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New Zealand Coelenterates Ctenophores from Cook Strait

Bolinopsis paragaster sp. nov. Text Fig II and III

Bolinopsis paragaster sp. nov. Text Fig II and III .

Specific Description: Oral lappets large, three-fifths the total length of the body; four short auricles about one-half the size of the oral lappets; paragastric canals unique, giving rise to two branches which traverse the inner surface of each oral lobe, then travel along the lower margin of the lobe till they join the meridional subventral canal of their respective sides; stomodeum short, and coloured with deep red-brown pigment; the funnel tube is long; and the tentacle bases are double.

The generic name Bolinopsis is used in this paper in the "sens emend.," of Mayer (1912). Specimens up to 50 mm. long were taken. As is usual with Bolinopsis they were extremely delicate in texture, the least current being sufficient to tear them to pieces. When swimming the specimens always kept the funnel axis vertical using the swimming plates and feeble movements of the oral lobes for locomotion. Specimens were taken during late Autumn (March and April) when they often formed a major part of the pelagic fauna.

Text Fig. II.

Text Fig. II.

Bolinopsis paragaster n.sp. MST, meridional subtentacular canal; MSV, meridional subventral canal; TB, tentacle base; S, stomodeum.

The species is described from a living specimen measuring 25 mm. in length (in the stomach axis) from the apical sense organ to the tip of the oral lobes. The two large oral lobes are about three-fifths the total length of the expanded page 5 animal, and there arc four short auricles with cilary combs on the margin. The sense organ is sunken in a small pit. The subventral meridional canals traverse the oral lobes of their respective sides as two parallel canals till nearly the abapical margin where they diverge, wind slighty in the oral lobe and then join a branch of the paragastric canal on the margin of the lobe. From this junction with the paragastric canals on the margin of the lobe, the meridional subventral canals continued to border the margin of their respective sides of the lobe until they meet and join with the meridional subtentacular canal of that side. The paragastric
Text Fig. III.

Text Fig. III.

Juvenile Bolinopsis paragaster n.sp. T, tentacle; P, paragastric canal; TB, tentacle base; S, stomodeum.

canals are unique. They give rise to two branches which traverse the inner surface of each oral lobe travelling along the margin of the lobe till they join the meridional subventral canal as described above. All the canals, but especialy the paragastric canals and the tentacular canals contain many tiny globules, more so than in other ctenophores. Many of these globules are coloured light red. The stomodeum is short, compressed in the stomodeal axis, and coloured with a deep red-brown pigment. Except for this deep red-brown pigment of the stomodeum and the light red globules in the canals the specimens are transparent and colourless. The funnel tube is long, and from its oral end two thick branches pass to the tentacle bases. The tentacle bases are enclosed in remnants of a tentacle sheath, and are unusual in that they are double in all specimens examined, i.e., there is a pair of tentacle bases on each side of the animal. Arising from this double tentacle base is a single tentacle which follows the contour of the margin of the mouth to the inner side of the two parallel branches of the paragastric canal and then follows these canals closely until just past their junction with the meridional subventral canals. Throughout their course they give rise to numerous contractile filaments.
page 6

The auricles hang down well below the mouth.

Several specimens were taken during hauls that we consider are juvenile B. paragaster. They showed similar localized pigment in the stomodeum, globular bodies in the paragastric canals and the tentacle bases were double. The largest specimen is 6 mm. in length and differs from the adult in possessing long rows of swimming plates and long meridional canals, tentacles based in definite sheaths and non-branching paragastric canals. No oral lobes are present and the subventral meridional canals end blindly. The meridional subtentacular canals join the paragastric canals of their respective sides. The stomodeum is flattened in the plane of the polar plate. A two-millimetre specimen had large swimming plates and the meridional canals ended blindly. The tentacles were similar to the 6 mm. specimen.