Aotearoa ballantinensis, Holleman, John J., 2007

Holleman, John J., 2007, Some New Zealand Polyclads (Platyhelminthes, Polycladida), Zootaxa 1560, pp. 1-17 : 9-11

Aotearoa ballantinensis n. sp.

( Figures 13–15 )

Material

Specimens were collected from Echinoderm Flat west of Leigh Marine Research Laboratory; Island Bay Marine Laboratory, Wellington and Castle Point north island. Specimens from south island were collected from the Kaikoura and Portobello peninsulas.

Morphology

External features: The specimens were cuneiform in outline, rounded anteriorly and tapering posteriorly. The largest specimen measured 23mm long and 10mm wide when moving. The dorsal surface is uniform medium yellowish brown shading to a reddish brown over the pharynx. The ventral surface is a pale light brown. The small marginal eyes form a wide band anteriorly that is reduced in width at the level of the pharynx continuing to completely encircle the rest of the margin. Small frontal eyes cover the area from the pharynx anteriorly. The tentacular eyes forming two distinct clusters, numbering 18 to 24, are located about half the distance from the cerebral organ to the margin. The large pharynx is about two thirds the length of the body with 8 major folds. The mouth is located in the posterior third of the pharyngeal pocket. The intestinal branches do not anastomose.

Reproductive anatomy: The common gonopore, located in the posterior sixth of the body, leads to a short antrum that extends dorsally. The small unarmed penis papilla is at the apex of the antrum. The lateral thin walled sperm ducts progress posteriorly converging medially at the posterior end of the pharynx. There they are reduced to two small ducts that are surrounded with a thin layer of circular muscle cells. The ducts converge medially uniting into an ejaculatory duct that makes an “s” curve receiving the prostatic duct prior to entering the base of the penis. The cylindrical free prostatic is positioned horizontally with a lining of smooth epithelium surrounded with a muscular wall which contains gland cells. The vagina opens to the common antrum on its posterior aspect curving anteriorly to a point above the prostatic vesicle where it curves dorsally then posteriorly receiving the common oviduct. As the vagina externa curves anteriorly shell glands surround the vagina media. Prior to the vagina media curving dorsally the ciliated epithelial lining is in 6 or 7 spiral folds. The vagina media curves posteriorly receiving the common oviduct then continues as the ductus vaginalis. The ductus vaginalis has three or four radial folds shortly before turning ventral to the vaginal pore which is immediately behind the common gonopore.

Remarks

Aotearoa ballantinensis differs from the other genera of the family Callioplanidae in the combination of cerebral-frontal eyes; absence of tentacles; common gonopore; free cylindrical prostatic vesicle; absence of seminal vesicle and spermiducal bulbs; and the presence of a ductus vaginalis. Hyman (1959b) describes a new genus Asolenia and Prudhoe (1982) describes the genus Ancoratheca which are distinguished from the other genera of the family Callioplanidae by the presence of a common gonopore and antrum. Aotearoa ballantinensis is different from Asolenia deilogyna Hyman, 1959 and Ancoratheca australiensis Prudhoe, 1982 in five major characteristics. First, Aotearoa ballantinensis has a small blunt conical penis and Asolenia deilogyna Hyman, 1959 has an elongate penis with a thick muscular wall while Ancoratheca australiensis Prudhoe, 1982 has a small muscular penis that is armed with a short stylet. Second, Aotearoa ballantinensis lacks a seminal vesicle while both Asolenia deilogyna Hyman, 1959 and Ancoratheca australiensis Prudhoe, 1982 have seminal vesicles with A. australiensis having a pair of spermiducal bulbs. Third, in Aotearoa ballantinensis the female antrum opens on the posterior wall of the common antrum while in Asolenia deilogyna Hyman, 1959 and Ancoratheca australiensis Prudhoe, 1982 it opens on the roof of the male antrum. Fourth, Aotearoa ballantinensis lacks a Lang’s vesicle but has a ductus vaginalis opening to the exterior a short distance posterior from the common gonopore. Asolenia deilogyna Hyman, 1959 lacks Lang’s vesicle but the vagina continues anteriorly as a paired uteri while in Ancoratheca australiensis Prudhoe, 1982 has a Lang’s vesicle which opens to the ventral surface through a small pore that is a short distance posterior to the common gonopore. A fifth characteristic that distinguishes Aotearoa ballantinensis from Asolenia deilogyna Hyman, 1959 and Ancoratheca australiensis Prudhoe, 1982 is the distribution and pattern of frontal, marginal and tentacular eyes. Aotearoa ballantinensis has frontal eyes that cover the area from the pharynx anteriorly, marginal eyes that encircle the margin and tentacular eye clusters. Asolenia deilogyna Hyman, 1959 has tentacular and cerebral eyes while Ancoratheca australiensis Prudhoe, 1982 has small marginal eyes on the anterior third of the margin, frontal eyes in a fan pattern anterior to the cerebral organ and tentacular eye clusters.

Aotearoa ballantinensis is very common in New Zealand occurring on both of the large islands. It differs from the other genera of the Stylochidae in the combination of cerebral-frontal eyes; absence of tentacles; common gonopore; free cylindrical prostatic vesicle; absence of seminal vesicle and spermiducal bulbs; and the presence of a ductus vaginalis. A stained wholemount has been designated the holotype, an unstained wholemount and a set of serial sagittal slides are designated as paratypes and have been deposited with the California Academy of Science, CAS Nos. 174341, 174342 and 173083 respectively.

Etymology

The genus name Aotearoa is Maori for New Zealand. The new species is named for Dr. William Ballantine in recognition of his efforts in establishing Marine Reserves in New Zealand.

Figures

FIGURES 13 – 15. Aotearoa ballantinensis. 13. Dorsal view. 14. Tentacular eyes. 15. Sagittal view of the copulatory complex.