Of Moreton Bay, Queensland Patricia KOTT Honorary Associate, Queensland Museum, PO Box 3300, South Brisbane, Qld 4101

VOLUME 54 Part 3 MEMOIRS OF THE QUEENSLAND MUSEUM BRISBANE 30 DECEMBER 2010 © Queensland Museum PO Box 3300, South Brisbane 4101, Australia Phone 06 7 3840 7555 Fax 06 7 3846 1226 Email [email protected] Website www.qm.qld.gov.au National Library of Australia card number ISSN 0079-8835 NOTE Papers published in this volume and in all previous volumes of the Memoirs of the Queensland Museum may be reproduced for scientific research, individual study or other educational purposes. Properly acknowledged quotations may be made but queries regarding the republication of any papers should be addressed to the Editor in Chief. Copies of the journal can be purchased from the Queensland Museum Shop. A Guide to Authors is displayed at the Queensland Museum web site www.qm.qld.gov.au/organisation/publications/memoirs/guidetoauthors.pdf A Queensland Government Project Typeset at the Queensland Museum A review of the Ascidiacea (Tunicata) of Moreton Bay, Queensland Patricia KOTT Honorary Associate, Queensland Museum, PO Box 3300, South Brisbane, Qld 4101. Email: [email protected] Citation: Kott, P. 2010 12 30. A review of the Ascidiacea (Tunicata) of Moreton Bay, Queensland. In, Davie, P.J.F. & Phillips, J.A. (Eds), Proceedings of the Thirteenth International Marine Biological Workshop, The Marine Fauna and Flora of Moreton Bay, Queensland. Memoirs of the Queensland Museum – Nature 54(3): 287-297. Brisbane. ISSN 0079-8835. ABSTRACT A review of the 95 species of the Ascidiacea recorded from Moreton Bay, Queensland shows that solitary species of Phlebobranchia and Stolidobranchia (53 species) dominate the fauna, there being few colonial species of either suborder and only 30 species of the almost exclusively colonial Aplousobranchia, eight being species of the Didemnidae recorded only from locations immediately to the north of the Bay rather than in its semi-enclosed waters. However, it is emphasised that much of the sampling within the Bay has been from muddy and sandy rather than hard substrates and this may have caused a bias in the material taken. An assessment of the geographic range of each of the species shows Moreton Bay to be the southern and northern limit for a number of species with, respectively, tropical and temperate affinities. This supports other studies indicating that Moreton Bay is at the centre of the eastern Australian tropical to temperate faunal transition zone. q Ascidiacea, Tunicata, Aplousobranchia, Phlebobranchia, Stolidobranchia, intertidal, subtidal, reef, taxonomy, checklist, biogeography. This study is based on the 4000 specimen lots of could smother small colonial zooids with exposed the Ascidiacea from Moreton Bay, and regions branchial apertures opening on the upper surface immediately to the north, registered in the of the colony. collections of the Queensland Museum. Some hard surfaces are provided by several ship- TAXONOMIC NOTES wrecks on Moreton I. and off the Gold Coast, Ninety-five species of the Class Ascidiacea reefs on the eastern side of the islands facing the are represented in the collections from Moreton Pacific Ocean, and rocky headlands such as Bay, Caloundra and Flinders Reef (see Table 1). Kings Beach (in the northern part of the Bay). Their taxonomy is discussed in Kott (1972–2006). Only a few locations are described as ‘rocky Colonial species are known in the three sub - reef’ or ‘Acropora reef’. However most ascidians divisions (suborders) of the Ascidiacea. In one, were taken from habitats where sediments such Aplouso branchia, the colonial habit is almost as sand, mud and shell grit, and various mixtures universal, solitary species occurring only in rare of these, prevail. This may reflect a collecting and exceptional cases. In the Stolidobranchia bias that favours the large solitary species that about half of the higher level taxa (families and dominate this species list. Many of the records subfamilies) are colonial. In the Phlebobranchia, are from dredge, grab and trawl collecting in most species are large and solitary, only a couple connection with the late Prof. W. Stephen son’s of families being colonial. Colonies are formed surveys of the benthic fauna (e.g. Stephenson et by vegetative replication (budding or fission) al. 1970, 1974, 1976). Colonial species that closely that interrupts the growth of individuals and adhere to hard, clean substrates are not well results in progressively smaller, more numerous, sampled by these collecting methods; and usually and more simplified zooids united by test. The settle on upper surfaces where fine sedi ments parallel evolution of the colonial habit in each Memoirs of the Queensland Museum — Nature 2010 54(3) www.qm.qld.gov.au 287 Kott suborder reflects a striking degree of conver gence, PHLEBOBRANCHIA all colonial taxa tending toward larger and more Thirteen of the species of Phlebobranchia are integrated colonial systems, and simpli fied body listed, characterised by their flat branchial sacs organs, especially reductions in the size of the and single