Alastair M. M. Richardson

Multiple drivers of decline in the global status of freshwater crayfish (Decapoda: Astacidea)

Rates of biodiversity loss are higher in freshwater ecosystems than in most terrestrial or marine ecosystems, making freshwater conservation a priority. However, prioritization methods are impeded by insufficient knowledge on the distribution and conservation status of freshwater taxa, particularly invertebrates. We evaluated the extinction risk of the worlds 590 freshwater crayfish species using the IUCN Categories and Criteria and found 32% of all species are threatened with extinction. The level of extinction risk differed between families, with proportionally more threatened species in the Parastacidae and Astacidae than in the Cambaridae. Four described species were Extinct and 21% were assessed as Data Deficient. There was geographical variation in the dominant threats affecting the main centres of crayfish diversity. The majority of threatened US and Mexican species face threats associated with urban development, pollution, damming and water management. Conversely, the majority of Australian threatened species are affected by climate change, harvesting, agriculture and invasive species. Only a small proportion of crayfish are found within the boundaries of protected areas, suggesting that alternative means of long-term protection will be required. Our study highlights many of the significant challenges yet to come for freshwater biodiversity unless conservation planning shifts from a reactive to proactive approach.

Evolution underground: A molecular phylogenetic investigation of Australian burrowing freshwater crayfish (Decapoda: Parastacidae) with particular focus on Engaeus Erichson

Phylogenetic relationships and species boundaries of Australian burrowing freshwater crayfish belonging to the genera Engaeus, Engaewa, Geocharax, Gramastacus and Tenuibranchiurus are investigated using combined mitochondrial and nuclear DNA sequence data and Bayesian and Maximum Parsimony methods. Phylogenies are statistically compared to previously published hypotheses. Engaeus, Engaewa, Geocharax, Gramastacus and Tenuibranchiurus form a strongly supported monophyletic clade. This grouping is independently supported by morphology but unites geographically highly disjunct lineages. Our data show two cryptic species in Geocharax, one cryptic species in Gramastacus and two cryptic species within the highly divergent Engaeus lyelli lineage. Using a Bayesian relaxed molecular clock method, the 16S rDNA data show generic-level diversification coinciding with the transition from a wet to arid palaeoclimate near the mid Miocene.

Cryptic diversity in Engaeus Erichson, Geocharax Clark and Gramastacus Riek (Decapoda:Parastacidae) revealed by mitochondrial 16S rDNA sequences

Nucleotide sequence data from the mitochondrial 16S rDNA region were utilised to investigate phylogenetic relationships and species boundaries among Australian freshwater crayfish belonging to the genera Engaeus Erichson, 1846, Geocharax Clark, 1936 and Gramastacus Riek, 1972. Geocharax and Gramastacus were found to be monophyletic genera but one species currently assigned to Engaeus may belong to another genus. Relationships between the three existing genera were not resolved. Analysis of species boundaries within Geocharax suggests that there are an additional two species in this genus, and our analysis of Gramastacus indicates that undescribed populations from central New South Wales may comprise a second species. The data provide at least one instance of a taxon crossing the Great Dividing Range and provide confirmation of previously proposed hypotheses seeking to explain trans-Bass Strait distributions of species.

Local distributions of sandhoppers and landhoppers (Crustacea: Amphipoda: Talitridae) in the coastal zone of western Tasmania

Twelve species of talitrid amphipods were recorded from pitfall transects across the supralittoral and maritime zones at three localities on the west coast of Tasmania; three were sandhoppers, the rest were landhoppers. There was a sharp demarcation between the highest range of the sandhoppers and the lowest range of the landhoppers. Organic content and sodium content of the substrate in the range of the sandhoppers were very low, but rose sharply as the sand was colonised by plants, and landhoppers replaced sandhoppers. Coastal group landhopper species were restricted to a zone about 40–70 m above the high tide mark. Cooler, wetter weather increased the activity of sandhoppers, but only affected landhopper activity slightly. These differences support the idea that landhoppers did not evolve directly from sandhopper ancestors.

Sea-level changes and palaeo-ranges: reconstruction of ancient shorelines and river drainages and the phylogeography of the Australian land crayfish Engaeus sericatus Clark (Decapoda: Parastacidae)

Historical sea levels have been influential in shaping the phylogeography of freshwater‐limited taxa via palaeodrainage and palaeoshoreline connections. In this study, we demonstrate an approach to phylogeographic analysis incorporating historical sea‐level information in a nested clade phylogeographic analysis (NCPA) framework, using burrowing freshwater crayfish as the model organism. Our study area focuses on the Bass Strait region of southeastern Australia, which is marine region encompassing a shallow seabed that has emerged as a land bridge during glacial cycles connecting mainland Australia and Tasmania. Bathymetric data were analysed using Geographical Information Systems (GIS) to delineate a palaeodrainage model when the palaeocoastline was 150 m below present‐day sea level. Such sea levels occurred at least twice in the past 500 000 years, perhaps more often or of larger magnitude within the last 10 million years, linking Victoria and Tasmania. Inter‐locality distance measures confined to the palaeodrainage network were incorporated into an NCPA of crayfish (Engaeus sericatus Clark 1936) mitochondrial 16S rDNA haplotypes. The results were then compared to NCPAs using present‐day river drainages and traditional great‐circle distance measures. NCPA inferences were cross‐examined using frequentist and Bayesian procedures in the context of geomorphological and historical sea‐level data. We found distribution of present‐day genetic variation in E. sericatus to be partly explained not only by connectivity through palaeodrainages but also via present‐day drainages or overland (great circle) routes. We recommend that future studies consider all three of these distance measures, especially for studies of coastally distributed species.

