Ascidians of New Zealand. Part X.—Ascidians from North Auckland

Transactions and Proceedings of the Royal Society of New Zealand, Volume 84, 1956-57, Page 577

Ascidians of New Zealand. Part X.—Ascidians from North Auckland By Beryl I. Brewin University of Otago [Received by Editor, May 17, 1956.] Summary The number of ascidians recorded from the North Auckland region is raised from thirteen to thirty-three, this survey extending the northerly distribution of seventeen species. Two new species are described—Amaroucium cottrelli and Sigillinaria aurea (both from the West Coast)—and a fuller description than the original is given for Didemnum paradoxum (Nott.). The material which forms the basis for this paper was collected by the author from coastal rocks at Whangarei Heads (W.H.), in the bay of Islands (B. of I.), and at Omapere, in the Hokianga Harbour (O.). It also includes three species collected by Mr. W. Dawbin from a West Coast beach out from Dargaville (D.) after a storm. (Of these only one was recognisable.) Michaelsen (1922, 1924) recorded 13 species, which were collected off Cape Maria van Diemen (M. v. D.), the Three Kings Islands (T.K.), North Cape (N.C.), Cape Brett (C.B.), and from the Kaipara Harbour (K.). Michaelsen's species (marked †) together with those in the present collection are listed below, and the total number of species recorded from the region is now 33. List of Species. Synoicidae Locality 1. †Macroclinum arenaceum Mich. N.C. 2. †Amaroucium circumvollutum (Sluit.) N.C. 3. Amaroucium thomsoni Brewin W. H. 4. Amaroucium phortax Mich. B. of I., W. H. 5. Amaroucium nottii Brewin B. of I. 6. Amaroucium cottrelli, n.sp O. 7. Sigillinaria opaca Brewin B. of I. 8. Sigillinaria aurea, n.sp. O. Didemnidae 9. * Known from dredged specimens.†Leptochinides diemenensis Mich. M.v.D. 10. Didemnum candidum Sav. B. of I, W. H. 11. *†Didemnum chondrilla Mich. N.C. 12. Didemnum paradoxum (Nott.) W. H. 13. †Didemnum psammatodes (Sluit.) var. maculatum (Nott.) M.v.D. Polycitoridae 14. *†Polycitorella mariae Mich. M.v.D. 15. *†Clavellina sigillaria Mich. M v.D. 16. Sycozoa sigillinoides Less. D. Rhodosomatidae 17. †Corella eumyota Traust. O., B. of I., K Botryllidae 18. Botryllus magnicoecus (Hart.) W. H. Styelidae 19 *†Theodorella torus Mich. B of I 20. Okamia thilenii (Mich.) B. of I. 21. Arnbackia novae-zealandiae Brewin B. of I. 22. Asterocarpa cerea (Sluit.) O., B. of I., W.H. 23. †Asterocarpa coerulea (Q. and Gaim.) O., B. of I., W.H, N.C. 24. Cnemidocarpa bicornuata (Sluit.) B. of I. 25. Cnemidocarpa nisiotis (Sluit.) B. of I. 26. *†Cnemidocarpa madagascariensis Hart. var. regalis Mich. T.K.

Pyuridae Pyuridae 27. †Pyura trita (Sluit.) N.C. 28. *Pyura subuculata (Sluit.) B. of I., C.B., W.H. 29. Pyura rugata Brewin O. 30. Pyura cancellata Brewin B. of I. 31. Pyura pulla (Sluit.) B. of I. 32. Microcosmus kura Brewin. W. H. Molgulidae 33. Molgula mortenseni (Mich.) B. of I. This survey extends the northerly distribution in New Zealand of the following 17 species:—Amaroucium thomsoni, Amaroucium nottii, Amaroucium phortax, Sigillinaria opaca, Didemnum candidum, Corella eumyota, Botryllus magnicoecus, Okamia thilenii, Arnbackia novae-zealandiae, Asterocarpa cerea, Cnemidocarpa bicornuata, Cnemidocarpa nisiotis, Pyura cancellata, Pyura pulla, Pyura rugata, Microcosmus kura and Molgula mortenseni. The majority of specimens fall within the range of variability given for the species in previous papers of this series. The zooids of Botryllus magnicoecus bear a somewhat longer atrial lappet than that characteristic of the specimens from the Hauraki Gulf. Specimens of Asterocarpa cerea are of the small orange form common in the Hauraki Gulf. The specimens of the simple ascidians collected from the Hokianga Harbour (West Coast)—Corella eumyota, Asterocarpa cerea, Asterocarpa coerulea and Pyura rugata—all fall within the lower size range recorded for the species. (Paucity of development of these ascidians may be due to the small amount of current in the wider reaches of the Hokianga Harbour, the entrance to which is straddled by a large sand bar.) Very little is known of the ascidian fauna of the West Coast, the heavy surf being non-conducive to tadpole settling and little collecting having been done within the harbours, hence it is not surprising that the two new species here recorded come from this coast. Description of Species Amaroucium cottrelli, n.sp. (Plate I, Figs. Ia, Ib). Colonies (Fig. 1b) aggregations of flat-topped sandy lobes, up to 12 mm wide and 10 mm in height above the substratum. Test light yellow, heavily impregnated with sand-grains, containing numerous small test cells. Zooids yellow, in irregular systems, several systems per lobe. Common cloacal apertures 1 mm in diameter, 3 to 4 mm apart. Zooids (Fig. Ia) up to 4.5 mm long, 0.3 to 0.5 mm wide in the pharyngeal region, which has 15 fine longitudinal muscle bands, 11 to 12 transverse Post-abdomen approximately one-half zooid length, musculature showing very slight concentration on the ventral side. Branchial aperture six-lobed, atrial with a single stout lappet. Pharynx with 16 tentacles of two or three orders of size. Dorsal lamina with 11 to 12 curved languets. On each side 12 to 13 rows of 10 stigmata, 3 times as long as wide, parastigmata absent. Oesophagus short; stomach short with 5 longitudinal folds; intestine without marked constriction; anal aperture bi-lobed. Eleven to 22 testis lobes in the posterior ¾ of post-abdomen. Ovary anterior to testis. Tadpoles up to 1.0 mm long, 0.25 mm wide in head region present in specimens collected December 10, 1952. Distribution: Hokianga Harbour (coastal rocks, seaweed holdfasts, Omapere). Type Specimen: In the Otago Museum. Remarks: This species is easily distinguished by its stigmatal arrangement from the other sandy lobed Amaroucium spp. recorded from New Zealand.

