Pseudopecoeloides scomberi Hafeezullah, 1971

Aken'Ova, Thelma, Cribb, Thomas & Bray, Rodney, 2009, Seven species of Pseudopecoeloides Yamaguti, 1940 (Digenea, Opecoelidae) from temperate marine fishes of Australia, including five new species, ZooKeys 5 (5), pp. 1-32 : 28-30

Pseudopecoeloides scomberi Hafeezullah, 1971

(Syn. Pseudopecoelus scomberi ( Hafeezullah, 1971) Madhavi, 1975 )

Host: Scomberoides lysan (Forsskål) ( Carangidae : Perciformes ), doublespotted queenfish.

Locality: off Dunwich, Stradbroke Island, Queensland, 27°30′S, 153°24’E, February 1994.

Site: Intestine.

Material studied: 1 specimen.

Voucher specimen: Queensland Museum, Reg. No. QM G 230516.

Description ( Figures 23-24 ): Based on single gravid, unflattened, laterally mount-ed worm.

Body elongate, slender, subcylindrical; maximum width in region of gonads, 3,088 × 288; width to length ratio 1:10.7. Oral sucker ventrally subterminal, subspherical, 154 × 141. Ventral sucker close to anterior end, larger than oral sucker, subspherical, on very short peduncle, 167 × 148, sucker width ratio 1:1. Forebody short, contains gland cells, 298 long, 9.7% of body length. Pharynx large, spherical, 103 × 103; pharynx to oral sucker width ratio 1:1.4. Oesophagus distinct, short. Intestinal bifurcation, dorsal to ventral sucker. Caeca long, open into excretory vesicle close to posterior extremity to form uroproct ( Figure 24 ).

Testes 2, entire, subspherical, separate, tandem, in anterior part of posterior half of body; anterior 193 × 167; posterior 135 × 298. Post-testicular area 1,053 long, 34.1% of body length. Prepharynx distinct, short. Cirrus-sac absent. Seminal vesicle naked, long, tubular, elongate and saccular at posterior end, extends from about level of intestinal bifurcation to level posterior to ventral sucker. Ejaculatory duct relatively short. Genital atrium small. Genital pore sinistrally submedian, anterior to intestinal bifurcation, level with posterior margin of pharynx, 180 from anterior end, 5.8% of body length.

Ovary pre-testicular, entire, subspherical, 141 × 116. Uterine seminal receptacle apparently present. Uterus coils between anterior margin of ovary and point dorsal to ventral sucker. Metraterm indistinct. Eggs large, oval, operculate, 51-58 (54) × 26- 35 (32). Vitelline follicles extend from 578 from anterior extremity, 18.7% of body length, to 32 from posterior extremity; fields confined to hindbody, extending from level posterior to ventral sucker almost to posterior extremity, confluent dorsally and ventrally in post-testicular area; lateral, ventral and dorsal to caeca, with bilateral interruptions adjacent to testes and ovary.

Excretory pore terminal. Excretory vesicle I-shaped; narrow terminal portion surrounded by gland cells; vesicle widens and passes anteriorly to overlap posterior margin of ovary.

Comments: Pseudopecoeloides scomberi was described and figured, from the needlescaled queenfish Somberoides tol (Cuvier) in the Gulf of Mannar, as having a uroproct ( Hafeezullah, 1971). Madhavi (1975) examined worms from the same host and locality and concluded that the species belonged in Pseudopecoelus von Wicklen, 1946 , in which the caeca end blindly, as she did not observe a uroproct in either whole-mounts

or sections. Bray (1987) also examined two whole-mounted museum specimens of this species from the barred queenfish S. tala (Cuvier) off India, and two specimens from S. tol off Malaysia, but could not detect a uroproct. Madhavi (1975) stated that “the ends of the caeca establish close contact with the bladder but apparently do not open into it”. We interpret Madhavi’s observation to mean that she was still not quite certain as to the presence or absence of a uroproct.

The specimen from Scomberoides lysan is almost identical in every metrical feature and in general appearance to those described by Hafeezullah (1971) from S. tol , except as follows. The vitelline follicles in the present material are interrupted bilaterally in areas adjacent to the gonads, whereas they are continuous in Hafeezullah’s material, although, in his figure of the worm, the vitelline follicles thin out around the gonads. Hafeezullah’s worms are also much larger than the present material, being 6,828 -7,056 × 504-583 compared with 3,088 × 288 ( Table 2 ). Since the present report is based on a single specimen, it was not possible to assess variation in the vitelline distribution or size in this species. The “inconspicuous cirrus-sac” observed by Hafeezullah (1971) in P. scomberi was not seen in the present material. Although the occurrence of a vestigial cirrus-sac is not characteristic of most species of Pseudopecoeloides , it does not preclude the inclusion of P. scomberi in the genus, since it was observed by Yamaguti (1970) in some specimens of P. akule and in P. wekeula . Madhavi (1975) considered Hafeezullah’s material to be a species of Pseudopecoelus but, because of the observations we have made regarding the caecal ends in the present material ( Figure 24 ) and the fact that these worms are practically indistinguishable morphologically, we are treating the present material and Hafeezullah’s as conspecific. Moreover, their hosts are congeners. The presence of a uroproct necessitates the return of this species to Pseudopecoeloides .

Figures

Figs 23-24. Pseudopecoeloides scomberi Hafeezullah, 1971 ex Scomberoides lysan.23. Whole-mount lateroventral view. 24. Ventral view of posterior end showing uroproct. Scale bars: 23, 500 µm; 24, 100 µm.