Sabellastarte australiensis (Haswell, 1884)

Knight-Jones, Phyllis & Mackie, Andrew S. Y., 2003, A revision of Sabellastarte (Polychaeta: Sabellidae), Journal of Natural History 37 (19), pp. 2269-2301 : 2285-2287

Sabellastarte australiensis (Haswell, 1884)

(figure 6)

Spirographis australiensis Haswell, 1884 . Sydney, New South Wales. Type not registered, but material (AMS G11203, G2045, 20625) labelled Spirographis australiensis or ‘ australis’, dated 1898 and later altered to S. indica , could well be some of Haswell’s original material.

Sabella fusca Grube : McIntosh, 1885 (NHML 85.12.11388), Sydney.

Sabellastarte japonica Marenzeller : Benham, 1916 (AMS E4639), Babel Is., Bass Strait.

Additional material. Sydney, AMS G11204 (as Sabellastarte ), 4280 (as S. indica ), W 4408 (as S. sanctijosephi ); Flinders Pier, Victoria, AMS 14129 (as S. indica ) and Arrawarra (P.K.J.) about 300 miles N of Sydney.

The following description is mainly based on the largest of six specimens from Arrawara, with data in parentheses from the largest specimen from Flinders Pier.

Description. Body without crown 82 (145) mm long, 12 (14) mm wide with about 165 (150) segments, of which seven to eight (eight) are thoracic (figure 6A); crown 32 (50) mm long with short, ventrally involuting base of up to three (two) spirals (figure 6B); radioles about 150 (190) on each side, many interdigitating giving appearance of two rows (figure 6C), rounded or subquadrangular in cross-section (figure 6E, F, G), interradiolar web vestigial (length less than length of a typical thoracic ventral shield), tips beyond pinnules short and blunt (figure 6H); dorsal lips about 15 (7) mm long, grooved, with midrib support and webbed to base of adjacent radiole (no pinnular support); thorax wider than long, all thoracic tori indenting sides of ventral shields; last thoracic torus nearly half length of first; first segment about as long as following thoracic segments (viewed from side and discounting height of collar); dorsal collar low, with transverse margins above shallow collar pockets each side of midline (figure 6B), lateral margins sharply extended anteriorly to well above junction of crown and thorax (figure 6C); ventral collar forming two distinct, subtriangular lappets (figure 6D); anterior margin of first ventral shield with medial embayment and subtransverse margins each side; tube, chaetae and uncini similar to those of S. spectabilis ; thoracic fascicle 7 with 54 chaetae, abdominal fascicle 24 with 65 chaetae; intersegmental eyes minute.

Mature specimens dark liver-brown on crown base, collar and rest of thorax (same areas as S. spectabilis and S. magnifica ), but dorsal abdomen also dark brown and ventral shields paler (fawn). The general body surface lacks irregular dark flecks. The crowns of the Arrawara material are pale pink or orange without radiolar pigment bands, with or without a brown line along the outside of each rachis. These darker lines were mentioned by Haswell, who also noted that the ‘pinnules were almost white with a faint tinge of green’, probably the blood pigment chlorocruorin. The crown of the Flinders Pier material is banded with brown.

Habitat. Haswell (1884) noted that his material occurred at low water on the shores of Port Jackson (=Sydney Harbour). The Arrawarra material was found protruding from rock crevices in a small, but deep pool (exposed at low water) on the Marine Station promontory.

Variation. The smallest specimen examined from Arrawara (crown 18 mm long, rest of body 42.6×5.7) is somewhat paler in colour, but nevertheless has a darkish brown dorsal abdomen like those of mature specimens. The crown is already interdigitating, but each side of the base forms no more than a circle. Most specimens have irregular thoracic segments (e.g. a missing parapodium on one side or the other), evidence of regeneration.

Remarks and distribution. Haswell noted that a New Zealand species Sabella grandis Baird (1865, a valid species as Sabella grandis Cuvier was not published, see above) may be identical with this species, but Baird’s material (NHML 1852.8.16.7) is very different and a species of Pseudobranchiomma .

Sabellastarte australiensis resembles S. fallax Quatrefages in being a large species with a short dorsal collar and short crown, but the crown of S. fallax is without radiolar interdigitation and does not spiral. Sabellastarte magnifica , S. spectabilis and S. pectoralis differ from S. australiensis in having a longer crown without spirals and, apart from S. pectoralis , have longer dorsal collar lappets. Sabellastarte pectoralis also differs in having paired ridges towards the tip of the radioles and in having a flecked surface.

Sabellastarte australiensis seems to occur only in Australia, from Victoria to New South Wales.