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New Zealand Coelenterates Ctenophores from Cook Strait

Order Lobata

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Order Lobata

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.
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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.

Discussion

B. paragaster can be distinguished from B. infundibulum (L. Agassiz) Mayer 1912 the type species, by its longer oral lobes, shorter comb rows, less deeply sunken sense organ and by the simple windings of the subventral meridional canals in the oral lobes; from B. vitrea (L, Agassiz) Mayer 1912 by possessing subventral comb rows only slightly longer than the subtentacular rows, whereas B. vitrea has the subventral rows about twice as long as the subtentacular; from B. elegans Mertens 1833 by the lack of body papillae, and from B. mikado Moser 1907. 1908 by the very much shorter subventral comb rows which are less than half the length of those displayed by B. mikado, which extend from the apical pole to nearly the lower border of the oral lobe. In B. paragaster the subventral rows do not extend beyond the level of the mouth. Further, the sense organ of B. mikado is far more deeply sunken than in B. paragaster. B. paragaster shows some similarity to B. ovalis Bigelow 1904 which has proportionally longer lobes than most other species of the genus. Bigelow (1912) considers, however, that B. oralis and B. hydactina Chun 1880 are varieties of B. vitrea so that the same character that separates B. vitrea from B. paragaster, namely the difference in length of the subventral comb rows, will also distinguish B. ovalis and B. hydactina from B. paragaster. B. chuni described by von Lendenfeld (1884) from South Australian waters can be distinguished from B. paragaster by the extraordinary thickness of its oral lobes, and by the fact that the paragastric canals lie at some distance from the stomach. In addition to the characters outlined above B. paragaster possesses several unique features that distinguish it from all the known species of the genus, viz.: double tentacle bases; branched paragastric canals that join the meridional subventral canals on the lower margin of the oral lobe and a short densely pigmented stomodeum and relatively long infundibulum. Unfortunately, the juvenile specimens do not throw any light on the manner in which the branched paragastric canals arise, as in both specimens no oral lobes are present and the normal non-branched condition of the canals is displayed. Double tentacle bases however seem to be characteristic of the species in the juvenile stage of development, and should assist in making possible early recognition of the species.

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Lesueuria pinnata sp. nov. Text Fig. IV.

Specific Description: Four, papillated, fin-like flaps, are situated beside the meridional subventral bands of swimming plates and what appear to be short transverse canals are found below each swimming plate; oral lobes about one-quarter the total length of the animal and the auricles slightly shorter than the oral lobes; peripheral canal system at present unknown.

This species is common during calm weather in autumn but is very difficult to capture on account of its size and delicate nature, while an hour or so of confinement is sufficient to start disintegration. The description of this species is taken from the preserved specimen and observations on several living specimens. The average size of specimens was 160 to 200 mm. long and the largest was 290 mm. The stomodeum of the species is long and the infundibulum short. The meridional canals unfortunately are not distinct. In cross section the body is dumb-bell shaped, with the stomodeum corresponding in position to the handle of the dumb-bell. In general outline the body is long and considerably flattened in the tentacular axis, which has a deep wide groove running from the oral toward the aboral end and disappearing in the region of the funnel tube. There are two oral lobes of very delicate texture about one-quarter the total length of the body. The four auricles are straight and ribbon-like and somewhat shorter than the oral lobes. The stomodeal axis is 60 mm. in width and the distance between the meridional subventral and meridional subtentacular canals of opposite sides is 20 mm. Aborally, the end is bluntly pointed, and the subtentacular comb rows commence from the inner sides of two gelatinous projections that form a groove in which the sense organ is situated. Otherwise the rows of swimming plates are of the general lobate type with the individual plates very wide and short. What appear to be short transverse canals pass through the base of each comb plate. Gelatinous dark-coloured, fin-like flaps are situated beside the meridional subventral bands of swimming plates. Along the outer margin of these fin-like flaps is a row of tiny papillae each with a projecting centre. In the preserved specimens these could be traced to the margin of the oral lobe but this is difficult in the living specimens as the papillae are unpigmented in this region. Aborally, they are pigmented and show as a thin dark line. The centres of the papillae however are devoid of pigment. The rest of the animal is unpigmented and slightly opaque.

Discussion

It is with hesitation that we revive the genus Lesueuria Milne-Edwards, 1841, to receive these New Zealand specimens of the O. Lobata, for Mortensen (1912) unhesitatingly concluded that Lesueuria is nothing else than a regenerating Bolina (Syn. Bolinopsis Mayer 1912). All the present specimens fall within the generic description of Lesueuria as defined by Mayer (1912). "Lobatae with rudimentary oral lappets and with long, ribbon-shaped auricles. The peripheral gastrovascular system is simple, without complex windings." At present we see no adequate reason page 8
Text Fig. IV.

Text Fig. IV.

Lesueuria pinnata n. sp. Drawing reconstructed from a photograph. F, fin-like flap beside subventral row of swimming plates; CC, canal-like structures below each comb plate; PL, papillose margin of flap.

page 9 for concluding that our specimens are regenerating from a damaged condition, so that the characters displayed by the New Zealand specimens, i.e., small oral lappets and long ribbon-shaped auricles properly assign them to the genus Lesueuria and not Bolinopsis. Lesueuria and Bolinopsis have been taken on the same day and can readily be distinguished one from the other. The oral lobes of the present specimens of Lesueuria are about one-quarter the total length of the body, whereas in Bolinopsis, the lobes are usually nearly two-thirds the total body length. The type species is L. vitrea Milne-Edwards 1841, of the Mediterranean. L. hyboptera "the so-called American species is more nearly rectangular in outline than the oval-shaped L. vitrea. In L. hyboptera the body is wider both above and below than it is in the middle, thus giving the appearance of a laterally flattened hour glass." (Mayer 1912.) The body shape of L. pinnata is more like L. hyboptera than L. vitrea but the oral lobes are longer than in either of these species. L. pinnata can further be distinguished from L. vitrea and L. hyboptera by the presence of four, fin-like, marginally papillose, flaps alongside the meridional subventral bands of swimming plates and by what appear to be small transverse canals below each of the comb plates.

Leucothea multicornis (Eschscholtz) 1825 (Syn. Eucharis multicornis Eschscholtz 1825)

This species observed in autumn during very calm weather was one of the most delicate ctenophores taken, and extremely difficult to handle, as it extruded great quantities of slime when captured. Any slight movement of the boat always tore the specimens to pieces so that only fragments ever reached the laboratory. Specimens average between 150 mm. and 200 mm. but specimens larger than 200 mm. have been taken. Specimens smaller than 150 mm. were seldom encountered. The oral lobes are very large and once were seen spread on the surface of the water as figured by Chun (1880). The auricles are very long with cilia on one side only. The body surface is papillated, each being about 10 mm. long and bearing a cap of large globular cells. These papillae are mobile and extensible. They respond to tactile stimuli bending to touch if possible the stimulating object. The individual plates of the comb rows are large. All specimens examined were in part damaged. The canal system and tentacle structure were difficult to determine accurately. Sufficient evidence was obtained however for us to be sure that the New Zealand specimens are correctly assigned to L. multicornis.