Ascidians of New Zealand. Part IV
Ascidians In the Vicinity of Christchurch
[Read before Otago Branch, May 3, 1949; received by the Editor, May 4, 1949.]
Michaelsen (1922, 1924) records eight ascidians from the vicinity of Christchurch, one described by Sluiter, and the rest by himself from specimens from the Mortensen Expedition, and collections in the Berlin Museum (Ledenfeld bequest) and the Natural History Museum, Hamburg (Suter legacy).
The list given below includes species collected by the author from intertidal coastal rocks, wharf piles and sea anchors at Lyttelton (L), Diamond Harbour (DH), Taylor's Mistake (TM), and the Heathcote estuary causeway (H); those in the Canterbury University College collections from Menzies Bay (MB) and near Port Levy (P); and those recorded by Michaelsen (marked m).
|1. Aplidium thomsoni Brewin||TM|
|2. Didemnum psammatodes (Sluit.) (m)||L|
|3. Didemnum candidum Sav. (m)||L, TM|
|4. Diplosoma macdonaldi Herdman||L, MB, DH|
|5. *Distaplia taylori, n.sp.||TM|
|6. Distaplia fasmeriana Michaelsen||TM|
|7. *Ciona intestinalis (Linnaeus)||L|
|8. Ascidia aspersa (Müll.)||L|
|9. Corella eumyola transtedt (m)||L, H. DH. MB|
|10. Botryllus leachi Savigny||L|
|11. Botryllus schlosseri (Pallas)||L, H|
|12. Astcrorpa cerea (Sluiter)||L, DH, TM|
|13. Cnemidocarpa noraezelandiae (Mich.) (m)||L|
|14. Cnemidocarpa nisiolis (Sluiter)||L, DH, MB|
|15. Cnemidocarpa bicornuata (Sluiter)||L, DH, MB|
[Footnote] * Species not hitherto recorded from New Zealand.
|16. Pyura suteri (Mich.) (m)||L, TM, S†|
|17. Pyura cancellata Brewin||L, TM|
|18. Pyura pulla (Sluiter) (m)||L, TM, S†|
|19. Pyura pachydermatina (Herdman) (m)||L, TM, S†|
|20. Ctenicella novaeselandiae (Mich.) (m)||L|
|21. *Eugyra novae–zealandiac, n.sp.||P|
The local distribution cited is that known to date and not exhaustive. Cnemidocarpa novaezelandiac and Ctenicella novaeselandiae, recorded from Lyttelton by Michaelsen, have not been collected since.
Both in the Heathcote Estuary and in the Lyttelton boat harbour the ascidian population is a heavy one, but whereas in the former it is confined to two equally dominant forms, Corella eumyota and Botryllus schlosseri, in the latter fifteen species at least are represented, and of them the dominant forms are Cnemidocarpa nisiotis, Cnemidocarpa biornuata, Pyura cuncellata and Botryllus schlosseri. At Taylor's Mistake, an ocean beach, nine ascidians were collected, and of these Aplidium thomsoni and Pyura suteri were the dominants.
In the account that follows, descriptions are given only of the genera and species in the author's collection not described previously in this series, the range of variability of the other species being as follows. Didemnum psammatodes, Didemnum candidum, Diplosoma Macdonaldi, Distaplia fasmeriana, Ascidia aspersa, Corella eumyota, Botryllus leachi, Asterocarpa cerea, Pyura suteri, and Pyura pulla fall within the range of variability given for specimens from Otago Harbur as also do the following, with the exceptions stated. Aplidium thomsoni shows more prolific growth, the dark sand-impregnated colonies having an irregular, almost, lobed, surface and being up to 12·25 cm. in length (3·9 cm., Otago). Botryllus schlosseri also grows more prolifically (18 cm., greatest length, Lytttelton; 10 cm., Otago) and has a wider colour range including yellow, fawn, and brown. Three specimens of Pyura cancellata have 9 stigmata per mesh (5 to 7, Otago). Two specimens of Pyura canchydermatina have 32 branchial tentacles (12 to 20, Otago). All specimens of Cnemidocarpa bicornuata are of the white type with move or less dark blue pigment in the dorsal portion of the mantle and the bands on the siphonal linings—a variety incorporated in the species by Michaelsen (1922). [Note: orange-tinted specimens only are found in Otago waters and the Hauraki Gulf, blue-tinted specimens only in the vicinity of Christchurch, intermediate in geographical position). They have no parastigmatic vessels, 5 to 9 stigmata per mesh (7 to 10, Otago) and a gut loop ¾ to 7/8 of the length (½, Otago).
