Ascidians of New Zealand
Part XII—Ascidians of the Hauraki Gulf, Part III
[Received by Editor, August 21. 1957.]
The number of ascidians species recorded from the Hauraki Gulf is raised from 38 to 44. Amaroucium cotrelli Brewin, Amaroucium thomsoni Brewin, Sigillinaria arenosa Brewin, and Leptoclinides diemenensis Michaelsen are recorded from the locality for the first time and two new species, Amaroucium powelli and Lissoclinum notti are described, together with Leptoclinides diemenensis, not previously recorded in this series.
The present survey is based on the study of ascidians dredged from 25 to 45 fathoms in the Hauraki Gulf, others washed up on the Takapuna Beach and Mission Bay in the drift after storms, and some collected on intertidal rocks at Rangitoto, Takapuna and Leigh.
The species present in dredgings were Amaroucium scabellum (45 fathoms), Amaroucium powelli (25, 45 fathoms), Synoicum haurakiensis (25, 45 fathoms), Didemnum candidum (25, 45 fathoms), Cystodytes dellachiaiae (6–10 fathoms), Polycitor (Eudistoma) circumvallatum (8 fathoms). Corella eumyota (8 fathoms), Okamia thilenii (8 fathoms), Cnemidocarpa bicornuata (6–10 fathoms), Asterocarpa cerea (25 fathoms), Styela plicata (25 fathoms).
Extensions to the known geographical distribution in the Hauraki Gulf region are recorded for Sigillinaria novae-zealandiae, Didemnum tuberatum, Okamia thilenii, Alloeocarpa minuta, Pyura carnea, Molgula mortenseni (all now recorded from the Waitemata Harbour proper) and Amaroucium thomasi (collected on coastal rocks at Leigh).
The following six ascidians are recorded from the Hauraki Gulf for the first time:
|Amaroucium cotrelli Brewin||Leigh|
|Amaroucium thomsoni Brewin||Mission Bay, Takapuna|
|Amaroucium powelli n. sp.||Off Tiri Tiri (25 fathoms)|
|Off Little Barrier (45 fathoms)|
|Sigillinaria arenosa Brewin||Leigh|
|Leptoclinides diemenensis Michaelsen||Mission Bay|
|Lissoclinum notti, n. sp.||Rangitoto|
Description of Species
Amaroucium powelli, n.sp. (Fig. 1, A1, A2, A3, A4).
Colonies deep brown in colour, small and club-shaped (Fig. 1, A3) or cushion-shaped. lobed and up to 7 cm in the maximum diameter (Fig. 1, A1), attached to shells of Dosinia lambata (Gould) and/or small stones. Test leathery, with numerous small irregularly-shaped test cells and small rounded pigment cells. Zooids arranged in irregular double rows running down the lobes. Common cloacal apertures 0.1 mm to 0.2 mm in diameter, usually confined to the distal half of the lobes.
Zooids (Fig. 1, A2) dark brown, up to 9 mm long, 0.3 mm wide in the pharyngeal region, which has 10 or more fine longitudinal muscle bands, 11 transverse Post-abdomen approximately ⅔ zooid length, musculature tending to lateral concentration Branchial apertures 6-lobed, atrial with one long stout lappet.
Pharynx with 16 tentacles of 3 orders of size regularly aranged; dorsal lamina of 11 curved languets; on each side 12 rows of 10 stigmata, up to 4 times as long as wide. No parastigmatic vessels. Oesophagus narrow; stomach halfway down abdominal region, short with 4 longitudinal folds; intestine widening after the bend; anal aperture bi-lobed.
Thirty or more testis blocks in a double row in the posterior ½ or ⅓ of the post-abdomen. Ovary immediately anterior to testis. Tadpoles (Fig. 1, A4) up to 1.1 mm long, 0.25 mm wide in the head region present in the mantle cavities of specimens collected December, 1950.
Distribution. Hauraki Gulf (off Tiri Tiri, 25 fathoms, December, 1950; between Little Barrier Island and Great Barrier Island, 45 fathoms, May, 1948).
Type Specimen. In the Otago Museum.
Note. This species is clearly separated by colony form as well as by various internal features from the other Amaroucium spp. with 4–6 stomach folds recorded from New Zealand waters.
Leptoclinides diemenensis Michaelsen (Fig. 1, B1, B2, B3).
Lit: 1924. Leptoclinides diemenensis, Michaelsen, Vidensk Medd. naturh. Foren, 77, pp. 331–336, Fig. 12.
