Macrourimegatrema brayi Blend & Dronen & Armstrong 2004, n. sp.

Macrourimegatrema brayi n. sp. (Figs. 1–3)

Synonyms: Genus novum B, species nova #1 of Armstrong (1974); Opecoelidae gen. n. B, sp. n. #1 of Bray (1995, p. 182, 184); Genus novum A, species nova of Blend (1996); Opecoelidae indet. of Klimpel et al. (2001, p. 63, 64).

Type­host: Bathygadus macrops Goode & Bean, Macrouridae, Gadiformes, bullseye grenadier, TCWC symbiotype 10608.02.

Type­locality: Northeastern Gulf of Mexico, 28°53'N, 86°57'W, depth = 655 m, 29 June 1971.

Other hosts: Bathygadus favosus Goode & Bean, TCWC symbiotype 6303.25; Bathygadus melanobranchus Vaillant, Vaillant’s grenadier, TCWC symbiotype 7038.03; Gadomus arcuatus (Goode & Bean), doublethread grenadier, TCWC symbiotype 8801.02, Macrouridae, Gadiformes.

Other localities: Northeastern, northcentral, and western Gulf of Mexico, 23°17'N, 97°02'W, depth = 1,006 –1,079 m, 12 July 1976; 27°28'N, 85°13'W, depth = 728 m, 22 June 1971; 27°38'N, 85°15'W, depth = 637 m, 23 June 1971; 28°02'N, 85°37'W, depth = 583 m, 24 June 1971; 28°15'N, 86°06'W, depth = 586 m, 26 June 1971; 28°17'N, 86°21'W, depth = 655 m, 26 June 1971; 28°22'N, 86°31'W, depth = 710 m, 26 June 1971; 28°29'N, 86°58'W, depth = 783–841 m, 13 May 1985; 29°12'­ 29°15'N, 87°36'­ 87°45'W, depth = 709–793 m, 01 July 1999; 30°11'N, 88°45'W, depth = 13 m, 12 June 1971 (host caught in deeper water but expected to have been snagged/left in trawl and collected at this shallower station); Caribbean Sea off Panama, 9°05'N, 81°18'W, depth = 591 m, 29 October 1970; Caribbean Sea off Colombia, 9°32'N, 76°38'W, depth = 1,454 m, 03 November 1970.

Site: Pyloric cecum; intestine.

Deposited specimens: BMNH holotype 2004.3.18.95, BMNH paratypes 2004.3.18.67–94, BMNH vouchers 2004. 3.18.5–66, USNPC paratypes 094587.00­ 094589.00, USNPC vouchers 094590.00­094593.00, HWML vouchers 45684­45693, CNHE vouchers 4939–4940.

Prevalence: B. macrops 11% (33/303); B. favosus 19% (4/21); B. melanobranchus 16% (5/31); G. arcuatus 40% (4/10).

Intensity: B. macrops range 1–88; B. favosus range 1–6; B. melanobranchus range 1– 2; G. arcuatus range 1–2.

Mean intensity: B. macrops 4.2 (138/33); B. favosus 2.8 (11/4); B. melanobranchus 1.2 (6/5); G. arcuatus 2.5 (10/4).

Relative density/abundance: B. macrops 0.5 (138/303); B. favosus 0.5 (11/21); B. melanobranchus 0.2 (6/31); G. arcuatus 1 (10/10).

Etymology: The generic designation in part comes from the family of fish parasitized by this digenean (macrourids) and the Greek “mega,” referring to the large size of this parasite, and “trema” for trematode. The species designation is for Dr. Rodney A. Bray, Department of Zoology, BMNH in recognition of his long­standing contributions to our knowledge of the helminths of deep­sea fishes.

Description. Measurements and proportions are given in Table 2. With the characteristics of the genus. Body large, elongate, narrow, flattened dorsoventrally. Forebody short, pyriform to slightly attenuate. Hindbody slightly to deeply crenulate, occasionally ruffled, elongate with nearly parallel sides; posterior extremity rounded to lanceolate; separated from forebody by constriction. Tegument smooth. Pre­oral lobe absent. Oral sucker funnel­shaped, terminal. Acetabulum slightly protuberant, sometimes bordered by puckered margin, subspherical, wider than long, located close to anterior extremity. Prepharynx short. Pharynx muscular, oval. Esophagus long, thick­walled. Intestinal bifurcation at level of or immediately anterior to acetabulum. Ceca narrow, thick­walled with dark­staining cells, terminating blindly a short distance from posterior extremity.

Testes 2, smooth to slightly lobed, oval to subspherical, tandem, median, contiguous to short distance apart, just postequatorial in middle third of body, intercecal. Cirrus sac thinwalled, clavate to comma­shaped, extending short distance posterior to acetabulum. Seminal vesicle winding and tubular; basal portion composed of a large chamber­like region the anterior extreme of which is folded back on itself posteriorly reaching approximately halfway to posterior end of cirrus sac, then recurving anteriorly forming 2 adjacent small dilations, the most anterior of which narrows forming a short canal that proceeds anteriorly to form club­shaped sperm­filled ejaculatory duct; small dark­staining cells surrounding distal end of ejaculatory duct. Pars prostatica absent or indistinct; prostate gland cells present. Genital pore barely submedian, bifurcal or just prebifurcal, immediately anterior to or at anterior margin of acetabulum in angle formed by esophagus and left cecum.

Ovary smooth to slightly indented, subspherical to transversely elongate, median, equatorial, immediately pretesticular and far removed from acetabulum and cirrus sac. Seminal receptacle canalicular, ellipsoid to almost barbell­shaped, extending laterally, filling most of intercecal region of body just anterodorsal to ovary. Vitelline reservoir large, median to submedian, dorsosinistral and anterior to ovary, ventral to sinistral portion of seminal receptacle, with 2 pairs of preovarian vitelline ducts running laterally from reservoir. Laurer’s canal extensive, very convoluted, surrounded by dark­staining cells throughout, anterosinistral to vitelline reservoir and on opposite side of midline from majority of seminal receptacle, opening some distance anterior to level of oötype on dorsal surface just dextral to left cecum. Oviduct arising from anterosinistral margin of ovary, looping posteriorly over anterodextral margin of ovary, turning anteriorly and joining Laurer’s canal and vitelline reservoir before leading into median oötype. Uterus coiled, preovarian, extending in narrow intercecal band from ovary anterior to acetabulum where distal loop extends dorsolateral to anterior end of cirrus sac. Muscular metraterm present and surrounded by small dark­staining cells. Vitellaria follicular, circumcecal, extending laterally from at or very near level of posterior margin of acetabulum to posterior extremity, confluent in posttesticular region, lateral to testes and ovary, and present in intertesticular region, between anterior testis and ovary, and lightly in immediate preovarian space passing over uterus. Some specimens lacking vitelline follicles directly lateral to gonads. Eggs smooth, oval, yellow, non­filamented, operculate.

Excretory vesicle tubular passing between testes, sinistral to posterior testis and dextral to anterior testis, terminating at or near level of ovary. Excretory pore subterminal.