A review of Australian Siphonicytara Busk (Bryozoa : Cheilostomatida)

Until recently, species of the deep-water ascophoran genus Siphonicytara have been recorded from only two areas, nearly 10,000 km apart. Three species were known from the East Indies and one from the southwest Indian Ocean. A hitherto unrecognized species is now known from the southern-most Philippine region, and six new species have recently been described from New Caledonia. A further new species from relatively shallow water, S. occidentalis, is described here from Western Australia. Examination of fossil specimens from the Tertiary of Victoria and South Australia has shown that specimens attributed to Parina clypeata Waters have a close relationship with Siphonicytara, and the species is referred here to this genus, as is Mucronella airensis Maplestone. Another Tertiary species with a similar distribution, 'Eschara elevata' Waters not Tenison Woods, is assigned to Siphonicytara irregularis (Maplestone). The stratigraphic range for the family extends from the Late Eocene to Recent. Eschara elevata Tenison Woods sensu stricto is the type species of the genus Tubitrabecularia Bassler, and a discussion of the nature and status of this genus is included. A key to the species described is given.

Calescharidae, a new family for the Tertiary to Recent Genera Caleschara MacGillivray and Tretosina Canu and Bassler (Bryozoa: Cheilostomata)

A new family of Cheilostomata, the Calescharidae, is introduced for the genus Caleschara MacGillivray and its Recent Australian typespecies, C. denticulata(MacGillivray), which is redefined from type and other material. The Australian Tertiary genus Tretosina Canu & Bassler and its type species,T. arcifera Canu & Bassler, are closely related,and are also assigned to the Calescharidae. The history and significance of family attributions of both genera are outlined, and RecentC. denticulata from Australian and other localities is distinguished from the Late Tertiary Victorian species C. parva Maplestone. Caleschara lithconis, sp. nov., from the Late Eocene of Victoria is one of the earliest known species: its morphology closely resembles a Recent form from the Philippines, C. junctifera Canu & Bassler. Another Recent species, Caleschara minuta (Maplestone) from the GilbertIslands, is a senior synonym of three other Indo-Pacific species,C. levinseni Harmer, C. laxa Canu & Bassler and Floridinella arculifera Canu & Bassler, and resembles the European Paleocene C. squamosa. Three other related species are briefly discussed. Close relationships to other families are problematic and are discussed; divergence in the early history of the cheilostomes is inferred.

Revision of tertiary species of Anaskopora Wass (Bryozoa: Cribrimorpha)

The subgenus Anaskopora Wass, 1975 is raised to generic rank, separated from the genus Corbulipora, and redefined. The type species, Cribrilina elevata MacGillivray, 1895, is a Tertiary fossil from Victoria with small globular colonies formed principally by a special kind of interzooidal frontal budding. Other Tertiary fossil species with a similar colony structure, here assigned to Anaskopora, are Cribrilma cornuta MacGIllIvray, 1895 and Lepralia rotundata MacGillivray, 1895. Two further new Tertiary species, A. simplex and A. mesa, from Victoria and South Australia have small encrusting colonies. A key to species is given.

Revision of the multiphased genus Corbulipora MacGillivray (Bryozoa: Cribrimorpha)

Corbulipora MacGillivray is redefined to include only species which occur in successive growth phases. The fossil type species, Corbulipora ornata MacGillivray, occurs in an encrusting ancestrulate phase, an erect quadriserial, ovicellate phase, and a frontally-budded partially kenozooidal phase. The encrusting ancestrulate phase of the Recent species, C tubulifera (Hincks), is the type species of the genus Acanthocella Canu and Bassler, which is a junior synonym of Corbulipora. The succeeding, ovicellate, flustrine phase, known as Watersia militaris (Waters), is the type species of Watersia, another junior synonym of Corbulipora. It produces a third bilaminar phase known as C. oriparma, a synonym of C. tubulifera. This has rhizoids and develops further flustrine phases. Fossil specimens assigned to Acanthocella tubulifera in the past are here considered to be the primary encrusting phase of a bilaminar phase, known as Corbuhpora suggerens (Waters). from which it has become separated. A thinly calcified intervening erect phase similar to the flustrine phase of C. tubulifera IS inferred to have existed but not to have been preserved as a fossil. Some species previously referred to Watersia are assigned to Klugeflustra Moyano which, like Neoflustra Lopez Gappa, has flustrine colomes with large, hyperstomial ovicells, unlike those of the family Flustridae sensu stricto. A key to species of Corbulipora and their various phases is given.