[Footnote] † Sumner (S).
Description of Species
Family Polycitoridae Michaelsen, 1904
Genus Distaplia Della Valle, 1881
(as emended by Michaelsen, 1924)
Distaplia taylori n.sp. (Text-fig. 1)
Colonies small, flat, irregularly oval, with smooth rounded edges, up to 4 cm. long and 3 mm. high. Pale pink pigment cells in mantle wall and just below surface of test. Test else-where colourless with numerous small test cells. Round or oval systems of 6 to 11 zooids (Text-fig. 1Δ). Common cloacal apertures 2·0 to 3·5 mm. apart, up to 1·3 mm. wide, the surrounding test elevated to form a thin ring 0·5 mm. higher than general surface of colony.
Zooids up to 2 mm. long and 1 mm. wide in pharyngeal region, which has 15 to 18 longitudinal muscle bands, 3 transverse. The rectaloesophageal region short and abdominal region narrower than pharyngeal. Vascular processes short at right angles to body. Branchial aperture with six short lobes, atrial surmounted by one wide toothed lappet (Text-fig. 1B).
Text-fig. 1—Distaplia taylori. (A) Colony. X 2/3. (B) Right side of zooid. X 76. (C) Zooid with brood pouch. X 27.
Gut. Pharynx with 16 tentacles of three orders of size regularly arranged; dorsal lamina of three narrow languets. On each side, 4 rows of 14–16 stigmata, 6 to 9 times as long as wide, longest in posterior row. Parastigmatic vessels absent.
Oesophagus short. Stomach ovate, smaller towards posterior end, ridges too low to affect even contour (Text-fig. 1B). Intestine wide. Reservoir of intestinal gland large, thin-walled between middle of stomach and intestine.
Reproductive System. Hermaphrodite zooids. Gonads in posterior end of gut loop or projecting slightly beyond it posteriorly. Testis,
rosette of 4 to 6 pear-shaped lobes. Ovary between and behind posterior lobes of testis. Brood pouch present in summer months, pear-shaped, connected to zooid by a long narrow neck (Text-fig. 1C), contains 1 to 3 embryos. Largest tadpole 2 mm. long, 0·5 mm. wide in head region, with 1 or 2 buds at time of liberation.
Distribution. Taylor's Mistake (inter-tidal coastal rocks at northern end).
Type Specimen. Otago Museum.
Note. This species resembles D. rosea, a northern hemisphere form in colony formation, but is distinguished from it by the greater number of stigmata per row and the shape and position of the vascular processes. It is unlike any species so far recorded from New Zealand or Australia.
Family Cionidae Lahille, 1887
Solitary individuals with an eight-lobed oral and a six-lobed atrial aperture. Longitudinal muscle fibres in a few parallel bundles on the wall of the mantle. Pharynx with internal longitudinal vessels bearing papillae and occasionally intermediate papillae. Stigmata straight, longitudinal. Dorsal lamina of languets. Intestine on the left side, partly or wholly behind the pharynx. Ovary in the intestinal loop, testicular lobes on the intestinal wall. Gonoducts accompany rectum.
Genus Ciona Fleming, 1882
Generic characters as for family.
Ciona intestinalis (Linnaeus), 1767. (Text-fig. 2)
1767. Ascidia intestinalis Linnaeus, Systema naturae, vol. 1, pt. 2. For Syn. sec: 1945, Ciona intestinalis, Van Name, Bull. Amer. Mus. Nat. Hist., vol. 84, p. 160.
Body elongate quadrilateral, tapering somewhat anteriorly, compressed laterally, attached by posterior end or by part of one side also. Test may be prolonged posteriorly to form short holdfasts, soft, flexible, gelatinous, either colourless or with light green pigment at
anterior end where low warty outgrowths occur though mainly confined to siphonal regions. Branchial aperture terminal, atrial 1/5th to 1/6th of body length distant, both forwardly directed. Branchial with eight, atrial with six small marginal pigment spots between the lobes. Hydroids, compound ascidians, sponges as incrustations. Measurements based on the study of twenty-five specimens are: Length, 1·8 to 9·0 cm.; breadth, 0·8 to 1·5 cm.; depth, 1·3 to 2·5 cm.; distance to apertures, 0·4 to 1·5 cm.; branchial siphon, 0·6 to 1·2 cm. long, 0·4 to 0·8 cm. wide; atrial aperture, 0·4 to 1·0 cm. long, 0·3 to 0·7 cm. wide; thickness of test, up to 2 mm.
