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Volume 79, 1951
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Ascidians of New Zealand. Part VI
Ascidians of the Hauraki Gulf. Part II

[Read before the Otago Branch, April 11, 1950; received by Editor, April 29, 1950]

The material which forms the basis of this paper was collected on intertidal rocks at Leigh (Le) and Takapuna (T) and from shells of Xenophora corrugata dredged from 45 fathoms between Little and Great Barrier Is. (d).

List of Species.
Synoicidae Locality.
1. *Amaroucium nottii n. sp. Le
2. Amaroucium phortax Michaelsen Le, T
3. *Synoicum haurakiensis n. sp. d
4. Sigillinaria novae-zelandiae Brewin Le
Didemnidae.
5. Didemnum candidum Savigny Le, T, d
6. Didemnum albidum (Verrill) Le
7. Diplosoma macdonaldi Herdman Le, T
Polycitoridae.
8. Polycitor (Eudistoma) circumvallatum (Sluiter) Le, T
9. Cystodytes dellachiaiae Della Valle Le, T
10. Distaplia taylori Brewin T, Le
Perophoridae.
11. *Perophora annectans Ritter Le
Rhodosomatidae.
12. Corella eumyota Traustedt Le, T
Botryllidae.
13. Botryllus leachi Savigny Le
14. Botryllus magnicoecus (Hartmeyer) Le
Styelidae.
15. Okamia thilenii (Michaelsen) Le
16. *Allococarpa minuta n. sp. Le
17. Asterocarpa coerulea (Quoy & Gaimard) Le, T
18. Asterocarpa cerea (Sluiter) Le, T
19. Cnemidocarpa nisiotis (Sluiter) Le, T
20. Cnemidocarpa bicornuata (Sluiter) Le, T
Pyuridae.
21. Pyura subuculata (Sluiter) Le
22. Pyura cancellata Brewin Le, T
Molgulidae.
23. Molgula mortenseni (Michaelsen) Le

Species marked with an asterisk in the above list are those not hitherto recorded from New Zealand.

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Text Fig. 1. Amaroucium nottii. Left side of zooid. × 31.

Amaroucium phortax, Sigillinaria novae-zelandiae, Didemnum candidum, Diplosoma macdonaldi, Cystodytes dellachiaiae, Polycitor (Eudistoma) circumvallatum, Corella eumyota, Botryllus leachi, Okamia thilenii, Asterocarpa coerulea, Asterocarpa cerea, Pyura subuculata and Pyura cancellata fall within the range of variability given for the species in previous papers of the series. Specimens of Distaplia taylori differ from those from Taylor's Mistake (Brewin, Part IV) in having a deeper pigmentation (some being a dark crimson lake), a lower number of stigmata per row (12 to 15; 14 to 16 T.M.), and a greater number of embryos per brood pouch (1 to 5; 1 to 3 T.M.). Specimens of Cnemidocarpa bicornuata are all of the orange-pigmented type and one shows complete absence of gonads in the left side, the normal number being present in the right. One specimen of Cnemidocarpa nisiotis had 56 tentacles [30 to 44, Lyttelton; up to 65 in specimens from Queen Charlotte Sound (Michaelsen)]. Full descriptions of the other species in these localities follow.

Family Synoicidae Hartmeyer, 1908
Genus Amaroucium Milne-Edwards, 1841

Amaroucium nottii n.sp. (Text Fig. 1)

Colonies flat, incrusting, free from sand, irregular in outline, up to 12 cm long, 3 to 6 mm. in thickness. Test white or cream (turns dark brown in formalin), leathery, with numerous small test cells. Zooids brick red, in irregular stellate systems of 10 to 21. Common cloacal apertures up to 0·5 mm. long, 2 cm. apart.

