Stephanostomum tantabiddii, Bray, Rodney A. & Cribb, Thomas H., 2004

Bray, Rodney A. & Cribb, Thomas H., 2004, Stephanostomum tantabiddii n. sp. (Digenea: Acanthocolpidae) from Carangoides fulvoguttatus (Forsskål, 1775) (Perciformes: Carangidae) from Ningaloo Reef, Western Australia, Zootaxa 457, pp. 1-8 : 2-5

Stephanostomum tantabiddii n. sp. ( Figs 1–4 )

Type­host: Carangoides fulvoguttatus (Forsskål, 1775) , Carangidae ; yellowspotted trevally.

Site: Intestine.

Type­locality: Ningaloo Coral Reef, Western Australia (22°42’S, 113°40’E, Aug. 2003).

Prevalence: 1 of 2 (50%).

Intensity: 4.

Deposition of specimens: holotype QM G222056, paratypes QM G222057, BMNH 2004.2.13.14–15.

Etymology: The new species is named after Tantabiddi, from where we launched the boat for the collection of these specimens.

Description. Based on 4 whole­mount preparations of 3 worms and fragments of a fourth (remainder of specimen reserved for molecular studies). Measurements and ratios in Table 1. Body elongate, narrow, wider at oral and ventral suckers and in region of gonads ( Figure 1 ). Tegument spinous, unarmed patch immediately posterior to oral sucker, large spines densely packed in forebody, smaller in hindbody, sparser in hindbody, few seen posteriorly to testes. Oral sucker terminal, wider than long. Circum­oral spines in double ring, with distinct ventral hiatus, spines decrease in size markedly towards hiatus ( Figure 2 ). Ventral sucker oval, in anterior fifth of body. Prepharynx long. Pharynx pyriform. Oesophagus distinct. Intestinal bifurcation in posterior forebody. Caeca long, narrow, posterior caecal extremities obscured by vitelline follicles in 2 specimens, in 1 specimen lateral wall of caecal terminations abut and appear to merge with wall of excretory vesicle, luminal connection forming uroproct not confirmed.

Measurement, count or ratio descriptor Measurement, count or ratio Overall dimensions 12,230–14,874 × 511–615 (13,218 × 562) Width as % of length 4.1–4.5%

Body spines: anterior mid­ventral 19–23 (21) long

Body­spines: longest 32–37 (35) long

Oral sucker 159–184 × 296–343 (171 × 319) Oral sucker length as % of body­length 1.1–1.5 (1.3) %

Circum­oral spine counts 38–45 (42)

Circum­oral spines: anterior ventral 27–37 (33) long

Circum­oral spines: posterior ventral 26–41 (35) long

Circum­oral spines: anterior dorsal 96–100 (99) long

Circum­oral spines: posterior dorsal 79–93 (84) long

Ventral sucker (VS) 442–478 × 362–455 (461 × 396) Sucker­length ratio 1:2.5–3.0 (2.7)

Sucker width ratio 1:1.1–1.3 (1.2)

Forebody 1,757–1,798 (1,778) long Forebody as % of body­length 12.1–14.4 (13.6)%

Hindbody (HB) 10,032–12,599 (10,979) long Hindbody as % of body­length 82.0–84.7 (82.9)%

Prepharynx 894–985 (946) long

Prepharynx length as % of body­length 6.4–7.8 (7.2)%

Pharynx 295–302 × 199–279 (299 × 227) Pharynx length as % of body­length 2.0–2.4 (2.3)%

Oesophagus 212–284 (242) long

Intestinal bifurcation to ventral sucker 79–186 (136)

Anterior testis 838–977 × 355–382 (892 × 368) Anterior testis as % of body­length 5.6–8.0 (6.8)%

Posterior testis 888–965 × 349–421 (921 × 379) Posterior testis as % of body­length 6.1–7.9 (7.0)%

Distance between testes (DBT) 170–556 (322)

DBT as % of body­length 1.3–3.7 (2.3)%

Post­testicular region (PTR) 616–839 (727)

PTR as % of body­length 5.0–5.8 (5.5)%

Cirrus­sac (CS) 1,529–2,094 × 185–219 (1,856 × 201) Cirrus­sac length as % of body­length 12.5–15.5 (14.0)%

..... continued on the next page Measurement, count or ratio descriptor Measurement, count or ratio Distance from anterior end of CS to VS 254–455 (351)

Distance from posterior end of CS to VS 1,915–2,340 (2,075) Above dimension as % of VS to Ovary 30.7–32.2 (31.3)% Seminal vesicle (SV) 454–613 (531) long SV as % of internal male duct 26.4–30.0 (28.7)% Pars prostatica (PP) 713–1,165 (1,005) long PP as % of internal male duct 46.7–58.7 (53.6)% Ejaculatory duct (EJ) 296–359 (317) long EJ as % of internal male duct 14.5–23.5 (17.6)% Genital atrium 835–963 (910) long Ovary 367–448 × 245–319 (397 × 274) Ovary length as % of body length 3.0%

Ovary to ventral sucker (Ov­VS) 5,956–7,618 (6,651) Ov­VS as % of body­length 48.7–51.2 (50.2)% Ovary to anterior testis (Ov­AT) 894–1,406 (1,083) Ov­AT as % of body­length 7.3–9.4 (8.1)%

Eggs 72–84 × 37–44 (80 × 40). Anterior limit of vitellarium to VS 1,716–2,757 (2,156) Above dimension as % of HB­length 17.1–21.9 (19.5)%

Testes 2, oval, entire, tandem, well separated. Post­testicular region short. Cirrus­sac elongate, coiled or more less rectilinear ( Figure 3 ), reaching well into hindbody, anterior extremity distinctly posterior to ventral sucker. Seminal vesicle saccular, oval, undivided. Pars prostatica long, narrower distally, lined with anuclear cell­like bodies, surrounded by gland­cells. Ejaculatory duct short, wide, lined with closely packed rows of large blunt conical spines, with round bases seen as circles on wall, small naked region distally (Figure 4). Genital atrium long, reaching well into hindbody. Genital pore median, slit­like, immediately anterior to ventral sucker.

Ovary oval, entire, well separated from anterior testis. Mehlis' gland antero­dorsal to ovary. Pore of Laurer's canal not detected. Uterine seminal receptacle in proximal uterus ( Figure 5 ). Uterus narrow, intercaecal, pre­ovarian. Eggs numerous, large, tanned operculate. Metraterm short, slightly longer than ejaculatory duct, delimited by sphincter and small patches of external gland­cells, lining unarmed. Vitellarium follicular, just overlaps posterior end of cirrus­sac or not, fields confluent dorsally and almost confluent ventrally to uterus, confluent between ovary and anterior testis and between testes, slightly overlapping testes, confluent dorsally and ventrally in post­testicular region.

Excretory pore terminal. Vesicle apparently dividing just posteriorly to ovary.

Figures

FIGURES 1 – 5. Stephanostomum tantabiddii n. sp. 1. Ventral view of holotype, details of gut omitted in region of vitellarium. 2. Anterior extremity showing circum­oral and body spines. 3. Terminal genitalia, lateral view. 4. Ejaculatory duct showing armament. 5. Female proximal genitalia. Abbreviations: cs, conical spine; ej, ejaculatory duct; Mg, Mehlis’ gland; ov, ovary; pp, pars prostatica; sv, seminal vesicle; usr, uterine seminal receptacle; vh, ventral hiatus. Scale­bars: 1, 1 mm; 2, 4, 200 µ m; 3, 500 µ m.