Macvicaria vitellocopiosa, Aken'Ova & Cribb & Bray, 2008

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 : 41-43

Macvicaria vitellocopiosa n. sp.

Type-host: Sillaginodes punctatus (Cuvier) (Sillaginidae) .

Type-locality: Off American River, South Australia 35°48’S, 137°46’E.

Site: Intestine, gut.

Material studied: 8 Off American River, December 1995.

Type-material: Holotype: QM G 230404, paratypes: QM G 230405 - 230414, BMNH 2008.7.5.14-19.

urn:lsid:zoobank.org:act:E89B7000-D733-4028-9B49-8314E0337519

Description ( Figs 21-23 ).

Based on 6 unflattened adult whole-mount specimens and 2 sets of serial sagittal sections and measurements of 5 gravid, unflattened, dorso-ventrally mounted worms.

Body oval, robust, sub-cylindrical, maximum width in region of gonads, 683-1,250 (978) × 254-475 (388); width to length ratio 1:2.4-2.7 (2.5). Oral sucker ventrally subterminal, subglobular, 96-142 (118) × 100-152 (130). Ventral sucker pre-equatorial, larger than oral sucker, transversely oval, 149-233 (192) × 162-267 (220); sucker width ratio 1:1.6-1.8 (1.7). Forebody 209-322 (274) long, 25-31 (28)% body-length. Prepharynx distinct usually entirely dorsal to oral sucker, sometimes posterior to ventral sucker (n=1). Pharynx well developed, large, spherical, 60-86 (76) × 62-93 (76); pharynx to oral sucker width ratio 1:1.6-1.8 (1.7). Oesophagus short, thick walled, surrounded by cluster of gland cells. Intestinal bifurcation almost level with anterior margin of ventral sucker, 3-37 (15) anterior to ventral sucker. Caeca broad, terminate blindly close to posterior extremity.

Testes 2, entire, usually more or less oblique, distinctly oblique in one specimen, contiguous, in posterior half of body, anterior often roughly triangular, 95-176 (147) × 108-212 (167), posterior 100-226 (161) × 131-200 (171). Post-testicular area 106- 269 (181) long, 15-21 (18)% body-length. Cirrus-sac elongate, claviform, extends from point sinistral to pharynx, overlapping ventral sucker dorsally, to point posterior to posterior margin of ventral sucker, almost to anterior margin of anterior testis, thick walled, particularly at rounded posterior end, 241-449 (329) × 73-123 (95). Internal seminal vesicle tubular, occupies posterior third of cirrus-sac. Pars prostatica distinct, thick walled, surrounded by numerous gland cells. Ejaculatory duct long, thick walled, loops close to junction with pars prostatica. Genital atrium inconspicuous, small. Genital pore extra-caecal, antero-sinistral to intestinal bifurcation, at level of pharynx, 150- 253 (209) from anterior extremity, 18-24 (22)% of body-length.

Ovary entire, subglobular, contiguously antero-dextral or dextral to anterior testis, 79-128 (106) × 70-130 (104). Mehlis’ gland indistinct, sinistral to ovary, anterior to anterior testis, just posterior to posterior tip of cirrus-sac, usually obscured by eggs. Canalicular seminal receptacle large, saccular, elongate oval, may be dorsal to ovary, or mostly dorsal to anterior testis overlapping right side of posterior testis dorsally. Uterine coils few, mainly between anterior testis and ventral sucker, overlapping caeca ventrally and anterior testis and left side of ovary dorsally. Eggs large, oval, operculate, 53-83 (71) × 30-52 (40). Metraterm well developed. Vitelline follicles extend from 143-255 (201) from anterior extremity, 18-23 (21)% of body-length, to 18-23 (21) from posterior extremity; in 2 separate fields in forebody ventrally, confluent in posttesticular area and covering almost all surface of posterior testis and sides of anterior testis ventrally; dorsal field almost confluent, interrupted in the area of posterior half of ventral sucker only; lie lateral and dorsal to caeca and, ventral to caeca posterior to ventral sucker; anterior extent between posterior end of oesophagus and level of pharynx ventrally, almost to anterior margin of pharynx dorsally.

Excretory pore terminal. Excretory vesicle I-shaped, narrow posteriorly, widens anteriorly, anterior limit indiscernible in whole-mounts, terminates just posterior to anterior margin of anterior testis in sagittal section.

Etymology: The species name vitellocopiosa (L. vitellus, yolk; L. copiosa, richly provided with) refers to the abundance of the vitelline follicles in the new species.

Comments: Macvicaria vitellocopiosa n. sp. can be accommodated in Group C. It is similar to M. synagris , M. mutovitellina and M. flexuomeatus in many features but can be distinguished from them as follows:

M. synagris is fusiform, it has a larger ventral sucker relative to the oral sucker with a sucker width ratio of 1:2.5; a slightly smaller post-testicular space, a more anteriorly situated genital pore, caeca which do not extend beyond the posterior margin of the posterior testis and it has shorter eggs (51-66 long) ( Yamaguti, 1952).

M. flexuomeatus has a slightly less elongate form with a width to length ratio of 1:2.1-2.4 (2.2), a smaller post-testicular space at 11-18 (15)% of body-length and smaller eggs at 50-75 × 25-41 (65 × 32).

M. mutovitellina is a slightly more elongate form with a width to length ratio of 1:2.5-3.0 (2.8), with smaller eggs at 54-71 × 26-39 (63 × 31), a more conspicuous tegumental fold around the ventral sucker and less copious vitelline follicles..

M. skorai is more elongate with a width to length ratio of 1:2.5-4.2 (3.1), a shorter cirrus-sac that does not reach the ovary, short eggs at 43-55 × 23-35 and shorter caeca which terminate, apparently, near to the posterior margin of the posterior testis ( Zdzitowiecki, 1999).

The other members of Group C differ from M. vitellocopiosa in the same features as they do M. mutovillina and M. flexuomeatus .

Figures

Figs 21-23. Macvicaria vitellocopiosa n. sp. ex Sillaginodes punctatus. 21. Whole-mount ventral view. 22. Terminal genitalia. 23. Dorsal distribution of vitelline follicles. Scale bars: 21, 23, 250 µm; 22, 100 µm.