Zooids (Text Fig. 1) up to 6 mm. long, 0·4 mm. wide in pharyngeal region, which has 10 to 12 fine longitudinal muscle bands, 15 transverse. Post-abdomen ⅔ body length, musculature not concentrated on one side. Red pigmentation of pharynx and ovary retained in specimens preserved in formalin. Branchial aperture 6-lobed, atrial with one stout lappet.

Pharynx with 16 tentacles of 2 orders of size; dorsal lamina of 13 to 15 curved languets; on each side 14 to 16 rows of 8 to 10 stigmata, twice as long as wide. No parastigmatic vessels. Oesophagus narrow; stomach halfway down abdominal region, short with 4 to 5 longitudinal folds; intestine narrow at first, widening considerably before the bend; anal aperture slightly bi-lobed.

Fifteen to twenty-one testis blocks in posteior ⅓ or ½ of post-abdomen. Ovary immediately anterior to testis. Tadpoles up to 1·3 mm. long, 0·2 mm. wide in head region, present in mantle cavity May, 1949.

Distribution: Hauraki Gulf (Leigh—intertidal, on coastal rocks).

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Text Fig. 2. Synoicum haurakiensis. A. Entire colony. × 1. B. Right side of zooid. × 26.

Remarks: Three other species of Amaroucium recorded from New Zealand have but few (4 to 6) stomach folds and more than 10 rows of stigmata; Amaroucium scabellum (Michaelsen) with a sand-impregnated test and an entirely different mode of growth from the above; Amaroucium circumvollutum (Sluiter) characterized by strong concentration of muscle on one side of post-abdomen, a tripartite atrial lappet and a sand impregnated test; and Amaroucium oamaruensis Brewin with a sandy test, no atrial lappet and a greater number of stigmatal rows than the above.

The specific name is given in compliment to Mr. J. T. Nott, the first New Zealander to study compound Ascidians.

Type in the Otago Museum.

Genus Synoicum Phipps, 1774

Synoicum haurakiensis n.sp. (Text Fig. 2A, B)

Colonies (Text Fig. 2A) small, cherry red, globose, with or without a short stalk, up to 1·4 cm. long (stalk up to 0·4 cm.), 1·2 cm. wide. Stalk only, lightly impregnated with sand. Colonies not united by a basal membrane. Zooids in irregular stellate systems of 12 to 18. Common cloacal apertures 0·8 to 1·3 mm. long, 5 to 9 mm. apart. Test transparent, with numerous red pigment cells and small test cells.

Zooids (Text Fig. 2B) up to 1·2 cm. long, 1·0 mm. wide in pharyngeal region, which has 8 to 10 longitudinal muscle bands, 12 transverse. Post-abdomen ½ body length, musculature concentrated on one side. Branchial aperture with 6 lobes, atrial with one long lappet.

Pharynx with 16 tentacles of three orders of size; dorsal lamina of short curved languets which curve back at level of third stigmata from mid-dorsal line; on each side 12 to 13 rows of 12 to 14 stigmata, three to five times as long as wide. Oesophagus short, narrow; stomach round with numerous very small areolations; intestine narrow at first, with a slight swelling in middle of narrow portion, increasing considerably in diameter before the bend; anal aperture bi-lobed.

Ten to 18 testis lobes in posterior half of post-abdomen. Ovary immediately anterior to testis. Tadpoles (in mantle cavity May, 1948) up to 0·6 long, 0·02 mm, wide in head region.

Distribution: Hauraki Gulf (on shell Xenophora corrugata dredged 45 fathoms between the Barrier Islands).

Remarks: This species differs from Synoicum hypurgon (Mich.) recorded from the same

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district in zooid proportions [pharynx 1·0 mm. wide (⅓ mm. S. hypurgon); post-abdomen ½ body length (⅘ S. hypurgon)], in the possession of small areolations on stomach wall, in a slightly greater number of stigmata per row and in the concentration of a strong musculature on one side of the post-abdomen. It is separated from S. kuranui Brewin recorded from the east coast of Great Barrier Island, by colony formation and many anatomical features and it is not identical with any members of the genus recorded from Australia, America or the Antarctic.

