Macvicaria mutovitellina, 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 : 35-37

Macvicaria mutovitellina n. sp.

Type-host: Dactylophora nigricans (Richardson) (Cheilodactylidae) .

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

Site: Intestine.

Material studied: 14 Off Point Peron, December 1994.

Type-material: Holotype: QM G 230379, paratypes: QM G 230380 - 230389, BMNH 2008.7.5.1-5.

urn:lsid:zoobank.org:act:604CFAD5-C948-4547-846D-47E9F8A10091

Description ( Figs 10-15 )

Based on 13 gravid, whole-mount specimens and 1 set of serial sagittal sections. Measurements are of 10 gravid, unflattened, whole-mount worms.

Body robust, elongate-oval, sub-cylindrical, tapered at anterior end, rounded at posterior end, lateral margins roughly parallel, 833-1,108 (962) × 296-393 (349); width to length ratio 1:2.5-3.0 (2.8). Oral sucker almost terminal, subglobular, 95-123 (110) × 116-148(131). Ventral sucker larger than oral sucker, transversely oval, 183- 228 (203) × 207-261 (228); sucker width ratio 1:1.6-1.9 (1.7). Forebody contains few large and numerous small gland cells, 227-281 (261) long, 25-29 (27)% body-length. Prepharynx distinct, short, partly posterior and partly dorsal to oral sucker. Pharynx large, sub-spherical, 63-80 (71) × 71-99 (81); pharynx to oral sucker width ratio 1:1.5- 1.8 (1.6). Oesophagus distinct, short, thick walled. Intestinal bifurcation usually dorsal to anterior half of ventral sucker, 15-29 (21) posterior to anterior margin of ventral sucker, sometimes level with (n=4), and occasionally just anterior to anterior margin ventral sucker (n=1). Caeca terminate blindly close to posterior extremity.

Testes 2, transversely oval, tandem, contiguous, entire, anterior 101-159 (122) × 136-190 (172), posterior 133-167 (148) × 151-188 (174). Post-testicular area 138- 246 (180) long, 15-22 (19) % body-length. Cirrus-sac large, clavate, thick walled especially at posterior extremity, extends from about level of posterior margin of pharynx to level of ovary or anterior testis; 306-388 (347) × 78-104 (88). Internal seminal vesicle convoluted, occupies posterior half or third of cirrus-sac. Pars prostatica distinct, well developed, surrounded by numerous gland cells. Ejaculatory duct long, convoluted at posterior end, thick walled, surrounded by few gland cells. Genital atrium small. Genital pore extra-caecal, antero-sinistral to intestinal bifurcation, usually anterior to posterior margin of pharynx, sometimes level with oesophagus (n=3), 169-231 (200) from anterior end, 20-22 (21)% of body-length.

Ovary entire, spherical to sub-spherical, usually contiguous with anterior testis, sometimes separate (n=2), usually antero-dextral to anterior testis, occasionally dextral (n=1), 81-111 (94) × 89-112 (103). Mehlis’ gland distinct, sinistral to ovary, anterior to anterior testis. Canalicular seminal receptacle small, saccate, dorsal to anterior testis. Uterine coils usually extend from point just posterior to anterior margin of anterior testis to posterior margin of ventral sucker, overlapping left caecum ventrally and sometimes left side of ovary dorsally, occasionally coils extend to just anterior to posterior margin of anterior testis (n=1) or to posterior margin of posterior testis (n=1). Metraterm distinct, moderately long, well developed, overlaps left caecum to point just anterior to or just posterior to ventral sucker aperture. Eggs relatively large, tanned, usually few, oval, operculate, 54-71 (63) × 26-39 (31). Vitelline follicles extend from 173-314 (215) from anterior extremity, 17-34 (22)% body-length, to 8-19 (14) from posterior extremity; follicles in two separate fields in forebody ventrally, confluent in post-testicular area, covering almost all surface of posterior testis and posterior and or lateral portion of anterior testis and ovary ventrally; dorsal field almost confluent, interrupted in area of posterior half of ventral sucker, particularly in area of male terminal genitalia, sometimes follicles absent dorsally and ventrally (n=1) or feebly developed (n=2) in forebody; fields lie lateral, dorsal and ventral to caeca with unilateral or bilateral follicle-free patches in area of ventral sucker ventrally; anterior extent usually at level of posterior end of oesophagus, or posterior margin of pharynx, rarely at level of ventral sucker aperture (n=1).

