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Volume 77, 1948-49
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Ascidians of the Hauraki Gulf. Part I.

[Read at Otago Branch, May 6, 1947; received by Editor, May 12, 1947; issued separately, April, 1948.]

Summary.

This paper gives an account of eighteen species of ascidians collected in the Hauraki Gulf and brings the total number of species recorded from this region to twenty-nine. A new genus, Okamia has been established to cover compound Styelidae with gonads, usually of one sex, present on both sides of the body, the ovaries being posterior to the testes and sometimes present on one side only. Four new species are described, Aplidium (Amaroucium) thomasi, Pyura rugata, Pyura carnea, and Microcosmus kura, and Styela plicata is recorded from New Zealand for the first time. At the end of the description of Pyura subuculata (Sluit.) a discussion is given of the species and the conclusion reached that forms from Lyttelton and the Otago Harbour previously described as P. subuculata var. suteri should now be known as Pyura suteri Mich.

This paper is the second of a series dealing with ascidians of various coastal regions of New Zealand. The first of these, “Ascidians in the Vicinity of the Portobello Marine Biological Station, Otago Harbour,” was published in 1946 (Trans. Roy. Soc. N.Z.) and in it an account is given of the methods employed in investigating this group and of the literature covering the species recorded from New Zealand waters.

In the Hauraki Gulf region collections have been made by Nott, 1892, who described eight compound species from the North Shore Reef, by Cottrell, 1912, who described one simple ascidian from the rocky shores of the gulf, and by Michaelsen, 1922, 1924, who records the following seventeen species. These include those described by his predecessors as well as those collected in the gulf region by the Mortensen Expedition.

Synoicidae
1.

Macrolinum hypurgon Mich.

2.

*Amaroucium circumvollutum (Sluit.)

3.

*Amaroucium scabellum Mich.

Didemnidae
4.

Didemnum candidum Sav.

5.

Didemnum tuberatum (Nott)

6.

Didemnum albidum (Verr.)

7.

*Didemnum chondrilla Mich.

8.

Didemnum paradoxum (Nott)

9.

Didemnum psammatodes (Sluit.) var. maculatum (Nott)

Polycitoridae
10.

Cystodytes dellachiaiae (Della Valle) [formerly C. draschei Herd.]

Rhodosomatidae
11.

Corella eumyota Traust.

[Footnote] * Generic characters are given only for the genera which do not appear in the previous paper of this series (1946).

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Botryllidae

12.

Botryllus leachi Sav.

Styelidae

13.

Metandrocarpa protostigmatica Mich.

14.

Cnemidocarpa coerulea (Q. and Gaim.)

15.

Cnemidocarpa bicórnuata (Sluit.)

Pyuridae

16.

Pyura trita (Sluit.)

Molgulidae

17.

Ctenicella mortenseni Mich.

The species marked with an asterisk in the above list are forms recorded only from depths of 30 to 35 fathoms.

The material which forms the basis of the present paper was collected during the summers of 1945 and 1946 from coastal rocks in the following localities: North Shore, Rangitoto Island, Mission Bay, Kohimarama, St. Heliers Bay, and Wanganui Island, off Coromandel, and also from Horseshoe Reef, off St. Heliers Bay. The collection embraces six of the species included in the above list, seven species previously recorded from other parts of New Zealand, Styela plicata (Lesseur) recorded from Australia, but not so far recorded from New Zealand, and four new species, thus bringing the total number of species recorded from the Hauraki Gulf up to twenty-nine. One new genus, Okamia, has been erected in the family Styelidae to include a species previously recorded by Michaelsen as Metandro-carpa thilenii. A full discussion of the genus is given later in this article. The list below includes only the species that have been collected and identified by the author, and in the accounts that follow full descriptions are given only of those species not described in the previous paper of this series (1946), the local range of variability alone being given for the others.

List of Species.

Synoicidae

1.

*Aplidium (Amaroucium) thomasi n.sp.

2.

Aplidium (Amaroucium) phortax Mich.

Didemnidae

3.

Didemnum candidum Sav.

4.

Diplosoma macdonaldi Herdm.

Polycitoridae

5.

Cystodytes dellachiaiae (Della Valle)

Rhodosomatidae

6.

Corella eumyota Traust.

Botryllidae

7.

Botryllus leachi Sav.

8.

Botryllus schlosseri (Pallas)

Styelidae

9.

Okamia thilenii (Mich.)

10.

Asterocarpa cerea (Sluit.)

11.

Asterocarpa coerulea (Q. and Gaim.)

12.

Cnemidocarpa bicornuata (Sluit.)

13.

*Styela plicata (Lesseur)

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Pyuridae

14.

Pyura subuculata (Sluit.)

15.

*Pyura rugata n.sp.

16.

Pyura cancellata Brewin

17.

*Pyura carnea n.sp.

18.

*Microcosmus kura n.sp.

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

Description of Species.

Explanation of Lettering.

av. atrial velum oe. oesophagus
ecp. endocarp o.t. outer test
g. gonad r. rectum
gc. gastric caecum sd. sperm duct
i.t. inner test st. stomach
l. “liver” ♀ ovary
lv. larva ♂ testis

Order Krikobranchia Seeliger

Family Synoicidae Hartmeyer.

Genus Aplidium Savigny.*
Sub-genus Amaroucium (Milne-Edwards).

Aplidium (Amaroucium) thomasi n.sp. (Text Fig. 1; Plate 9, Fig. 7.)

This species forms small, thin, irregularly shaped light-orange masses on the undersurfaces and sides of rocks. A few specimens only have been collected and those on the southern side of Wanganui Island, off Coromandel. The largest colony measured 4·5 cm. in the longest diameter, 2 mm. in height at the edge of the colony and up to 5 mm. in height in the more central regions. There is no tendency towards mound formation around the common cloacal apertures, which are small (1 mm. in the longest diameter) and are separated by distances of 3 to 5 mm. The zooids lie very close to one another and do not appear to be arranged in any definite order around the common cloacal apertures. The test is fleshy, light-orange in colour and free from sand grains except in the basal regions. Numerous small test cells and a few large bladder cells are present throughout the test. The zooids are cream in colour with bright-yellow colouration on the stomach wall and light-brown pigmentation in the ripe eggs.

Zooids measure up to 8 mm. in length and 0·9 mm. in width in the pharyngeal region. The post-abdomen is long and narrow. The branchial aperture is surrounded by six short triangular lobes and the atrial aperture, which lies near the anterior end of the zooid, is surmounted by one long, wide lappet. The wall of the pharynx is broken by nine or ten rows of eight to ten stigmata, one and a half times as long as they are wide, except in the most posterior row, where they may be three times as long as they are wide. Ten to eleven rows of two to three longitudinal muscle fibres run down the pharynx

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wall, but there is no tendency to concentration on any side of the zooid. Two to three transverse muscle fibres are present between the rows of stigmata. Branchial tentacles are sixteen in number and of two orders of size regularly arranged. The dorsal lamina is composed of nine or ten thin languets which curve back at the level of the third or fourth stigmata from the mid-dorsal line. The oesophagus is short and leads to a short, rounded stomach with ten to twelve longitudinal folds. The intestine passes backwards for a short distance before it turns to run up towards the atrial aperture, and in the short, backwardly directed portion there are two well-marked constrictions.

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Text Fig. 1—Aplidium (Amaroucium) thomasi. Left side of zooid. × 20.

