The Toxicity and Uptake of As, Cr and Zn in a Stygobitic Syncarid (Syncarida: Bathynellidae)

Ecotoxicological data for obligate groundwater species are increasingly required to inform environmental protection for groundwater ecosystems. Bathynellid syncarids are one of several crustacean taxa found only in subsurface habitats. The aim of this paper is to assess the sensitivity of an undescribed syncarid (Malacostraca: Syncarida: Bathynellidae) to common groundwater contaminants, arsenic (III), chromium (VI) and zinc, and examine the bioaccumulation of As and Zn in these animals after 14-day exposure. Arsenic was the most toxic to the syncarid (14-day LC50 0.25 mg As/L), followed closely by chromium (14-day LC50 0.51 mg Cr/L) and zinc (14-day LC50 1.77 mg Zn/L). The accumulation of Zn was regulated at exposure concentrations below 1 mg Zn/L above which body concentrations increased, leading to increased mortality. Arsenic was not regulated and was accumulated by the syncarids at all concentrations above the control. These are the first published toxicity data for syncarids and show them to be among the most sensitive of stygobitic crustaceans so far tested, partly due to the low hardness of the groundwater from the aquifer they inhabit and in which they were tested. The ecological significance of the toxicant accumulation and mortality may be significant given the consequent population effects and low capacity for stygobitic populations to recover.

Scratching the surface of subterranean biodiversity: Molecular analysis reveals a diverse and previously unknown fauna of Parabathynellidae (Crustacea: Bathynellacea) from the Pilbara, Western Australia

Like other crustacean families, the Parabathynellidae is a poorly studied subterranean and aquatic (stygobiontic) group in Australia, with many regions of available habitat having not yet been surveyed. Here we used a combined approach of molecular species delimitation methods, applied to mitochondrial and nuclear genetic data, to identify putative new species from material obtained from remote subterranean habitats in the Pilbara region of Western Australia. Based on collections from these new localities, we delineated a minimum of eight and up to 24 putative new species using a consensus from a range of molecular delineation methods and additional evidence. When we placed our new putative species into the broader phylogenetic framework of Australian Parabathynellidae, they grouped with two known genera and also within one new and distinct Pilbara-only clade. These new species significantly expand the known diversity of Parabathynellidae in that they represent a 22% increase to the 109 currently recognised species globally. Our investigations showed that sampling at new localities can yield extraordinary levels of new species diversity, with the majority of species showing likely restricted endemic geographical ranges. These findings represent only a small sample from a region comprising less than 2.5% of the Australian continent.

Morphological and molecular characterisation of a new genus and new species of Parabathynellidae (Crustacea : Syncarida) in Queensland, Australia

A new genus and species in the family Parabathynellidae Noodt, 1965, Lockyerenella danschmidti, gen. et sp. nov., is described from Queensland, Australia. The species displays several distinctive character states within the Parabathynellidae, and a unique combination of character states. Interestingly, L. danschmidti is the only known species of Parabathynellidae in Australia (and in the world) to possess a long and robust seta on the last segment of the antenna, which is present in both males and females. The new genus is morphologically distinct from the known genera, but is more similar to Queensland species of Notobathynella Schminke, 1973 and Arkaroolabathynella Abrams & King, 2013 from South Australia, than to species from other areas of the continent. This is the first work to couple genetics to the morphological description of a stygofauna species in Queensland. Phylogenetic relationships between L. danschmidti and related genera from elsewhere on the continent were evaluated through the analysis of combined mitochondrial and nuclear DNA sequence data. This analysis revealed at least one new genus within the Parabathynellidae, confirming our morphological hypothesis.