Type in the Otago Museum.

Family Didemnidae Verrill, 1871
Genus Didemnum Savigny, 1816

Didemnum albidum (Verrill) 1871. (Text Fig. 3A, B)

For Syn. see: 1945, Didemnum albidum, Van Name. Bull. Amer. Mus. Nat. Hist., vol. 84, p. 80.

Colonies pale pink, incrusting, up to 2·5 cm. long, 0·5 to 1·0 mm. thick. Zooids not regularly arranged. Common cloacal apertures up to 0·4 mm. long and 3 mm. apart. Spicules (Text Fig. 3B) pigmented, 0·02 to 0·08 mm. in diameter, throughout test, slightly denser in a layer immediately below the surface and one below the zooids. Numerous small test cells.

Zooids (Text Fig. 3A) up to 0·9 mm. long, 0·3 mm. wide in pharyngeal region. Rectal-oesophageal region short. Abdomen wider than pharyngeal region. Branchial siphon with 6 lobes, atrial with one short lappet. A muscular process well developed in some zooids.

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Text Fig. 3. Didemnum albidum. A. Left side of zooid. × 36.
B. Spicules. × 250.

Pharynx with 16 tentacles, regularly arranged; dorsal lamina of three curved languets; on each side 4 rows of 6 to 8 (usually 7) stigmata, 2 to 3 times as long as wide. Oesophagus short, narrow; stomach short, round; intestine without marked constriction and with intestinal gland.

Testis bi-lobed. Sperm duct with 5 to 8 spiral turns. Ovary between testis and stomach. No tadpoles May, 1949.

Distribution: In New Zealand—off New Plymouth, Hauraki Gulf, Slipper Is., N.W. of Cape Maria van Diemen (Michaelsen), North Shore Reef (Nott), Leigh (on coastal rocks). Elsewhere—circum-North-polar species, extending down to Gullman's Fiord on the Swedish coast, Cape Cod on the Atlantic side of U.S.A., St. Lawrence Is., Bering Strait.

Note: Specimens recorded by Nott from Hauraki Gulf were light pink and yellowish-red and up to 4·0 mm. thick.

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Family Perophoridae Giard, 1872

Social or, exceptionally, compound colonies. Pharynx with simple tentacles, straight stigmata, internal longitudinal bars (occasionally rudimentary or absent) and dorsal languets. Intestine on left side with gonads in loop.

Genus Perophora Weigmann, 1835

Oral aperture usually with six, atrial with five lobes. Pharynx with longitudinal bars rudimentary or absent, and with a few (3 to 5) rows of stigmata.

Perophora annectans Ritter, 1893. (Text Fig. 4)

For Syn. see: 1945, Perophora annectans, Van Name, Bull. Amer. Mus. Nal. Hist., vol. 84, p. 168.

Colonies lemon yellow mats irregular in shape, up to 8 cm. long and 2 mm. thick. Zooids completely imbedded in test, opening separately to exterior. Test light yellow, transparent, gelatinous, free from sand, with numerous small test and pigment cells. Stolons narrow, confined to lower region of test, terminal knobs near periphery of colony.

Zooids (Text Fig. 4) up to 2·5 mm. long, 1·5 mm. wide. Apertures symmetrically placed at anterior end, branchial 10-lobed, atrial 6 to 8-lobed, lobes very small. Mantle thin with fine network of pigment cells. Circular and radial muscles on siphonal wall extend radially for a short distance over body.

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Text Fig. 4. Left side of zooid. × 30. Perophora annectans.

Pharynx with 20 to 24 tentacles, irregularly arranged; dorsal lamina of 4 curved languets; aperture of dorsal tubercle very small, round; on each side 5 rows of 20–24 stigmata, 6 to 10 times as long as wide; papillae on transverse vessels with anterior and posterior processes which do not form internal longitudinal vessels. Oesophagus short narrow; stomach short rounded; intestine narrow at first, 3 to 5 intestinal caeca.