Excretory pore terminal. Excretory vesicle I-shaped, with narrow posterior end, broadens and extends anteriorly to point just posterior to anterior margin of anterior testis as seen in sagittal section.

Etymology: The species name mutovitellina (L. muto, change; vitellus, yolk) is derived from the variable patterns of the distribution of vitelline follicles.

Comments: The distribution of vitelline follicles, posterior extent of cirrus-sac and arrangement of testes of Macvicaria mutovitellina n. sp. is characteristic of worms in Group C. The following species can be readily distinguished from M. mutovitellina and the other members of the group:

M. longicirrata is a more elongate form with the longest forebody, smallest ventral sucker and the smallest post-testicular space ( Manter, 1963).

M. longisaccus is also an elongate worm which can be distinguished from M. mutovitellina by its larger pharynx with a pharynx to oral sucker width ratio of 1:1.3, its slightly larger ventral sucker with a ventral sucker/oral sucker width ratio of 1:2.1, its longer forebody at 37% of body-length and a shorter post-testicular space at 18.0% of the body-length ( Fischthal & Kuntz, 1964)

M. gerridis has a body form similar to that of M. mutovitellina , a distinctly bipartite seminal vesicle and a shorter forebody ( Fischthal & Thomas, 1970). The only other species of Macvicaria which is reported to have a bipartite seminal vesicle is M. macassarensis in Group E.

M. synagris is closest to M. mutovitellina from which it can be distinguished by its body shape, much longer oesophagus, more conspicuous prepharynx, relatively narrower oral sucker and larger ventral sucker with a sucker width ratio of 1:2.5, caeca which do not reach well beyond the posterior margin of the posterior testis, a more anteriorly situated genital pore and an ovary separated from the anterior testis by the seminal receptacle ( Yamaguti, 1952). Furthermore, the vitelline follicles in the new species are more profuse, partly covering the ventral surface of the gonads and just entering the forebody anteriorly, whereas in M. synagris the ventral surface of the gonads is free of vitelline follicles which reach anteriorly to a point just posterior to the posterior margin of the pharynx and extend further anteriorly than in the new species.

M. jagannathi is a more elongate worm with a width length ratio of 1:4.7, a shorter forebody of about 20% of body-length, separated gonads, the cirrus-sac just encroaching into the hindbody and a greater distance between the ovary and the ventral sucker ( Gupta & Singh, 1985).

M. longibursata has small eggs (42-40 × 26-35), is relatively elongate (width: length ratio 1:4.6-4.7) and the vitellarium reaches to the oral sucker ( Zdzitowiecki & Cielecka, 1997).

M. deeghaensis is relatively elongate (width: length ratio 1:4.6-5.0), with a short forebody (about 17% of body-length), with separated gonads and a relatively long ventral sucker to ovary distance into which the cirrus-sac only encroaches slightly ( Gupta & Gupta, 1988).

M. skorai is similar to M. mutovitellina , but may be slightly more elongate (width: length ratio 1:2.53-4.16), the vitellarium reaches to the pharynx and is confluent in the forebody, the testes are distinctly oblique and the ventral sucker to ovary distance is slightly greater (Zdztowiecki, 1999).

Figures

Figs 10-12. Macvicaria mutovitellina n. sp. ex Dactylophora nigricans. 10. Whole-mount ventral view. 11. Terminal genitalia. 12. Dorsal distribution of vitelline follicles. Scale bars: 10, 12, 250 µm; 11, 100 µm.

Figs 13-15. Macvicaria mutovitellina n. sp. ex Dactylophora nigricans. 13. Whole-mount ventral view. 14. Terminal genitalia. 15. Dorsal distribution of vitelline follicles. Scale bars: 13, 15, 250 µm; 14, 100 µm.