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 OLDEST HORSESHOE CRAB: A NEW XIPHOSURID FROM LATE ORDOVICIAN KONSERVAT-LAGERSTÄTTEN DEPOSITS, MANITOBA, CANADA

Abstract:  A remarkable new fossil horseshoe crab, Lunataspis aurora gen. et sp. nov., from recently discovered Upper Ordovician ( c . 445 Ma) shallow marine Konservat-Lagerstätten deposits in Manitoba (Canada), is characterized by fusion of opisthosomal tergites into two sclerites. A broad mesosoma of six or seven fused segments, followed by a narrow metasoma of three reduced segments, represents an advanced transitional condition in the development of the xiphosurid thoracetron. Lunataspis further possesses a large crescentic prosomal shield bearing lateral compound eyes on weak ophthalmic ridges that flank a low cardiac lobe, and a keeled lanceolate telson. Lunataspis is much older than the proposed 'synziphosurine' stem lineage of Carboniferous and post-Palaeozoic Xiphosurida, yet is strikingly similar to crown group limuline horseshoe crabs, indicating that major features of the distinctive and highly conserved xiphosurid Bauplan evolved considerably earlier in the Palaeozoic than was previously suspected. In addition to establishing a new temporal benchmark for assessing hypotheses of early chelicerate relationships, the discovery of horseshoe crabs in a Late Ordovician marginal marine setting marks the earliest definitive record of this persistent ecological association.     

Political and social drivers for access to the countryside: the need for research on birds and recreational disturbance

The introduction of a statutory right of access to open country and registered common land in England and Wales in 2005 was a major milestone in a campaign traceable to the 19th century, with views strongly polarized between social classes and political parties, and between land owners and campaigners. More recently, access has also been recognized as a factor contributing to quality-of-life, public health, social diversity and rural economic issues. The mapping of access land revealed that 55% of it is also designated Site of Special Scientific Interest, where wildlife is legally conserved. This has generated a need to assess the implications of access in each case, and take measures to ensure nationally and internationally important features are protected, drawing on sound scientific principles. Early research, although competently undertaken, often failed to address population-scale effects significant at the designated-site level, enabling disputes and polarized 'beliefs' to be articulated. Hence, in addition to drawing up formal and transparent procedures for evaluating impacts and resolving difficulties, funds were released and a major programme initiated, commissioning applied research of direct relevance to the implementation of the legislation. This has pushed forward the boundaries of knowledge in a field which is both difficult and expensive to study. By gradually replacing 'belief' with evidence, this represents a case study in resolving environmental disputes.     

The biology and host searching behaviour of a Cynipoid parasite of aphidophagous syrphid larvae

Abstract. 1. Callaspidia defonscolombei was found to be a common, solitary, thelytokous parasitoid of aphidophagous syrphid larvae. In 1977 it was bivoltine with adults being most numerous in early August and late September. It is probably polyphagous.
2. An analysis of host searching behaviour suggests that females respond to an aphid odour bringing them to the region of an aphid colony.
3. Syrphid hosts are located within the aphid colony by response to a contact chemical. There is a host size preference, only larger second and third instar larvae being attacked.
4. Females inject a venom, which temporarily paralyses host larvae, and place the egg inside a cerebral ganglion.     

When rare species become endangered: cryptic speciation in myrmecophilous hoverflies

The myrmecophilous hoverfly, Microdon mutabilis, is listed as a ‘Rare’ or ‘Nationally Notable Species’ in UK Red Data Books. As an obligate social parasite, feeding only from ant colonies, its life‐style satisfies theoretical conditions under which cryptic speciation is predicted to evolve; namely, strong selection for nonmorphological adaptations that enhance its exploitation of a local subspecies or populations of its host. Samples of larvae and pupae in Ireland, Scotland and England showed that M. mutabilis exploits a single and different host ant species on different sites across its range. In nine southern English colonies, 95.6% of infested nests were of Myrmica scabrinodis whereas in six Irish and two Scottish colonies 100% and 94.2%, respectively, of the infested nests were of Formica lemani, despite M. scabrinodis being common at all sites. Although the adults from ‘scabrinodis’ (and lemani) populations are cryptic, morphometric measurements of pupae showed consistent diagnostic characters that were sufficiently distinct for these ecotypes to be classed as separate species. We conclude that M. mutabilis is the ‘lemani‐type’ and designate the ‘scabrinodis‐type’ as a new species, Microdon myrmicae spec. nov. Thus, one of the listed threatened species of the British Isles becomes two species, each possessing about half the number of populations and occupying half the range of the original ‘species’. Each also inhabits a different serai stage within grassland or heathland, and will require a different management regime if its declining populations are to be conserved. ‘M. mutabilis’ is reported with other host ant species on the European continent. In the light of our results, these may prove to be additional cryptic species. We suggest that cryptic speciation is apt to evolve in species, such as myrmecophiles, endoparasites and koinobiont parasitoids, whose life‐styles result in strong selection on their physiological or behavioural characters. The implications for Red Data Book classifications and for practical conservation are discussed. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 75 , 291–300.