A revision of the Tasmanian endemic freshwater crayfish genus Parastacoides (Crustacea : Decapoda : Parastacidae)

The freshwater crayfish genus Parastacoides Clark, 1936 was last reviewed by Sumner (1978). In that review Sumner synonymised several species, reducing the genus to one species, consisting of three subspecies. However, subsequent collections of specimens from previously unsurveyed areas, as well as field studies on habitat partitioning by the subspecies, cast doubt on the taxonomic status that Sumner proposed. Molecular studies suggesting the presence of several genetically distinct populations provided the stimulus for this review. A complete revision of the genus has led to the recognition of two new genera and 14 new species. Keys, descriptions, diagnoses, synonymies and distribution maps of the genera and species are provided. During the course of this study it was discovered that the type specimen attributed to the genus Parastacoides is a specimen of the genus Geocharax Clark, 1936. The name Parastacoides is a junior synonym of Geocharax, and new names for the genera previously described as Parastacoides have been raised.

Notes on the occurrence of Talitrus dorrieni Hunt (Crustacea Amphipoda: Talitridae) in south-west England

Summary The introduced amphipod crustacean Talitrus dorrieni is abundant in terrestrial localities on the Isles of Scilly, and has been found in three previously unrecorded localities in Cornwall. Although widespread on the islands, it is restricted to gardens and cultivated ground on the mainland. The origin of the colonies and the factors limiting their spread are discussed.

ASPECTS OF THE HINDLIMB MORPHOLOGY OF SOME AUSTRALIAN BIRDS OF PREY: A COMPARATIVE AND QUANTITATIVE STUDY

Abstract We quantified the extent of adaptive radiation in the evolution of the hindlimb in the bird-of-prey community on Tasmania. Assessments of the ecological capabilities of raptor species are often based on a visual inspection of their hindlimb structure, with little recourse to direct biomechanical or functional evidence. We examined the links between hindlimb structure and patterns of diet, foraging, and habitat use in raptors by analytically investigating tarsus, toe, and talon measurements. We identified groupings on the basis of dietary preference, hunting-killing technique, and phylogeny. We found that the bird-catching specialists, which possessed relatively long digits with short talons, were consistently separable. The large-mammal and fish specialists were equipped with relatively short and robust tarsi, and short digits with long and robust talons. The hindlimbs of medium-mammal specialists were characterized by long digits and a large digit 1 talon. However, the generalist group did not possess any specializations, because their structural elements were comparable to those of other dietary groups. An association was found between the ratio of toe to talon length and the selective pressures of prey capture and ease of killing. Morphological variation in this feature was consistent with phylogeny, because the Accipitridae were characterized by a larger ratio of toe to talon length on digits 1 and 2 than the Falconidae, and the diurnal raptors possessed an interdigital pattern of larger variation in ratio of toe to talon length than the nocturnal raptors. No link was found between dietary habit and tarsus length or robustness, because these features were apparently attributed to variations in hunting style. Our analysis highlights the interrelationship between the morphology of hindlimb structure and the functional pressures associated with predatory lifestyles. Aspects de la morphologie des membres postérieurs de quelques oiseaux de proie australiens : Une étude comparative et quantitative

Water uptake and loss via the urosome in terrestrial talitrid amphipods (Crustacea : Amphipoda)

The amount of exosomatic water in the ventral channel can be controlled by uptake and loss via the urosome in simplidactylate and cuspidactylate landhoppers, palustral talitrids and beachfleas, but not apparently by sandhoppers. Both water uptake and loss involve deliberate dabbing of the uropod tips (uropods 1 and 2 in simplidactylate landhoppers and palustral talitrids, uropod 3 in cuspidactylate landhoppers and beachfleas) on to a wet or dry substratum. Water flows rapidly into, or out of, the central channel via capillary spaces between the body parts. Transfer of water forward from the abdomen to thorax is apparently facilitated by the beating of the pleopods, or, in those species with highly reduced pleopods, by the elongate distal lobe of the peraeopod 6 gill, which lies between the bases of peraeopod 7 and the first abdominal epimeron. Water also pools beneath the telson and is taken into the gut by anal drinking in all the species observed. These observations suggest that landhoppers, beachfleas ...

Geographic ranges, sympatry and the influence of environmental factors on the distribution of species of an endemic Tasmanian freshwater crayfish

The Tasmanian endemic freshwater crayfish genus Parastacoides is presently under review and 14 species have been recognised. The distributions of the putative species have been mapped using museum data. The distribution of geographical ranges of the species is highly skewed. Most species are local or short-range endemics, with 11 of the 14 species (nearly 79%) having geographical ranges of less than 20 km2. Many sympatric contact zones exist where distributions of species meet and in some cases the sympatric species partition the habitat. The majority of species appear to be capable of exploiting a wide variety of habitat types. Ecological factors such as climate, vegetation, substrate, baseline geology and burrow type do not seem to be major determinants of species distributions, but adequate rainfall and a low evaporation rate appear to be the major factors determining the eastern boundary of Parastacoides. It is likely that historical factors have played an important role in determining the present distribution patterns.