posterior limit of oesophagus, 220-298 (251) from anterior end, 13-16 (15)% of body-length. Ovary entire, sub-spherical, anterior to and usually separated from anterior testis, occasionally contiguous with anterior testis (n=1), 90-134 (111) × 77-128 (101). Mehlis’ gland feebly developed, anterior to ovary. Canalicular seminal receptacle large, saccular, elongate, oval, usually overlaps ovary dorsally, occasionally displaced entirely sinistral to ovary (n=1), may extend posteriorly to overlap anterior margin of anterior testis or terminate close to posterior margin of ovary. Laurer’s canal present. Uterus coils intercaecally between anterior margin of ovary and posterior margin of ventral sucker, usually overlapping caeca dorsally and leading to genital pore without coiling. Eggs oval, operculate, 58-70 (63) × 26-29 (26). Metraterm indistinct. Vitelline follicles extend from 294-378 (336) from anterior extremity, 15.4-22.2 (19.7)% of body-length, to 38-67 (54) from posterior extremity; follicles feebly developed, particularly in forebody; fields mostly separate in hindbody, more or less confl uent in posttesticular area dorsally and ventrally; follicles lie lateral to caeca mostly, with anterior limit at about level of intestinal bifurcation. Excretory pore ventrally subterminal to terminal. Excretory vesicle I-shaped, anterior limit dorsal to posterior half of ovary, leads to pore through narrow duct. Etymology: The species name (Gr. mekistos, longest; Gr. morphe, shape) is derived from the fact that this species is the most elongate worm in its group.

Type-host: Sillago maculata Quoy & Gaimard (Sillaginidae). Type-locality: Off Tangalooma, Moreton Bay, S. E. Queensland. 27°14’S, 153°19’E. Site: Intestine.