Family CELLEPORIDAE Johnston, 1838

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Family CELLEPORIDAE Johnston, 1838

Compiler and date details

July 2001 - Dr Philip Bock

Celleporidae Johnston, 1838.

Introduction

This immense group of ascophorines has a worldwide distribution encompassing a presently unknown number of species. It was founded by Johnston (1838), the type genus, Cellepora Linnaeus, is restricted to two species only (Hayward, p.c.) but the additional genera added as the concept of the family clarified include a number, such as Celleporina and Osthimosia, whose taxonomic diversity has only recently been recognised. The identity of Cellepora Linnaeus, 1767, was finally resolved by Hayward (1979), following the selection of a neotype for the type species Millepora pumicosa Pallas (Ryland 1969), and the long-disregarded Celleporidae Johnston, 1838 was reinstated. Busk (1881, 1884) made the first significant contribution to celleporid taxonomy, describing 29 new species from the collections of the Challenger expedition. The number of described species has risen steadily over the past century but there has been no adequate monograph of the family, or any of its constituent genera. Core genera include Turbicellepora Ryland, which reaches highest taxonomic diversity in the northern hemisphere (Hayward, 1978), Celleporina Gray (1848), an especially speciose genus with a worldwide distribution and Osthimosia Jullien (1888), which is most diverse in cold southern hemisphere seas and includes numerous endemic Antarctic species. The total fauna present in any geographic area cannot be known until all previous descriptions and citations have been reassessed. Approximately 20 species of Celleporidae were previously recorded for Australia, but this must be considered a gross underestimate. However, several of the described species names are synonymous. Collections from Heron Island, Great Barrier Reef (Ryland & Hayward 1992, Hayward & Ryland 1995) have yielded five species of Celleporina, of which four were new species. Gordon's research on the New Zealand fauna (1984, 1989) revealed 23 species in the genera Celleporina, Osthimosia and Lagenipora Hincks (1877), of which 15 were previously undescribed. The Antarctic Celleporidae totals 14 species, nine of which have only recently been recognised (Hayward 1995).

Celleporid morphology can be baffling. Colony form is extremely plastic; the ancestrula and first few astogenetic generations generally form a unilaminar sheet, but thereafter rapid frontal budding gives rise to pisiform, nodular, massive, or erect and branching stagshorn growth. In almost all species the primary orifice is sinuate, although the sinus varies from a narrow slit, to a broad and shallow concavity. In almost all genera there is one or more adventitious avicularia associated with the orifice, and enlarged, vicarious avicularia are also characteristic. The ovicell is generally perforate, often with a marked frontal lacuna in the ectooecium, bordered by pores, which is termed a tabula. The frontal wall of celleporids is a cryptocystidean shield with few marginal septular pores.

The most speciose genus in Australian seas, and possibly worldwide, is Celleporina Gray. Colonies of Celleporina species are characteristically pisiform, encrusting erect substrata such as hydroids, algae and other bryozoans, but moundlike or nodular forms occur and a minority develop erect, branched growths. Celleporina is recognised by its well developed peristome, which is often tubular and conspicuous and bears one to many small avicularia on its rim; most often the avicularia are paired, lateral oral in position, with their tubular cystids obviously originating from the marginal septular pores of the zooid. The ovicell is also characteristic; globular, with a crescentic or semielliptical flattened tabula exposing ridged or smooth entooecium which is variously perforated. Most species of Celleporina bear enlarged avicularia, often spatulate, with a form characteristic to each species. Australian species of Celleporina include C. spatula, C. tiara, C. costata, C. platalea, and C. granum.

Osthimosia differs from Celleporina only in its non-porous tabula, which is typically small and tends to reduce in area through ontogeny. Osthimosia is principally a cold southern hemisphere genus, and there are 10 endemic Antarctic species (Hayward 1995). O. glomerata is a common species in southern Australia, and forms small pisiform colonies, usually growing on hydroid stems or other bryozoans.

Galeopsis and Spigaleos Hayward (1992) are erect, branching celleporids, with autozooids in whorls of four or five; both are cold water genera, and the latter, monotypical for S. horneroides (Waters), is endemic to Antarctica. G. pentagonus was described from New Zealand by Gordon (1989); it also is found in southern Australia.

In Spigaleos the sinuate primary orifice is immersed in a deep peristome with a median suboral avicularium, the proximal portion of which (actually distally directed) forms a projecting denticle above the secondary orifice; its globose ovicell has an extensive, smooth and imperforate, frontal tabula. In Galeopsis paired lateral suboral avicularia are linked by a calcified bridge, defining a pseudospiramen.

Turbicellepora ampla (Kirkpatrick) is the only species of its genus confirmed from Australia; it has a tropical Indo-West-Pacific distribution and has been recorded from Heron Island, Great Barrier Reef (Ryland & Hayward 1992). T. redoutei has been described by Harmer (1957); the synonymy included a species from southern Australia described by MacGillivray as Cellepora megasoma: this is probably a distinct species of Turbicellepora.

Buffonellaria is encrusting, with a prominent ovicell having a frontal tabula. Avicularia typically are paired, lateral to the orifice. The frontal often has raised ridges of calcification. The genus is known from southern Australia, but the species are not described. The genus was placed in the Celleporidae by Gordon (1984).

The earliest fossil record of the family is from the Late Cretaceous of northern Europe (Taylor 1993). Abundant fossil material occurs in the Tertiary of Victoria, but is poorly known.

Specimens in the QM thought to represent the genus,Buffonellaria Canu & Bassler, 1927 have been found in Queensland, but have not been identified to species level.

Diagnosis

Colony well to heavily calcified, encrusting, minute to massive, or erect and branched. Early astogenetic stages may be sheet-like, later growth is usually formed by frontal buds. The frontal shield is lepralioid, with marginal areolae, and the primary orifice is usually sinuate. Avicularia are adventitious and oral, or large and vicarious. The ovicell is often prominent, hyperstomial, and has a frontal area formed by a lacuna in the ectooecium, bordered by pores, termed a tabula.