Benthic foraminifera of the family Calcarinidae from Green Island Reef, Great Barrier Reef Province

The genera of calcarinids Calcarina and Baculogypsina are the dominant foraminifera in the surface sediment of Green Island Reef of the Great Barrier Reef Province, northeastern Australia. Two species of Calcarina are recognized: C. spengleri (Gmelin) and C mayori Cushman. Both species are common and widely distributed on the Great Barrier Reef and in the Indo-Pacific region but have been much confused in the literature. They are re-evaluated in this contribution. Hansen (1980) described and illustrated a neotype of C. spengleri which is different in appearance to the lectotype illustration of Gmelin, 1791. The neotype is inseparable from C. hispida Brady, 1884 and therefore the name spengleri has priority over hispida. Calcarina spengleri (Gmelin) is the dominant species at Green Island and is common in shallow water on the reef flat. Calcarina mayori Cushman, a smaller less hispid species, is subordinate to C. spengleri and dominates in deeper water off the reef flat. This species has commonly been reported as C. spengleri or C. hispida. The monotypic genus Baculogypsina, represented by Baculogypsina sphaerulata Parker & Jones, does not dominate in any region but is a shallow water high-energy species on Green Island Reef. These species are common and abundant epiphytes on a variety of reef top macroalgae, especially the reef-rim restricted algal turf. Due to their preference for shallow water, high-energy environments most calcarinid specimens suffer appreciable test surface degradation soon after death due to physical abrasion, breakage and bioerosion. Four taphonomic group, characterized by the preservation of Calcarina specimens are identified by cluster analysis of samples. Samples of groups 1 and 4, in which most Calcarina specimens are broken and abraded, characterize the reef flat where sediment reworking by. biological agencies involving callianassid shrimp and endolith activity are dominant, as well as physical processes of degradation. Group 2 samples are composed primarily of Calcarina spines and occur in the leeward shoals. Sediment grains in this area have a long surface residence time and are little affected by waves and current agitation. Spines are considered to represent the most resistant of Calcarina fragments. Group 3 samples contain the best preserved Calcarina at Green Island Reef and are located in the windward shoals. A high production rate applies in this zone but the tests have suffered significant impact damage indicating that physical processes dominate degradation. Group 4 samples typify shallow water samples close to the reef flat where physical energy plays a significant role in these areas and therefore has a high degree of abrasion and breakage. The distribution of all three calcarinid species is limited to the western Indo-Pacific. Despite the occurrence of C. spengleri around India, these calcarinids are otherwise absent from the Indian Ocean and also absent east of 170degreesW. They are shallow water tropical species and are particularly abundant on coral reef flats.