Mantle wall pale yellow deepening to orange around siphons. Six broad longitudinal muscle bands on each side, three and a-half supplying the branchial siphon, two and a-half the atrial (Text-fig. 2A, B). Numerous narrow circular muscles.
Gut. Pharynx with 36 to 90 simple filiform tentacles of two to four orders of size, irregularly arranged; opening of dorsal tubercle C–shaped with inrolled horns, open interval directed forward (Text-fig. 2D). (Variations of this plan enhibited in nine specimens); neural gland a small round cushion; dorsal lamina with 40 to 80 curved languets, number correlated with the size of the individual; 22 to 28 narrow longitudinal bars on each side, with long curved papillae at point of contact with transverse vessels (Text-fig. 2C), the latter of two sizes alternately arranged, smaller crossing the stigmata without interrupting them; 6 to 9 stigmata per mesh (6 and 7 usual count), number variable in different regions of pharynx of individual.
Position of intestinal loop as for genus. Oesophagus short narrow: stomach small round with 24 to 39 internal folds; intestine narrower than stomach. Anal aperture red, lobed, opening about 1 cm. from base of atrial siphon.
Reproductive System. Ovary a grey, compact, pear-shaped or occasionally somewhat bi-lobed mass in primary intestinal loop, Oviduct runs parallel with intestine, opening at base of atrial siphon, red and deeply lobed. Testis of many small pyriform or rounded lobes on wall of intestine and posterior part of stomach. Sperm duct runs from testis at junction of stomach and intestine along the side of ovary for a short distance and then parallel to oviduct, opening at base of atrial siphon. Ripe eggs in oviduct mid-November, 1948.
Distribution. In New Zealand, Lyttelton (Singly on wharf piles, sea anchors, etc., and in a large cluster under a float in the boat harbour).
Elsewhere—Mediterranean, Black Sea, Northern Europe, Arctic Coast of North America, Suez, Singapore, various Australian ports, Japan, Magellan Straits.
Remarks. Ciona intestinalis occurs in the more important harbours in widely distant parts of the world, probably owing to accidental transportation by ships, and its presence in Lyttelton can thus be accounted for.
Ascidia aspersa, another almost colourless ascidian of elongate quadrilateral form, is also present in Lyttelton harbour. Ciona
intestinalis can be distinguished from it in the field by the slight green pigmentation of the test and the proximity of the siphons (1/5th to 1/6th of body length apart, Ciona; ¼ to ½, Ascidia).
Family Styelidae Sluiter, 1895.
Genus Cnemidocarpa Huntsman, 1913
Cnemidocarpa nisiotis (Sluiter). (Text-fig. 3)
1900. Styela nisiotis, Sluiter, Tunic. Stillen Ocean, p. 21.
1909. Tethyum nisiotis, Hartmeyer, Bronn. Kl. Ord. Tierr., p. 1359.
1922. Cncmidocarpa nisiotis, Michaelsen, Vidensk. Medd. naturh. Foren., bd. 73, pp. 427–430.
Body globose, slightly longer in antero-posterior direction, attachment ventral or by portions of sides as well. Test light brown when body expanded, dark brown and wrinkled when contracted, with warty processes in region around siphons. Siphonal linings maroon with four pale yellow longitudinal bands. A few Polyzoa and fine red seaweeds as incrustations. Measurements based on the study of twenty-five specimens are: Length, 2·0 to 4·8 cm.; breadth, 1·3 to 2·6 cm.; depth, 1·5 to 3·5 cm.; distance between the apertures, 1·0 to 2·8 cm.; branchial siphon, 0·8 to 1·1 cm. long, 0·7 to 0·9 cm. wide; atrial siphon, 0·7 to 1·0 cm. long, 0·6 to 0·9 cm. wide; thickness of test, 0·6 to 2·0 mm.