Gonads in intestinal loop. Testis a fan of 2 to 7 lobes converging to sperm duct. Ovary between testis and stomach, with 1 to 3 ova. Tadpoles yellow, up to 1·5 mm. long, 0·4 mm. wide in head region, present in mantle cavity May, 1949.

Distribution: In New Zealand—Hauraki Gulf (intertidal—on rocks and seaweed holdfasts, Leigh). Elsewhere—Pacific Coast of America from Vancouver Island to San Diego.

Remarks: P. annectans is unique in the genus in forming compact colonies in which the zooids may be completely imbedded in a common test. The specimens described above differ from the type only in that they have (1) 5 rows of stigmata (4, Ritter) [specimens with 3 rows only were included in the species by Berrill, 1932, and 3 to 5 rows

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are recorded for the genus, Weigmann], (2) 20 to 24 stigmata per row [18, Ritter, though specimens with 24 are recorded by Huntsman, 1912], (3) a larger number of tentacles [10–14, Ritter] and (4) a larger number of branchial and atrial lobes of which Ritter states (1893, p. 41, line 2): “The number of lobes is not constant for either orifice.” Of these differences the only one of major importance is the number of stigmatal rows, but it is not sufficient to justify the erection of a new species, especially as P. annectans may easily have reached New Zealand on the hulls of ships plying between North America and New Zealand.

Family Botryllidae Verrill 1871
Genus Botryllus Gaertner, 1774

Botryllus magnicoecus (Hartmeyer) 1912. (Text Fig. 5)

For Syn. see: 1922, Botryllus magnicoccus, Michaelsen. Vidensk. Mcdd. Naturh. Foren., bd. 73. p. 480.

Colonies flat, irregular in outline, up to 10 cm. long, 2·8 cm. high. Colouring in life saffron yellow with purple or dark brown around anterior end of zooids; when preserved, dull purple. Numerous small test cells present. Systems elliptical or irregularly branched; common cloacal apertures round, 1 mm. in diameter, 2 to 5 cm. apart.

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Text Fig. 5. Botryllus magnicoecus. Left side of zooid. × 45.

Zooids up to 2·5 cm. long, 0·8 mm. wide in pharyngeal region. Musculature very fine. Branchial aperture smooth-edged; atrial large, ⅓ of body length from anterior end, lappet short, wide (Text Fig. 5). Pharynx with 16 tentacles of 3 orders of size regularly arranged; on each side 3 internal longitudinal vessels and 10 or 11 rows of 11 to 13 stigmata, 2 to 3 times as long as wide, parastigmatic vessels absent. Arrangement of stigmata E.4/2/2/3 D.L., E.4/2/2/4 D.L., E.4/2/3/4 D.L. Oesophagus short, curved; stomach globular with 10 to 11 folds and a long curved caecum; intestine wide, curved; anal aperture smooth-edged.

Testis rosette of 10 to 16 lobes in posterior third of body, those on left being the slightly more anterior. Ovary of one ovum on each side (occasionally two ova on one side) anterior to testis. Reproductive organs not present in specimens collected at Leigh, May, 1949. Testes present in all colonies collected at Tauranga, December, 1949, ovaries discernible in one. Tadpoles not seen.

Distribution: In New Zealand—Tauranga (Mich.), Leigh, Tauranga (intertidal coastal rocks, on holdfasts of seaweeds). Elsewhere—New South Wales (Herdm.), Mozambique (Mich.), South Africa (Hartm.), Dutch South-West Africa, Mediterranean (Mich.).

Note: The specimens described above agree with the type, but none reach the size of 5 mm. or have as many stigmata per row (14–16) as do zooids of Sacrobotryllus purpureum (Herdm.), a species considered synonymous by Michaelsen, 1922.

