Science & Mathematics

The orchid genus Rhizanthella is endemic to Australia and comprises two species, R. gardneri, which is known from a number of sites in S. W. Western Australia and R. slateri, which is now known from six confirmed sites in eastern Australia. One of the most remarkable characteristics of the genus is that almost the entire life cycle is spent underground.

Forty‐four species of aquatic Coleoptera are recorded, many for the first time, from coastal northeastern N.S.W. Only four (Hyphydrus elegans (Montrouzier), Megaporus nativigi Mouchamps, Rhantus suturalis (Macleay) and Gyrinus convexiusculus Macleay) are relatively common, most of the remainder being recorded only once or twice. Few species show any preference for the ecological type of dune lake/pond inhabited. The number of species per locality is apparently independent of the presence of possible fish predators, but is at least partly related to habitat heterogeneity. Copyright © 1981, Wiley Blackwell. All rights reserved.

The summer benthos of 24 lakes ranging from 1-204 g l-1 salinity contained 27 species of macroinvertebrates. The worm Antipodrilus timmsi, the ostracod Mytilocypris splendida, the amphipod Austrochiltonia subtenuis, the chironomids Procladius spp. and Chironomus duplex aand the snail Coxiella striata were common at lower salinities (3-ca. 30 g l-1) while the crustaceans Australocypris robusta and Haloniscus searlei, the chironomid Tanytarsus barbitarsis and a ceratopogonid larva dominated in salinities ca. 20-100 g l-1. Small ostracods were common from 40-150 g l-1. Diversity changed little with salinity. Mean dry biomass ranged from 0-3.94 g m-2; distribution between lakes was negatively skewed with a peak around 7 g l-1 salinity. Within many lakes, there was considerable spatial heterogeneity which in some cases seemed to result from different bottom characteristics or to point source enrichment. Many groups contributed to the standing crop at low to moderate salinities, and at high salinities crustaceans were important. The lakes were grouped into two low salinity associations, an association which comprised the Red Rock Lakes and a cluster of highly saline lakes. This reflects the grouping of species into halobiont, halophilic and salt-tolerant freshwater species. © 1983 Dr W. Junk Publishers.

Cyclestheria hislopi was first described as Estheria hislopi by Baird (1859), from Nagpur, India and has since been found circumtropically. There are only two records for Australia (Saars, 1887; Timms, 1979) suggesting a limited distribution there, but this conchostracan occurred commonly in collections made recently in tropical Australia to study cladocerans. The purpose of this note is to report on the taxonomic characteristics of these specimens and to document the distribution and habitat preferences of C. hislopi in Australia.

Twenty-two lakes, swamps and ponds on, or adjacent to, siliceous coastal dunes from Newcastle to Tweed Heads were investigated. Most of the waterbodies originated by deflation, with organic accumulation and development of perched water-tables involved in establishing those in higher dunes inland. Some were located in depressions in hard rock, blocked by dunes. Most had low total dissolved solids content with Na+ and Cl- dominant, but in and near frontal dunes Ca2+ and HCO3- were important and salinity was higher. Dissolved organic matter coloured the water of those with swampy environs. Humic waters were markedly acidic, frontal dune ponds alkaline, and lakes in contact with dunes near neutral. The physicochemical features of the only waterbody connected to the sea, Blue Lagoon, varied spatially and temporally with rainfall. Lake muds were dys. The dominant plants were all emergents, with Lepironia auriculata (Retz) prominent in most waterbodies on or near leached dunes. Calamoecia tasmanica (Smith) dominated the plankton; species diversity was higher in lakes in contact with dunes than in those surrounded by leached dunes. No euzooplankters were recovered from frontal dune ponds or Blue Lagoon. Overall, littoral invertebrates were reasonably diverse but limited in frontal dune ponds. Most notable was the restriction of molluscs and ostracods to sites on or adjacent to frontal dunes, the presence of some characteristic microcrustaceans in sites on or near leached dunes, and the ubiquity of many insect groups, particularly hemipterans and coleopterans. Benthos was depauperate in species and numbers in lakes surrounded by leached dunes; diversity and standing crops were higher in lakes in contact with dunes.