Mantle thick, fleshy, very muscular, yellow ventrally, maroon dorsally.
Gut. Pharynx with 30 to 44 simple filiform branchial tentacles of three or four orders of size irregularly arranged. (Note: Sluiter records for the type 41 branchial tentacles, Michaelsen up to 65 for specimens from Queen Charlotte Sound); opening of dorsal tubercle an elongate broken oval with out-turned ends (elaborations seen in many); neural gland a comparatively large cushion beneath and on both sides of the nerve cord (Text-fig. 3); dorsal lamina smooth, straight-edged; 4 longitudinal folds on each side, first and fourth narrowest; 11 to 13 small transverse vessels, including one of intermediate size, between two large; stigmata per mesh between folds, 4 to 6 (rarely 7), five times as long as wide; longitudinal vessels 78 to 103 on right, 73 to 98 on left, general arrangement as shown.
|Length of specimen||Arrangement of vessels on the right||Total|
Intestinal loop occupies almost the entire width and ¾ to 7/8 of the length of left side of body [over ½ of the body length, Sluiter (1900)]. Oesophagus short, narrow; stomach elongate, slightly wider than intestine and with 20 to 32 internal longitudinal folds and a typhlosole, with no pyloric caecum. Edge of anal aperture straight, unlobed.
Endocarps confined to left side [Sluiter figures those on the left but gives no indication of the arrangement on the right. Michaelsen (1922) clearly states that endocarps are lacking on the right side and the arrangement is as for the Cn. assymetra group]; 10 to 17 around the periphery of gut loop and 5 to 8 (average number 6) inside it.
Atrial velum very narrow, with one row of small tentacles, mainly filiform, but occasionally knobbed.
Reproductive System. Gonads with structure typical of genus present on upper two-thirds of mantle wall on each side. 2 to 4 on right, 2 to 3 on left where in a few specimens a certain amount of coalescence is seen. 1 or 2 bilobed gonads in eight specimens. Gonads on right only in a rudimentary condition in three specimens which were otherwise well-developed. Tadpoles not present August, 1948.
Text-fig. 3—Cnemidocarpa nisiotis. Dissection showing body opened from the ventral surface, pharynx removed. X 1.
Distribution. In New Zealand: French Passage (Sluiter), Queen Charlotte Sound (Michaelsen), in the vicinity of Christchurch (singly or in clumps on intertidal coastal rocks, wharf piles, etc., at Diamond Harbour, Menzies Bay, Taylor's Mistake and Lyttelton).
Remarks. Sluiter records a larger specimen 65 mm. long and 35 mm. wide, and figures gonads with crenulated edges. Michaelsen finding no specimens with such gonad form suggested that parasitic castration might be responsible for the irregular shape. However, in three of the specimens described above, specimens with well-developed and practically ripe gonads, the gonad shape depicted by Sluiter was seen. One specimen recorded by Michaelsen has an odd longitudinal vessel count—E.6(13)6(18)5(52)3(15)2(13) D.L.
Note. In the field Cn. nisiotis closely resembles Asterocarpa cerea, but can be distinguished from it by the larger size of the body and the stronger darker and more warty test.
Family Molgulidae Lacaze–Duthiers, 1877.
Genus Eugyra Alder and Hancock, 1870
[As amended by Michaelsen (1915) and Hartmeyer (1923).]
Body globular, unattached, covered with glandular fibrils and a coating, more or less complete, of fine sand; branchial aperture sixlobed, atrial four-lobed; branchial sac without folds, but with longitudinal folds or bands; the meshes regularly convoluted and produced into little cones, each being composed of a double spiral coil of vessels; which spirals, turning in opposite directions, meet at the apex; reproductive organs on one or both sides of the body.
Eugyra novae-zealandiae n.sp. (Text-figs. 4, 5)
Body unattached, spherical or elliptical, being elongated anteroposteriorly. Siphons close together in central region (Text-fig. 4A), branchial longer than atrial, both with short triangular lobes. Test colourless, transparent, with a coating of extremely short fine hairs except in the oval raised region around bases of siphons. Measurements based on the study of twenty-five specimens are: Length 1·0 to 1·5 cm.; breadth 0·8 to 1·2 cm.; depth 0·8 to 1·4 cm.; distance between the apertures 3·0 to 5·5 mm.; clear area around the siphons 7·0 to 9·0 mm.; branchial siphon (not fully expanded) 1·0 to 1·2 mm. long. 1·0 mm. wide; atrial siphon (not fully expanded) 0·8 to 1·1 mm. long, 0·8 mm. wide; thickness of test 0·4 mm. except in the basal region (0·7 mm.) and around the siphons (1·1 mm.).
