Phthinomita robertsthomsoni, 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 : 52-55

Phthinomita robertsthomsoni n. sp. ( Figs. 41–43 )

Type host: Siganus argenteus (Quoy & Gaimard) , Forktail Rabbitfish ( Perciformes : Siganidae ).

m; 42, 100 m.

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

Type locality: Lizard Island, northern Great Barrier Reef (14°40’S 145°27’E), Queensland .

Material examined: ex S. argenteus, Lizard Island (QLD), Aug. 2002, Jan. 2003, twenty­two specimens (Holotype no. QM G 225613 ; Paratype nos. QM G 225614–225622 ) .

Collector: M.J. Nolan.

Etymology

Specific name for our good friend and colleague Mr Ashley Roberts­Thomson who collected the first S. argenteus of this study.

Description

Based on 22 whole mounts. With features of genus. Body notched at male genital pore. Intestine; posterior caeca sinuous. Anterior testis originating at posterior end of intercaecal field, margins lobed. Posterior testis tear­shaped. Cirrus­sac tear­shaped. Internal seminal vesicle spherical, occupying most of cirrus­sac, positioned ventrally; ejaculatory duct straight; prostatic cells large. Ovary oblanceolate, overlapping posterior margin of anterior testis. Oviduct originating at centre of posterior margin of ovary, sinuous, dorsal to vas deferens, entering oötype postero­dorsally. Vitelline duct forming anterior to cirrus­sac, passing posteriorly sinuously, dextral to vas deferens; vitelline reservoir forming anterior to anterior margin of cirrus­sac, entering oötype posterodextrally. Oötype ovoid. Mehlis’ gland extending anteriorly to posterior margin of cirrussac, extending posteriorly to mid­section of posterior testis. Uterus extending from oötype, slightly sinuous, sinistral to oviduct. Uterine chamber forming anterior to posterior margin of ovary and anterior testis, ventral to ovary, sinuous, curving dorsally posteriorly to female pore. Vitelline follicles extending anteriorly past intestinal bifurcation, extending posteriorly to level female genital pore, sinistral and dextral to oesophagus, filling intercaecal field, dextral to anterior testis.

Remarks

This species possesses the characters differentially diagnostic of the genus Phthinomita and is here identified as a new species in that genus. Phthinomita robertsthomsoni is immediately distinguished by the combined possession of a body 3784–5706 (4851) long, a body 192 wide on average, an anterior testis 38–62% of the body length and 14.8–31.3 times longer than the posterior one, a posterior testis 15–46% of the body width, a cirrus­sac 64–96 (78) x 45–80 (64), an ovary 87–183 (138) x 64–144 (103) and a uterine chamber 257–385 (319) x 39–80 (59). The species differs further in having an anterior testis with the anterior margin in the posterior end of the intercaecal field, an ovary with an anterior margin lateral to the posterior margin of the anterior testis, a uterine chamber originating anteriorly to the posterior margin of both the anterior testis and the ovary and vitelline follicles extending anteriorly past the intestinal bifurcation.

There are in addition, 20–29 base differences (5.8–8.6% sequence divergence) between the ITS2 rDNA sequence of P. robertsthomsoni and the remaining Phthinomita species sequenced here. Between the sequences from P. robertsthomsoni (two replicates) from S. argenteus off Lizard Island and P. sasali (one replicate) from S. doliatus off Palau there are 20 base differences.

Figures

FIGURES 41–43. Phthinomita robertsthomsoni n. sp. from the intertrabecular spaces of ventricle (heart) of Siganus argenteus off Lizard Island. 41. Adult. Lateral view, whole mount. 42. Male terminal genitalia, lateral view. 43. Female terminal genitalia, lateral view. Scale­bars: 41,43, 250