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Family Styelidae Sluiter, 1895
Genus Alloeocarpa Michaelsen, 1900 (as emended
by Michaelsen, 1922)

Compound Styelidae with individuals closely packed or more or less independent. Pharynx without folds, with 5–16 longitudinal vessels. Polycarps of one sex, on left male only, on right female only.

Alloeocarpa minuta n.sp. (Text Fig. 6)

Individuals round, dome-shaped, separated by 0·5 to 2·0 mm., connected by fine stolons, free from sand, up to 2·5 mm. long, 1 mm. high, bright orangy-red. Apertures 0·5 to 1·0 mm. apart, branchial occupying slightly more central position. Attachment by ventral surface and ⅔ left side and ⅓ right side. Numerous small club-shaped vessels in peripheral part of test (as in A. affinis Bovien).

Pharynx with 16 or 24 tentacles of two or three orders of size regularly arranged; dorsal tubercle, small, rounded; dorsal lamina plain wide membrane; longitudinal vessels 6 to 7 on each side; stigmata 3 to 4 between vessels, 6–7 between endostyle and first longitudinal vessel, may be irregular in posterior end of pharynx, some even as depicted for Metandrocarpa protostigmatica (Michaelsen, 1922, p. 466); parastigmatic vessels present. Oesophagus short; stomach short, round, with 13–15 longitudinal folds and a curved caecum; intestine wide, strongly curved; anal aperture smooth-edged.

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Text Fig. 6. Alloeocarpa minuta. Dissection showing body opened from the ventral surface, pharynx removed. × 15.

A few scattered endocarps. Gonads unisexual. One to 3 testes on left, on anterior half of mantle; sperm ducts very short. Two to 6 ovaries on right in anterior ⅔ of mantle, oviduct short, broad. Largest tadpole 1·4 mm. long, 0·2 mm. wide in head region. Tadpoles in all stages of development in ventral region of mantle cavity, May, 1949.

Distribution: Hauraki Gulf (intertidal, on rocks and ascidian tests, Leigh).

Remarks: This species is most closely related to A. capensis Hartmeyer from South Africa and A. affinis Bovien from Campbell Island. It differs from both in absence of long sperm ducts, and in number of stigmata between longitudinal vessels [4–6, A. capensis; 6–8, A. affinis (with 12 between endostyle and first longitudinal vessel)] and from A. capensis in colony formation also.

Type in the Otago Museum.

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Family Molgulidae Lacaze-Duthiers, 1877
Genus Molgula Forbes and Hanley, 1848

Molgula mortenseni (Michaelsen), 1922. (Text Figs. 7A, B; 8)

For Syn. see: 1922, Ctenicella mortenseni, Michaelsen, Vidensk. Medd. Naturh. Foren., bd. 73, p. 365.

Body globular (Text Fig. 7A), attached by posterior end or part of one side. Test somewhat warty around siphons, impregnated with fine sand grains and shell fragments, without incrustations. Branchial siphon 6-lobed, with 12 light blue internal bands; atrial 4-lobed with

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Text Fig. 7. Molgula mortenseni.
A. Individual. × 0.6.
B. Dissection showing body opened from the ventral surface, pharynx removed. × 2.5.

8 bands. Measurements based on the study of 12 specimens are: length, 0·9 to 2·0 cm.; breadth, 0·5 to 1·4 cm.; depth, 0·4 to 2·3 cm.; distance between apertures 0·3 to 1·2 cm.; branchial siphon 2·0 to 4·0 mm. long, 1·5 to 3·0 mm. wide; atrial siphon, 2·0 to 3·0 mm. long, 1·5 to 3·0 mm. wide; thickness of test 0·2 to 0·3 mm.

Mantle with orange pigment around siphons, anterior region clearly marked, musculature well-developed in siphonal region only.

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Text Fig. 8. Molgula mortenseni. Portion of pharynx near endostyle. × 30.

