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Volume 78, 1950
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Ascidians of New Zealand. Part V
Ascidians From the East Coast of Great Barrier Island

[Read before Otago Branch, May 3, 1949; received by the Editor, May 4, 1949.]

The following species were collected by the author in January, 1949. There are no previous records from the locality.

Synoicidae

1.

Aplidium thomsoni Brewin

2.

Aplidium (Amaroucium) thomasi Brewin

3.

Aplidium (Amaroucium) phortax Mich.

4.

*Synoicum kuranui n.sp.

5.

*Sigillinaria novae-zealandiac n.sp.

6.

*Sigillinaria arenosa n.sp.

7.

*Sigillinaria opaca n.sp.

Didemnidae

8.

*Didemnum chilense Arnback

9.

*Leptoclinides sluiteri n.sp.

Rhodosomatidae

10.

Corella eumyota Traust.

Styelidae

11.

*Arnbackia novae-zealandiae n.sp.

12.

Asterocarpa cerea (Sluit.)

13.

Asterocarpa coerulea (Q. and Gaim.)

14.

Cnemidocarpa nisiotis (Sluit.)

Pyuridae

15.

Pyura subuculata (Sluit.)

* Species not previously recorded form New Zealand.

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: Aplidium thomsoni, Aplidium (Amaroucium) phortax and Corella eumyota fall within the range of variability given for specimens from Otago Harbour (Brewin, 1946); Asterocarpa cerea and Asterocarpa coerulea within the range given for specimens from the Hauraki Gulf (Brewin, 1948), as also do the following with the exceptions stated. Aplidium (Amaroucium) thomasi shows more prolific growth, being up to 10 cm. long (4·5 cm., Hauraki Gulf). In the two specimens of Pyura subuculata collected, branchial tentacles numbered 34 and 40 (20 to 32, Hauraki Gulf) and one specimen had 8 pharyngeal folds (7 only, Hauraki Gulf; 8 and even a rudimentary 9th, Michaelsen). Cnemidocarpa nisiotis falls within the range of variability given for specimens from the vicinity of Christchurch (Brewin, 1950).

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Family Synoicidae Hartmeyer, 1908

Genus Synoicum Phipps, 1774

Colonies massive or divided into lobes. Zooids usually in systems, elongate, with many rows of stigmata. Branchial aperture six-lobed, atrial usually with a three-parted lappet. Stomach wall smooth or with rounded areolations.

Synoicum kuranui n.sp. (Text-fig. 1)

Colonies irregular sandy mats, up to 8 cm. long, composed of small capitate lobes joined by basal membrane up to 1 mm. thick. Lobes up to 1·5 cm. in height and 0·6 cm. in diameter in head region, which is flat-topped, bright crimson (being only lightly impregnated with sand grains), not clearly marked off from stalk and not more than 0·2 cm. wider than it (Text-fig. 1A). Round or oval systems of up to 10 light crimson zooids. Common cloacal apertures 1 mm. in diameter. Test deep crimson throughout, semi-transparent, with numerous small test cells and few bladder cells, outer layer only impregnated with sand.

Zooids up to 9·0 mm. long, 1·0 mm. wide in pharyngeal region, which has 10 to 13 fine longitudinal muscle bands, 9 transverse. Post-abdomen up to 2/3 body length. Branchial aperture with six short lobes, atrial with wide three- to five-parted lappet.

Gut. Pharynx with 16 tentacles of three orders of size, regularly arranged; dorsal lamina of 10 short languets curving back at level of fourth stigmata from dorsal edge; on each side, 10 rows of 14 to 15 stigmata, 3 ½ times as long as wide.

Oesophagus very short; stomach short, round, with lightly raised rounded areolations; intestine narrow at first, increasing in diameter before the bend, anal aperture in lower half of mantle bi-lobed.

Reproductive System. Up to 16 testis lobes in an irregular double row in posterior third of post-abdomen. Ovary just anterior to testis. No tadpoles (late January).

Picture icon

Text-Fig. 1–Synoicum kuranui. (A) Portion of colony. X 0.9. (B) Right side of zooid. X 28.