Colonies in the form of encrusting mats (or cushions, Michaelsen), irregular in outline, up to 4 mm in height above the substratum (2 to 9 mm, Michaelsen). Present specimens adhering to the seaweed Carpophyllum maschalocarpum. Colouring bright orange (light reddish grey, Michaelsen). Branchial apertures round, 0.5 to 1.5 mm apart. Common cloacal apertures round, 1 mm in diameter, up to 8 mm apart (not seen with certainty, Michaelsen). Spicules (Fig. 1, B2) colourless up to 35μ in diameter (up to 48μ, Michaelsen) stellate with 8 to 10 points in optical section. Test rather cartilagenous, semi-transparent (upper 0.2 mm colourless with 3 or 5 layers of thin-walled bladder cells and numerous small test cells, 0.2 mm immediately below spiculated and lightly pigmented; remainder with numerous small test cells and pigment cells and an occasional spicule or bladder cell).
Zooids (Fig. 1, B1) up to 1.5 mm long (2.5 mm, Michaelsen) 0.5 mm wide in the pharyngeal region “Seitenorgane” in the form of backwardly directed sacs with narrow opening to the pharyngeal region. Rectal-oesophageal region about ½ the length of the pharyngeal. Abdomen usually a direct continuation of the pharyngeal region but occasionally at right angles to it. Two or three finger-like outgrowths project from the left side of the abdomen, some with bladder-like terminations. Branchial siphon long, atrial long, backwardly-directed and with a diaphragm.
Pharynx with 16 tentacles of two orders of size regularly arranged; dorsal lamina of three long languets curving backwards opposite the second stigmata from the mid-dorsal line; on each side 4 rows of 12 stigmata up to 6 times as long as wide. Oesophagus narrow; stomach short; intestine widening somewhat after the bend, anus bi-lobed.
Testis a rosette of 4 or 5 lobes. Vas deferens with 6 or 7 spiral coils. Ovary in intestinal loop.
The largest tadpole measured from specimens collected December. 1950, was 2.3 mm long and 0.6 mm wide in the head region (Fig. 1, B3)
Distribution. Cape Maria Van Diemen, 50 fathoms, 5/1/1915; Hauraki Gulf (Mission Bay, after storm, 28/12/50).
Note. Though the present specimens are not quite so large as those recorded by Michaelsen, in all respects except colour (which well may be variable in this species) they resemble very closely those described by Michaelsen.
Genus Lissoclinum Verrill, 1871.
Colony incrusting, with stellate calciferous spicules in test Zooids with four rows of stigmata. Atrial aperture with a languet. Testis divided into two or more lobes, sperm duct not spirally coiled. Common cloacal cavities usually greatly developed.
Lissoclinum notti, n.sp. (Fig. 1, C1, C2, C3).
Colonies violet or brown, forming thin incrustations up to 2 mm thick, found on coastal rocks. Zooids not in marked systems. Common cloacal apertures circular, 1 mm in diameter, up to 5 mm apart. Test showing definite layering—a typical section from surface to base being 0.05 mm clear and without spicules, 0.15 mm with pigment cells and spicules, 0.6 mm without spicules, 1.2 mm densely spiculated Bladder cells not discernible in the surface layer. Large cloacal cavities at the zooid level Spicules (Fig. 1, C2) 10μ to 40μ in diameter, rays usually ridged, broad, with irregular blunt ends.
Zooids (Fig. 1, C1) up to 1 mm long and 0.4 mm wide in the pharyngeal region, which is up to 7 mm long.
Rectal-oesophageal region short, abdomen usually lying at right angles to the pharynx Branchial siphon with six short lobes, atrial aperture wide, surmounted by a short atrial languet. Several finger-like outgrowths (most of which have terminal dilations) project from the left side of the abdomen.
Pharynx with 16 to 20 tentacles of three orders of size; dorsal lamina of 3 curved languets curving back opposite the second stigmata from the mid-dorsal line; on each side four rows of 8 or 9 stigmata up to 4 times as long as wide. Oesophagus short, stomach short, round, and smooth-walled; no marked intestinal constrictions Anus bi-lobed.
Testis lobe single but showing faint indications of division into two portions Sperm duct without spiral coiling. Ovary in a small sac-like diverticulum projecting backwards from the abdominal region. Many embryos at various stages of development present below the zooids in specimens collected in January, 1951. The largest tadpole measured was 1.2 mm long and 0.3 mm wide in the head region (Fig. 1, C3).
Distribution. Hauraki Gulf (Rangitoto Island, coastal rocks, January 10, 1951).
Type Specimen. In the Otago Museum.
Note. This is the first Lissoclinum species recorded from New Zealand waters.
The author is indebted to Dr. A. W. B. Powell, Dr. J. E. Morton, and members of the Auckland University College Field Club for dredged material and to the Marine Department for transport and for material collected by the research launch “Ikatere”.