Pseudopecoeloides arripi, 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 : 15-22

publication ID 10.3897/zookeys.5.54

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Pseudopecoeloides arripi


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

Type-host: Arripis georgianus (Valenciennes) ( Arripidae : Perciformes ), Australian ruff.

Type-locality: Off Woodman Point; Western Australia, 32°08’ S 115°45’ E, November and December 1994 GoogleMaps .

Other localities: Off Coogee Beach , Western Australia, 32°07’ S 115°46’ E, November and December 1994 GoogleMaps ; Off Kingscote, Kangaroo Island , South Australia 35°40’ S 137°39’ E, December 1995 GoogleMaps .

Site: Intestine.

Material studied: Ex Arripis georgianus : from W.A.: 8 from Coogee Beach; 9 from off Woodman Point; 6 from S.A.: off Kingscote, Kangaroo Is.

Type-material: Holotype: Queensland Museum, Reg. No. QM G 230455, paratypes: Queensland Museum , Reg. Nos. QM G 230456 - G 230488, BMNH Reg. Nos. 2008.12.9.9-27.

Description (Figures 12-14): Based on 15 gravid, unflattened, whole-mount specimens and 2 sets of serial sagittal sections from Arripis georgianus off W.A. Measurements are of 10 gravid, unflattened laterally and dorso-ventrally mounted worms. Measurements of worms off S.A. are given in Table 4.

Body elongate, broader and more rounded at posterior than anterior end; maximum width in region of gonads, 2,161 -4,152 (3,361) × 210-347 (280); width to length ratio 1:9.3-14.0 (12.0). Oral sucker ventrally subterminal, subspherical, 129- 221 (165) × 114-179 (145). Ventral sucker pedunculate, close to anterior end, smaller than oral sucker, 73-94 (84) × 82-108 (91); sucker width ratio 1:0.5-0.7 (0.6). Ventral sucker peduncle 302-657 (484) × 106-131 (120), 10.3-16.7 (14.4) % of body length. Forebody short, with numerous gland cells, 288-409 (344) long, 8.9-14.6 (10.4) % of body length; ventral sucker peduncle to forebody length ratio 1:0.60-0.96 (0.73). Prepharynx distinct, very short, with posterior end surrounded by gland cells. Pharynx

well developed, spherical to subspherical, with gland cells along posterior margin, 59- 105 (85) 70-109 (94); pharynx to oral sucker width ratio 1:1.4-1.8 (1.5). Oesophagus short, well developed, usually curved or looped. Intestinal bifurcation usually dorsal to ventral sucker, occasionally level with anterior margin of ventral sucker peduncle (n=1), 25-67 (49) posterior to anterior margin of ventral sucker peduncle. Caeca long, thick-walled, unite with excretory vesicle to form uroproct.

Testes 2, entire, subspherical, always separate, tandem, in posterior half of body; anterior 199-367 (298) × 145-254 (203); posterior 235-426 (339) × 151-282 (214). Post-testicular region moderately long, 633-1,323 (1,054) long, 27.8-38.2 (31.4) % of body length. Cirrus-sac absent. Seminal vesicle long, naked, sinuous, tubular and narrow anteriorly, large and saccate posteriorly; posterior portion 112-332 (224) × 55-142 (95). Pars prostatica distinct, surrounded by gland cells. Ejaculatory duct indistinct. Genital atrium small. Genital pore close to anterior end, antero-sinistral to intestinal bifurcation, at point slightly posterior to pharynx, 155-220 (190) from anterior end, 4.5-7.2 (5.8) % of body length.

Ovary pre-testicular, entire, subspherical, usually separated from anterior testis, sometimes contiguous (n=6), 81-199 (153) × 75-180 (135). Mehlis’ gland distinct, antero-dorsal and dorsal to ovary. Uterine seminal receptacle usually in posterior loops of uterus, with uterus sometimes almost completely full of sperm (n=3). Uterus coils between anterior margin of ovary and region of seminal vesicle, overlaps caeca ventrally then passes anteriorly dorsal to or alongside seminal vesicle to genital pore without coiling; anterior portion of uterus sometimes crammed with eggs and greatly distended (n=3); uterine coils more concentrated posteriorly. Metraterm distinct, short; anterior extremity surrounded by gland cells. Eggs oval, operculate, tanned, sometimes malformed (n=3), 51-74 (59) × 20-39 (28). Vitelline follicles entirely posterior to ventral sucker peduncle, extend from 554-1,018 (747) from anterior extremity, 18.8- 25.8 (22.0) % of body length, to 14-70 (42) from posterior extremity, with bilateral interruptions in areas adjacent to testes and sometimes in area just anterior to ovary; fields confluent dorsally and ventrally in post-testicular area, confluent or almost so in inter-testicular area and dorsally in uterine area, separate ventrally; follicles lie lateral, dorsal and ventral to caeca with anterior extent usually variously between anterior and posterior margins of enlarged posterior portion of seminal vesicle, occasionally level with (n=1) or just posterior to seminal vesicle (n=1).

Excretory pore terminal. Excretory vesicle I-shaped, long; posterior end forms narrow duct surrounded by gland cells; broader anterior portion extends anteriorly to about mid-body overlapping posterior half of ovary dorsally.

Etymology: This species is named after Arripis Jenyns, 1840 the host genus.

Comments: The material off South Australia is similar to that off Western Australia; however, a few differences worth noting were observed. The specimens from Western Australia are generally larger than those from South Australia, with a slightly longer forebody, but the ventral sucker of the latter is larger relative to the oral sucker. The most significant of these difference is the difference in the size of the ventral sucker, which may relate to the allometric growth of the worms, although it is possible that different species are involved . Pseudopecoeloides arripi sp. n. can be accommodated in Group A and distinguished from the other species in the group by being less elongate than P. tenuis and P. hickmani sp. n. but more elongate, as shown by the width to length ratio, with a longer post-testicular area than P. psettodi , P. capucini and P. wekeula ( Table 1 View Table 1 ), and by having a shorter post-testicular region than P. tenuis , relative to the body length. The new species has a forebody shorter than P. capuccini and P. wekeula but longer than P. tenuis , P. psettodi and P. hickmani sp. n. relative to the body length, and a larger pharynx relative to the oral sucker than P. tenuis and P. psettodi . Furthermore, P. arripi sp. n. has larger eggs than P. hickmani sp. n. and its body tapers only slightly and ends abruptly in a rounded posterior end, whereas in the latter it tapers gradually to a rather pointed extremity. P. arripi sp. n. is closest to P. opelu but can be distinguished from it by its slightly larger pharynx to oral sucker width ratio of 1:1.4-1.8 (1.5) versus 1:1.8 and its longer post-testicular region relative to the body length. These two species can further be separated by the more anterior position of the intestinal bifurcation in the new species, being at the level of the anterior margin of the ventral sucker peduncle rather than as it is in P. opelu .

Because the size of the pharynx of Pseudopecoeloides arripi sp. n. and P. opelu overlap, the main basis for separating these two species is the non-overlapping size of the post-testicular region, which we consider to be significant in species of Pseudopecoeloides . In addition, it is noteworthy that P. opelu is known only from a carangid, the mackerel scad Decapterus macarellus , off Hawaii ( Yamaguti, 1970).


Queensland Museum

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