First fossil finds of some Australian Bryozoa (Cheilostomata)

The abundant fossil record of well-preserved Bryozoa in samples from the Tertiary of Victoria and South Australia includes some 'first fossil finds' which are recorded here. Several are of species known from the Recent of the Australian or Indo-West-Pacific regions, but some represent genera with a much wider temporal and geographical range. Of the 11 species illustrated, six are known, or may be inferred, to have inhabited 'sand fauna' environments. Specimens of one species are complete enough to allow its formal description as Chlidoniopsis inopina sp. nov.

Dimorphic brooding zooids in the genus Adeona Lamouroux from Australia (Bryozoa: Cheilostomata)

The genus Adeona is a characteristic and common part of the Australian shelf fauna, extending to the tropical Indo-West Pacific. The genus first appears in the fossil record of the Miocene of south-eastern Australia. Zooid dimorphism has been recognised initially from subtle differences in the external appearance, which have not been described previously. Detailed examination has shown enlarged brooding zooids with marked differences from autozooids in the internal structure of the peristomes and in the occurrence of a primary calcified orifice.

A review of Australian Conescharellinidae (Bryozoa : Cheilostomata)

The family Conescharellinidae Levinsen is defined and is regarded as comprising seven cheilostome genera (Conescharellina, Bipora, Trochosodon, Flabellopora, Zeuglopora, Crucescharellina and Ptoboroa). The astogeny of colonies, that consists of frontally budded zooids with "reversed" orientation, is briefly described and compared between genera. The morphology of zooids and heterozooids is defined and keys to genera and Australian species are provided. Taxa that were first described from Australia or from reliable subsequent records are redescribed and illustrated where possible. Australian specimens that have been identified as non-Australian species, have generally been found to be distinct and are here redescribed as new species. Some non-Australian records of specimens previously assigned to Australian species have also been re-examined. These are described and sometimes referred to other taxa. Altogether, eight previously described species that have not been found in the present material are discussed and 27 taxa are described from collections, principally from the eastern and southern coasts of Australia and from the Tertiary of Victoria. Eighteen of these are considered to be new species. Where possible, type or at least topotype material of previously described species has been examined. Colonies from the collections of Museum Victoria (NMV) and the Natural History Museum, London (BMNH), have been examined. New species from Australia described here are: Conescharellina cognata, C. ecstasis, C. diffusa, C. obscura, C. stellata, C. plana, C. perculta, C. pustulosa, C. ocellata, C. macgillivrayi, C. humerus; Trochosodon fecundus, T. asymmetricus, T. diommatus, T. aster, T. anomalus, T. praecox and Crucescharellina australis. In addition, the New Zealand bryozoan Trochosodon multiarmatus (Gordon, 1989) (not Bipora multiarmata Maplestone, 1909) is described as Trochosodon gordoni sp. nov.

New species of Otionellina and Selenaria (Bryozoa-Cheilostomata) from the South West Shelf, Western Australia

Recent sediment samples recovered from the mid-latitude South West Shelf (SWS) of Western Australia (23°- 32° S) by a scientific team aboard the RV Franklin have produced large numbers of free-living, lunulitiform bryozoans. Among these are three undescribed species, Otionellina boneae sp. nov., Selenaria kayae sp. nov., and Selenaria meganae sp. nov. The Australasian lunulite fauna is both diverse and abundant and the new species bring the total of described taxa to sixty (P. Cook unpub.). Twelve lunulite species have been recorded from the SWS. These findings have extended the known geographical range of several lunulite species.