The testis is situated in the posterior two-thirds of the post-abdomen and is composed of fourteen to twenty-one lobes arranged in a double row around the sperm duct which runs straight up towards the atrial aperture. The ovary lies immediately in front of the testis. Tadpoles are light brown in colour and undergo development within the mantle cavity. They were present in specimens collected in January, 1947, and the largest measured 0·9 mm. in length and 0·25 mm. in width in the head region. (Plate 9, Fig. 7.)

Distribution: Wanganui Island, off Coromandel, Hauraki Gulf.

Remarks: From a careful survey of the literature of the genus it is apparent that the species described above is not identical with any previously described. It is distinguished from A. stelliferum (Sluiter) and A. foliaceum (Sluiter) by the structure of the test and the size and arrangement of the zooids, and from A. constrictum (Sluiter) by the size of the zooids and the number of atrial lappets. The specific name is given in compliment to Professor Thomas, late Professor of Zoology, Auckland University College.

Note: The arrangement of the testis lobes places this species in the sub-genus Amaroucium, though the number of rows of stigmata in the pharynx is more in agreement with that laid down for members of the sub-genus Aplidium.

Type Specimen: Otago Museum.

Aplidium (Amaroucium) phortax Michaelsen.

Synonymy and Literature: 1946, Aplidium (Amaroucium) phortax f. typica, Brewin, Trans. Roy. Soc. N.Z., vol. 76, p. 92.

Specimens of this species were commonly found on the under-surfaces and sides of rocks in all six collecting grounds. Some of

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the zooids were larger than any recorded from Otago Harbour, reaching 15 mm. in length and 1 mm. in width in the pharyngeal region and having the pharynx broken by thirteen to fourteen rows of ten or eleven stigmata.

This is the most northerly record of this species in New Zealand. Var. ptychodes was not seen.

Distribution: In New Zealand—f. typica—Tauranga (Mich.), d'Urville Island (Sluit.), Otago Harbour (Brewin), Hauraki Gulf; var. ptychodes Mich.—Stewart Island (Mich.). Elsewhere—f. typica—Chatham Islands (Sluit.).

Family Didemnidae Verrill.

Genus Didemnum Savigny.

Didemnum candidum Savigny.

Synonymy and Literature: 1924, Didemnum candidum, Michaelsen, Vidensk. Medd. naturh. Foren., bd. 77, pp. 358, 359.

This species, though by no means common, was collected in all six collecting grounds, and no specimens showed any features not covered by previous descriptions. It has been recorded from the Hauraki Gulf by both Nott, 1892, and Michaelsen, 1924.

Genus Diplosoma MacDonald.

Diplosoma macdonaldi Herdman.

Synonymy and Literature: 1930, Diplosoma macdonaldi, Van Name, New York Acad. Sci., vol. 10, pt. 4, p. 440.

Colonies identical with those described from Otago Harbour (Brewin, 1946) were collected on seaweeds washed up on Kohimarama Beach after a heavy storm and also on seaweeds in rock pools on Wanganui Island, off Coromandel. They did not show any features not covered by previous descriptions. The species has been recorded from the Hauraki Gulf by the author (1946).

Family Polycitoridae Hartmeyer.

Genus Cystodytes von Drasche.

Disk-shaped calcareous spicules in the test, arranged in an overlapping manner so as to form capsules often enclosing the bodies of the zooids except in the thoracic region, which may be extended or drawn back into the capsule. Spicules may be few or poorly developed. There are often scattered calcareous granules or spicules in the test. Branchial sac with four rows of stigmata; stomach rounded and smooth-walled; gonads situated beside the intestinal loop and consisting of an ovary containing several eggs in various stages of development and testes forming a rosette-like cluster of pyriform glands.

Cystodytes dellachiaiae (Della Valle). (Text Fig. 2; Plate 9, Fig. 9.)

Synonymy and Literature: 1921, Cystodytes dellachiaiae, Van Name. Amer. Mus. Nat. Hist., vol. 44, p. 360.

Several colonies of this species were collected on the under-surfaces and sides of rocks on Rangitoto Island, where it is the most common compound ascidian, and one colony was collected on the southern side of Wanganui Island, off Coromandel. Of these, all

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except one was white in colour, the other being tinged with brown. Violet-red specimens have been recorded from Queen Charlotte Sounds (Mich., 1924). The colour range of the species as given by Van Name (1921) is black, brown, purple, pale buff and almost white. Colonies form smooth, leathery, irregularly shaped masses up to 8 cm. in the longest diameter. The edges are distinctly rounded, and in the central portions the colonies reach a thickness of 3 to 5 mm. The zooids are 0·7 to 1·5 mm. apart and are not arranged in definite systems. The test contains numerous small test cells, numerous bladder cells, and, in the coloured forms, oval pigment cells as well. Thin, disk-like, slightly concave, calcareous white spicules (Plate 9, Fig. 9) [0·4 to 0·5 mm. in diameter] form capsules which surround the posterior portion of each zooid. According to Nott (1892), granules and peculiar tree-like masses of calcareous matter are present in the test, but no such structures are present in the specimens in the present collection.

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Text Fig. 2—Cystodytes dellachiaiae. Right side of zooid. × 45.

The zooids measure up to 5 mm. in length and 1·3 mm. in width in the pharyngeal region. The rectal-oesophageal region is short and the abdominal region is wider than the pharyngeal. The apertures are both situated on well-developed tubes of which the atrial is by far the longer. Both bear six short triangular lobes. The wall of the pharynx is broken by four rows of eighteen to twenty stigmata, six to seven times as long as they are broad. The branchial tentacles are forty to fifty in number and of two or three orders of size. The mantle musculature is very well developed and it is only occasional specimens that can be obtained in a completely relaxed state. The dorsal lamina is composed of four curved languets. The oesophagus is short, the stomach round and smooth-walled, and the intestine comparatively narrow and without any marked constrictions. The intestine takes two almost right-angled turns before it runs up towards the atrial aperture. There are no external intestinal glands.

The gonads lie beside the intestinal loop. The testis consists of six to ten or more pear-shaped lobes from which the sperm duct runs up parallel to the distal portion of the intestinal loop to open near the atrial aperture. The ovary lies just anterior to the testis. Tadpoles are recorded in the mantle cavity of specimens collected in September (Nott, 1892).

Distribution: In New Zealand—Auckland Harbour (Nott), Queen Charlotte Sound, Hauraki Gulf (Michaelsen). Elsewhere—Mediterranean (Della Valle), West Indies (Van Name), Philippine Islands, Brazil (Herdman).

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Remarks: The author has no doubt that the specimens described above are identical with those previously recorded from New Zealand and placed by Michaelsen in the species C. draschei Herdman. This species is considered by Van Name to be synonymous with C. dellachiaiae (Della Valle) which would appear to be, like Didemnum candidum and Diplosoma macdonaldi, a very widely distributed species.

Order Diktyobranchia Seeliger.

Family rhodosomatidae hartmeyer.

Genus Corella Alder and Hancock.

Corella eumyota Traustedt.

Synonymy and Literature: 1945, Corella eumyota, Van Name, Bull. Amer. Mus. Nat. Hist., vol. 84, p. 212.

Specimens were found in all six collecting grounds, but were by no means as common as they are in the Otago Harbour. They either fall within the larger-size range given for Otago specimens or slightly exceed it, reaching up to 5·4 cm. in length. Other points worthy of note are: test thickness 0·2 to 0·6 mm. (0·2 to 0·3 mm., Otago), branchial tentacles up to ninety-six in number (up to seventy-eight, Otago), dorsal lamina up to forty-eight languets (up to thirty, Otago), and internal longitudinal vessels up to one hundred and twenty, sixty on each side (up to ninety-two, Otago).

