Family LICHENOPORIDAE Smitt, 1867

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Family LICHENOPORIDAE Smitt, 1867

Compiler and date details

July 2001 - Dr Philip Bock

Introduction

The family was established by Smitt (1867). Waters (1889) and Harmer (1915) contributed towards a clarification of colony morphology and the nature of the brood chamber, the ontogeny of which was detailed by Borg (1926). All Recent species were reviewed by Borg (1944), who proposed dividing the family according to the degree of extrazooidal calcification, and introduced a new family, Disporellidae, for species with open alveoli. Most taxonomists continue to recognize a single family.

Lichenoporids develop discoid colonies which may be domed or deeply cupped. The basal lamina is often conspicuous and in cupped colonies may be very wide, perhaps developed in response to spatial competition on crowded substrata. Autozooids may be in strictly connate rows or in alternating series, or occasionally in fascicles; peristomes may be decumbent, or erect, free and very elongate. The rim of the peristome is frequently produced into one or more sharp points, and interior spinules are present in many species which may be taxonomically significant. The ooeciostome may be single or multiple; it is broadly flared in Patinella, but forms a simple open tube in Disporella. Colonies may be symmetrical, with zooid rows radiating from a single centre, or multicentred, and even meandriform. Adventitious 'daughter' colonies are budded peripherally or frontally in many species. Lichenoporids are predominantly shallow water organisms; most encrust hard substrata often occupying refugial habitats, but a number are common as algal epiphytes.

The genus Lichenopora has conical or turbinate colonies with a small attachment zone, and is only known as fossils from Europe and New Zealand. The encrusting discoid colonies which have been referred to Lichenopora mainly belong to the genus Patinella, and are largely restricted to the Northern Hemisphere.

The two genera Patinella and Disporella have a worldwide distribution, taxonomy is difficult and there has been no modern review of the family, or its Australian representatives (Bock 1982). Two Indo-West-Pacific species occur commonly in Australian seas, viz. Lichenopora novaezelandiae Busk (1875) and Disporella buski Harmer (1915), originally described from New South Wales and Torres Strait. Specimens of both species have been figured from Heron Island at the south end of the Great Barrier Reef by Ryland & Hayward (1992) and Hayward & Ryland (1995). MacGillivray (1884, 1887) and Haswell (1880) described a number of Recent Australian species, several of which were discussed by Harmer (1915) and Borg (1944). Borg introduced Lichenopora watersi from South Australia, Victoria and New South Wales and discussed Disporella echinata (MacGillivray), which was illustrated, as Lichenopora echinata, by Bock (1982). An extensive Tertiary fauna was described by MacGillivray (1895). At present, it is not possible to estimate the total number of species in the local fauna, nor the proportion of endemic species. Borg's (1944) review also included four new species described from Antarctica.

Fossil lichenoporids are known from the Cretaceous of Europe (Taylor 1993), and are found in Tertiary sediments of southern Australia.

Diagnosis

Colony well calcified, encrusting, often discoid, with a wide rim of undifferentiated basal lamina, which may be raised round the colony to form a cup. All calcified walls are interior walls. Zooids grow radially, sometimes becoming differentiated into fascicles, at the margins of zooid series. The gonozooid is an extrazooidal space with a distinct roof and a tubular or flared ooeciostome.