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Distribution. East Coast of Great Barrier Island (inter-tidal rock pools).

Remarks. In colony formation S. kuranui bears some resemblance to S. arenaceum (Mich, 1924) and S. stewartense (Mich., 1924), but in zooid formation it differs from each in many respects including number of stigmatal rows, and stigmata. The zooid is more like, but not identical with, that of S. hypurgon (Mich., 1924), but the colonies differ markedly. The specific name “Kuranui” is given on account of the very red colouration.

Type Specimen. Otago Museum.

Note. The post-abdomen is connected to the abdomen by its narrowest part, but the author does not feel justified in placing it, for this reason alone, in the genus Aplidiopsis Lahille, which is characterised by an elongate post-abdomen connected to the abdomen by a slender neck—a genus moreover described by Van Name (1945, p. 66) as “imperfectly understood, if valid.”

Genus Sigillinaria Oka, 1933

Colony with short, thick, club-shaped branches. Zooids with body in three divisions, thorax, abdomen and post-abdomen. Apertures both six-lobed, opening directly on the surface of the colony. Hermaphrodite, both testis and ovary in the post-abdomen.

Sigillinaria novae-zelandiae n.sp. (Text-fig. 2)

Colonies brilliant orange, massive, irregular in outline, up to 14 cm. long, with large clubshaped lobes joined by a basal membrane not more than 3 mm. thick (Text-fig. 2A). Lobes up to 5 cm. long, 1·75 cm. wide in the head region, which is clearly differentiated from the stalk and up to 3·5 cm. long. No systematic arrangement of the orange, opaque zooids. Test clear, orange, gelatinous, free from sand grains, with small test and pigment cells.

Zooids up to 20 mm. long, 1·0 mm. wide in pharyngeal region, which occupies only 1/8 of zooid length, 20 fine longitudinal muscle bundles, weak transverse. Post-abdomen up to ⅗ of body length. Branchial and atrial siphons short, with short, rounded lobes.

Picture icon

Text-Fig. 2–Sigillinaria, novae-zealandiae. (A) Portion of colony. X 0.45. (B) Left side of zooid. X 14.

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Gut. Pharynx with 24 tentacles of three orders of size; dorsal lamina of three curved languets; on each side 3 rows of 21 to 25 very long narrow stigmata; no parastigmatic vessels.

Oesophagus long, narrow; stomach small, ovoid, smooth walled; intestine narrow at first, widening to three times its previous length before the bend (Text-fig. 2B).

Reproductive Organs. Up to 35 testis lobes in central half of post-abdomen. Ovary one-quarter way down post-abdomen, just anterior to testis. No tadpoles (late January, 1949).

Distribution. East coast of Great Barrier Island (inter-tidal rock crevices).

Remarks. No members of this genus have been recorded from New Zealand and the species described above differs from other species of the genus in many respects, including a far lower count of stigmatal rows.

Type Specimen. Otago Museum.

Sigillinaria arenosa n.sp. (Text-fig. 3)

Colonies small, sanely, irregular in outline, up to 5 cm. long, composed of short, flattopped lobes, 0·8 to 1·5 cm. long and up to 1·0 cm. wide. Peripheral lobes arising from others, central lobes united by thin basal membrane (Text-fig. 3A). Head of lobe tapering gradually into stalk, which tapers to basal membrane. No systematic arrangement of zooids. Test firm, transparent, light yellow, superficially impregnated with sand and with numerous small test cells.

Zooids up to 6 mm. long, 1·2 mm. wide in pharyngeal region, which has 20 to 22 strong longitudinal muscle bundles, 9 to 10 transverse. Post-abdomen ½ body length. Branchial and atrial siphons long, with long triangular lobes.

Gut. Pharynx with 16 to 24 tentacles of three orders of size; dorsal lamina of 9 to 10 short curved languets; on each side 9 or 10 rows of 20 to 24 stigmata, four times as long as wide; parastigmatic vessels.

Oesophagus short; stomach short; intestine wide, without marked constrictions (Text-fig. 3B).

Reproductive Organs. Up to 17 testis blocks in an irregular double row in posterior half of post-abdomen Ovary centrally placed in post-abdomen. No tadpoles (late January, 1949).