This species has a wide distribution (Brewin, 1946, p. 110) and has been recorded previously from practically the whole length of New Zealand.

Order Ptychobranchia Seeliger.

Family Botryllidae Verrill.

Genus Botryllus Gaertner and Pallas.

Botryllus leachi Savigny.

A few small colonies of this form were found on seaweeds washed up on Mission Bay after a heavy storm. They in no way differed from the Otago specimens, but whereas in the Otago Harbour B. leachi was of commoner occurrence than B. schlosseri, in the Hauraki Gulf the reverse seems to be the case.

This species has been recorded previously from the Hauraki Gulf and the distribution to date is given in the previous paper of this series (p. 112).

Botryllus schlosseri (Pallas).

A few colonies of this species were found on seaweeds in rock pools on Wanganui Island, off Coromandel, and numerous colonies were found on seaweeds washed up on Mission Bay after a heavy storm. They in no way differed from those described from Otago Harbour. Tadpoles were present in the peribranchial cavities of specimens collected in January, 1946.

Distribution: In New Zealand—North Island [exact locality not known] (Mich.), Otago Harbour (Brewin), Hauraki Gulf. Elsewhere—East Coast of America and the whole of Europe (Mich.).

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Family Styelidae Sluiter.

Genus Okamia n.gen.

This genus consists of compound Styelidae with a branchial sac without folds and with a smaller number (about five to 10) of internal longitudinal vessels on each side; with gonads, mostly, if not all, of a single sex; with ovaries lying posterior to the testes, which are present on both sides of the body, the ovaries sometimes being confined to the left side of the body.

Note: Since Michaelsen's revision of the compound Styelidae (1904) the classification of this group has been based mainly on the presence or absence of longitudinal folds in the branchial sac and the structure and manner of arrangement of the gonads. In Michaelsen's original diagnosis of the genus Metandrocarpa (1904, p. 69), in which he has placed M. thilenii, a New Zealand species, the portion referring to the gonads reads thus: “Geschlechtsorgane in eingeschlechtlichen Polycarpen jederseits ventral neben der Medianlinie, in der vorderen Partie weibliche, in der hinteren Partie männliche.” However, when in 1922 Michaelsen amended this genus to house two New Zealand forms, M. thilenii Mich, and M. photostigmatica Mich., he describes the gonads thus (1922, p. 416): “Polycarpe meist sämtlich eingeschlechtlich, jederseits männliche und weibliche, selten gelentlich zwei Polycarpe verschiedenen Geschlechts mehr oder weniger innig zu einem Zwitterorgan verwachsen.” The most important living worker in this group, Dr. Willard Van Name (1945, p. 241) interprets Michaelsen's amendment thus: “The gonads are mostly, if not all of them, each of a single sex, and are present on both sides of the body, the female only in the anterior part, the male in the posterior part. The male gonads consist each of a single testis,” though from Michaelsen's explanation of the amendment it is apparent that he considered the significant point of the diagnosis to lie not in the particular arrangement of the polycarps of different sexes (female anterior, male posterior), but in that male and female are present on both sides of the body.

The author has no doubt but that the specimens collected from Little Passage, Hauraki Gulf, and described below are identical with Michaelsen's Metandrocarpa thilenii. Thirty zooids from eight different colonies exhibited the gonad arrangement depicted in Text Fig. 3, the ovaries lying on the left side of the body on the arc of a circle posterior to the arc of the testes on that side. Three zooids, however, showed the gonad arrangement depicted by Michaelsen (1922, p. 459) in which the arc of the ovaries is slightly more extensive and one or two ovaries lie on the other side of the mid-ventral line. From these facts it is obvious that the presence of male and female gonads on both sides of the body is the exception rather than the rule in this species, and hence the species cannot be fitted easily into Michaelsen's genus Metandrocarpa even with the amended diagnosis, and the fact that the ovaries lie posterior to the testes removes it from the genus Metandrocarpa as interpreted by Van Name (1945). For these reasons and also because of the fact that the diagnosis of the genus Metandrocarpa seems to be completely unsatisfactory, it seems desirable that the species M. thilenii Mich. should be lifted from the genus Metandrocarpa

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and placed in a new genus, as diagnosed above and which the author proposes to call Okamia.

Okamia theilenii (Mich.). (Text Fig. 3, Plate 9, Figs. 1, 8.)

Synonymy and Literature: 1922, Metandrocarpa thilenii, Michaelsen, Vidensk. Medd. naturh. Foren., bd. 73, p. 457.

Colonies of this species were very common on the undersurfaces and sides of rocks, mussels, etc., on the mainland side of Little Passage, which lies between Wanganui Island and the Coromandel mainland. The colonies form large, irregularly shaped mats up to twelve inches in the longest diameter. The zooids vary in colour from dull red to slate blue in different colonies and the siphonal linings are in all cases a brilliant red. The colony has a very thin basal membrane not more than 1 mm. in thickness. The zooids are joined by the basal membrane and occasionally by the lower third as well. They are packed very closely together (Plate 9, Fig. 1) and often the lower half of a zooid may be pushed into a square shape. Young zooids develop from any region of the lower third of the adult zooid.

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Text Fig. 3—Okamia thilenii. Dissection showing body opened from the ventral surface, pharynx removed. × 7.5.

Individuals measure up to 10 mm. in length, 3 mm. in breadth, and 3 mm. in depth, and the siphonal apertures, which are situated at equal distances from the centre of the top surface, are from 1·5 to 2 mm. apart and 0·4 to 0·5 mm. in height. The test is thin, 0·1 to 0·3 mm. in thickness, and in colonies growing in a region washed by a strong current is free from sand grains or incrustations, though in specimens from still backwaters it may be quite heavily impregnated with fine particles of sand. The mantle wall is a dark dull red in colour and is well supplied with fine muscle fibres. On each side of the wall of the pharynx there are ten longitudinal vessels separated by few or many stigmata according to their position in the pharynx, there being usually nine in the mesh next the endostyle, two in the mesh next the dorsal lamina and four in the intervening meshes. The stigmata are five to six times as long as they are wide and are usually crossed by a parastigmatic vessel. The branchial tentacles are thirty-two to forty-eight in number and of one or two orders of size. The dorsal tubercle is a small round cushion and the dorsal lamina a plain straight membrane. The gut loop lies on the left side of the body and

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consists of a short narrow oesophagus; a wide stomach bearing twenty to twenty-two longitudinal folds arranged on a slight spiral and with a hook-shaped gastric caecum; and a long smooth-walled intestine which takes a sharp turn close to the stomach and then runs straight up towards the atrial aperture. The anal aperture is smooth and two-lipped. Small pigmented endocarps are present on both sides of the mantle wall and number from ten to fifteen on the right and from eight to ten on the left. Atrial tentacles are present. They are very small and extremely numerous.

The gonads are of one sex, the testes being light-coloured, pear-shaped structures with well-marked gonoducts, and the ovaries being brownish-red rounded structures. The ovaries are arranged in a single row along the arc of a circle and lie towards the posterior end of the left side of the body. The arc of the ovaries may extend just slightly past the mid-ventral line. Testes are present on each side of the body, where they are arranged in a single row along the arc of a circle, the row on the left side being always anterior to the row of ovaries. Ovaries are from five to ten in number in the Coromandel specimens, and testes five to eight in number on the right side of the body, nine to thirteen in number on the left side of the body. The eggs ripen in January. They are bright orange in colour and extremely large (0·5 mm. in diameter) compared with the size of the zooid. They undergo development within the mantle cavity and become large orange tadpoles heavily pigmented at the anterior end (Plate 9, Fig. 8). The largest measured 3·5 mm. in length and 0·5 mm. in width in the head region.

