Macvicaria dextrocaula, 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 : 43-46

Macvicaria dextrocaula n. sp.

Type-host: Notolabrus parilus (Richardson) (Labridae) .

Other host: Notolabrus fucicola (Richardson) (Labridae) .

Type-locality: Off Point Peron, Western Australia 32°18’S, 115°38’E.

Other localities: Off North Mole , Western Australia 32°03’S, 115°43’E .; Off American River , South Australia 35°48’S, 137°46’E .

Site: Intestine.

Material studied: Ex Notolabrus parilus : 9 from off Point Peron Western Australia & from off North Mole , December 1994 ; Ex Notolabrus fucicola : 1 from off American River , South Australia, December 1995 .

Type-material: Holotype: QM G 230415 , paratypes: QM G 230416 - 230422, BMNH 2008.7.5.40-43.

urn:lsid:zoobank.org:act:313FE42B-9AFC-4B01-A471-99DAFDE6153F

Description ( Figs 24-29 )

Based on 11 gravid, unflattened dorso-ventrally and laterally mounted specimens and 1 set of serial sagittal sections from Notolabrus parilus . Measurements of worm from Notolabrus fucicola are given in Table 3 .

Measurements are of 5 gravid, unflattened, dorso-ventrally mounted worms. Body elongate-oval, sub-cylindrical, sharply inflected dorsally in area of ventral sucker in lateral view, with maximum width in region of ventral sucker, 936-1,455 (1,202) × 295-466 (362); width to length ratio 1:3.2-3.6 (3.3). Oral sucker ventrally subterminal, sub-spherical, 129-169 (147) × 141-196 (164). Ventral sucker sub-spherical, close to mid-body, completely surrounded and almost completely enclosed by tegumental fold, 181-234 (212) × 197-276 (237), sucker-width ratio 1:1.4-1.5 (1.4) Forebody moderately long, 307-514 (408) long, 32-35 (34)% body-length. Prepharynx indistinct, short, always entirely dorsal to oral sucker. Pharynx well developed, subglobular, usually partly dorsal to oral sucker, rarely entirely dorsal to oral sucker (n=1); 49-65 (55) × 65-90 (79); pharynx to oral sucker width ratio 1:1.9-2.2 (2.1). Oesophagus short, thick walled. Intestinal bifurcation 96-222 (163) anterior to ventral sucker. Caeca terminate blindly close to posterior extremity.

Testes 2, entire, subspherical, tandem, contiguous to overlapping, close to posterior end of body, anterior 63-132 (98) × 112-194 (147); posterior 85-148 (115) × 112- 196 (150). Post-testicular area short, 105-137 (127) long, 9.4-13(11)% body-length. Cirrus-sac well developed, tubular, long, slender, extends from just posterior to intestinal bifurcation overlapping right caecum to point anterior to or posterior to ventral sucker aperture, 226-366 (297) × 34-60 (43). Internal seminal vesicle, slender, tubular, occupies posterior half of cirrus-sac, posterior portion surrounded by prostatic cells. Pars prostatica small, inconspicuous, surrounded by few gland cells. Ejaculatory duct relatively long, with few prostatic cells in rows along its length. Genital pore dextrally sub-median, caecal to extracaecal, just posterior to intestinal bifurcation, surrounded by gland cells, 209-290 (240) from anterior end, 17 -24 (20)% body-length.

Ovary pretesticular, entire, subspherical, contiguously overlaps anterior testis, 90- 139 (104) × 103-152 (127). Mehlis’ gland distinct antero-dorsal to ovary. Canalicular seminal receptacle saccular, antero-dorsal to ovary. Uterus coils between anterior testis and posterior margin of ventral sucker, sometimes overlapping caeca; terminal portion usually crammed with eggs. Metraterm distinct, surrounded by gland cells. Eggs oval, operculate, 39-56 (48) × 22-34 (28). Vitelline follicles extend from 130-185 (162) from anterior extremity, 11-18 (14)% of body-length, to 8-24 (15.4) from posterior

extremity; follicles in two separate fields ventrally, confluent dorsally in forebody with interruption in ventral sucker area; fields lie lateral, ventral and dorsal to caeca with anterior limit usually anterior to posterior margin of pharynx, sometimes level with posterior margin (n=2) or up to anterior margin of pharynx (n=1).

Excretory pore usually ventrally subterminal, occasionally dorsally subterminal (n=1). Excretory vesicle I-shaped, posterior end narrow, surrounded by gland cells, wider anterior portion passes anteriorly to overlap posterior third of ovary dorsally.

Etymology: The specific name dextrocaula (L. dextra, right; L. caula, opening) refers to the worm’s dextrally located genital pore.

Comments: One of the characteristics of Macvicaria species is their sinistral, ventrolateral, caecal or extra-caecal genital pore ( Bartoli, Bray & Gibson 1989). Since M. dextrocaula does not have a sinistral genital pore, like other members of the genus, the definition of Macvicaria is amended with respect to the position of the genital pore, to receive the new species as follows: genital pore sinistral or dextral, ventro-lateral, caecal or extra-caecal.

The specimens from Notolabrus fucicola are very similar to those from N. parilus except in the length of the post-testicular space, which is greater in the single worm from N. fucicola , 17.2% of body-length versus a maximum of 13.2% of body-length in the specimens from N. parilus . The specimen from N. fucicola also had slightly larger eggs than the worms from N. parilus . We interpret these slight differences either as induced by fixation or normal intraspecific variation.

Macvicaria dextrocaula can be accommodated in Group D as defined above. The new species can further be distinguished from the other species, apart from M. georgiana , by the distribution of the vitelline follicles which always reach further anteriorly, to the level of the pharynx, usually close to its anterior margin and from all other species by its strong dorsal inflection. Macvicaria dextrocaula differs from M. heronensis , M. issaitschikowi and M. georgiana by its smaller eggs.

Figures

Figs 24-26. Macvicaria dextrocaula n. sp. ex Notolabrus parilus. 24. Whole-mount ventral view. 25. Whole-mount lateral view. 26. Terminal genitalia. Scale bars: 24, 25, 250 µm; 26, 100 µm.

Figs 27-29. Macvicaria dextrocaula n. sp. ex Notolabrus fucicola and N. parilus. 27. Whole-mount ventral view. 28. Dorsal distribution of vitelline follicles.29. Dorsal distribution of vitelline follicles (ex N. parilus). Scale bars: 27, 28, 29, 250 µm.

Tables

Table 3. Measurements (in µm) of Macvicaria dextrocaula n. sp. (n = 1) from Notolabrus fucicola, Off American River, South Australia

Total length	1,168
Maximum width	326
Length/width	3.6
Oral sucker length	140
Oral sucker width (OSW)	154
Pharynx length	51
Pharynx width	68
OSW/pharynx width	2.3
Ovary length	122
Ovary width	125
Anterior testis length	90
Anterior testis width	105
Posterior testis length	102
Posterior testis width	105
Forebody-length (FBL)	390
FBL as % of body-length	33.4
Ventral sucker length	190
Ventral sucker width (VSW)	219
VSW/OSW	1.4
Anterior extremity to genital pore (AEGP)	231
AEGP as % body-length	19.8
Cirrus-sac length	329
Cirrus-sac width	44
Seminal vesicle length	124
Seminal vesicle width	39
Intestinal bifurcation to ventral sucker	178
Post-testicular region (PTR)	201
PTR as % of body-length	17.2
Anterior extremity to vitellarium (AEV)	145
AEV as % of body-length	12.4
Posterior extremity to vitellarium	27
Eggs	49-56 (52) × 23-37 (31), n=8