Family MICROPORIDAE Gray, 1848

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Family MICROPORIDAE Gray, 1848

Compiler and date details

July 2001 - Dr Philip Bock

Microporidae Gray, J.E. 1848. List of the Specimens of British Animals in the Collection of the British Museum. Part 1. Centroniae or radiated animals. London : Trustees of the British Museum 173 pp. [115].

Introduction

The family Microporidae was introduced by Gray (1848) for European Micropora, type species M. coriacea. It is a large family with over 25 genera currently assigned to it. Colonies are encrusting or erect. The autozooids are outlined by a raised mural rim, and the opesia is small and distal, outlined and defined by an extensive, flat cryptocyst, which is pierced by at least one pair of opesiules. These accommodate the passage of parietal muscles. Zooids communicate through small pore chambers. The ovicell is hyperstomial, often partly immersed, and closed by the operculum; it is usually imperforate, and sometimes umbonate. Interzooidal and vicarious avicularia are often present.

Gray proposed the genus Micropora, with Flustra coriacea as the only species. The material he was using was that identified by Johnston (1847), as Flustra coriacea (Esper, 1791). Harmer (1926), argued that Esper's species was actually not published until 1806-1816, and also was a synonym of Cellepora nobilis Esper, 1796 (now Calpensia) and thus was not a valid species. Harmer proposed that the material that Johnston misidentified be accepted as the type species of Micropora, as Flustra coriacea Johnston (not Esper), nevertheless admitting that this was not in accordance with the Rules of Zoological Nomenclature.

Several genera exhibit all the characteristics of the type genus, but others have different morphologies and almost certainly require family assignments of their own. One of the genera occurring in Australia, Mollia, has little in common with Micropora, or other Microporidae, and is dealt with at the end of this chapter.

Micropora is a genus with a world-wide distribution. The type species, M. coriacea, has been credited with a vast range, but this is being progressively restricted as populations are analysed in detail. The species illustrated by Bock (1982) has avicularia, and cannot be M. coriacea. It resembles that illustrated by Wass & Yoo (1983) as M. cf. normani. All specimens came from southern Australia and are characterised by a pair of distal slit-like opesiular indentations and a pair of small, rounded opesiules. Gordon (1986) regarded M. cf. normani as partly identical with M. elegans Maplestone (1901), which he had illustrated with New Zealand material in 1984. However this species, first described from the Tertiary of Victoria, does not possess the second pair of rounded opesiules. The whole question requires examination of the type material. Bock (1982) also figured M. stenostoma (Busk), which has two pairs of large opesiules, paired oral spines and large ovicells. It was originally described from Tasmania by Busk (1854) and also occurs on the Victorian coast, where it encrusts Sargassum. Several other species of Micropora have been recorded from Australia, including M. variperforata Waters, which was found from the Great Barrier Reef by Ryland & Hayward (1992). Micropora also occurs in the Antarctic and sub-Antarctic. Hayward (1995) described sub-Antarctic M. brevissima and Antarctic M. notialis, both of which occur as broad sheets on hard substrata. Hayward also described species of four other southern genera. These are the rare and inconspicuous Apiophragma hyalina, the extensive unilaminar colonies of Andreella uncifera, the flustrine Flustrapora magellanica, and the erect, branching colonies of Ogivalia elegans, which may reach a height of 50 mm.

Harmer (1926) defined two new species of Calpensia. C. pulchra was recorded from Torres Strait. The second species, C. reversa, from Ceylon, later was made the type species of the genus Dibunostoma (Cheetham 1963). The relationships of Dibunostoma seem to be with the Thalamoporellidae. C. pulchra has neither avicularia nor ovicells and its relationships require further investigation.

The genus Opaeophora is represented by the species O. lepida, first described as Monoporella from Bass Strait by Hincks (1881), and discussed and illustrated by Gordon (1986, as Manzonella) from New Zealand. Additional specimens have been collected from Bass Strait, but these records have not yet been documented.

The genus Mollia is traditionally assigned to the Microporidae, but species have no opesiules; the Australian records of Amphiblestrum patellarium figured by MacGillivray (1886) require investigation. Small colonies, which have been referred to Mollia patellaria, frequently occur encrusting the basal surface of living lunulitiform species, particularly those of Lunularia (Parker & Cook 1994).

Diagnosis

Colony encrusting, in sheets, sometimes associated with algae, or erect, well calcified, occasionally flustrine. Autozooids with well developed, flat cryptocyst pierced by one or more pairs of opesiules. Avicularia interzooidal or vicarious. Ovicell hyperstomial, imperforate.