Distribution: In New Zealand—Tauranga (Thil. legacy, Berlin Museum), New Plymouth (Michaelsen), Hauraki Gulf.

Remarks: Type specimens of this form are not available, but the author has no doubt but that the specimens described above belong to Metandrocarpa thilenii Mich., which the author proposes to place in the newly constructed genus Okamia. The gonad count given by Michaelsen slightly exceeds that of the Coromandel specimens, but in a group showing a wide range of variability such a minor difference may easily be due to local variation.

Genus Asterocarpa Brewin.

Asterocarpa cerea (Sluiter).

Specimens of this species were found either singly or in small clumps (two to five individuals) on the under-surfaces and sides of rocks on the eastern side of Wanganui Island, off Coromandel, and on a Cystophora species washed up on Mission Bay after a heavy storm. Externally they differed from the specimens recorded from the Otago Harbour in that the average size was slightly less and in that orange as well as pink pigment was present in the test. Internally the only difference lay in the number of stigmata per mesh (six to eleven, Hauraki Gulf; ten to fourteen, Otago Harbour). As in all other points the specimens from both localities are identical, the differences noted above may be considered as due to local variation in the one species.

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Asterocarpa cerea has not been recorded from the North Island previous to this, but its presence or the presence of a near relative would be expected, as A. gregaria (Kesteven), a closely allied form, is recorded from Tasmania.

Distribution: In New Zealand—d'Urville Island (Sluiter), Queen Charlotte Sound, Stewart Island (Mich.), Otago Harbour (Brewin), Hauraki Gulf. (Sluiter has also recorded this species from the Malayan Archipelago, but Michaelsen is very dubious about the correctness of this statement.)

Asterocarpa coerulea (Quoy and Gaimard). (Text Fig. 4, Plate 9, Fig. 10.)

Synonymy and Literature: 1922, Cnemidocarpa coerulea, Michaelsen, Vidensk. Medd. naturh. Foren., bd. 73, p. 445.

Specimens of this species are very common and are found singly or in groups of two or three on the under-surfaces and sides of rocks in all but the muddiest regions of the Hauraki Gulf. The body is characterised by dark blue pigmentation of the dorsal surface and to varying extents of the sides as well. The ventral region is white or a pale buff. Attachment is by part of the ventral region and may involve a portion of one of the sides as well. The body is laterally compressed and elongate parallel to a line joining the siphons. The siphonal openings are situated at the summit of cone-like elevations of the body, and of these the one carrying the branchial aperture is the longer and is placed at the end of the body. The siphonal linings are dark blue in colour. The test is thin, leathery, not markedly wrinkled and practically free from incrustations. The blue pigmentation extends through about two-thirds of the thickness of the test, the inner lining of which is a pearly white. Measurements based on the study of twenty-five specimens are: length, 2·0 to 4·3 cm.; breadth, 1·2 to 2·0 cm.; depth at the branchial siphon, 1·4 to 3·0 cm.; depth at the atrial siphon 1·2 to 2·0 cm.; branchial siphon, 6·4 to 8·0 mm. long, 3·0 to 5·0 mm. wide; atrial siphon, 4·0 to 6·0 mm. long, 2·5 to 4·5 mm. wide; distance between the apertures, 1·4 to 2·7 cm.; thickness of test, 1·5 to 3·0 mm.

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Text Fig. 4.—Asterocarpa coerulea. Dissection showing body opened from the ventral surface, pharynx removed. × 2.

The mantle wall is a deep buff colour and the musculature is well developed, especially in the regions of the siphons. From these regions muscle bands run out over the wall of the mantle and extend

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to the ventral surface. There is also a thin overlying band of circular muscle fibres. On each side of the pharynx there are four longitudinal folds of which that nearest the endostyle is the smallest. Longitudinal vessels number thirty-six to fifty-nine on the right side, thirty-eight to fifty-nine on the left side and the general arrangement is as shown:

Length of specimen. Arrangement of vessels on the right. Total.
2.0 cm. E.3(3)2(8)3(9)2(6)—D.L. 36
3.0 cm. E.4(5)4(9)4(10)4(8)—D.L. 48
3.3 cm. E.4(7)4(11)4(11)4(7)1D.L. 53
3.7 cm. E.4(8)4(11)4(13)4(11)—D.L. 59

Transverse vessels show little difference in size, there being usually three to four small ones between two slightly larger ones. The number of stigmata per mesh between the folds ranges from six to twelve. The stigmata are five to six times as long as they are wide and there are no parastigmatic vessels. Branchial tentacles are simple, filiform, sixty-four to one hundred and eight in number, and of three or four orders of size, sometimes regularly arranged, sometimes not. The shape of the opening of the dorsal tubercle was the same in nine specimens only, where it took the form of a horseshoe with slightly inrolled horns and the aperture directed forwards. Variations on this form included S-shapes, single spirals, and closed loops. The neural gland is a narrow elongate structure lying along the anterior half of the nerve cord. The dorsal lamina is a plain wide membrane. The gut loop is narrow and occupies the posterior half or the posterior third of the left side of the body. The oesophagus is narrow and short and leads to a long, thin-walled stomach, the wall of which is thrown into sixteen to twenty internal longitudinal folds and a typhlosole. There is no pyloric caecum. The edge of the anal aperture is smooth. The atrial velum is narrow and bears one row of fine filiform or knobbed tentacles. The atrial tentacles are not swollen at the base. Small endocarps are scattered over both sides of the mantle wall, there being nineteen to fifty-eight on the right, and thirteen to forty on the left, of which two to seven lie in the gut loop.

Gonads occur in clusters of which five to twenty-one are present on the right side of the body, six to eleven on the left side, and the number on the right side in most cases exceeds that on the left. The number of gonoducts per cluster ranges from one (in a few cases only) to eighteen. In many cases the number of gonads per cluster was calculated from the number of gonoducts counted in transverse sections of gonad clusters (see Plate 9, Fig. 10). In other specimens the short white gonoducts could be counted under a low-power dissecting microscope. In two moderately small specimens (2·0 and 2·2 cm. in length) no trace of gonads could be found. The gonads of this species differ from those of A. cerea in that they are very much shorter and are packed more closely together. Tadpoles were not seen.

Distribution: In New Zealand—Firth of Thames, Bay of Islands (Quoy and Gaimard), Hauraki Gulf, Great Barrier Island (Cottrell), North Cape, Bay of Islands, Slipper Island (Michaelsen).

Remarks: As gonads and gonoducts in this species are very small, no doubt in the past a cluster of gonads has been taken to represent

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one gonad only. Michaelsen (1922), however, noted the small gonoducts in sections of the gonads and remarks (p. 450). “Es mag fraglich sein, ob diese Art der Gattung Polycarpa oder der Gattung Cnemidocarpa zuzuordnen sei.” The genus Asterocarpa Brewin was erected to house the “Cnemidocarpa humilis” group in which many small gonads are joined in clusters and in which the gonoducts open in any direction. It is obvious from the study of the gonads of the species described above that it also does not belong to the genus Cnemidocarpa, but to the genus Asterocarpa.

Genus Cnemidocarpa Huntsman.

Cnemidocarpa bicornuata (Sluiter).

Synonymy and Literature: 1922, Cnemidocarpa bicornuata, Michaelsen, Vidensk. Medd. naturh. Foren., bd. 73, p. 440.