Distribution. East coast of Great Barrier Island (inter-tidal rock crevices).

Picture icon

Text-fig. 3 Sigillinaria arenosa.
(A) Portion of colony, natural size.
(B) Left side of zooid. X 17.5

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Remarks. This species differs from S. aequalisiphonis (Ritter and Forsyth) in number of stigmata, absence of longitudinal folds in stomach, and absence of a constriction in the intestine. It is quite unlike the other species described to date.

Type Specimen. Otago Museum.

Sigillinaria opaca n.sp. (Text-fig. 4)

Colonies irregularly-shaped mats up to 60 cm. long, with small capitate lobes joined by a sand-encrusted basal membrane up to 4 mm. thick. Lobes up to 2 cm. long and 1·5 cm. wide, head region somewhat flattened, not clearly differentiated from stalk. Zooids yellow, opaque, not arranged in systems. Test light yellow, semi-transparent, gelatinous, with numerous small test cells.

Zooids up to 10 mm. long, 0·6 mm. wide in pharyngeal region, which occupies 1/7 to 1/8 of body length and has a very strong, highly contractile musculature. Post-abdomen ½ body length. Branchial and atrial siphons short with short rounded lobes.

Gut. Pharynx with 16 short tentacles; dorsal lamina of three curved languets; on each side 3 rows of 9 to 10 stigmata, three times as long as wide; no parastigmatic vessels.

Oesophagus long, narrow; stomach short with four longitudinal folds; intestine long, narrow, without marked constrictions.

Reproductive Organs. Ovary in extreme anterior end of post-abdomen; 12 to 18 testis occupy most of post-abdomen. Tadpoles (Text-fig. 4B) in oviduct (late January, 1949), 1·0 mm. long, 0·3 mm. wide in head region.

Distribution. East coast of Great Barrier Island (large inter-tidal rock crevice, southern end of Aerodrome Bay).

Remarks. Of all the known species, this most closely resembles S. novae-zelandiae, but is distinguished from it by the colony formation, longitudinal folds in stomach, and many other features.

Type Specimen. Otago Museum.

Picture icon

Text-fig. 4—Sigillinaria opaca.
(A) Portion of colony, natural size.
(B) Left side of zooid. X 35.

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Family Didemnidae Verrill, 1871

Genus Didemnum Savigny, 1816

Didemnum chilense Arnback. (Text-fig. 5)

1929. Didemnum chilense, Arnback, Novaya Zemlya. Arkiv. f. Zool., vol. 21a, no. 6, pp. 1–27.

1945. Didemnum chilense, Van Name, Rull. Amer. Mus. Nat. Hist., vol. 84, p. 92.

Colonies thin, pale pink, irregular in outline, up to 5 cm. long, 1–1·5 mm. thick, surface rough, due to heavy spiculation. No regular arrangement of zooids. Common cloacal apertures up to 0·5 mm. long, 1 to 4 mm. apart. Spicules (Text-fig. 5B) 0·017 to 0·031 mm. in diameter. Test evenly spiculated throughout, with numerous small test cells.

Zooids up to 1·8 mm. long, 0·3 mm. wide in pharyngeal region. Rectal-oesophageal region short, abdomen wider than pharyngeal region (Text-fig. 5A). Branchial siphon long, six-lobed; atrial without lappet, very wide, exposing practically the whole dorsal side of pharynx. A well developed muscular process projects from centre of zooid.

Gut. Pharynx with 16 tentacles, of three orders of size, regularly arranged; dorsal lamina of 4 curved languets; on each side 4 rows of 7 to 9 stigmata, four times as long as wide.

Oesophagus short, narrow; stomach short, round; intestine without marked constrictions.

Reproductive Organs. Testis large, undivided. Sperm duct with 9 to 10 spiral turns. Ovary between testis and stomach. No tadpoles (late January, 1949).

Distribution. In New Zealand: East coast of Great Barrier Island (inter-tidal, on holdfasts of seaweed). Elsewhere: off the Guatecas Is., Chile (Arnback-ChristieLinde).