Pharynx with 16 to 20 tentacles, of approximately equal length, with two (very occasionally three) orders of branching; opening of dorsal tubercle small, a recumbent S; neural gland round, domed, under dorsal tubercle and to right of nerve cord; dorsal lamina a plain membrane, not as wide as first fold; on each side 7 longitudinal folds, with longitudinal vessels arranged thus:

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Length of Specimen Arrangement of Vessels on the right Total
1·5 cm. E.–(4)–(5)–(7)–(7)–(7)–(7)–(6)–D.L. 43
1.7 cm. E.–(5)–(6)–(8)–(8)–(7)–(6)–(6)–D.L. 46
2·0 cm. E.–(6)–(7)–(7)–(7)–(7)–(8)–(8)–D.L. 50

Note: Longitudinal vessels fade out towards posterior end of the folds.

Stigmata (Text Fig. 8) mainly straight, eight to nine times as long as wide, parastigmatic vessels present; curved stigmata in the summits of some folds and near endostyle; 1 or 2 rows of stigmata between two large transverse vessels. Intestinal loop 1/2 to 2/3 body length. Oesophagus very short; stomach surrounded by “liver” except on left side; intestine smooth, narrow, loop open only at reflected end; anal aperture straight, smooth (Text Fig. 7B).

Kidney bean-shaped, far back on right. Atrial velum wide.

Gonad on left anterior to primary intestinal loop, on right centrally placed. Ovary anterior to testis, partly covered by it. Gonoducts opening towards atrial aperture, close together, sperm duct more posterior. No tapdoles May, 1949.

Distribution: In New Zealand—Hauraki Gulf, Tokuma Bay, off New Plymouth, Stewart Island (Michaelsen), Leigh (intertidal coastal rocks).

Remarks: The specimens described above agree very closely with Michaelsen's description of M. mortenseni. The number of longitudinal vessels is slightly greater (42 in Michaelsen's only sample), but the basic arrangement is the same (E.–(4)–(5)–(7)–(7)–(7)–(7)–(5)–D., Michaelsen).

Tadpoles

Tadpoles were present in May in the mantle cavities of Amaroucium nottii, Amaroucium phortax, Synoicum haurakiensis, Perophora annectans, Okamia thilenii, and Alloecarpa minuta and in the brood pouch of Distaplia taylori.

Summary

An account is given of the intertidal ascidian fauna of Leigh and Takapuna and of two specimens dredged between Great and Little Barrier Islands. Nine species are recorded for the first time from the Hauraki Gulf, Amaroucium nottii, Amaroucium haurakiensis, Sigillinaria novae-zelandiae, Polycitor (Eudistoma) circumvallatum, Distaplia taylori, Perophora annectans, Botryllus magnicoecus, Alloeocarpa minuta, and Cnemidocarpa nisiotis, and the total number of species recorded from this locality is now 38. Three new species are described, Amaroucium nottii, Amaroucium haurakiensis and Alloeocarpa minuta. Perophora annectans is recorded from New Zealand for the first time.

References

These include those given in the previous papers of the series (Trans. Roy. Soc. N.Z., vols. 76, 77, 78) as well as the following:

Berrill, N. J., 1932. Ascidians of the Bermudas. Biol. Bull., vol. 62, pp. 77–78.

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Huntsman, A. G., 1912. Holostomatous Ascidians from the Coast of Western Canada. Contrib. Canadian Biol., Ottawa, pp. 103–185.

Ritter, W. E., 1893. Tunicata of the Pacific Coast of North America. I. Perophora annectans n.sp. Proc. Cal. Acad. Sci., ser. 2, vol. iv, pp. 37–85.

Explanation of Lettering
av—atrial velum ilv—internal longitudinal ad—sperm duct
ecp—endocarp vessel sto—stolon
gc—gastric caecum la—embryo ♂—male
l—liver r—kidney ♀—female