This species was very common in all six localities in the Hauraki Gulf. The majority of specimens collected resembled the Otago Harbour specimens in that the body was a bright orange wtih four bands of magenta pigment in the siphonal linings. A few specimens, however, were almost brown, and still others a bluish orange. The only internal difference to note is that whereas in the Otago specimens the gut loop did not occupy more than one-half of the length of the left side of the body, in a few of the Hauraki Gulf specimens it occupied two-thirds of the length of the body.

Distribution: In New Zealand—French Pass (Sluiter), Firth of Thames (Quoy and Gaimard),? Queen Charlotte Sounds, Stewart Island (Mich.), Otago Harbour (Brewin), Hauraki Gulf. Elsewhere—? Chatham Islands (Sluit.).

Genus Styela Fleming.

Gonads few and large, two or more on each side. Testes separated from ovary, attached to the body wall, negatively stereotrophic, and elongated in a direction perpendicular to the body wall, lobes diverging. Ducts of gonads open near the atrial siphon. Pharynx with four folds on each side. Aperture of the dorsal tubercle curved and its open interval directed forwards and to the left. Anus with distinct lobes. Atrial velum narrow, its inner surface covered with tentacles. Siphonal spinules well developed, truncated or pointed.

Styela plicata (Lesseur). (Text Fig. 5, Plate 9, Figs. 2, 12.)

Synonomy and Literature: 1945, Styela plicata, Van Name, Bull. Amer. Mus. Nat. Hist., vol. 84, p. 295.

This species is very common at low-tide level at Wanganui Island off Coromandel and an occasional specimen was found on Horseshoe Reef off St. Heliers Bay. The test, which is dull white in colour or faintly tinged with pink, is usually thrown into six to eight low, irregular, longitudinal folds (Plate 9, Fig. 2). A few specimens are without folds. The siphonal linings bear four bands of purple pigment. The branchial siphon is terminal and the atrial a little way back on the dorsal side. The ventral side of the body is usually definitely convex and the general body shape is ovoid, due to dorso-ventral elongation. Specimens are attached to shells, rocks, seaweed fronds, etc., and often by root-like elongations of

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the test. Measurements based on the study of twenty-five specimens are: length, 1·0 to 3·3 cm.; breadth, 1·2 to 3·6 cm., depth, 1·5 to 6·4 cm.; distance of apertures, 0·6 to 1·4 cm.; branchial aperture, 0·5 to 0·6 cm. in length, 0·6 cm. in diameter; atrial aperture, 0·4 to 0·5 cm. in length, 0·5 cm. in diameter; thickness of test, 1·0 to 5·3 mms., the greatest thickness being in the region of the ridges. The test is very leathery in nature and its inner lining is light brown in colour.

The mantle wall is white in colour and the musculature is well developed, there being a thin sheet of circular fibres as well as strong longitudinal bands of muscle fibres. Siphonal spinules (Plate 9, Fig. 12) measure 0·01 to 0·017 mm. in length, and 0·010 to 0·015 mm. in width. On either side of the pharynx there are four longitudinal folds, of which that next the endostyle on each side is the smallest, the others being approximately equal in size. Longitudinal vessels number 80 to 134 on the right side and 78 to 128 on the left side of the body—and in all but four specimens the number on the right side slightly exceeded that on the left. The arrangement of the vessels is as shown:—

Length of Specimen. Arrangement of vessels on the right. Total.
1.2 cm. E.4(12)5(15)4(14)4(18)4D.L. 80
2.0 cm. E.5(14)4(19)4(18)5(18)4D.L. 91
3.0 cm. E.5(17)6(18)7(18)8(18)5D.L. 102
3.0 cm. E.5(21)8(24)6(28)6(32)4D.L. 134
3.3 cm. E.5(19)4(24)6(22)5(26)4D.L. 115

Transverse vessels are irregularly arranged, larger vessels lying closer to one another near the dorsal lamina than they do elsewhere. The stigmata are elongate, three or four times as long as they are wide, and are from six to nine in number in the meshes between the folds. Parastigmatic vessels are always present. The branchial tentacles are simple, filiform, and from twenty-six to forty-two in number, and of two or three orders of size not regularly arranged. The opening of the dorsal tubercle is C shaped with the opening directed forwards and the horns strongly inrolled, and the form was very constant, variations being seen in two specimens only. The neural gland is a round, cushion-like structure surrounding the nerve cord. The dorsal lamina is a plain wide membrane. The gut loop is wide and occupies at least two-thirds of the length of the entire width of the left side of the body. The oesophagus is long and narrow; the stomach, which is a brilliant orange in colour, is wide and its internal lining is thrown into twenty-seven to thirty-four longitudinal folds and a typhlosole; the intestine, which is only half the width of the stomach, runs forward for a short distance, bends back almost parallel to the stomach, partly overlies the oesophagus and then runs forward again to a point in front of the atrial aperture and finally takes a short bend backwards. There is a definite constriction behind the anal opening which is wide and has a much-lobed edge. The wall of the intestine carries many endocarp-like structures. The atrial velum is narrow and bears one row of short filiform tentacles which have slightly swollen bases. Endocarps are very small and very numerous and are found on all parts of the mantle wall.

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Text Fig. 5.—Styela plicata. Dissection showing body opened from the ventral surface, pharynx removed. × 1. A and B Gonads showing various stages of development of the testes.

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Fig. 1—Portion of a colony of Okamia thilenii, × ½. Fig. 2—Styela plicata, × ½. Fig. 3—Pyura subuculata, × ½. Fig. 4—Pyura rugata, × ½. Fig. 5—Microcosmus kura, × ½. Fig. 6—Pyura carnea. × ½. Fig. 7—Tadpole of Aplidium (Amaroucium) thomasi, × 50. Fig. 8—Tadpole ot Okamia thilenii, × 50. Fig. 9—Spicules of Cystodytes dellachiaiae, × 50. Fig. 10—Transverse section through gonad cluster of Asterocarpa coerulea, showing gonoduct openings. Fig. 11—Test of Pyura carnea, showing outer and inner test, × 1. Fig. 12—Spinules of Styela plicata, × 300. Fig. 13—Spinules of (a) Pyura subuculata (b) Pyura rugata (c) Pyura carnea (d) Microcosmus kura, × 400.

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The gonads are narrow elongate structures with gonoducts opening near the atrial aperture. Each gonad consists of a narrow central ovary, along each side of which small branched testes are arranged (Text Fig. 5 A, B). On the right side the number of gonads is variable, from four to seven being present. Some of these may be branched. On the left side the usual number is two, one lying in front of the gut and the other lying in the downwardly directed loop of the intestine. In some specimens only one gland is present on the left. Tadpoles of this species were not seen.

Distribution: In New Zealand—Hauraki Gulf. Elsewhere—Philadelphia (Lesseur), Naples (d. Chiage), Tarent (Costa), Adriatic Sea, Tahiti, Guahine, Palau, Raiatea (Heller), Rio de Janiero, Montevideo, Havana, St. Thomas, St. Croix, St. Vincent, Mauritius, Sydney (Traustedt), Yokohama (Traustedt and Weltner), Messina, Porto Rico, Hakodate (Hartmeyer), Bermuda (Van Name).

This is a cosmopolitan species occurring on the coast in warmer parts of the Atlantic, Pacific, and Indian Oceans and in the Mediterranean Sea.

Note: The Hauraki Gulf specimens differ in no way from those described as Styela plicata and the presence of the species in the warm waters of the Gulf would be expected from the geographical range given above.

Family Pyuridae Hartmeyer.

Genus Pyura Molina.

