https://doi.org/10.24199/j.mmv.1976.37.06 30 June 1976 THE ASCIDIAN FAUNA OF WESTERN PORT, VICTORIA, AND A COMPARISON WITH THAT OF PORT PHILLIP BAY By Patricia Kott Queensland Museum Abstract The taxonomy of 59 species of ascidians from Western Port and Port Phillip Bay, Victoria, is discussed. The ascidian fauna of Western Port is markedly more diverse than that of Port Phillip Bay. The biogeographical affinities of the species are assessed and the implications of the differences in species composition in the two areas are investigated. Introduction each of these sheltered embayments are there- fore of special zoogeographic and ecological A previous collection of ascidians from Port interest in view of the likelihood of isolation Phillip Bay has been reported on by Millar of endemic and relict species. (1966) but prior to that no major work has There are 59 species in the collections, of been devoted to the ascidian fauna of Victoria. which one, Ciona intestinalis is probably in- The greater part of the present material has troduced. These species, are set out in Tables been collected for the National Museum of 1 and 2 together with others previously re- Victoria by the Underwater Research Group corded from Port Phillip Bay and Western (Western Port Survey). Additional records of Port but not represented in these collection. species occurring in Western Port, available Aspects concerning the biogeography and habi- from independent collections made by Mrs. J. tat of the ascidian fauna of these locations is Watson and Mr. K. Duke on parts of the discussed below. adjacent Victorian coast, from Mallaooota near the Victorian—N.S.W. border to Portland Species List Harbour and Cape Nelson, have been included in the present work. APLOUSOBRANCH1A These collections are of particular interest CIONIDAE in relation to the fauna of St. Vincent Gulf Ciona intestinalis where large collections have recently been CLAVELINIDAE made and reported on (see Kott, 1972 a, b). Clavelininae n. sp. Information on the better known fauna of Port Oxycorynia pseudobaudinensis cylindrica Jackson and Moreton Bay to the north is also Podoclavella available. (Kott, 1952; 1957; 1962; 1963; Holozoinae Atapozoa mirabilis 1972 c, d). These locations are all large em- pedunculata bayments in the Australian coastline, essen- Sycozoa cerebriformis tially marine, and tidal. They are, however, Sycozoa POLYCITORIDAE all protected from the direct swell of the pyriforme southern ocean, and receive some fresh-water Eudistoma runoff from the water-ways emptying into them POLYCLINIDAE EUHERDMAN1INAE and from the shores surrounding them. Pseudodistoma cereum The distribution of this sessile ascidian fauna Dumus arenijerus is limited by the short free-swimming life of POLYCLININAE the pelagic larvae. Consequently species adap- Polyclinum marsupiale ted to protected localities could be restricted Aplidium depressum in their distribution by lack of suitable sites Aplidium lobatum for settlement on the open coast. The phylo- Aplidium triggiensis genetic relationships of the ascidian fauna of 53 54 PATRICIA KOTT Synoicum hypurgon Microcosmus australis Synoicum sp.? Microcosmus nichollsi Sidneyoides tamaramae Microcosmus helleri DIDEMNJDAE Microcosmus stolonifera Trididemnum cerebrijorme Microcosmus squamiger Trididemnum cyclops MOLGULIDAE Didemnum candidum Molgula mollis Didemnum spongioides Molgula sabulosa Didemnum skeati SYSTEMATICS Didemnum moseleyi Ciona intestinalis Linnaeus Didemnum patulum Ciona intestinalis Linneaus, 1767, p. 1087. Kott, 1952, Didemnum turritum p. 319 for synonymy and description. Didemnum augusti New Records: Port Phillip Bay (Oil wharf, Didemnum roberti Yarra River; artificial reef). Didemnum lambitum Distribution: See Kott, 1952. Lissoclinum fragile Remarks: Kott (1969) has suggested that the Lissoclinum ostrearium cosmopolitan occurrence of this species, which Diplosoma translucida is recorded from harbours and wharf piles in Diplosma rayneri all regions outside the Antartic, is due to its Polysyrwraton orbiculum transport on ships' hulls. Polysyncraton victoriensis n. sp. Oxycotynia pseudobaudiensis sp. nov. PHLEBOBRANCHIA ASCIDIIDAE (Fig. 1) Clavelina baudinensis Kott, 87 (part: speci- ASCIDIINAE 1957, p. men with larger larvae) ?Millar, 1966, p. 363. Kott, Phallusia depressiuscula 1972a, p. 4. Ascidia Sydneyensis Type Locality: Laverton Bay (Victoria) Ascidia gemmata Holotype: Australian Museum A.M. Y1113. STOLIDOBRANCHIA Paratypes: W. Aust. Rottnest I., AM Y1112 STYELIDAE (Kott 1957). S. Aust.: Carickalinga Head, BOTRYLLINAE South Australian Museum S.A.M. E876; Botrylloides leachii Rapid Head S.A.M. E 877 (Kott 1972a). Botrylloides nigrum Vict. (Western Port): Balnarring Beach, A.M. POLYZOINAE Y1122 (Kott 1957); Crawfish Rock; Flinders Symplegma viride Jetty, N.M.V. (new records). Amphicarpa diptycha Description: The colonies are 5-8 cm high Polyandrocarpa lapidosa and the wider terminal part of the head is 2 STYEL1NAE cm in diameter terminally. In the upper half Polycarpa thelypanes of the colonies the test is delicate and