Do landscape health indices reflect arthropod biodiversity status in the eucalypt woodlands of eastern Australia?

Ecosystem or landscape health indices are important tools for land managers. While strong predictable relationships between these indices and biotic diversity are often generalized, they are seldom validated. Here we use data from a semi‐arid eastern Australian woodland to examine the relationships between arthropod community structure and two sets of landscape health indicators: landscape function analysis (LFA), and a terrestrial index of ecological integrity based on common vegetation metrics (structure, composition and function; SCF). Hierarchical partitioning revealed that the ability of LFA or SCF to account for variation in arthropod richness was low, with the variable of importance taxon‐dependent. Similarly, multivariate analyses indicated relatively weak and inconsistent relationships between LFA and SCF indices and arthropod assemblage structure. Results obtained for additional habitat attributes commonly used in terrestrial vegetation monitoring were similar. Our study indicates that strong predictable relationships are rarely apparent, particularly for arthropods. This indicates that these indices have limited use as surrogates of arthropod biodiversity. These results are contrary to the past literature, highlighting the need for additional research and the development of a conceptual and empirical framework linking health indices and arthropod biodiversity. This is necessary to further the theoretical and practical application of these measurements in environmental management.     

ORDOVICIAN FISH FROM THE ARABIAN PENINSULA

Abstract:  Over the past three decades Ordovician pteraspidomorphs (armoured jawless fish) have been recorded from the fringes of the Gondwana palaeocontinent, in particular Australia and South America. These occurrences are dominated by arandaspid agnathans, the oldest known group of vertebrates with extensive biomineralisation of the dermoskeleton. Here we describe specimens of arandaspid agnathans, referable to the genus Sacabambaspis Gagnier, Blieck and Rodrigo, from the Ordovician of Oman, which represent the earliest record of pteraspidomorphs from the Arabian margin of Gondwana. These are among the oldest arandaspids known, and greatly extend the palaeogeographical distribution of the clade around the periGondwanan margin. Their occurrence within a very narrow, nearshore ecological niche suggests that similar Middle Ordovician palaeoenvironmental settings should be targeted for further sampling.     

The Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962: cranial anatomy,functional morphology,taxonomy, and relationships

The cranial anatomy of the Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962 is described in detail for the first time on the basis of two principal specimens: the holotype (SAM‐PK‐K337) and referred skull (SAM‐PK‐K1332). In addition several other specimens that have a bearing on the interpretation of the anatomy and biology of Heterodontosaurus are described. The skull and lower jaw of Heterodontosaurus are compact and robust but perhaps most notable for the heterodont dentition that merited the generic name. Details of the cranial anatomy are revealed and show that the skull is unexpectedly specialized in such an early representative of the Ornithischia, including: the closely packed, hypsodont crowns and ‘warping’ of the occlusal surfaces (created by progressive variation in the angulation of wear on successive crowns) seen in the cheek dentition; the unusual sutural relationships between the bones along the dorsal edge of the lower jaw; the very narrow, deeply vaulted palate and associated structures on the side wall of the braincase; and the indications of cranial pneumatism (more commonly seen in basal archosaurs and saurischian dinosaurs). Evidence for tooth replacement (which has long been recognized, despite frequent statements to the contrary) is suggestive of an episodic, rather than continuous, style of tooth replacement that is, yet again, unusual in diapsids generally and particularly so amongst ornithischian dinosaurs. Cranial musculature has been reconstructed and seems to conform to that typically seen in diapsids, with the exception of the encroachment of M. adductor mandibulae externus superficialis across the lateral surface of the temporal region and external surface of the lower jaw. Indications, taken from the unusual shape of the occlusal surfaces of the cheek dentition and jaw musculature, are suggestive of a novel form of jaw action in this dinosaur. The taxonomy of currently known late Karoo‐aged heterodontosaurids from southern Africa is reviewed. Although complicated by the inadequate nature of much of the known material, it is concluded that two taxa may be readily recognized: H. tucki and Abrictosaurus consors. At least one additional taxon is recognized within the taxa presently named Lanasaurus and Lycorhinus; however, both remain taxonomically problematic and their status needs to be further tested and may only be resolved by future discoveries. The only other named taxon, Geranosaurus atavus, represents an invalid name. The recognition of at least four distinct taxa indicates that the heterodontosaurids were speciose within the late Karoo ecosystem. The systematics of Heterodontosaurus and its congeners has been analysed, using a restricted sample of taxa. A basal (nongenasaurian) position within Ornithischia is re‐affirmed. There are at least four competing hypotheses concerning the phylogenetic placement of the Heterodontosauridae, so the evidence in support of the various hypotheses is reviewed in some detail. At present the best‐supported hypothesis is the one which places Heterodontosauridae in a basal (non‐genasaurian) position; however, the evidence is not fully conclusive and further information is still needed in respect of the anatomy of proximate outgroups, as well as more complete anatomical details for other heterodontosaurids. Heterodontosaurids were not such rare components of the late Karoo ecosystem as previously thought; evidence also suggests that from a phylogenetic perspective they occupied a potentially crucial position during the earliest phases of ornithischian dinosaur evolution. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011.     