male and female gonads associated ovary relative to the testis. This last condition, with the large gut loop embedded in the pallial possibly associated with internal fertilisatio n and body wall to the left of the branchial sac. Eleven the liberation of embryos (brooded in the adult species are large, soltary individuals with a firm, colony as free-swimming tailed larvae) is a strategy characteristically translucent gelatinous test; likely to contribute to population maintenance. although in this collection there is an unusually It is one of the most significant aspects of the large number of species (Adagnesia opaca, Agnezia colonial habit in all suborders. glaciata. Microgastra granosa and Ascidia scaevola) On the other hand, irrespective of suborder, with a thin test brittle with embedded sand that most solitary species are externally ferti lised and resembles the test of some Polycarpa and Molgula the adult body organs (branchial sac, gut and species (Stolido branchia) and suggests that habitat liver diverticulae and especially the gonads) tend require ments may be the principal environmen- to be larger and more elaborate, presu mably to tal pressure selecting some components of the accommodate the needs of the large, solitary, exter - ascidian fauna of Moreton Bay. These species nally fertilised individuals. How ever, although appear to be adapted for a benthic habitat on the colonial taxa present in Moreton Bay are in the sea floor, and the body muscles are modi- the minority, they can be placed in the same geo - fied to operate the closure of the apertures, rather graphic groups (based on their known range) as than the general contraction of the body the solitary taxa (see below). There are ecological Two species are colonial (family Perophoridae), reasons such as substrate and the range of habi - the small, replicated zooids joined by ectoder- tats available that can explain the dominance of mal stolons from which they develop, as they large solitary species in these waters, however are added to the growing colony. Embryos gener - there are no obvious biological reasons. Apart ated from the ovaries in the gut loop in the left from the massive colonies of the stolidobranch side of the atrial cavity are released into a brood Polyandrocarpa colemani, the colonial species most pouch on the right. These are eventually libera - conspicuous in Moreton Bay are similar thin, ted from the colony as free-swimming tailed sheet-like investing colonies irrespective of the larvae. This viviparous habit is characteristic of suborders to which they belong, viz, Polyzoinae colonial ascidians in contrast to the oviparous and Botryllinae (Stolidobranchia) and Didemnidae externally fertilised habit of solitary species. (Aplouso branchia). The charac teristics of the sub- STOLIDOBRANCHIA orders are summarised below and a Key to the Stolidobranch species have the gut loop bent families represented in Moreton Bay is given. up into the pallial wall on either the right or the APLOUSOBRANCHIA left side of the pharynx. One or more gonads are Twenty-nine species represent this exclusively embedded in the pallial wall on both sides of the colonial group. They have relatively small zooids body. Branchial sacs are folded thus increasing with small branchial sacs, the gut loop in an the filtering area — a factor that is especially abdomen behind the pharynx and a gonad of important in large solitary individuals. each sex either enclosed in the gut loop or Species usually have rough, leathery test, stretched out behind it. Although they tend to although in some, the body wall is closely ad - have colony forms similar to some colonial Stolido - herent to the thin test which has sand embed - branchia, replication is even more prolific, ded, making it rigid, brittle and non-contractile. usually resulting from segmentation of the Body muscles in these species tend to be adap - zooids, the replicates developing from endoder- ted to the opening and closing of apertures rather mal tissue in each segment. Only Clavelinidae than the contraction of the whole body wall. are exceptional, their replicates being gener ated These adaptations are similar in a number of from mesodermal tissue in the terminal ampul - phlebobranch species, suggest ing that these com - lae of the test vessels. ponents of the ascidian fauna may be responding 288 Memoirs of the Queensland Museum — Nature 2010 54(3) Ascidiacea of Moreton Bay to the same environmental pressures. The majority 8. Gonads on one side of body; branchial sac (41) of Stolidobranchia reported from Moreton without folds . .....(Phlebobranchia) 9 Bay are solitary. — Gonads on both sides of body; branchial sac Colonial species of the Stolidobranchia (Styeli- folded . ........(Stolidobranchia) 12 dae) bud prolifically from ectodermal tissue of 9. Gonads enclosed in gut loop. ......10 the pallial body wall or from vessels in the test — Gonads not enclosed in gut loop. ...... in which they are embedded. These replicated ..................Plurellidae zooids are small and simplified, the branchial 10.

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