Macvicaria heronensis Bray & Cribb, 1989

Aken'Ova, Thelma, Cribb, Thomas & Bray, Rodney, 2008, Eight new species of Macvicaria Gibson and Bray, 1982 (Digenea: Opecoelidae) from temperate marine fishes of Australia, ZooKeys 1, pp. 23-58 : 46-48

Macvicaria heronensis Bray & Cribb, 1989

Host: Trachinotus coppingeri (Gunther) (Carangidae) .

Locality: Off Point Lookout, Stradbroke Island, Queensland. 27°26'S, 153°32'E.

Site: Intestine.

Material studied: 1 from off Point Lookout, Stradbroke Island, Queensland. Voucher specimen: QM G 230423.

Description ( Figs 30-32 )

Based on 1 gravid unflattened whole-mount specimen. Measurements are of the single gravid, unflattened whole-mount.

Body fusiform, pointed at anterior and posterior ends, maximum width in region of ventral sucker; 1,101 × 243; width to length ratio 1:4.5. Oral sucker ventrally subterminal, sub-spherical, 78 × 88. Ventral sucker larger than oral sucker, transversely oval, protuberant, surrounded by tegumental fold, in posterior part of anterior half of body; 136 × 169, sucker-width ratio 1:9. Forebody moderately long, 389 long, 35.3% body-length. Prepharynx distinct, short, almost entirely dorsal to oral sucker. Pharynx well developed, subglobular, 45 × 58; pharynx to oral sucker width ratio 1:1.5. Oesophagus distinct, moderately long. Intestinal bifurcation in anterior half of forebody, 156 anterior to ventral sucker. Caeca reach close to posterior extremity, terminate blindly. Excretory pore terminal. Excretory vesicle I-shaped, extends anteriorly to overlap posterior margin of ovary.

Testes 2, entire, sub-spherical, tandem, contiguous, in posterior third of body; anterior 58 × 71; posterior 97 × 65. Post-testicular area 207 long, 18.8% body-length. Cirrus-sac long, narrow, claviform, sigmoid anteriorly, thick walled, 266 × 39; extends from point just posterior to posterior margin of pharynx to overlap anterior margin of ventral sucker dorsally. Internal seminal vesicle tubular, long, narrow, loops anteriorly, occupies more than half of cirrus-sac. Pars prostatica distinct, small, surrounded by gland cells. Ejaculatory duct long, narrow, thick walled. Genital atrium small. Genital pore antero-sinistral to intestinal bifurcation, situated just posterior to posterior margin of pharynx, closer to lateral margin of body than median line, 136 from anterior end, 12.4% of body-length.

Ovary pretesticular, entire, subspherical, contiguously antero-dextral to anterior testis, 65 × 55. Mehlis’ gland indistinct. Canalicular seminal receptacle large, saccate, dorsal to ovary. Laurer’s canal present. Uterus coils between anterior testis and posterior margin of ventral sucker, passes dorsally to cirrus-sac. Eggs large, oval, operculate, 68- 84 (76) × 29-32 (31). Metraterm dorsal to ejaculatory duct. Vitelline follicles extend from 156 from anterior extremity, 14.2% body-length, to 39 from posterior extremity; follicles confluent dorsally in forebody and dorsally and ventrally in post-testicular area, in 2 separate fields ventrally in forebody; dorsal, ventral and lateral fields interrupted in ventral sucker area; fields lie lateral, ventral and dorsal to caeca; anterior extent level with genital pore.

Comments: Bray & Cribb (1989) described Macvicaria heronensis from the lethrinids Lethrinus chrysostomus and Gymnocranius audleyi [= bitorquatus] from off Heron Island. Barker et al. (1994) subsequently recorded it from the pomacentrid Parma polylepis . This is the third report, and for the first time, from a carangid in temperate waters. The worm in this study compares more or less favourably with the one figured as 9B in Bray & Cribb (1989), except that in our specimen the uterus extends posteriorly to overlap the anterior margin of the anterior testis, whereas in Bray & Cribb’s specimens, the uterus reaches only to the anterior margin of the anterior testis and they mentioned that in three of their specimens, the uterus overlapped the anterior testis only slightly. The forebody in our worm is also slightly longer than in Bray and Cribb’s worms, 35% versus 31-32% of the length of the body. These differences may simply extend the variation of M. heronensis , or may link it to M. issaitschikovi , whose uterus has been illustrated and described by Layman (1930), Yamaguti (1938) and Manter & Van Cleave (1951) as extending to the posterior edge of the anterior testis. Further comments on points of comparison between our worm and the worms described by Bray & Cribb (1989) should await examination of more specimens from temperate waters to determine whether or not more than one species is involved.

Figures

Figs 30-32. Macvicaria heronensis Bray & Cribb, 1989 ex Trachinotus coppingeri. 30. Whole-mount ventral view. 31. Terminal genitalia. 32. Dorsal distribution of vitelline follicles. Scale bars: 30, 32, 250 µm; 31, 100 µm.