Phthinomita brooksi, 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 : 40-43

Phthinomita brooksi n. sp. ( Figs. 26–28 )

Type host: Siganus virgatus (Valenciennes) , Barhead Rabbitfish ( Perciformes : Siganidae ). Site in host: Intertrabecular spaces of ventricle (heart). Type locality: Ningaloo Reef (21°54.6’S 113°58.4’E), Western Australia. Material examined: ex S. virgatus, Ningaloo Reef (WA) , Aug. 2003, twenty­six specimens (Holotype no. QM G 225548; Paratype nos. QM G 225549–225552 and QM G 225558–225562). Collector: M.J. Nolan.

Etymology

Specific name for Dr Daniel Brooks, for his contributions to digenean phylogenetic theory.

Description

Based on 26 whole mounts. With features of genus. Body distinctly notched level with male genital pore. Intestine; posterior caeca irregular, distal terminations expanded. Anterior testis originating posterior to intercaecal field, margins lobed, appearing segmented or convoluted, containing dorso­ventral muscle fibres. Posterior testis elliptical, margins lobed. Cirrus­sac elongate, elliptical, sinuous, narrow ventrally, widening dorsally. Internal seminal vesicle occupying most of cirrus­sac, of similar shape to cirrus­sac; ejaculatory duct straight or sinuous, prostatic cells small. Ovary ovoid to spherical, posterior to posterior margin of anterior testis. Oviduct passing posteriorly sinuously, entering oötype postero­dextrally. Vitelline duct forming anterior to cirrus­sac, passing posteriorly sinuously; vitelline reservoir forming lateral to posterior margin of cirrus­sac, entering oötype posteriorly. Oötype ovoid. Mehlis’ gland extending anteriorly past posterior portion of distinct notch in body wall, extending posteriorly to mid­section of posterior testis. Uterus extending from oötype, sinuous, sinistral to oviduct. Uterine chamber forming laterally to posterior margin of ovary, passing posteriorly slightly sinuously, narrowing posteriorly, passing dorsally to female pore. Vitelline follicles occupy intercaecal field anteriorly, posteriorly extending past ovary.

Remarks

This species agrees well with the characters of Phthinomita and appears most closely related to the type species, P. symplocos . These species share similar body length: width ratios, the relative length of the oesophagus, and the relative lengths of the anterior and posterior caeca and the position of the anterior testis relative to the intestine. They also share a similarly sized posterior testis and ovary (relative to body size) and the relative position of the cirrus­sac and ovary from the posterior end. Most of these similarities are also shared with P. adlardi ; the exception is the position of the anterior testis relative to the posterior caeca (the anterior testis of P.adlardi originates posterior to the intercaecal field, but, antero­sinistral to the distal termination of the right posterior caecum). Phthinomita brooksi differs from P. symplocos , in having a highly lobed (and possibly convoluted) anterior testis and a uterine chamber that originates laterally to the posterior margin of the ovary. The new species differs from P. adlardi in having an anterior testis occupying 12–24% of the body length instead of 38–59% and having an anterior testis 2.4–6.8 times longer than the posterior testis rather than 12.6–38.2 times longer. Phthinomita brooksi differs further in having the combination of an elongate and slightly sinuous cirrus­sac (that may be 7.0 times longer than wide), a very distinct notch level with the male genital pore and vitelline follicles that do not extend anteriorly past the intestinal bifurcation.

There are in addition, 2–34 base differences (0.5–10.3% sequence divergence) between the ITS2 rDNA sequence of P. brooksi and the remaining Phthinomita species sequenced here. There are two bases different between the sequences from P. brooksi (10 replicates) from S. virgatus from Ningaloo Reef and P. sasali n. sp. (one replicate) from S. doliatus from Palau.

Figures

FIGURE 26. A,B. Phthinomita brooksi n. sp. from the intertrabecular spaces of ventricle (heart) of Siganus virgatus from Ningaloo Reef. Adult. Medially twisting laterally at level of “arrow a”, ventral side to the right, whole mount. Scale­bar: 250 m.

FIGURES 27–28. Phthinomita brooksi n. sp. 27. Male terminal genitalia, lateral view. 28. Female terminal genitalia, lateral view. Scale­bars: 27, 100 m; 28, 250 m.