Pyura subuculata (Sluiter). (Text Fig. 6, Plate 9, Figs. 3, 13A.)

Synonomy and Literature: 1900, Cynthia subuculata, Sluiter, Zool. Jahrb., bd. 13, p. 27; 1922, Pyura subuculata, Michaelsen, Vidensk, Medd. naturh. Foren, bd. 73, p. 406; not, 1908, Pyura subuculata var. suteri, Michaelsen, Mitt. naturh. Mus. Hamburg, bd. XXV, p. 259; or, 1946, Pyura subuculata, Brewin, Trans. Roy. Soc. N.Z. Inst., vol. 76, p. 119.

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Note: Both the above references are to P. subuculata var. suteri and at the end of the description of it given by Brewin (1946), the author notes that when a further survey had been made of the genus Pyura in New Zealand, var. suteri might be raised to specific rank. The specimens from the Hauraki Gulf described below agree very closely with the description given by Sluiter (1900). These specimens obviously do not belong to the same species as those described from Otago Harbour as P. subuculata var. suteri, and it is obvious that the latter is not merely a variety of P. subuculata but a separate species and should be known as Pyura suteri Michaelsen.

Specimens are found singly or more often in clumps either of this species alone or of Pyura rugata and Microcosmus kura as well. They are very common under overhanging ledges of rock in the Mission Bay—St. Heliers area and on wharf piles at Rangitoto Island, and are also found in the other areas in the Gulf. The body is a yellowish grey in colour, longer than it is deep, and bears long, tapering siphons which do not contract into the body (Plate 9, Fig. 3). The branchial siphon is always slightly longer than the atrial and though the two may diverge widely in solitary specimens, in specimens growing in clumps they usually run parallel to one another and in whatever direction is most advantageous. The siphon linings bear four bands of bright blue pigment. The test is practically free from incrustations and is faintly wrinkled, with marked longitudinal wrinkles on the outer surfaces of the siphons. Attachment in solitary specimens is usually ventral; in clumped forms it involves portions of the sides as well. The test is leathery and its inner lining is a milky white in colour. Measurements based on the study of nineteen specimens are: length, 1·4 to 3·8 cm.; breadth, 0·8 to 2·5 cm.; depth at the branchial siphon, 1·1 to 3·2 cm.; depth at the atrial siphon, 0·9 to 2·6 cm.; branchial siphon, 0·6 to 1·1 cm. long, 0·2 to 0·3 cm. wide; atrial siphon, 0·4 to 0·9 cm. long, 0·2 cm. wide; distance between the bases of the siphons, 0·3 to 0·6 cm.; distance between the siphonal apertures, 0·8 to 2·7 cm.; thickness of test, 0·3 to 0·8 mm. except at the base, where it may be considerably thicker.

The mantle wall is purple dorsally, yellow ventrally, and the musculature is very well developed, especially in the siphonal regions, from which large bundles run out over the mantle wall but do not quite reach the ventral surface. Siphonal spinules (Plate 9, Fig. 13A) measure 0·010 to 0·014 mm. in length and 0·006 to 0·013 mm. in width. On either side of the pharynx there are seven longitudinal folds, of which that next the endostyle is almost rudimentary. Longitudinal vessels number 71 to 123 on the right side, 78 to 123 on the left side, and the general arrangement is as shown:—

Length of Specimen. Arrangement of vessels on the right Total
1.4 cm. E.—(3)1(10)2(12)2(13)2(13)2(11)1(13)1D.L. 86
2.6 cm. E.—(7)2(13)2(14)4(16)3(16)3(13)3(13)1D.L. 110
3.8 cm. E.—(7)3(14)3(16)3(17)3(19)2(16)3(15)2D.L. 123
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Text Fig. 6—Pyura subuculata. Dissection showing body opened from the ventral surface, pharynx removed. × 1.5.

Between two large transverse vessels there are usually seven smaller of which the middle one is intermediate in size. In the meshes between the folds there are six to eight stigmata, usually six, and these are two, rarely three, times as long as they are wide and invariably crossed by a fine parastigmatic vessel. The branchial tentacles are branched, twenty to thirty-two in number, and are of three orders of size, not regularly arranged. They exhibit three, very rarely four, orders of branching and only the first and second branches are of any length. In eleven specimens the opening of the dorsal tubercle was horseshoe-shaped with inrolled horns, but in the other specimens great variation was shown, lyre-shaped openings occurring and even extremely complex convoluted ones. The neural gland is a narrow structure present on both sides of the nerve cord, but that portion to the right of it is usually confined to the region just posterior to the dorsal tubercle. The dorsal lamina is composed of forty to fifty-eight short curved languets. The gut loop is wide and extends at least two-thirds of the way up the left side of the body, its course resembling that depicted for the species by Sluiter (1900, Plate 5, Fig. 4). There is little difference in the width of oesophagus, stomach, and intestine. The anal opening is wide and the edge slightly lobed. The “liver” is composed of one large bifid lobe situated near the junction of stomach and intestine and several extremely small lobes between the large one and the oesophagus. The small “liver” lobes are in some specimens paired. The atrial velum is narrow and has a straight edge.

There is one long gonad on each side. (In one specimen two very short gonads were present on the right side.) The gonoducts open towards and fairly close to the atrial aperture. The gonad on the right side is divided into twenty-two to thirty-nine hermaphrodite lobes and that on the left side is divided into twenty-one to thirty-five. Tadpoles of this species were not seen.

Distribution: In New Zealand—French Passage, Sumner (Sluiter),? Cape Brett (Michaelsen), Hauraki Gulf.

Remarks: The specimens described above agree very closely with the description of P. subuculata given by Sluiter (1900). No specimens from this locality, had more than seven longitudinal folds. Eight and nine have been recorded for some specimens by Michaelsen.

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Pyura rugata, n.sp. (Text Fig. 7, Plate 9, Figs. 4, 13B.)

Specimens are usually found packed tightly together in massive clumps, either of this species alone or of Pyura subuculata and Microcosmus kura as well. This species is extremely common under overhanging ledges of rock in the Mission Bay—St. Heliers area and fairly common in all other localities as well. The body is orangy pink in colour, longer than it is deep, and the siphons are very short and not at all obvious in preserved specimens. The siphonal linings are a dark red, with four bands of brilliant blue pigment. The test (Plate 9, Fig. 4) is very rough and uneven, with irregular folds, furrows, and ridges, the latter often with rough, angular edges and the general appearance is of a grooved rocky substance. The test may form a hold-fast for coralline algae and small green seaweeds. Attachment is usually by the ventral surface, but, due to clump formation, some or all of the sides may be involved as well. The test is leathery and the internal lining milky white in colour. Measurements based on the study of twenty-five specimens are: length, 2·0 to 3·2 cm.; breadth, 0·9 to 2·5 cm.; depth, 1·2 to 2·7 cm.; distance between the siphonal apertures, 0·7 to 1·7 cm.; thickness of test, 0·3 to 0·5 mm., except at the base, where it may be considerably thicker.

The mantle wall is purple dorsally, orange ventrally, and the musculature is well developed in the siphonal regions, from which bands of fibres run out over the wall of the mantle. They do not quite reach the ventral surface. Siphonal spinules (Plate 9, Fig. 13B) measure 0·009 to 0·013 mm. in length and 0·005 to 0·01 mm. in width. On either side of the pharynx there are seven longitudinal folds, of which that next the endostyle is by far the smallest. Longitudinal vessels number 93 to 134 on the right side, 90 to 131 on the left side, and the arrangement is as shown:—

Length of Specimen. Arrangement of vessels on the right. Total.
2.0 cm. E.—(4)2(10)2(13)2(16)2(15)2(11)2(11)1D.L. 93
2.5 cm. E.—(7)2(13)2(15)2(17)2(17)2(13)1(16)1D.L. 110
2.5 cm. E.—(7)2(13)2(15)3(18)1(20)2(16)1(15)1D.L. 116
3.2 cm. E.—(8)3(16)3(19)2(21)2(20)2(18)1(18)1D.L. 134
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Text Fig. 7—Pyura rugata. Dissection showing body opened from the ventral surface, pharynx removed. × 2.

