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.
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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.