Ankistromeces dunwichensis, Nolan & Cribb, 2006

Nolan, Matthew J. & Cribb, Thomas H., 2006, An exceptionally rich complex of Sanguinicolidae von Graff, 1907 (Platyhelminthes: Trematoda) from Siganidae, Labridae and Mullidae (Teleostei: Perciformes) from the Indo-west Pacific Region, Zootaxa 1218 (1), pp. 1-80 : 24-30

Ankistromeces dunwichensis n. sp. ( Figs. 9–11 )

Type host: Siganus fuscescens (Houttuyn) , Black Spinefoot ( Perciformes : Siganidae ).

Site in host: Intertrabecular spaces of ventricle, and atrium (heart).

Type locality: North Stradbroke Island, Moreton Bay (27°23’S 153°26’E), Queensland .

Material examined: ex S. fuscescens , North Stradbroke Island (QLD), Mar. 2003, one specimen (Holotype no. QM G 225524 ) (a second specimen sequenced for ITS2) .

Collector: M.J. Nolan.

Etymology

Specific name for Dunwich, North Stradbroke Island, the only locality where this species has been found so far.

Locality: 1. Bribie Island; 2. Heron Island; 3. Lizard Island; 4. Ningaloo Reef; 5. North Stradbroke Island; 6. Palau.

Description

Based on one whole mount. With features of genus. Body not distinctly notched at male genital pore. Testis originating posterior to intercaecal field, but antero­dextrally to distal termination of left posterior caecum, margins irregular. Cirrus­sac dorsally directed. Internal seminal vesicle ovoid, occupying ventral region of cirrus­sac; ejaculatory duct sinuous, antero­dorsally directed; prostatic cells small. Ovary with lobed margins, transversely tear­shaped, ventrally orientated, abutting posterior margin of testis. Oviduct not seen. Vitelline duct forming anterior to anterior margin of cirrus­sac, passing posteriorly sinuously, ventral to vas deferens and cirrus­sac, entering oötype posteriorly. Oötype ovoid, antero­ventrally directed. Mehlis’ gland extending anteriorly to posterior margin of cirrus­sac, extending posteriorly to anterior margin of excretory vesicle. Uterus extends anteriorly from oötype, ventral to vas deferens and cirrus­sac, sinistral to vitelline duct and vitelline follicles, level with posterior margin of ovary passes dorsally across mid­line, sinistral to ovary, at anterior margin of ovary loops posteriorly to form uterine chamber. Uterine chamber convoluted anteriorly, sinuous posteriorly, extends from anterior margin of ovary to anterior margin of cirrus­sac. Vitelline follicles compacted; originate in posterior half of body, extend posteriorly to posterior margin of uterine chamber, sinistral to posterior caecum, testis and ovary, dextral to proximal uterus, ventral to vas deferens, proximal uterus and uterine chamber.

Remarks

This species clearly belongs in Ankistromeces as it possesses the key characters of a vestigial oral sucker, an H­shaped intestine (anterior caeca short, posterior caeca very long), a single testis, a predominantly post­ovarian uterus, a uterine chamber (albeit convoluted), separate genital pores and in the absence of an auxiliary external seminal vesicle. Ankistromeces dunwichensis n. sp. is clearly distinguished from the type species, A. mariae , in the combination of the position and relative size of the testis, the shape of the body wall adjacent to the male genital pore, the shape and relative size of the ovary, the shape and relative width of the uterine chamber and vitelline follicle distribution. Ankistromeces mariae has a testis that originates at the posterior end of the intercaecal field and occupies 30–56% of the body length and 80–98% of the body width, a distinct notch level with the male pore and a spherical ovary that occupies 3–5% of the body length and 64–84% of the body width. This species also has a relatively straight uterine chamber that occupies 33–52% of the body width and vitelline follicles that start in the anterior half of the body. In contrast, A. dunwichensis has a testis that originates posterior to the intercaecal field and occupies 11% of the body length and 67% of the body width, m; 10, 100 m. no distinct notch level with the male pore and a transversely tear­shaped ovary with lobed margins that occupies 1% of the body length and 58% of the body width. The new species also possesses a uterine chamber that is convoluted anteriorly and sinuous posteriorly, and occupies 25% of the body width and vitelline follicles that originate in the posterior half of the body.

There are in addition, 16–20 base differences (4.7–5.8% sequence divergence) between the ITS2 rDNA sequence of A. dunwichensis and the remaining Ankistromeces species sequenced here.

Figures

FIGURES 9–11. Ankistromeces dunwichensis n. sp. from intertrabecular spaces of ventricle and atrium (heart) of Siganus fuscescens off North Stradbroke Island. 9. Adult. Dorsal anteriorly, medially twisting laterally at level of “arrow a”, ventral side to the right, whole mount. 10. Male terminal genitalia, lateral view. 11. Female terminal genitalia, lateral view. Vitelline duct omitted as obscures path of proximal uterus. Oviduct not observed in single specimen. Scale­bars: 9,11, 250