Picture icon

Text-fig. 5—Didemnum chilense. (A) Left side of zooid. X 45. (B) Spicules. X 175.

Remarks. The specimens described above are identical with the type in everything except colouration (type—greyish-white, Great Barrier—pale pink). D. mortenseni, recorded from Stewart Island by Michaelsen, resembles the above species in the shape of the atrial aperture, but differs from it in the shape of the spicules, the shape of the branchial lobes, and the form of the testis. None of the other species recorded from New Zealand remotely resemble it.

Genus Leptoclinides Bjerkan, 1905

Differs from Didemnum only in having the atrial aperture at or posterior to the middle of the thorax, produced into a short tube with a circular, often funnel-shaped orifice directed obliquely backwards.

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Four rows of stigmata; sperm duct coiled; testis single or divided. As Van Name (1945, p. 96) remarks, “This is hardly worthy of more than sub-generic rank, but is commonly recognised as a genus.”

Leptoclinides sluiteri n.sp. (Text-fig. 6)

Colonies dull grey with blue or green tint, thin, irregular in outline, up to 9 cm. long, 1·5 mm. thick. Zooids in systems of 9 to 15 or irregularly arranged. Common cloacal apertures oval, up to 1 mm. long, 2 to 5 mm. apart. Spicules stellate, 0·012 to 0·025 mm. in diameter, practically absent in surface layer, densely packed in a narrow region directly below it, lightly but evenly scattered elsewhere. Test with numerous small test cells, round bladder cells, and elongate, blue pigment cells numerous in densely spiculated region and around zooids.

Zooids up to 1·0 mm. long, 0·3 mm. wide in pharyngeal region. Rectal-oesophageal region not exceeding pharynx in length, abdomen wider than pharynx. Branchial siphon long, muscular, with six short lobes, atrial muscular, produced backwards from level of third stigmatal row. Small “seitenorgane” in a few zooids.

Picture icon

Text-fig. 6—leptoclinidcs sluiteri. (A) Right side of zooid. X 90. (B) Spicules. X 160.

Gut. Pharynx with 16 tentacles; dorsal lamina of 4 curved languets; on each side 4 rows of 9 to 10 stigmata, seven to eight times as long as wide.

Oesophagus straight, narrow, about same length as stomach, which is smooth-walled, ovoid; intestine narrower at its commencement.

Reproductive Organs. Testis, rosette of 4 to 5 pear-shaped lobes. Sperm duct with 9 to 10 spiral turns. Ovary between testis and stomach. Tadpoles present (late January, 1949) up to 2 mm. long and 0·4 mm. wide in head region.

Distribution. East coast of Great Barrier Is. (inter-tidal, common on branches and holdfasts of seaweeds).

Remarks. The two species of Leptoclinides previously described from New Zealand differ from the above; L. diemenensis in zooid structure, L. sparsus in presence of large, star-shaped pigment cells. No species so far recorded from Australia, S. America or the Antarctic is identical with that described above.

Type Specimen. Otago Museum.

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Family Styelidae Sluiter, 1895

Genus Arnbackia n.gen.

Compound Styelidae with internal folds and internal longitudinal vessels in the pharynx. Gonads of one sex, male mainly on the right, female mainly on the left side.

Note. Since Michaelsen's revision of the compound Styelidae (1904) the classification of the group has been based on presence or absence of longitudinal folds in the branchial sac and the structure and manner of arrangement of the gonads. There seems little doubt that another revision of the classification of the group will be necessary soon. The genera Heterocarpa Lac. Duth. and Del. and Alloeocarpa Mich. differ from Arnbackia in having male gonads on the left and female on the right side of the body, and Alloeocarpa [in its amended form (Michaelsen, 1922)] also differs from it in having no longitudinal folds in the branchial sac.

Type. A. novae-zelandiae.

