Echinoplana celerrima Haswell, 1907

Holleman, John J., 2007, Some New Zealand Polyclads (Platyhelminthes, Polycladida), Zootaxa 1560, pp. 1-17 : 4-5

Echinoplana celerrima Haswell, 1907

( Figures 4–6 )

Synonym

Echinoplana tenerrima Prudhoe, 1982 Morphology

External features: The specimens are an elongated oval with the largest specimen measuring 25mm long and 7mm wide. Tentacles are lacking. The dorsal surface is translucent yellow-brown shading darker middorsally. The ventral surface lacks pigment. Cerebral and tentacular eyes are clustered together forming two long rows. The larger tentacular eyes number 8-12 with the smaller cerebral eyes number 28 to 32. The pharynx is located in the middle third of the body with eight pairs of folds. The mouth is in the posterior third of the pharyngeal pocket. Intestinal branches do not anastomose.

Reproductive anatomy: The lateral sperm ducts extend from anterior to the pharynx turning medially immediately after the posterior end of the pharynx. The ducts unite to form the ejaculatory duct just prior to it entering the muscular seminal vesicle which curves upward and anteriorly to enter the anterior end of the long, convoluted and constricted prostatic vesicle which is oriented posteriorly. The prostatic vesicle has a thick muscular wall lined with tall glandular epithelium. The lining of the prostatic is in radial folds. As the prostatic vesicle approaches the extensive musculature of the cirrus-sac the ejaculatory duct narrows and curves dorsally to enter the dorsal end of the cirrus. The cirrus is lined with numerous cuticular spines that are graduated in size from very small at the base of the cirrus to large at the free end which opens directly to the exterior. A male antrum is lacking. The female gonopore is located at a moderate distance — Prudhoe (1982) states 2–3mm — from the male gonopore immediately posterior to a corrugated ventral sucker. The narrow vagina externa extends dorsally and curves anteriorly, surrounded by shell glands, continuing as the vagina interna. The vagina interna has numerous lateral diverticula as it extends anteriorly to a point posterior to the male gonopore where it turns dorsal to receive the short dorsal common oviduct. A short extension of the vagina beyond the entrance of the common oviduct is termed by Prudhoe (1982) as a rudimentary Lang’s vesicle.

Remarks

The sectioned specimen is identical with the extensive descriptions of Haswell (1907b), Galleni (1978) and Prudhoe (1982). The one exception is that Haswell’s (1907b) original diagram, plate 37 figure 2, shows the sperm ducts continuing posteriorly after the medially lateral branches fuse prior to entering the seminal vesicle. This configuration was not observed. Echinoplana celerrima was originally described by Haswell (1907b) from Port Jackson, Sydney Harbor, Australia. A second occurrence of E. celerrima was reported from the Tuscan coast near Livorno by Galleni (1978). Prudhoe (1982) reports on the presence of E. celerrima in the South Australian Museum collection from the Yorke Peninsula. The geographic distribution of E.

celerrima is mainly in the colder waters of the Australian-New Zealand region with one exception in the Mediterranean which Prudhoe (1982) suggests as possibly being introduced by ship.

Three specimens, one as a cleared wholemount, one as a stained wholemount and the third as a set of serial sagittal sections have been deposited in the California Academy of Science., CAS Nos. 174333, 174334 and 174335 respectively.

Figures

FIGURES 4 – 6. Echinoplana celerrima. 4. Dorsal view. 5. Cerebral and tentacular eyes, enlarged. 6. Sagittal view of copulatory complex.