Cardicola watsonensis, Nolan & Cribb, 2006

Nolan, Matthew J. & Cribb, Thomas H., 2006, Cardicola Short, 1953 and Braya n. gen. Digenea: Sanguinicolidae) from five families of tropical Indo-Pacific fishes (, Zootaxa 1265 (1), pp. 1-80 : 30-31

Cardicola watsonensis n. sp.

( Figs 27–30 )

Type host: Siganus corallinus (Valenciennes) , Coral Rabbitfish ( Perciformes : Siganidae ).

Site in host: Atrium and ventricle (heart).

Type locality: Lizard Island, northern Great Barrier Reef (14º40’S 145º27’E), Queensland .

Material examined: ex S. corallinus, Lizard Island ( QLD), Aug. 2002, Jan. 2003, one specimen (no QM G 225228 ) (two specimens sequenced for ITS2) .

Prevalence of Infection : One of forty­three S. corallinus from Lizard Island infected with three specimens .

Collector: M.J. Nolan.

Etymology

Specific name for the only site off Lizard Island (Watson’s Bay) where the new species has been found so far.

Description

Based on one whole mount. With features of genus. Body elliptical, 982 x 186, 5.3 times longer than wide ( Figure 27 ). Tegumental spine rows 5–10 (8) wide, 5–6 spines per row. Nerve chords conspicuous; nerve commissure 91 or 9% of body length from anterior end. Oral sucker obovate, 24 x 22, delimited posteriorly by fine membrane and slight body constriction, bearing unknown number of concentric rows of fine spines ( Figure 28 ). Mouth 13 from anterior end. Oesophagus sinuous, width relatively consistent along length, posterior half surrounded by gland cells, 517 or 53% of body length. Intestine X­shaped; anterior caeca equal, sinuous, right anterior caecum 134 long, left anterior caecum 134 long, length 14% of body length, wider than posterior pair, right anterior caecum dorsal to oesophagus; posterior caeca convoluted, unequal, right posterior caecum 242 long, left posterior caecum 272 long; length 28% of body length, 2.0 times longer than anterior pair, regular in outline compared to anterior caeca, terminal extremities expanded. Testis extending laterally to intercaecal field, terminating before posterior margin of posterior caeca, 241 or 25% of body length x 116 or 62% of body width, 2.1 times longer than wide. Vas deferens originates at posterior margin of testis medially, passing posteriorly sinuously, expanding distally to form seminal vesicle. Seminal vesicle elliptical, 116 or 12% of body length from posterior end, 80 x 49, 1.6 times longer than wide ( Figure 29 ). Ejaculatory duct straight, posteriorly directed; prostatic cells not seen. Male genital pore sinistral, sub­marginal. Ovary reniform, anteriorly intercaecal, posteriorly extending outside field, 87 or 9% of body length x 127 or 68% of body width, 181 or 18% of body length from posterior end. Oviduct originating dorso­anteriorly to postero­dextral margin of ovary, at posterior margin expands to form oviducal seminal receptacle, narrowing level with anterior margin of seminal vesicle, continuing posteriorly, joining with vitelline duct posteriorly to seminal vesicle. Oviducal seminal receptacle elliptical, 48 x 25, 1.9 times longer than wide, dorsal to ovary. Vitelline duct seen posterior to posterior margin of testis, passing posteriorly sinuously, ventral to ovary, oviducal seminal receptacle, vas deferens and seminal vesicle. Oötype elliptical, posterior to seminal vesicle, 32 x 27. Mehlis’ gland not seen. Uterus convoluted, passing antero­sinistrally from oötype, crossing midline lateral to oötype, then passing antero­dextrally, dorsal to oötype, oviduct, oviducal seminal receptacle and vas deferens, but ventral to seminal vesicle, lateral to oviducal seminal receptacle passes sinistrally across midline, ventral to ovary, then passes postero­dextrally to join metraterm ( Figure 30 ). Metraterm ovoid, dorsally directed, 43 x 25. Female genital pore opening dorso­medially, lateral to oviducal seminal receptacle, anterior to seminal vesicle, antero­dextral to male genital pore. Eggs spherical, 21–22 (21) x 16–18 (17) (n=3). Vitellarium follicular, anteriorly extending past nerve commissure, posteriorly extending to level of oviducal seminal receptacle, anteriorly dorsal to lateral nerve chords, both dorsal and ventral to oesophagus, intestine and testis, posteriorly ventral to ovary. Excretory vesicle spherical, 5 in diameter. Excretory pore not seen.

Remarks

This species shows close affinity with the characters differentially diagnostic of the genus Cardicola and is here identified as a new species in that genus. Cardicola watsonensis n. sp. is distinguished by the combined possession of an oral sucker, an oesophagus that is sinuous and that extends 53% of the body length, posterior caeca that are convoluted and extend 28% of the body length, an elliptical seminal vesicle with a long posteriorly directed ejaculatory duct, a male genital pore that opens anteriorly to the oötype, a reniform ovary that is almost entirely post­caecal and vitelline follicles that extend anteriorly past the nerve commissure and posteriorly to the level of the female genital pore.

Cardicola watsonensis n. sp. appears most similar to C. bartolii n. sp., also from S. corallinus . Both species have an oral sucker, an oesophagus that is sinuous (by comparison to Cardicola mugilis ), oesophageal glands that surround only the posterior half of the oesophagus, convoluted posterior caeca, a testis that is mostly intercaecal (does not extend posteriorly to this field) and is rectangular with irregular margins and a seminal vesicle that is no more than 13% of the body length from the posterior end. These two species also have an ovary that is anteriorly intercaecal, a uterus that extends anteriorly past the posterior margin of the ovary (but not past the anterior margin as in Cardicola congruenta ) and is entirely postcaecal and vitelline follicles that extend anteriorly past the nerve commissure. Cardicola watsonensis n. sp. differs from C. bartolii n. sp. in having an entirely convoluted uterus that extends anteriorly from the oötype rather than one that is convoluted posteriorly, sinuous anteriorly and that extends posteriorly from the oötype before looping anteriorly, a reniform ovary rather than a bilobed one, a male genital pore that opens anteriorly to the oötype rather than lateral to it and vitelline follicles that extend posteriorly to the level of the female pore rather than to the posterior margin of the ovary.

Figures

FIGURES 27–30. Cardicola watsonensis n. sp. from the atrium and ventricle (heart) of Siganus corallinus off Lizard Island. 27. Adult, whole mount, dorsal view. 28. Anterior region, dorsal view, showing vestigial oral sucker delimited by fine membrane. Spines not seen on single specimen as anterior end folded dorsally. 29. Male terminal genitalia, dorsal view. 30. Female terminal genitalia, dorsal view. Vitelline duct and vitelline reservoir omitted from figure as they obscure the path of the oviduct, oviducal seminal receptacle and uterus as they pass posteriorly. Mehlis’ gland not seen in this specimen. Scale­bars: 27, 250 m; 28–30, 100 m.