A review of some common Indo-Malayan and western Pacific species of Chthamalus barnacles (Crustacea: Cirripedia)

The type specimens of the common tropical intertidal barnacles Chthamalus malayensis and C. moro, were re-investigated and compared with other specimens of Chthamalus from the Indian Ocean, Indo-Malaya, northern Australia, Vietnam, China and the western Pacific, using ‘arthropodal’ as well as shell characters. Chthamalus malayensis occurs widely in Indo-Malayan and tropical Australian waters. It ranges westwards in the Indian Ocean to East Africa and northwards in the Pacific to Vietnam, China and the Ryukyu Islands. Chthamalus malayensis has the arthropodal characters attributed to it by Pope (1965); conical spines on cirrus 1 and serrate setae with basal guards on cirrus 2. Chthamalus moro is currently fully validated only for the Philippines, Indonesia, Taiwan, the Xisha (Paracel) Islands, the Ryukyu Islands, the Mariana Islands, the Caroline Islands, Fiji and Samoa. It is a small species of the ‘challengeri’ subgroup, lacking conical spines on cirrus 1 and bearing pectinate setae without basal guards on cirrus 2. It may be a ‘relict’ insular species. Chthamalus challengeri also lacks conical spines on cirrus 1 and has pectinate setae without basal guards on cirrus 2. Records of C. challengeri south of Japan are probably erroneous. However, there is an undescribed species of the ‘challengeri’ subgroup in the Indian Ocean, Indo-Malaya, Vietnam and southern China and yet more may occur in the western Pacific. The subgroups ‘malayensis’ and ‘challengeri’ require genetic investigation. Some comments are included on the arthropodal characters and geographical distributions of Chthamalus antennatus, C. dalli and C. stellatus

Family-level AMBI is valid for use in the north-eastern Atlantic but not for assessing the health of microtidal Australian estuaries

Analysis of benthic macroinvertebrate samples at a higher taxonomic level than species, e.g. family, potentially provides a more cost-effective protocol for environmental impact assessments and monitoring as it requires less time, funds and taxonomic expertise. Using the AMBI database, species ecological group scores are shown to be coherent within families. Faunal data from a wide range of environmental impact scenarios in the north-eastern Atlantic demonstrate that AMBI, calculated from mean values for families, exhibits a strong linear relationship with species-level AMBI, the correlation improving by using square-root transformed rather than untransformed abundances. In many regions of the world, however, the sensitivity of benthic macroinvertebrates to environmental perturbations is unknown, precluding the use of AMBI for environmental assessments. Yet the families are essentially the same as in the AMBI database. The utility of family-level AMBI is tested using data for four south-western Australian estuaries previously subjected to environmental quality assessments, but where only 17 species of the 144 taxa are included in the AMBI database. Although family-level AMBI scores reflect differences in environmental quality spatially and temporally within an estuary, they do not follow variations in environmental quality among estuaries. Indeed, south-western Australia estuaries are numerically dominated by families with high AMBI scores, probably due to the detrimental effects of natural accumulations of organic material in estuaries with long residence times. As taxonomic distinctness follows trends in environmental quality among estuaries, as well as temporally and spatially within a system, it provides an appropriate substitute for assessing the 'heath' of microtidal estuaries.