Euryhaliotrema sagmatum, Kritsky & Boeger, 2002

Kritsky, Delane C. & Boeger, Walter A., 2002, 41: New and previously described species of Dactylogyridae (Platyhelminthes) from the gills of marine and freshwater perciform fishes (Teleostei) with proposal of a new genus and a hypothesis on phylogeny, Zoosystema 24 (1), pp. 7-40 : 26

Euryhaliotrema sagmatum n. sp.

( Fig. 9 )

TYPE SPECIMENS. — Holotype ( CNHE 4015 ); 21 paratypes ( USNPC 91422 , HWML 16429 , CNHE 4016 , MNHN 26 HG Tg 157-158).

ETYMOLOGY. — The specific name is from Greek (sagmatos = a saddle) and refers to the germarium forming a saddle over the anterior end of the testis.

TYPE HOST AND LOCALITY. — Gills of Umbrina xanti (Sciaenidae) : Chamela Bay, Jalisco, Mexico, 19°28’N, 105°08’W, 5. VI.1999.

DESCRIPTION

Body 870 (753-1016; n = 9) long, flattened dorsoventrally; greatest width 244 (194-301; n = 9) usually at level of testis. Cephalic region broad, short; cephalic lobes moderately to well-developed. Eyes subequal, members of posterior pair farther apart than members of anterior pair; accessory granules in cephalic region. Pharynx subspherical, 81 (67-95; n = 11) in greatest width, with posterior circular lobe. Peduncle broad, tapering posteriorly; haptor subovate, 105 (88-117; n = 6) wide, 58 (50-62; n = 6) long. Ventral anchor 26 (24-28; n = 4) long, with large perpendicular superficial root, short deep root, short evenly curved shaft, point reaching level of tip of superficial root; base 20 (18-21; n = 3) wide. Dorsal anchor 20 (19-21; n = 8) long, delicate, with elongate superficial root, short deep root, evenly curved short shaft, point not reaching level of tip of superficial root; base 17 (16-18; n = 8) wide. Ventral bar 30 (28-33; n = 12) long, yoke shaped, with anteromedial swirled protuberance, posterior shield absent; dorsal bar 37 (35- 41; n = 10) long, broadly U-shaped, expanded medially. Hook 12 (11-13; n = 16) long, shank uniform; FH loop about shank length. Copulatory organ 97 (78-105; n = 10) long, a coil of about one and a half counterclockwise rings; coil diameter 18 (17-20; n = 9). Accessory piece 47 (43-53; n = 9) long, comprising rod with complex distal pincher-like termination, lacking articulation process. Testis 144 (122-171; n = 4) long, 74 (65-88; n = 4) wide, ovate; seminal vesicle forming C-shaped loop posterior to base of copulatory organ; one prostatic reservoir lying within loop of seminal vesicle. Germarium 165 (148-187; n = 7) long, 58 (41-65; n = 7) wide, usually proximally bilobed, overlying anterior end of testis; oviduct extending ventral to seminal receptacle; ootype not observed; uterus delicate, ventral. Vaginal aperture dextroventral, with muscular-appearing posterior thickened wall distally; vaginal canal tubular, straight to slightly arced anteriorly, with proximal end indenting seminal receptacle. Seminal receptacle medial, irregular, pregermarial. Vitellaria dense.

REMARKS

Euryhaliotrema sagmatum n. gen., n. sp. is sister species to E. bychowskyi n. comb. Both species are relatively large dactylogyrids with dorsoventrally flattened bodies, an anteromedial protuberance on the ventral bar, and a vaginal tube that indents the seminal receptacle. They differ in comparative morphology of the dorsal and ventral anchors (small, delicate in E. sagmatum n. gen., n. sp.; base massive in E. bychowskyi n. comb.).

Figures

FIG. 9. — Euryhaliotrema sagmatum n. gen., n. sp.; A, whole mount (ventral view); B, vagina (ventral view); C, hook; D, copulatory complex (ventral view); E, ventral bar; F, dorsal bar; G, ventral anchor; H, dorsal anchor. Scale bars: A, 200 µm; B-H, 25 µm.