Mantle colourless, musculature fine, radiating and circular fibres forming a very open network on or near bases of siphons and a few extending as far as the ventral surface.
Text-fig. 4—Eugyra norae-zealandiae. (A) Individual, natural size. (B) Dissection showing body opened from the ventral surface, pharynx removed. X 2 ½.
Gut. Pharynx with 16 to 18 tentacles of two or three orders of size irregularly arranged and showing three orders of branching; opening of dorsal tubercle a small, almost closed, ring; neural gland a round cushion to the right of the extremely short, nerve cord; dorsal lamina wide, smooth, extending posteriorly to end of oesophageal opening and on left side of it; wall without folds, with 6 wide internal longitudinal vessels on each side, and with 6 transverse rows of 7 infundibula. Two long uninterrupted spiral stigmata, making 6 to 7 complete turns, occupy each infundibulum (Text-fig. 5).
Gut loop occupies entire width and slightly over ½ length of left side of body. Oesophagus short, narrow; stomach short, wide, with large, irregular, longitudinal glandular patches; intestine smooth, wide, forming a loop slightly open at reflected end, tightly closed near stomach. Anal aperture straight, smooth-edged. No “liver.”
Kidney, small, bean-shaped, far back on right side.
Reproductive Organs. Ovaries spherical, one on each side. Testis, much-branched, as large or larger than ovary, lying close to it. Oviduct
short. Testis-duct running across ovary or parallel to edge of ovary and opening near oviducal opening (Text-fig. 4). Gonad on left in primary intestinal loop, on right centrally placed. Tadpoles not present (August, 1947).
Distribution. Off Port Levy (dredged from muddy bottom at “three faces”).
Remarks. The most closely allied species is E. kerguelenensis Herdman, but the specimens described above differ from it in the following points: (1) The structure of the pharynx—that of E. kerguelenensis having eight very regular longitudinal rows of large infundibula on each side, six in each of the rows except the ventralmost, which has twelve. (2) The composition of the male reproductive orgau—there being numerous small, often considerably, branched testes on each side in E. kerguelenensis.. (3) The external appearance —in E. kerguelenensis the area surrounding the siphons is depressed and definitely rectangular in shape.
Commensals and Parasites
The bivalve Modiolacra impacta (Herr.) in the test of a few specimens of Cnemidocarpa nisiotis; copepods of the family Notodelphidac in the branchial sacs of Cnemidocarpa nisiotis, Cnemidocarpa bicornuata and Pyura suteri, but not in Asterocarpa cerea, which, however, in this locality has a heavy test infestation of parasite copepods of the family Lernaeidae.
Explanation of Lettering
ilv.—internal longitudinal vessel
The author is specially indebted to Professor Percival and members of the Zoology Department of Canterbury University College for their assistance with the collecting of material from this locality.
An account is given of nineteen species of ascidians collected in the vicinity of Christchurch. This brings the total number of species recorded from this region to twenty-one. Two new species, Distaplia taylori and Eugyra novae-zealandiae, are described, and Ciona intestinalis is recorded from New Zealand for the first time.
These include those given in the first paper of the series (Brewin, 1946, pp. 130–131), as well as the following:—
Brewin, B. I., 1946. Ascidians in the Vicinity of the Portobello Marine Station, Otago Harbour. Trans. Roy. Soc. N.Z., vol. 76, pp. 87–131.
— 1948. Ascidians of the Hauraki Gulf, Pt. I. Trans. Roy. Soc. N.Z., vol. 77, pp. 115–138.
— 1940. Ascidians from Otago Coastal Waters. Trans. Roy. Soc. N.Z., vol. 78, pp. 54–63.
Michaelsen, W., 1900. Die holosomen Ascidien des magalhaesisch-sudgeorgeischen Gebietes. Zoologica, vol. 12, no. 31, pp. 1–148.
Van Name, W. G., 1945. The North and South American Ascidians. Bull. Amer. Mus. Nat. Hist., vol. 84, pp. 1–470.