Family ADEONIDAE Busk, 1884

Museums

Regional Maps

• Adeonellidae Gregory, 1893.

 

Introduction

The family Adeonidae was originally introduced by Busk (1884), as Adeonae, and has been discussed by Harmer (1957), by Cook (1973), and most recently by Gordon (1989). At least five genera have their major representatives in Australian waters.

The family is characterised by large colonies, which are usually erect. The autozooids have umbonuloid frontal shields surrounded by large, areolate septular pores, pierced by a central spiramen or spiramina. The primary orifice is not easily seen, even at the growing edge, as the thick secondary calcification obscures it. Examination of the frontal wall interior shows the shape of the primary orifice, as well as the centrally located spiraminal pore (or pores), and the ring scar where the umbonuloid frontal membrane is attached (Lidgard 1996). The secondary orifice may be round or transversely ellipsoidal. Embryos are brooded in an ovisac, often in enlarged, modified gonozooids with wide orifices. Avicularia are regularly adventitious and suboral, or vicarious with acute mandibles which are slung on paired condyles.

Colonies of Adeona were among the first bryozoans collected from Australia. The type species, Adeona grisea, was introduced by Lamouroux (1812). Colonies may be erect, with flattened, bifurcating branches (adeoniform), but the best-known are large, fan-shaped or anastomosing, honeycomb-like, and fenestrate. The fenestrae are formed by bifurcation of autozooid series and anastomosis after a number of generations, leaving an oval or circular fenestra; these are regularly spaced over the colony. Adeona is usually pigmented, colonies being dark red, purple or black; the fenestrae may show contrasting colours. Adeona grisea has colonies attaining a height and diameter of 100 mm, but some species have dimensions three times this size. Colonies are anchored by a spreading mass of partially calcified rhizoids, which also forms an extremely thick, but slightly flexible stem. The stem segments have been preserved as fossils and were described by Hall (1897). The frontal shield of zooids of a large colony become thickened by a considerable depth of calcification, which becomes extrazooidal, particularly at the centres of fan-shaped expanses, where stress is greatest. These raised 'veins' of thickening become a noticeable feature of large colonies. Brooding zooids are not enlarged and are hardly noticeable. As with many other bryozoans, the zooids are capable of regeneration at the broken edges of a colony: the various types of regeneration for a single colony of a species of Adeona were described by Wass (1983). In A. grisea, the fenestrae are surrounded by vicarious avicularia. Bock (1982) figured two species, noting that although four species were recorded from Victoria, their distributions were inadequately known.

The early stages in the astogeny of colonies of Adeona have some unusual characters. Larval settlement occurs on erect sponges or other bryozoans, several centimetres above the seafloor. Colony growth proceeds both upward and downward. The main colony extends upward as a bilaminar branch, which branches, to form fenestrate sheets in most Australian species. The growth downward from the ancestrula forms a stem constructed of calcified segments articulated with bundles of cuticular tubes. As the stem reaches the sediment-water interface, it ramifies to form a rootlet-complex. The stem also thickens and may divide into multiple branches. Secondary calcification also thickens the upper part of the stem complex. Ultimately the host animal dies or is overgrown, and the large colony of the Adeona is supported by a stout, but slightly flexible, trunk (Bock & Cook 2000).

Colonies of Adeonellopsis may have colonies with erect, laterally compressed, bilaminar branching lobes up to 50 mm high (A. sulcata), or a honeycomb of anastomosing plates 250 mm in diameter and height. Bock (1982) called this last species, A. foliacea, 'spectacular', and it is common in South Australia and Victoria. A. pentapora Canu & Bassler (1929) has narrow, blade-shaped branches and a pair of symmetrical suboral avicularia. This form has been identified, as A. yarraensis (Waters 1881), from many localities in the Indo-West Pacific as far north as Japan (Harmer, 1957; Gordon, 1984, 1989). However, it is different from the Miocene fossil A. yarraensis (Gordon 1993); further work is needed to confirm its Australian distribution. The purple colonies of A. baccata encrust algae and seagrass stems from South Australia. The zooids become covered by large calcified excrescences and were figured by Gordon & Parker (1991). Gonozooids in Adeonellopsis are large and have multiporous spiramina (Ström 1977).

The genus Bracebridgia was introduced by MacGillivray (1886) for Mucronella pyriformis Busk. It has small, branching colonies and the zooids have a small proximal mucrone. A centrally located avicularium is located proximal to the orifice, and a small spiraminal pore may be present. B. emendata, a fossil species from Victoria figured by MacGillivray (1895) is closely similar to unnamed specimens from South Australia. All records require examination.

Cucullipora tetrasticha is another Tertiary species described by MacGillivray (1895). The Recent colonies figured under this name have similarities to both Cucullipora and Bracebridgia (Wass & Yoo 1983), and probably require their own generic assignment. It is interesting that the Australian Tertiary genus Dimorphocella is represented by a Recent South African species, D. moderna, which has large, fan-like, purple fenestrate colonies very like Adeona (Hayward & Cook 1983).

Australian records have been made of about 18 species from this family; of which nearly all are endemic. It is expected that there are many undescribed species, particularly of the genus Adeonellopsis.

Adeonellopsis is moderately common in water depths of about 10 m, and has been recorded from depths of more than 900m, but most records of species of the family range from 25 m to 180 m.

According to Taylor (1993), the earliest record of Adeonellopsis is from the Early Eocene of the London Clay, and of Bracebridgia from the Early Eocene of the Indian Ocean.