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Between two large transverse vessels there are usually seven small ones, of which the middle one is intermediate in size. However, this arrangement is not regular, and there may be from five to nine small vessels between two large ones. The number of stigmata per mesh between the longitudinal folds ranges from four to nine, and parastigmatic vessels are invariably present. The branchial tentacles are branched, twenty-one to thirty-nine in number, and are of three orders of size, irregularly arranged. They exhibit three, and occasionally four, orders of branching and, as the first and second branches are long, a feathery appearance is given to them. In fifteen specimens the opening of the dorsal tubercle took the form of a horseshoe with inrolled horns, and variations on this theme were exhibited in the other ten specimens. The neural gland is small and lies on both sides of the nerve cord, though that portion to the right of it usually takes the form of a small rounded cushion just below the dorsal tubercle. The dorsal lamina is composed of from thirty-six to fifty short curved languets, and there is no correlation between the number of languets and the size of the animal. The gut loop is wide and extends along the entire length of the body, and the most anterior portion of the loop lies further forward than the line of the bases of the branchial tentacles. There is little difference in width of stomach, oesophagus and intestine, the intestine being sometimes slightly wider than the other two regions. The anal aperture is wide and the edge is distinctly lobed. The “liver” is composed of one large bifid lobe situated near the junction of stomach and intestine, and usually three small lobes between the large one and the oesophagus. The small lobe nearest the oesophagus is sometimes paired. The atrial velum is narrow and somewhat frilly.

There is one long gonad on each side, each with the gonoduct openings close to the atrial aperture. The gonad on the right side is divided into twenty to forty hermaphrodite lobes, that on the left into twenty-one to forty hermaphrodite lobes. Tadpoles of this species were not seen.

Distribution: Hauraki Gulf.

Remarks: This species is distinguished from P. subuculata (Sluit.) by the external appearance, the greater length of the gut loop, the smaller the size of the siphonal spinules, and the smaller average number of longitudinal vessels between the folds. It is distinguished from P. trita (Sluit), recorded from this locality, by the external appearance, the distance apart of the siphons (between one-third and one-half of the body length, P. rugata; one-fifth of the body, P. trita), the shape of the spinules, and the greater length of the gut loop. It is not identical with any species recorded from Australian or Antarctic waters, and the author proposes to make it a new species under the name P. rugata, the specific name referring to the roughness of the test.

Type Specimen: Otago Museum.

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Pyura cancellata Brewin.

This species has been recorded previously from Otago Harbour and Auckland Harbour and the original description of the species (Brewin, 1946, pp. 121–123) embraces specimens collected from Devonport and St. Heliers Bay. Specimens in the present collection from Rangitoto Island and Coromandel include some larger than those previously recorded (up to 4·5 cm. in length, 3·0 cm in breadth, and 2·3 cm. in depth), and some with a greater number of branchial tentacles (up to 32). In all specimens from the Hauraki Gulf the number of branchial folds is seven.

Distribution: Otago Harbour, Hauraki Gulf.

Pyura carnea n.sp. (Text Fig. 8, Plate 9, Figs. 6, 11, 13C.)

This species is common in the sandy shallows of Little Passage, between Wanganui Island and the Coromandel mainland, and occasional specimens were found in rock pools on Wanganui Island. The body is large, but is usually imbedded in sand so that only the light-pink, mound-like siphonal regions are visible. The test, though leathery, is somewhat spongy in appearance, and in the ventral and lateral regions is in most cases heavily impregnated with sand (Plate 9, Fig. 3). The siphonal linings are a brilliant scarlet in colour and are broken by four narrow bands of blue pigment. Attachment is either by the ventral surface or involves portions of the sides as well. Specimens found in the sandy shallows are attached to large cockle shells, mussel shells and small rocks. Two or three specimens are sometimes found together, but, on the whole, the species is a solitary one. The test is cancellous and can be separated into two layers (Plate 9, Fig. 11)—an outer layer, up to 8 mm. in thickness, usually heavily impregnated with sand and a thin and shiny inner layer, which adheres closely to the mantle wall. The two layers are connected by narrow strands of tissue, and are continuous right to the siphonal apertures. (In Pyura cancellata the outer test forms rampart-like structures around each siphon, which is covered by the softer inner layer alone.) Measurements based on the study of fifteen specimens are: length, 3·0 to 6·5 cm.; breadth, 1·7 to 4·5 cm.; depth at the branchial aperture, 2·5 to 6·3 cm.; depth at the atrial aperture, 2·0 to 5·2 cm.; branchial siphon, 1·0 to 1·7 cm. long, 0·7 to 1·0 cm. wide; atrial siphon, 0·7 to 1·2 cm. long, 0·6 to 0·9 cm. wide; distance between the apertures, 1·5 to 3·0 cm.; thickness of test 0·2 to 1·0 cm., of which the inner layer makes up 0·1 to 0·5 mm., the cancellous region 0·5 to 5·5 mm., and the outer region 0·1 to 8·0 mm.

The mantle wall is vermilion in colour dorsally, pink ventrally, and the musculature is very strongly developed. Siphonal spinules (Plate 9, Fig. 13C) measure 0·015 to 0·02 mm. in length and 0·012 to 0·015 mm. in width. On either side of the pharynx there are eight to ten longitudinal folds, the usual number being nine, and the five folds nearer the dorsal lamina being comparatively large, the others decreasing in size towards the endostyle, that nearest the endostyle being very small and in many cases extending only halfway down the pharynx. Longitudinal vessels number 152 to 226 on the right side and 144 to 221 on the left side, and the general arrangement is as shown:—

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Length of Specimen. Arrangement of vessels on the right. Total.
6 cm. E.1(4)3(15)4(21)5(21)7(27)5(28)5(27)4(24)4(21)—D.L. 226
5.0 cm. E.—(3)2(12)3(22)4(25)4(26)4(28)4(23)4(15)1D.L. 180
4.0 cm. E.—(3)1(12)2(16)3(16)3(18)3(20)3(18)2(14)1(16)1D.L. 152
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Text Fig. 8—Pyura carnea. Dissection showing body opened from the ventral surface, pharynx removed. × 1.25.

There is no regular arrangement of transverse vessels, there being six to thirten small ones between two large ones according to the position in the pharynx. In the meshes between the longitudinal folds there are from four to seven elongate stigmata, two to three times as long as they are broad. Parastigmatic vessels are sometimes present. The branchial tentacles are twenty to thirty-two in number, are of two orders of size, and exhibit three or four orders of branching. In ten of the fifteen specimens examined the opening of the dorsal tubercle was horseshoe-shaped with once- or twice-inrolled horns and with the opening directed forwards. The other specimens had more convoluted openings. The neural gland is a narrow elongate structure. The dorsal lamina is composed of thirty-three to sixty-eight curved languets, and there is no correlation between the number of languets and the size of the body. The gut loop occupies the entire length and almost three-quarters of the width of the left side of the body. There is little difference in width of the various portions of the gut. The edge of the anal aperture is distinctly lobed. The “liver” is composed of a few small and one large bifid or trifid lobe situated near the junction of stomach and intestine. The atrial velum is extremely narrow.