Notes on astogeny of some Petraliellidae (Bryozoa) from Australia

Members of the bryozoan family Petraliellidae share the capacity to develop basal rhizoids, which anchor the unilaminar, semi-repent parts of the colonies above the substratum, and enable them to overgrow other, competing sessile forms. Little is known of the larval behaviour and settlement, or the early astogeny of species. Ancestrulate colonies of the Australian Tertiary lunulitiform species Smittia biincisa are referred to the genus Riscodopa , and together with Riscodopa paucipora sp. nov. are described and compared with the Recent species R. cotyla and R. parva from New Zealand, and with R. hyalina sp. nov. from New South Wales, Australia. All the Recent species are known to develop basal rhizoids, and an early astogeny similar to that of many other small, rooted bryozoans, comprising the post-metamorphosis development of a binary complex, including rhizoid and feeding elements, is inferred for Riscodopa . Observations on living Hippopetraliella magna from Queensland suggest that both the ancestrular morphology and early astogeny show a capacity for semi-repent growth, even though they do not include rhizoid development. Larvae metamorphose without direct attachment, and the ancestrula develops elongated, partially calcified supporting processes, which raise the early stages of growth above the substratum. A similar kind of ancestrula has been found in preserved specimens of Mucropetraliella ellerii .

Exechonella (Exechonellidae: Bryozoa, Cheilostomata) from the recent and miocene of Southern Australia

The cheilostome family Exechonellidae Harmer, 1957 is widely distributed in time and space. The genus Exechonella Duvergier, 1924 has a pan-tropical to subtropical distribution from the Eocene to the Recent and is represented by several Australian species from the Tertiary of Victoria and the Recent ofthe southern and eastern coasts. Some species exhibit a wide range of variation in morphological characters, and one, Exechonella papillata, "appears to be new, and is described here. Nearly all specimens are encrusting, but one Tertiary Victorian species has erect, cylindrical, branching colonies. Recent samples, from a depth range of 40-190 metres, include large colonies of several thousand zooids. Frontal wall structures include marginal septular pores connecting between the visceral and hypostegal coeloms, and frontal foramina. Avicularia and homologous structures derived from frontal septular pores are illustrated. The structure of the frontal foramina in different populations of Tertiary E. marginata, demonstrates a major development of hypostegal coelom not found in other species, but resembling that found in another exechonellid genus, Stephanopora Kirkpatrick, 1888.

New species of the Bryozoan Genera Batopora and Lacrimula (Batoporidae) from Australia

Examination of samples of bryozoans from the south- eastern slope sediments of Australia ("Franklin" SLOPE Stations 6, 7), has revealed the presence of many specimens of several genera with species which have minute, rooted colony forms. Among these are new species of the genera Batopora Reuss (B. problematica) and Lacrimula Cook (L. affinis). The structure of colonies is briefly described. The family Batoporidae is considered to contain only these two genera, although they have relationships with the discoidal genus Orbitulipora, and similarities in colony form to the genera assigned to the Conescharellinidae.

Evolution in a cold climate

A brief appraisal of marine fossils from high latitudes and episodically cold climate especially in east Australia and New Zealand during Late Palaeozoic and Early Mesozoic times shows patterns of evolution and survival that differ from those adduced for the palaeotropics and Northern Hemisphere. Examples taken from amongst phyla Scyphozoa, Bryozoa, Brachiopoda and Classes Bivalvia and Class Cephalopoda suggest these attributes:
1. Evolution and demise of species and genera proceeded at a rate close to that known for palaeotropical and Northern Hemisphere macro-invertebrates, but involved fewer families and orders.
2. Possibly, intraspecific variation was greater amongst southern palaeohemisphere Permian species than in those of the Permian palaeotropics.
3. There was no proven diminution of life at the end of the Guadalupian (Middle Permian) at southern high latitudes, where however the fossil record is meagre for this interval. Younger Wuchiapingian and Changhsingian faunas were moderately diverse.
4. There is no evidence for a high latitude Southern Hemisphere anoxic event in the Early Triassic despite claims of a world-wide anoxic interval. Nor has any substantial volcanic eruption or bolide impact left any marked traces in the sedimentary record.
5. As a consequence, some major groups such as Bryozoa and Conulariida (Staurozoa) survived the end- Permian extinction shock in the Southern Hemisphere.
6. Other major groups appear to have survived better in the south than in the north, notably, mollusc Bivalvia and Cephalopoda. It therefore appears likely that Triassic seas were restocked substantially from the Southern Hemisphere and that the Permian extinction shock was asymmetric with respect to latitudes in its distribution and affect.