Euryhaliotrema potamocetes, 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 : 15-17

Euryhaliotrema potamocetes n. sp.

( Fig. 3 )

TYPE SPECIMENS. — Holotype ( INPA 405 ); 40 paratypes ( USNPC 91381 , 91382 , 91383 , 91384 , 91385 , HWML 16425 , INPA 406 a-t, MNHN 22 HG Tg 145-148).

ETYMOLOGY. — The specific name is from Greek (potam/o = river + cet/o = monster + - es = an agent or doer) and refers to the habitat of this species.

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) : 21 voucher specimens, 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 91392). Plagioscion squamosissimus (Sciaenidae) : four voucher specimens, Manaus Fish Market, Manaus, Amazonas, Brazil, 13.IX.1978 ( USNPC 91387); voucher specimen, Puerto Ayacucho Fish Market (Rio Orinoco), Amazonas, Venezuela (according to vendor, the host was imported from Caicara de Orinoco, Bolivar, Venezuela) 24.III.1999 ( USNPC 91386); 13 voucher specimens, Belém Fish Market, Iquitos, Loreto, Peru, VII.1999 ( USNPC 91388, 91389, 91390, 91391).

DESCRIPTION

Body 460 (276-619; n = 15) long, fusiform; greatest width 95 (76-129; n = 23) usually at level of testis. Cephalic region broad; cephalic lobes moderately developed. Eyes infrequently dissociated; members of posterior pair larger, closer together than members of anterior pair; accessory granules in cephalic, anterior trunk regions. Pharynx ovate, greatest width 27 (22-34; n = 20). Peduncle broad, tapered posteriorly; haptor subhexagonal, 71 (62-88; n = 15) wide, 63 (44-77; n = 16) long. Anchors similar; each with poorly defined deep root, elongate superficial root, straight shaft, point extending past level of tip of superficial root; ventral anchor 32 (30-34; n = 16) long, base 15 (13-17; n = 16) wide; dorsal anchor 29 (27-30; n = 13) long, base 14 (12-15; n = 9) wide. Ventral bar 35 (33-37; n = 9) long, straight to broadly U-shaped, ends enlarged, usually with delicate anteromedial muscle-attachment plate, posterior shield absent; dorsal bar 35 (32-38; n = 10) long, broadly U-shaped, with short broad posterior shield. Hook 14-15 (n = 38) long, with uniform shank; FH loop about shank length. Copulatory organ a coil with about two and a half counterclockwise rings, 119 (110-128; n = 5) long, coil diameter 18 (17-20; n = 28); bulbous base large. Accessory piece 19 (16-22; n = 15) long, comprising variable sheath along distal shaft of copulatory organ, articulation process attached to base of copulatory organ. Testis 70 (31-98; n = 12) long, 36 (29-45; n = 12) wide, ovate; seminal vesicle sigmoid, pyriform; two prostatic reservoirs, dextral reservoir with thick wall. Germarium irregular, 56 (24-78; n = 15) long, 29 (23-40; n = 15) wide; oviduct, ootype not observed; uterus delicate, ventral. Vaginal aperture marginal, with small distal vestibule; proximal vaginal canal a narrow sclerotized tube with posterior loop near midlength prior to discharging into large medial seminal receptacle lying anterior to germarium; vitellaria dense.

REMARKS

Euryhaliotrema potamocetes n. gen., n. sp. is the apparent sister group for the remaining species of the genus found on Plagioscion spp. and is the only freshwater species possessing an articulated copulatory organ and accessory piece. In this respect it more closely resembles E. paralonchuri n. comb. and E. atlantica n. gen., n. sp., both of which form the sister group of the freshwater clade. Euryhaliotrema potamocetes n. gen., n. sp. differs from these marine counterparts in lacking a vaginal bulb at the vaginal aperture.

Figures

FIG. 3. — Euryhaliotrema potamocetes 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, dorsal bar; G, ventral anchor; H, dorsal anchor. Scale bars: A, 200 µm; B-H, 25 µm.