some- Cnemidocarpa etheridgii times glassy and transparent and encloses the PYURIDAE body of the zooids which are never separate. Pyura australis On the upper surface the test forms only Pyura cataphracta slight rounded protruberances over the anter- Pyura irregularis ior aspect of the zooids. In some colonies the Pyura albanyensis zooid bearing upper part may be subdivided Pyura lepidoderma into several lobes. The slightly bulbous stalk Pyura scores biensis narrows toward the base and is only slightly Pyura stolonifera praeputialis longer than half the height of the colony. The Halocynthia hispida test of the stalk is firm and opaque and some- Herdmania momus times slightly leathery externally. ASCIDIAN FAUNA OF WESTERN PORT 55 Zooids are from six to eight mm. In pre- species C. baudinensis Kott, 1952. Most of the servative they are a bluish colour and have previously described specimens of that species dark accumulations of pigment in the mid line excepting only those recorded by Millar (1966) dorsal and ventral to the branchial have been re-examined. siphon. There are 12 to 20 longitudinal Clavelina baudinensis from Cape Vlamingh, muscles on the thorax and, depending on their Rottnest Island and from Laverton Bay have degree of coalescence, they may vary in num- small larvae (0-5 mm) in which the simple ber on each side of the body. From six to eight papillae without accessory suckers are sup- of the most ventral bands are aligned at a ported around the anterior end of the body slight angle with the longitudinal axis of the which is not separated into a frontal plate. body and break up into branches over the In these larvae the tail completely circles the anterior half of the endostyle. Of the remain- body. These colonies can. be distinguished ing longitudinal muscle bands more than half from the present species mainly by their long- extend into the branchial siphon and the others er, narrow and cylindrical stalk. The anterior into the atrial siphon. Posteriorly the bands extremity of the zooids project more from the extend along both sides of the abdomen. There anterior surface of the test than in O. pseudo- are from 16 to 20 rows each of 20 to 30 baudinensis. Zooids of C. baudinensis exam- rectangular stigmata with a well developed ined have a maximum of 12 longitudinal thor- transverse membrane between each row. In acic muscles of which only a single band the mid dorsal line this membrane is expanded subdivides across the mid-line, ventral to the into the usual triangular, pointed languets. branchial aperture. In C. baudinensis there The gut forms a simple and fairly short loop appears to be a more restricted range in the (seldom longer than the thorax), enclosing stage of development of embryos in the peri- the gonads. The anus opens at the base of the branchial cavity. Although some eggs are peribranchial cavity and is bordered with min- present in the oviduct they do not appear to ute rounded lobes. The stomach has no true start their development there as in the genus structural folds. Tt is present in the middle to Pycnodavella. In its colony and zooid form, posterior one third of the abdomen. There is C. baudinensis does appear to be closely re- no prestomach. lated to O. pseudobaudinensis; however, its Larvae are present only in the colonies from larvae and the degree to which eggs are ap- Rottnest Island and Laverton Bay (see Kott, parently fertilised in the atrial cavity suggest 1957: larger larvae). They are large, 0-9 mm that it is a more primitive species. In O. long with the tail wound threequarters of the pseudobaudinensis the oblique arrange- ment of the ventral way around the body. Triradiate papillae are thoracic muscles effects a depression of the anterior part supported around a flattened frontal plate. of the thorax and draws it towards the postero-dorsal part The adhesive cells rise in a cone from tho of the thorax. The atrial aperture simultan- centre of a depressed area which forms a eously becomes terminal as in P. cylindrica, fairly primitive papillary sucker or cup. The thus facilitating the liberation of large larvae. embryos appear to start their development in In C. baudinensis larvae are smaller and more the proximal part of the oviduct and complete easily liberated through the normally oriented it in the right side of the peribranchial cavity aperture; and the more parallel arrangement of where they demonstrate a wide range in stages longitudinal thoracic muscles does not apocar of development. The most mature embryos to affect the relative position of the siphons. are present anteriorly. In neither of these species is the whole ventral Remarks: The separate identity of the present surface withdrawn toward the postero-dorsal species was first suggested by the different part of the thorax as is the case in Podocla- larvae present in colonies from Rottnest and vella cylindrica where there is a special brood Victoria which had all been assigned to the pouch ensuring the retention of embryos. 56 PATRICIA KOTT Podoclavella cylindrica (Quoy and Gaimard) the Antarctic (see Kott, 1969).