Euryhaliotrema monacanthus, 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 : 19-21

Euryhaliotrema monacanthus n. sp.

( Fig. 5 )

TYPE SPECIMENS. — Holotype ( INPA 409 ); 26 paratypes ( USNPC 91408 , 91409 , 91410 , HWML 16427 , INPA 410 a-l, MNHN 24 HG Tg 153-154).

ETYMOLOGY. — The specific name is from Greek (monas = single + akantha = a thorn) and refers to the presence of a single anchor pair in the haptor.

TYPE HOST AND LOCALITY. — Gills of Plagioscion sp. (Sciaenidae) : Igarapé Zamula, Rio Negro near Barcelos, Amazonas, Brazil, 00°51’S, 62°46’W, 19.X.1996.

MATERIAL EXAMINED. — Plagioscion sp. (Sciaenidae) : Voucher specimen, Rio Paduairi (southern tributary), downstream from confluence of Rio Unini and Rio Negro above Novo Airão, Amazonas, Brazil, 02°20’S, 61°20’W, 4.X.1989 ( USNPC 91414). Plagioscion squamosissimus (Sciaenidae) : five voucher specimens, Caicara de Orinoco Fish Market (Rio Orinoco), Bolivar, Venezuela, IV.1999 ( USNPC 91411); two voucher specimens, Rio Nanay, Pampa Chica, 4.54 km west of Iquitos, Loreto, Peru, 03°45’09”S, 73°17’00”W, 7.VIII.1999 ( USNPC 91412); voucher specimen, confluence of Rio Amazonas and Rio Tamshiyaca, about 3 km south of Tamshiyacu, Loreto, Peru, 04°01’42”S, 73°08’45”W, 28.VII.1999 ( USNPC 91413).

DESCRIPTION

Body 331 (210-515; n = 16) long, fusiform; greatest width 81 (62-94; n = 14) near midlength. Cephalic region broad; cephalic lobes moderately developed. Members of posterior pair of eyes larger, closer together than members of anterior pair; eye granules variable in size; accessory granules uncommon in cephalic, trunk regions. Pharynx spherical, 21 (15-25; n = 17) in diameter. Peduncle broad, relatively long; haptor subhexagonal, 77 (68-86; n = 11) wide, 58 (44- 71; n = 15) long. Ventral anchor 32 (30-35; n = 10) long, with elongate depressed superficial root, poorly defined deep root, broadly curved shaft, point extending well past level of tip of superficial root; base 14 (12-16; n = 6) wide. Ventral bar 46 (43-50; n = 14) long, straight, rod shaped, with delicate anteromedial muscleattachment plate, posterior shield absent. Dorsal anchors, dorsal bar absent. Hook 16-17 (n = 24) long, with shank varying slightly in width; FH loop about shank length. Copulatory organ a loose coil of about two counterclockwise rings, 51 (48-53; n = 4) long, coil diameter 7 (6-8; n = 6). Accessory piece 23 (21-25; n = 5) long, comprising variable sheath terminally paralleling distal shaft of copulatory organ; articulation process absent. Testis 50 (39-60; n = 7) long, 25 (17-30; n = 8) wide, ovate; seminal vesicle pyriform; two prostatic reservoirs, pyriform. Germarium subovate to pyriform, 41 (24-53; n = 10) long, 24 (15-31; n = 10) wide, slightly overlapping testis; oviduct, ootype not observed, uterus delicate, ventral. Vaginal aperture marginal, distally funnel- shaped; vaginal canal short, straight; seminal receptacle pregermarial, pyriform to irregular; vitellaria dense.

REMARKS

Euryhaliotrema monacanthus n. gen., n. sp. differs from all congenitors in lacking a dorsal anchor/bar complex. Phylogenetic analysis suggests that this species originated within the freshwater clade of Euryhaliotrema n. gen. species and does not support proposal of a new genus for this unique species. Euryhaliotrema monacanthus n. gen., n. sp. is sister species to E. lovejoyi n. gen., n. sp. (see Remarks for E. lovejoyi n. gen., n. sp. for differentiation).

Figures

FIG. 5. — Euryhaliotrema monacanthus n. gen., n. sp.; A, whole mount (composite, ventral view); B, vagina (ventral view); C, hook; D, copulatory complex (ventral view); E, ventral bar; F, ventral anchor. Scale bars: A, 100 µm; B-F, 25 µm.