Stephanostomum talakitok, Bray & Cribb, 2006

Bray, Rodney A. & Cribb, Thomas H., 2006, Stephanostomum talakitok n. sp. (Digenea: Acanthocolpidae) from the golden trevalley, Gnathanodon speciosus (Perciformes: Carangidae), from Ningaloo Reef, Western Australia, Zootaxa 1104 (1), pp. 59-68 : 60-64

Stephanostomum talakitok n. sp. ( Figs 1 –3)

Type­host: Gnathanodon speciosus (Forsskål) , Carangidae ; golden trevally.

Site: Intestine.

Type­locality: Ningaloo Coral Reef , Western Australia (22°42S, 113°40E, April, 2000) .

Prevalence: 1 of 1 (100%).

Intensity: 22.

Deposition of specimens: holotype QM G223027 , paratypes QM G223028–223040 , BMNH 2005.10 .28.1–7.

Etymology: Talakitok is a Philippine vernacular name for the host­species.

Description (Based on 21 whole­mount preparations). Measurements and ratios in Table 1. Body elongate, narrow, widest in region of testes ( Figure 1 ). Tegument spinous, unarmed patch immediately posterior to oral sucker, spines large and densely packed in forebody, smaller in hindbody, becoming sparse in hindbody, only detectable to level of ovary. Oral sucker terminal, distinctly wider than long. Circum­oral spines in double ring, without distinct ventral hiatus; spines decrease in size markedly towards ventral median line; mid­ventral spine small, pointed ( Figure 2 ). Ventral sucker oval, in anterior third of body. Prepharynx long. Pharynx pyriform. Oesophagus distinct. Intestinal bifurcation in extreme posterior forebody or at level of anterior margin of ventral sucker. Caeca long, narrow, form uroproct.

Testes 2, oval, entire, tandem, contiguous. Post­testicular region short. Cirrus­sac elongate, coiled ( Figure 3 ), reaches well into hindbody; anterior extremity dorsal to ventral sucker. Seminal vesicle saccular, oval, undivided, often coiled anteriorly. Pars prostatica long, narrower distally, lined with anuclear cell­like bodies, surrounded by gland­cells. Ejaculatory duct long, wide, lined with closely packed small cupolas, with round bases seen as circles on wall of duct, with distinct naked region distally. Genital atrium short, never reaching into hindbody. Genital pore median, slit­like, immediately anterior to ventral sucker.

Ovary oval, entire, almost always contiguous with anterior testis, occasionally slightly separated. Mehlis' gland antero­dorsal to ovary. Laurer's canal opens dorsally in region of ovary. Uterine seminal receptacle in proximal uterus. Uterus narrow, intercaecal, preovarian. Eggs large, tanned operculate. Metraterm slightly shorter than cirrus­sac, lining unarmed. Vitellarium follicular, overlaps posterior end of cirrus­sac; fields confluent ventrally and dorsally to uterus, lateral to and slightly overlaps gonads, confluent dorsally and ventrally in post­testicular region.

Excretory pore terminal. Anterior extent of vesicle not detected, even in immature specimens.

Figures

FIGURES 1–3. Stephanostomum talakitok n. sp. 1. Ventral view of holotype, with uterus and cirrus­sac in outline only. 2. Anterior extremity showing circum­oral and body spines. 3. Terminal genitalia, lateral view. Abbreviations: ej, ejaculatory duct; pp, pars prostatica; sv, seminal vesicle. Scale­bars: 1, 1mm; 2, 3, 200 µm.