Pseudopecoeloides hickmani, 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 : 7-9

Pseudopecoeloides hickmani Aken’Ova, Cribb & Bray, sp. n.

urn:lsid:zoobank.org:act:E746A0FA-213E-40BC-8F23-FB350658E8DD

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

Type-locality: Off North Mole, Fremantle, Western Australia, 32°03´S, 115°43´E, December 1994.

Site: Intestine, pyloric caeca, rectum.

Material studied: 8.

Type-material: Holotype: Queensland Museum, Reg. No. QM G 230442, paratypes: Queensland Museum , Reg. Nos QM G 230443 - 230451, BMNH Reg. Nos 2008.12.9.1-6.

Description ( Figures 4-6 ): Based on 7 gravid, unflattened, laterally and dorsoventrally mounted whole-mounts and 1 set of serial sagittal sections. Measurements are of the 7 gravid, unflattened, laterally and dorso-ventrally mounted worms.

Body elongate, slender, subcylindrical, tapers gradually to narrow point posteriorly, rounded at anterior end; maximum width in region of gonads, 3,204 -4,929 (4,213) × 205-301 (249); width to length ratio 1:15.6-19.2 (17.0). Oral sucker subspherical, ventrally subterminal, 131-175 (159) × 112-155 (134). Ventral sucker pedunculate, close to anterior extremity, smaller than oral sucker, subspherical, 71-79 (73) × 78-92 (85); sucker width ratio 1:0.5-0.8 (0.6). Ventral sucker peduncle 425-863 (650) × 97-109 (102) wide, 13.3-17.5 (15.3) % of body length. Forebody short, containing numerous gland cells, 337-399 (362) long, 7.7-10.5 (8.7) % of body length; peduncle to forebody length ratio 1:0.4-0.8 (0.6). Prepharynx distinct, feebly developed, very short. Pharynx subspherical, wide, 66-89 (79) × 71-101 (87); pharynx to oral sucker width ratio 1:1.4-1.6 (1.5). Oesophagus relatively short, thick-walled. Intestinal bifurcation close to anterior end, dorsal to ventral sucker peduncle, 49-98 (68) posterior to anterior margin of ventral sucker peduncle. Caeca long, narrow, unite with excretory vesicle close to posterior extremity to form uroproct.

Testes 2, entire, may be subspherical or broadly fusiform, separate, tandem, in posterior half of body; anterior 273-396 (335) × 169-246 (210); posterior 298-383 (350) × 164-257 (203). Post-testicular area 1,005 -1,639 (1,472) long, 31.4-37.1 (34.9) % of body length. Cirrus-sac absent. Seminal vesicle tubular, long and sinuous anteriorly, large and saccular posteriorly, extends from point level with, anterior to or posterior to anterior margin of ventral sucker peduncle to point variously between posterior margin of peduncle and anterior margin of ovary; posterior saccular portion 156-278 (202) × 54-106 (84). Pars prostatica distinct, large, elongate, with openings of numerous ducts, surrounded by gland cells. Ejaculatory duct short. Genital atrium large. Genital pore antero-sinistral to intestinal bifurcation, about half way between anterior and posterior margins of pharynx, 184-213 (197) from anterior end, 4.0-5.9 (4.7) % of body length.

Ovary pre-testicular, entire, subspherical, 116-197 (163) × 129-168 (142). Mehlis’ gland distinct, anterior to ovary. Uterine seminal receptacle present. Laurer’s canal present, thick-walled, opens slightly anterior to or posterior to anterior margin of ova-ry, at point dorsally antero-sinistral to ovary, close to lateral margin of worm. Uterine coils occupy area between point anterior to anterior margin of ovary and various levels posterior to posterior tip of seminal vesicle, overlapping caeca ventrally, then following course of seminal vesicle to open into genital atrium. Metraterm indistinct. Eggs oval, operculate, 44-71 (55) × 20-42 (26). Vitelline follicles restricted to hindbody, extend from 793-1,137 (919) from anterior extremity, 20.4-24.8 (21.9) % of body length, to 33-64 (49) from posterior extremity; fields lateral, ventral and dorsal to caeca, confluent dorsally and ventrally in post-testicular and inter-testicular areas, and dorsally in pre-ovarian region, interrupted at level of anterior and posterior testes; anterior limit usually slightly overlaps seminal vesicle, sometimes slightly posterior to it (n=2), occasionally at level of posterior margin of seminal vesicle (n=1), or to point just posterior to anterior margin of large distended portion of seminal vesicle (n=1).

Excretory pore terminal to slightly dorsally subterminal. Excretory vesicle I-shaped, long, tubular, reaches anteriorly to overlap posterior margin of ovary, terminates at point anterior to mid-body.

Etymology: This species is named for V. V. Hickman in recognition of his contribution to the systematics of marine digeneans in the Australian region.

Comments: Specimens of Pseudopecoeloides hickmani sp. n. have an oral sucker greater than the ventral sucker, placing the species in Group A. It can be distinguished from members of this group as follows: it has a greater length/width ratio than P. tenuis , P. psettodi , P. capucini and P. wekeula ; and it has a smaller pharynx than P. tenuis , a larger pharynx than P. psettodi , P. capucini and P. wekeula , relative to the size of the oral sucker ( Table 1 ). The ventral sucker peduncle in the new species is longer than that of P. tenuis relative to the length of the forebody; its forebody is shorter and its post-testicular area longer relative to the length of the body than those of P. wekeula and P. capucini . P. hickmani sp. n. closely resembles P. opelu in most of its metrical features and by the fact that they are both from carangids, but it can be distinguished from the latter by its more elongate form with a width to length ratio of 1:17 versus 1:11, a slightly larger pharynx with a pharynx to oral sucker width ratio of 1:1.5 versus 1:1.8 and a longer post-testicular area measuring 31.4-37.1 (34.9) versus 21.3% of the body length.

Figures

Figs 4-6. Pseudopecoeloides hickmani sp. n. ex Pseudocaranx wrighti. 4. Whole-mount latero-ventral view. 5. Terminal genitalia. 6. Ventral view of posterior end showing uroproct. Scale bars: 4, 1mm; 5, 200 µm; 6, 100 µm.