(Figs. 92–97)

Type host and locality: Mahogony snapper, Lutjanus mahogoni (Cuvier) (Lutjanidae): 5 mi. E of Maria Chiquita, Colón, Panama (coordinates not available), 14 November 1972.

Site of infection: Gills.

Specimens studied: Holotype, USNPC 101364; 9 paratypes, USNPC 101365, BMNH 2008.11.19.57-60.

Etymology: This species is named for Dr. E. V. Zhukov, formerly of the USSR Academy of Sciences, Leningrad, Russia, in recognition of his pioneering work on the monogenoids of the Gulf of Mexico.

Description: Specimens contracted and in poor condition; greatest width of body usually at level of gonads; peduncle frequently elongate. Cephalic lobes poorly developed. Eyespots apparently lacking lenses. Pharynx subspherical. Testis subspherical; vas deferens, seminal vesicle not observed. MCO comprising small cup-shaped base, gently tapered sigmoid tubular shaft; shaft a near imperceptible coil (direction undetermined). Prostate, prostatic reservoir not observed. Germarium subovate. Vaginal pore, vagina, seminal receptacle not observed. Ventral anchor with elongate tapered superficial root, short deep root, slightly curved shaft, recurved point; distal shaft and point with delicate superficial grooves. Dorsal anchor with elongate slender superficial root, inconspicuous deep root with lightly sclerotized flap, straight shaft, recurved point; distal shaft and point superficially grooved. Ventral bar with 2 anteromedial pockets, ends directed posterolaterally; dorsal bar forming wide U. Hook distribution typical, except some hooks frequently on trunk at level of testis.

Measurements: Body 238 (204–290; n = 8) long; greatest width 107 (96–120; n = 9). Haptor 65 (54–75; n = 8) long, 73 (68–77; n = 8) wide. Pharynx 23 (21–28; n = 8) wide. MCO 58 (46–67; n = 9) long. Ventral anchor 43 (40–46; n = 10) long; dorsal anchor 59 (56–62; n = 10) long. Ventral bar 36 (35–37; n = 9) long; dorsal bar 36 (34–38; n = 9) long. Hook 12 (11–13; n = 14) long. Germarium 27 (21–32; n = 3) long, 24 (21–29; n = 3) wide; testis 40 (36–42; n = 3) long, 37 (35–40; n = 4) wide.

Remarks: Specimens of this species were mounted by personnel of the Gulf Coast Marine Laboratory prior to initiation of this study. All specimens were mounted unstained in glycerine jelly, are strongly contracted, and are in generally poor shape, which precluded obtaining some information on soft internal structures. The MCO of H. zhukovi resembles that of H. cornigerum and H. heteracantha, both species of which have been recorded from the mahogony snapper in the Gulf of Mexico by Zhukov (1976). Haliotrematoides zhukovi differs from these species by lacking spurs on the inner surface of the shafts of the anchors (present on dorsal anchors of H. cornigerum and on both dorsal and ventral anchors of H. heteracantha).