There is one long gonad on each side. The gonoducts open near the atrial aperture. The gonad on the right is divided into ten to seventeen lobes, that on the left into seven to sixteen lobes. In all cases the lobes are irregularly arranged. Tadpoles of this species were not seen.

Distribution: Hauraki Gulf.

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Remarks: As far as can be ascertained from a careful survey of the literature of this genus, this species is not identical with any previously described. Both this species and P. cancellata Brewin have a cancellous test, but P. cancellata can be distinguished easily by the smooth, leathery test and the rampart-like extensions (of the outer test) around each siphon. The two species are found in the same locality at Wanganui Island, though as far as is known at present P. carnea has a more restricted distribution than P. cancellata.

Type Specimen: Otago Museum.

Genus Microcosmus Heller.

Branchial sac has more than four longitudinal folds on each side. Dorsal lamina is a plain untoothed membrane. Tentacles are compound. Intestine forms a narrow loop, on the left side of the body. Gonads on both sides, that on the left partly covering the intestine.

Microcosmus kura n.sp. (Text Fig. 9; Plate 9, Figs. 5, 13 D.)

Specimens of this species were found in all collecting grounds in the Hauraki Gulf; they were most commonly found on the underside of overhanging ledges of rock between tide marks in the Mission Bay-St. Heliers region. They occasionally grow singly, but are more often found in clumps together with Pyura subuculata and Pyura rugata. The body is a dark dull red in colour and irregularly spheroidal in shape (Plate 9, Fig. 5). Older specimens are often almost completely masked by coralline algae, small green seaweeds, hydroids, bryozoans, etc., but in younger specimens without incrustations the test is seen to be leathery and to bear small warty processes, especially in the portions near the siphons. Attachment is by the ventral surface and usually by portions of the sides as well, specimens from the centre of a clump often having the dorsal surface alone free. The test is free from sand grains, but is often inhabited by specimens of the bivalve Modiolacra impacta (Herr.). Measurements based on the study of twenty-five specimens are: length, 1·5 to 4·0 cm.; breadth, 1·3 to 4·8 cm.; depth, 1·0 to 3·2 cm.; distance between the apertures, 0·8 to 2·5 cm.; branchial siphon, 0·4 to 0·7 cm. long, 0·3 to 0·4 cm. wide; atrial siphon, 0·3 to 0·6 cm. long, 0·2 to 0·3 cm. wide; thickness of test, 0·5 to 4·0 mm.

The mantle wall is thin and yellow in colour, and the musculature is well developed, especially in the region of the siphons from which bundles radiate out over the mantle wall. There is also an over-lying layer of circular muscles. Siphonal spinules (Plate 9, Fig. 13 D) measure 0·013 to 0·021 mm. in length and 0·010 to 0·013 mm. in width. On each side of the pharynx there are from seven to nine longitudinal folds. In all cases the fold next the endo-style does not extend for the entire length of the pharynx, and in some cases the second fold from the endostyle is also a short one. The folds are large near the dorsal lamina (the second from it is slightly smaller than those on either side of it) and decrease in size towards the endostyle. Longitudinal folds number 114 to 193 on the right side and 123 to 193 on the left side and the general arrangement is as shown:—

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Length of Specimens. Arrangement of vessels on the right. Total.
3.5cm. E.—(10)1(14)2(19)1(21)2(22)2(22)2(23)2(20)1(20)1D.L. 185
3.0cm. E.—(11)2(17)1(18)1(19)2(20)2(21)2(17)1(21)1D.L. 156
2.5cm. E.—(7)1(17)3(20)3(20)3(22)2(23)2(17)1(24)1D.L. 166
2.5cm. E.1(4)1(8)1(13)1(16)2(17)1(17)1(13)1(15)2D.L. 114
2.0cm. E.—(9)1(15)1(17)2(18)1(20)1(21)1(16)1(21)1D.L. 146
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Text Fig. 9—Microcosmus kura. Dissection showing body opened from the ventral surface, pharynx removed. × 2.6.

Transverse vessels are irregularly arranged, the larger vessels being closer together near the dorsal lamina than they are elsewhere. Six to eight narrow elongate stigmata are present in the meshes between the folds, and fine parastigmatic vessels are usually present. The branchial tentacles are branched, sixteen to twenty in number (usual count sixteen) and three or occasionally four times compound. The shape of the opening of the dorsal tubercle is almost constant, being a horseshoe-shape with twice-inrolled horns and having the open interval directed forwards. The neural gland lies mainly on the right of the nerve cord and is either a small, rounded cushion situated near the anterior end or a narrow elongate structure lying almost along the entire length of the nerve cord. The dorsal lamina is a plain smooth membrane. The gut loop occupies five-sixths or seven-eighths of the length of the left side of the body, and is very narrow, its branches lying close together except at the anterior end where the space between the branches is occupied by a portion of the left gonad. There is little difference in width of the various portions of the gut loop, except that two outgrowths (?“problematical organs”) are usually present on the inner side of the anterior end of the descending loop of the intestine. The anal aperture has a smooth edge. The “liver” opens into the proximal end of the stomach and is composed of one or two finely divided lobes.

The siphonal linings are characterised by the presence of small, scattered, filiform tentacles near the body proper as well as the presence of spinules near the outer edge.

One long gonad is present on each side of the body, that on the left lying partly in the gut loop. Each gonad is composed of two to

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five masses or segments arranged along a curved gonoduct. The gonoducts open near the atrial aperture. In ripe gonads the ovaries are yellow and the testes a brilliant orange. Tadpoles of this species were not seen.

Distribution: Hauraki Gulf.

Remarks: This species is not identical with any so far recorded from New Zealand, Australian, or Antarctic waters. It most closely resembles M. exasperatus Heller, but is distinguished from it by the number of longitudinal vessels between the folds (one to three, average one, M. kura; one to five, average three or four, M. exasperatus) and by the double incurling of the horns of the dorsal tubercle. These two features also serve to distinguish it from M. hirsutus Sluiter recorded from the Chatham Islands, as also does the absence of sand in the outer layers of the test. The specific name refers to the dark red colouring of the test.

Type Specimen: Otago Museum.

Tadpoles.

All the species recorded in this region were collected over the summer months and tadpoles of many were not seen. In January, 1946, tadpoles were present in the mantle cavities of the following species: Aplidium (Amaroucium) thomasi, Aplidium (Amaroucium) phortax, Botryllus schlosseri, and Okamia thilenii.

Commensals.

The bivalve Modiolacra impacta (Herr.) was present in the test of Microcosmus kura and occasionally in the test of Pyura rugata. Amphipods were present in the common cloacal cavities of the majority of the compound forms and in the pharynx of half the specimens of Pyura carnea, and copepods of the family Notodelphidae were found in the branchial sacs of Styela plicata, Pyura subuculata, Pyura rugata, and Pyura carnea.

References.

These include all those given in the previous paper of the series, pp. 130, 131, as well as the following:—

Brewin, B. I., 1946. Ascidians in the Vicinity of the Portobello Marine Biological Station, Otago Harbour. Trans. Roy. Soc. N.Z., vol. 76, pp. 87–131.

Michaelsen, W., 1904. Revision der compositen Styeliden oder Polyzoinen. Jahrb. Wiss. Anst., Hamburg, vol. 21, pp. 1–124.

Van Name, W. G., 1945. The North and South American Ascidians. Bull. Amer. Mus. Nat. Hist., vol. 84, pp. 1–476.