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The paper describes Ctenophores of the Orders Cydippida, Lobata, and Cestida from the waters of Cook Strait. New Zealand. Three new species are described and figured. Pleurobrachia helicoides n. sp. has a cylindrical body; comb rows extending nearly the whole length of the body; paragastric canals as wide as the stomodeum; tentilla tightly coiled into a barrel-shaped orange-pink helix: Bolinopsis paragaster n. sp. has unique branched paragastric canals which unite with the subventral meridional canals on the margin of the oral lobe; double tentacle bases; Lesueuria pinnata n. sp. has four fin-like flaps, marginally papillose, beside the subventral meridional bands of swimming plates; oral lobes about ¼ the total body length. Bolinopsis, Lesueuria, Leucothea and Cestum are recorded from New Zealand waters for the first time.
The Ctenophores described in the present paper were collected by Mr. Kaberry, now of the Marine Department. Wellington, in the course of his postgraduate researches in the Department of Zoology at this College. They can be said to be fairly representative of the species found in New Zealand waters for the year Cestum veneris. The authors wish to thank Prof. L. R. Richardson for his helpful advice with this paper.
This species has been recorded from New Zealand waters by Moser (P. pileus are efficient fish catchers. On several occasions larval fish observed when the net was taken on board were missing when the haul was later examined. Once P. pileus was seen to come in contact with a larval fish as large as itself. The fish seemed to die immediately and in approximately an hour was within the stomodeum. The economic importance of this habit has been emphasized elsewhere. (Bigelow,
Specific Description: Body of living specimen cylindrical, with long comb rows extending from the aboral pole to nearly the oral pole; meridional canals slightly greater in length than the comb rows broad paragastric canals, nearly as wide as the stomodeum; tentilla. tightly coiled into a barrel-shaped helix, orange-pink in colour.
Specimens were taken on two occasions—Pleurobrachia—midway between the outer body wall and the funnel axis. The tentacles give rise at long intervals to lateral filaments tightly coiled into barrel-shaped helicles which are orange-pink in colour. To the naked eye the tentacle resembles the fishing thread of a young Physophora. The helicles were not seen to uncoil. The bottom of the tentacle sheath is filled with liquid of refractive index similar to the oil bubble in a fish egg. The apical sense organ when first examined in the living animal is prominent, projecting above the polar surface, but as the specimens become fatigued it sinks into a pit and the surrounding tissue between the swimming plates swells upward to form the walls of the pit. The funnel tube is nearly one-third the length of the body, and of constant diameter. The paragastric canals are greatly flattened and very wide, as wide as the stomodeum. No genital products are visible in the meridional canals.
The very broad paragastric canals distinguish P. helicoides from all known species of Pleurobrachia. They can further be distinguished by body shape, pigmentation, etc. Firstly they are distinguished from P. pileus O. F. Muller P. bachei A. Agassiz P. globosa Moser P. pigmentata and P. striata Moser P. crinata Moser P. australis (Benham) Euplokamis australis Benham P. helicoides is similar to P. australis and both species have been taken from Cook Strait, but not at the same time. The weight of evidence is such that despite the general similarity in appearance and canal structure P. helicoides does not fall within the specific description of P. australis as given by Benham. The broad paragastric canals, tightly coiled tentilla, the presence of colour, and the lack of a funnel-shaped collar round the mouth distinguish P. helicoides from P. australis. Nevertheless it must be borne in mind that only a few specimens of each species have been examined and it would not be surprising to find in a genus where wide variation in form, colour, and even canal structure is permissible within a species that examination of a large number of specimens would yield sufficient evidence for the specific description of P. australis to be widened to include those forms at present distinguished as P, helicoides. P. helicoides may be in fact only a seasonal variant.
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 (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.
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
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.
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.
B. paragaster can be distinguished from B. infundibulum (L. Agassiz) Mayer B. vitrea (L, Agassiz) Mayer B. vitrea has the subventral rows about twice as long as the subtentacular; from B. elegans Mertens B. mikado Moser 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 B. oralis and B. hydactina Chun 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 (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.
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.
It is with hesitation that we revive the genus Lesueuria Milne-Edwards, Lesueuria is nothing else than a regenerating Bolina (Syn. Bolinopsis Mayer Lesueuria as defined by Mayer (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 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 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.
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 (L. multicornis.
On five occasions during prolonged calm weather, specimens of this ctenophore were seen. Specimens were taken on March 9th from water 15.5°C. and on May 13th from water 12.25°C. and on this later date the species was plentiful,
C. veneris. All specimens were colourless and were smaller than those recorded by Mayer. The largest New Zealand specimen taken was about 350 mm. long and the smallest 10 mm., whereas Mayer records a size range between 800 and 1500 mm.
Cestum is predominantly a warm water ctenophore, (Mayer, C. veneris in New Zealand waters, but it has no reputation like the Gulf Stream in this respect. Moreover in latitude 41° S., a water temperature of 12.25°C. does not indicate a warm current. We suggest that they have not been reported from the temperate regions for two reasons, viz: the necessary calm periods with brilliant sunshine for collection are not of sufficient duration; and secondly, that C. veneris is not readily netted but must be sighted and then collected by a method of dipping.