Fig. Ia.—Amaroucium cottrelli. Right side of zooid. Fig. Ib.—Colony of Amaroucium cottrelli Fig. 2a1, a2.—Sigillinaria aurea. Left side of zooid. Fig. 2b.—Tadpole of Sigillinaria aurea. Fig. 2c.—T.S. abdominal region of Sigillinaria aurea showing shape of stomach. Fig. 3a.—Didemnum paradoxum. Left side of zooid. Fig. 3b.—Tadpole of Didemnum paradoxum Fig. 3c.—Spicules of Didemnum paradoxum.

Sigillinaria aurea n.sp. (Plate I, Figs. 2a1, a2, 2b, 2c) Colonies not lobate, irregular fleshy mats up to 8 cm in the greatest diameter, 8 mm in height above substratum. No systematic arrangement of the yellow zooids. Test transparent, colourless, free from sand grains, containing numerous small test cells. Zooids (2a1, a2) up to 7 mm long, 0.7 mm wide in pharyngeal region, which occupies only 1/14th of zooid length. Post-abdomen ½ zooid length. Branchial and atrial siphons each with six lobes. Pharynx with 32 tentacles of three orders of size, regularly arranged. Dorsal lamina of 2 curved languets. On each side 3 rows of 15 to 17 stigmata, no parastigmatic vessels. Oesophagus very long, narrow; stomach short, dorso-ventrally compressed with 3 or 4 low longitudinal folds (Fig. 2c); intestine immediately behind stomach narrow but widening considerably before it turns to run up towards the atrial siphon; anal aperture smooth. Up to 24 testis lobes in the posterior half of post-abdomen. Ovary immediately anterior to testis. Tadpoles (Fig. 2b) in all stages of development present in oviduct in specimens collected December 10, 1952. Largest 1.3 mm long, 0.4 mm wide in head region. Distribution: Hokianga Harbour (coastal rocks, Omapere). Type Specimen: In the Otago Museum. Remarks: This species differs from other recorded species of Sigillinaria in the non-lobate form of the colony, and in stigmatal arrangement. Didemnum paradoxum (Nott.) (Plate I, Figs. 3a, 3b, 3c). 1892. Polysyncraton paradoxum and P. fuscum, Nott, Trans. N.Z. Inst., vol. 24, pp. 318–323, Plate XXVIII. 1920. Didemnum paradoxum var. maheinum, Michaelsen, Krikobr, Ascid. westl. Ind. Oz., Didemnid., p. 12. 1924. Didemnum paradoxum, Michaelsen, Vidensk. Medd. naturh. Foren. bd. 77 p. 344. Colonies white or light brown (white, reddish brown or black, Nott.) incrusting, up to 6 cm long, 2 to 3 mm in height above substratum. Zooids not regularly arranged. Common cloacal apertures 1.0 mm in diameter, up to 5 mm apart. Spicules up to 18μ in diameter, rays very narrow, rounded at the ends, and approximating closely (Fig. 3c), absent from surface layer, elsewhere evenly distributed. Test with numerous test cells and also bladder cells except in the surface layer. Zooids (3a) up to 1.2 mm long, 0.4 mm wide in the pharyngeal region. Rectal-oesophageal region 0.1 mm long. Abdomen wider than pharynx. Branchial siphon with 6 lobes, atrial aperture surmounted by one well-marked lappet (no lappets, var. maheinum, Mich.). Vascular processes, bulbous or filamentous, project from the oesophageal region. Pharynx with 16 tentacles of 3 orders of size, regularly arranged. Dorsal lamina with 3 curved languets. On each side 4 rows of 7 stigmata (no definite number given by Nott. who figures 5; 6–8 var. maheinum, Michaelsen). Oesophagus short, narrow; stomach short, round; slight intestinal constriction immediately posterior to stomach. Testis with 7 to 8 lobes (4–6 var. maheinum, Michaelsen). Sperm duct with 2–4 spiral turns (usually 2). Ovary between testis and stomach, quite typical and not as figured by Nott. Tadpoles present in cloacal canals of specimens collected December 12, 1952. Distribution: Auckland Harbour, Whangarei Heads (coastal rocks). var. maheinum: Seychelles. Tadpoles Tadpoles were present in December, 1952, in Amaroucium nottii, Amaroucium phortax, Amaroucium cottrelli, Sigillinaria opacta, Sigillinaria aurea, Didemnum candidum, Didemnum paradoxum, Okamia thilenii, Arnbackia novae-zealandiae and in October, 1950, in Sycozoa sigillinoides. Acknowledgment I wish to thank the New Zealand University Grants Committee for a travelling grant in connection with collection of material. Beryl I. Brewin,Zoology Department, University of Otago, Dunedin.