Identification of electrophysiologically-active compounds for New World screwworm, Cochliomyia hominivorax, in larval wound fluid

Abstract Acidic and non-acidic fractions from extracts of fluid from sheep wounds infested with larvae of Cochliomyia hominivorax (Coquerel) were analysed by linked gas chromatography and electroantennography in order to detect electrophysiologically-active compounds that could be potential attractants. Responses to twenty-six electrophysiologically-active compounds were observed and, on the basis of electron impact and chemical ionization mass spectrometry and co-chromatography with authentic compounds, twenty-five of these compounds were characterized. The most abundant compounds identified in the larval wound fluid were straight and methyl-branched aliphatic carboxylic acids, ranging from C₂- to C₅-carbon chain length. Butanoic acid, for example, was found to be present at approximately 0.45mg/ml. Aliphatic carboxylic acids with longer chain lengths were also observed but in trace amounts. Three aromatic carboxylic acids, benzoic, phenylethanoic and 3-phenylpropanoic acids were also present but only phenylethanoic and 3-phenylpropanoic acids elicited electroantennographic responses. Phenol and indole were by far the most abundant components of the non-acid fraction of the larval wound fluid with all other components, except δ-valerolactam, present at levels of less than 5% that of phenol which was present at a concentration of 0.05 mg/ml.
Electroantennographic studies of straight-chain aliphatic carboxylic acids showed that pentanoic acid elicited the strongest response from C. hominivorax. Similar studies showed that 1-octen-3-ol elicited stronger responses than 3-methylphenol, indole, phenol or dimethyldisulphide. 3-Methylindole, which was not found in the wound fluid, also elicited a strong response.
The potential behavioural significance of these compounds is discussed in relation to that of known attractants of C. hominivorax and other dipteran pests of mammals.     

Phylogenetic relationships within the Eurasian cattish family Siluridae (Pisces: Siluriformes), with comments on generic validities and biogeography

A numerical cladistic analysis, based on 23 terminal groups and 63 morphological characters, was done to infer phylogenetic relationships within the Eurasian catfish family Siluridae. Nine hundred and forty-five equally most parsimonious trees (134 steps, consistency index 0.634) were found that differ in their resolutions of four polychotomies. Strict consensus of these trees includes ten internal nodes, does not support monophyly of Silurus, Ompok and Kryptopterus , as usually defined, and offers ambiguous support for monophyly of Wallago. Silurus and Kryptopterus are each composed of two non-sister group clades, and Ompok is composed of at least two such clades. Heuristic searches constrained by monophyly of Silurus, Ompok or Kryptopterus yielded trees five or six steps longer than the shortest trees free of constraints. The strict consensus also infers a basal dichotomy that separates the Siluridae into a temperate Eurasian clade with about 20 nominal species and a subtropical/tropical south and southeast Asian clade with about 75 nominal species. The distributions of these clades overlap in a relatively narrow region of east Asia. A heuristic search for trees 1 step longer than the shortest trees yielded 253890 trees. A strict consensus of these trees also infers a basal dichotomy between the above-mentioned clades. This analysis revealed four additional putative synapomorphies of the Siluridae, pending further resolution of the family's outgroup relationships.