Arnbackia novae-zelandiae n.sp. (Text-fig. 7)

Colony formation closely resembles that of Okamia thilenii (Brewin, 1948, Plate 9, Fig. 1), irregular in outline up to 3 cm. long. Basal membrane a fraction to 1 mm. thick. Mature individuals approximating, newly formed individuals separated by up to 3 mm. Individuals up to 6 mm. long, 4 mm. wide, 4 mm. deep. Siphonal apertures at equal distances from centre of top surface, 1·0 to 1·5 mm. apart, 1·0 to 1·5 mm. long, linings bright red. Test dull, reddish brown, rugose, 0·2 to 0·4 mm. thick, relatively free from sand grains and incrustations. Mantle deep red, with many fine muscles.

Picture icon

Text-fig 7—Arnbackia novae-zealandiae. Dissection showing body opened from the ventral surface, pharynx removed. X 7.5.

Gut. Pharynx with 16 to 24 tentacles of three orders of size; dorsal tubercle very small; dorsal lamina smooth, straight-edged; on each side two longitudinal folds (one only on left in one specimen): stigmata per mesh 6 to 8, four to five times as long as wide; para-stigmatic vessels present; longitudinal vessels as follows:

D.L. (8)3(8)4 E. Total 23.
D.L. (6)3(6)4 E. Total 19.

Oesophagus short; stomach short, wide, with 16 to 18 folds and

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a hook-shaped gastric caecum; intestine smooth, wide; anal aperture unlobed, straight-edged.

Endocarps small, scattered, on both sides of body. Atrial tentacles not visible.

Reproductive Organs. Gonads of one sex; 25 to 35 testes, confined to right side (in a few specimens 1 or 2 extend slightly over to left), pear-shaped with marked gonoducts, light in colour; 5 to 8 bright orange ovaries, each with a single egg, in an are on left side [in a few specimens are extends slightly over to right] (Text-fig. 7). Tadpoles in mantle cavity (late January, 1949), large orange, resembling those of O. thilenii (Brewin, 1948, Plate 8, Fig. 8), but without pigment bars; up to 2·5 mm. long, 0·6 mm. wide in head region.

Distribution. East coast of Great Barrier Is. (on test of Cnemidocarpa nisiotis and seaweed holdfasts in inter-tidal rock crevices, Aruawhero Bay).

Type Specimen. Otago Museum.

Tadpoles

Tadpoles present in late January in mantle cavity or common cloacal canals of the following species: Aplidium thomsoni, Aplidium (Amaroucium) thomasi, Aplidium (Amaroucium) phortax, Sigillinaria opaca, Leptoclinides sluiteri, and Arnbackia novae-zealandiae.

Commensals

Amphipods in common cloacal canals of A. thomsoni, A. (A.) thomasi, A. (A.) phortax and in burrows in test of Sigillinaria novae-zealandiae. Copepods of the family Notodelphidae in branchial sac of Cnemidocarpa nisiotis and Pyura subuculata.

Explanation of Lettering

  • ecp.—endocarp

  • em.—tadpole

  • gc.—gastric caccum

  • h.—heart

  • mp.—muscular process

  • sd.—sperm duct

  • st.—stomach

  • ♂—ovary

  • ♀—testis

Summary

An account is given of fifteen species collected from the East coast of the Great Barrier Island. A new genus, Arnbackia, has been established to cover compound Styelidae with pharyngeal folds and with gonads of one sex, male mainly on the right and female mainly on the left side of the body. Six new species are described, Synoicum kuranui, Sigillinaria novae-zealandiae, Sigillinaria arenosa, Sigillinaria opaca [Note: this genus has not been recorded previously from New Zealand], Leptoclinides sluiteri, and Arnbackia novae-zealandiae. Didemnum chilense is recorded from New Zealand for the first time.

References

These include all those given in the previous papers of the series as well as the following:

Arnback, Christie, Linde, 1929. Chilean Tunicates. Ascidians from the Guaitecas Islands. Novaya Zemlya. Arkiv. f. Zool., vol. 21a, no. 6, pp. 1–27.

Brewin, B. I., 1950. Ascidians from the Vicinity of Christchurch, N.Z. Trans. Roy. Soc. N.Z., vol. 78, pp. 344–353.

Oka, A., 1933. Ueber Sigillinaria, eine neue Synascidiengattung aus Nordpazifik. Proc. Imp. Acad. Tokyo, vol. 9, pp. 78–81.