 

Diagnosis

Colony encrusting or erect, arising from an encrusting base and anchored by partially calcified, kenozooidal rhizoid system. Highly calcified, branching, bilaminar, sometimes fenestrate, often massive and very large. Zooids with umbonuloid frontal shield, with marginal areolae and central spiramen complex. Secondary orifice subterminal, with adventitious, oral avicularia; other interzooidal and vicarious avicularia typically present. Brooding in interior ovisacs of enlarged zooids with dimorphic orifices.

 

General References

Bock, P.E. 1982. Bryozoans (Phylum Bryozoa). pp. 319-394 in Shepherd, S.A. & Thomas, I.M. (eds). Marine Invertebrates of Southern Australia. Handbook of the Flora and Fauna of South Australia Adelaide : Government Printer Part 1 491 pp.

Bock, P.E., & Cook, P.L. 2000. Early astogeny of Adeona colonies. pp. 161-167 in Herrera Cubilla, A., & Jackson, J.B.C. (eds). Proceedings of the 11th International Bryozoology Association Conference. Balboa : Smithsonian Tropical Research Institute.

Busk, G. 1884. Polyzoa. Pt. I. Cheilostomata. Report on the Scientific Results of the Voyage of H.M.S. Challenger 1873–1876, Zoology 10: xiv, 216

Canu, F., & Bassler, R.S. 1929. Bryozoa of the Philippine region. United States National Museum Bulletin 100: 1-685

Cook, P.L. 1973. Preliminary notes on the ontogeny of the frontal body wall in the Adeonidae and Adeonellidae (Bryozoa, Cheilostomata). Bulletin of the British Museum (Natural History) Zoology 25: 243-263

Gordon, D.P. 1984. The marine fauna of New Zealand: Bryozoa: Gymnolaemata from the Kermadec Ridge. New Zealand Oceanographic Institute Memoir 91: 1-198

Gordon, D.P. 1989. The marine fauna of New Zealand: Bryozoa: Gymnolaemata (Cheilostomida Ascophorina) from the western south Island continental shelf and slope. New Zealand Oceanographic Institute Memoir 97: 1-158

Gordon, D.P. 1993. The ascophorine infraorders Cribriomorpha, Hippothoomorpha and Umbonulomorpha mainly from New Caledonian waters. Mémoires du Muséum national d'Histoire naturelle, Paris [1936-1950] 158: 299-347

Gordon, D.P., & Parker, S.A. 1991. Discovery and identity of 110-year-old Hutton Collection of South Australian Bryozoa. Records of the South Australian Museum (Adelaide) 25: 121-128

Hall, T.S. 1897. On the occurrence of the anchoring tubes of Adeona in the older Tertiaries of Victoria with an account of their structure. Proceedings of the Royal Society of Victoria 9: 1-4

Harmer, S.F. 1957. The Polyzoa of the Siboga Expedition. Part 4. Cheilostomata Ascophora II. Siboga-Expéditie Report 28D: 641-1147

Hayward, P.J. & Cook, P.L. 1983. The South African Museum's Meiring Naude Cruises. Part 13, Bryozoa II. Annals of the South African Museum 91: 1-161

Lamouroux, J.V.F. 1812. Extrait d'un mémoire sur la classification des Polypes coralligènes non entièrement pierreux. Nouveau Bulletin des Sciences, par la Société Philomatique de Paris 3: 181-188

Lidgard, S. 1996. Zooidal skeletal morphogenesis of some Australian and New Zealand Adeonellopsis (Cheilostomatida). pp. 167-177 in Gordon, D.P., Smith, A.M., & Grant-Mackie, J.A. (eds). Bryozoans in Space and Time. Wellington : NIWA.

Macgillivray, P.H. 1886. Descriptions of new or little-known Polyzoa. Part 9. Transactions and Proceedings of the Royal Society of Victoria 22: 128-139

Macgillivray, P.H. 1895. A monograph of the Tertiary Polyzoa of Victoria. Transactions of the Royal Society of Victoria ns 4: 1-166

Ström, R. 1977. Brooding patterns of Bryozoans. pp. 23-89 in Woollacott, R.M., & Zimmer, R.L. (eds). Biology of Bryozoans. New York : Academic Press xvii 566 pp.

Taylor, P.D. 1993. Bryozoa. pp. 465-489 in Benton, M.J. (ed.). The Fossil Record 2. London & New York : Chapman & Hall 845 pp.

Wass, R.E. 1983. Regeneration of calcification in the Adeonidae (Bryozoa: Cheilostomata). Memoirs of the Association of Australasian Palaeontologists 1: 305-310

Wass, R.E. & Yoo, J.J. 1983. Cheilostome Bryozoa from the Southern Australian Continental Shelf. Australian Journal of Marine and Freshwater Research 34: 303-354

Waters, A.W. 1881. Fossil cheilostomatous Bryozoa from S.W. Victoria, Australia. Quarterly Journal of the Geological Society of London 37: 309-347

 

History of changes

Published	As part of group	Action Date	Action Type	Compiler(s)
11-Jul-2019	GYMNOLAEMATA Allman, 1856	11-Jul-2019	MODIFIED
25-Mar-2014	BRYOZOA Ehrenberg, 1831	25-Mar-2014	MODIFIED	Dr Robin Wilson (NMV) Elizabeth Greaves (NMV)
		12-Feb-2010	(import)