Pseudopecoeloides lesteri, Aken'Ova & Cribb & Bray, 2009

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 : 9-15

publication ID 10.3897/zookeys.5.54

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Pseudopecoeloides lesteri


Pseudopecoeloides lesteri View in CoL Aken’Ova, Cribb & Bray, sp. n.

Type-host: Pseudocaranx dentex (Bloch & Schneider) ( Carangidae : Perciformes ), white trevally.

Other host: Pseudocaranx wrighti (Whitley) ( Carangidae : Perciformes ), skipjack trevally.

Type-locality: Off Kingscote, Kangaroo Island, South Australia, 35°40’S, 137°39’E, December 1995.

Other locality: Off North Mole, Fremantle, Western Australia, 32°03’S, 115°43’E, December 1994.

Site: Intestine.

Material studied: Ex Pseudocaranx dentex : 4 off Kingscote; ex Pseudocaranx wrighti : 2 off North Mole.

Type-material: Holotype: Queensland Museum, Reg. No. QM G 230452, paratypes: Queensland Museum , Reg. Nos QM G 230453 -4, BMNH Reg. No 2008.12.9.7-8.

Description ( Figures 7 View Figs 7-9 -11): Based on 6 gravid, unflattened, laterally mounted worms from Pseudocaranx dentex and P. wrighti and 1 set of sagittal serial sections. Measurements are based on 3 gravid, unflattened, laterally mounted specimens from P. dentex ; measurements of worms from P. wrighti are given in Table 3 View Table 3 .

Body elongate, slender, subcylindrical; maximum width in region of gonads, 1,373 -1,587 (1,482) × 158-170 (163); width to length ratio 1:8.5-10.0 (9.1). Oral sucker spherical to subspherical, opening nearly terminal, 85-95 (89) × 84-89 (86). Ventral sucker pedunculate, close to anterior end, larger than oral sucker, subspherical, 105-107 (106) × 119-125 (123); sucker width ratio 1:1.4-1.5 (1.4). Ventral sucker peduncle short, broad, 218-232 (225) × 132-158 (145), 14.6-15.9 (15.2) % of body length. Forebody relatively short, contains numerous gland cells, 261-323 (296) long, 19.0-21.7 (19.9) % of body length; peduncle to forebody length ratio 1:1.2-1.3 (1.3). Prepharynx distinct, short, feebly developed. Pharynx large, spherical to subspherical, 67-77 (72) × 76-77 (76); pharynx to oral sucker width ratio 1:1.1-1.2 (1.1). Oesophagus short, thin walled, surrounded by gland cells. Intestinal bifurcation dorsal to ventral sucker, 8-49 (28) posterior to anterior margin of ventral sucker peduncle. Caeca long, open into excretory vesicle close to posterior extremity to form uroproct ( Figure 9 View Figs 7-9 ).

Testes 2, entire, subspherical, usually separated, contiguous in one specimen, tandem, in posterior half of body; anterior 136-147 (141) × 94-125 (113); posterior 146-165 (159) × 104-129 (120). Post-testicular area 289-384 (325) long, 19.4-24.2 (21.9) % of body length. Cirrus-sac absent. Seminal vesicle long, tubular, narrow and convoluted anteriorly, large and vesicular posteriorly; posterior portion 100-107 (103) × 50-60 (55). Pars prostatica distinct, large, surrounded by gland cells. Ejaculatory duct thick-walled, with distinct sphincter at anterior extremity (see Figure 8 View Figs 7-9 ), surrounded by gland cells. Genital atrium small. Genital pore antero-sinistral to intestinal bifurcation, close to anterior extremity, 124-133 (129) from anterior end, 8.4-9.0 (8.7) % of body length.

Ovary pre-testicular, entire, usually contiguous with anterior testis, separate in 1 specimen, spherical to subspherical, 71-77 (74) × 67-73 (69). Mehlis’ gland distinct, anterior to antero-dorsal to ovary. Uterine seminal receptacle present. Laurer’s canal present, thick-walled, opens dorso-sinistrally to ovary, at about level of its anterior margin. Metraterm distinct, thick-walled, with distinct sphincter at anterior extremity, surrounded by gland cells; thick-walled muscular structure appears to enclose anterior extremities of ejaculatory duct and metraterm ( Figure 8 View Figs 7-9 ). Eggs relatively large, operculate, 64-75 (69) × 27-44 (34). Vitelline follicles restricted to hindbody, extend from 499-623 (553) from anterior extremity, 33.8-41.9 (37.3) % of body length, to 26-40

(35) from posterior extremity; fields confluent dorsally and ventrally in post-testicular area, dorsally or not between posterior margin of posterior testis and anterior limit with interruptions in areas around gonads, separate ventrally, with follicles lying lateral, ventral and dorsal to caeca; anterior limit slightly posterior to posterior margin of seminal vesicle.

Excretory pore terminal. Excretory vesicle I-shaped, long; posterior extremity forms short narrow duct surrounded by gland cells; vesicle reaches to ovary.

Etymology: This species is named for Professor R. J. G. Lester for his contributions to marine parasitology.

Comments: The specimens from Pseudocaranx wrighti are almost identical to those from P. dentex in general appearance and in all metrical features ( Tables 2 View Table 2 , 3 View Table 3 ) and are considered to be conspecific.

Pseudopecoeloides lesteri sp. n. can be accommodated in Group B. P. mugilis and P. gracilis can immediately be distinguished from all the other worms in the group; P. mugilis has the shortest post-testicular area relative to the body length and P. gracilis is the least elongate and has the largest ventral sucker relative to the size of the oral sucker ( Table 2 View Table 2 ). P. lesteri can be distinguished from the remaining species by its greater sucker ratio, larger pharynx relative to the oral sucker, longer forebody and shorter post-testicular area relative to the body length. It is more elongate than P. akule but less so than P. scomberi , as shown in their length/width ratios. The genital pore of the new species is more posteriorly situated than in P. scomberi ( Table 2 View Table 2 ).


Queensland Museum

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