Further studies on the occurrence of freshwater Microturbellaria in the British Isles

Five new British records of freshwater Microturbellaria are illustrated: Gieysztoria infundibuliformis, Castrada lanceola, Castrada neocomensis, Castrada viridis and Strongylostoma elongatum. These species together with a new species, Macrostomum johni described by Young (1972), are woven into the fabric of the existing key for the group (Young, 1970). All six species were recorded from the littoral zone of lakes in Caernarvonshire, N. Wales. The times of the recordings are indicated.     

The scarcer freshwater fishes of the British Isles

This, the first of two papers on the scarcer freshwater fishes of the British Isles, gives an account of the introduced species. Nineteen species are included. The natural distribution of these fishes, the history of their introduction, their success in acclimatization, and their present distribution in the British Isles are given. A brief discussion on the introduction of exotic fishes to aquatic ecosystems follows.     

Cytological studies on some mosses from the British Isles

The results of cytological investigations on 95 populations from 60 species of mosses are given. These results include studies of gametophyte mitoses from 26 of the species concerned. The technique for obtaining gametophyte mitotic preparations is described. Karyotype comparisons are made within the genera Polytrichum and Dicranum and the value of such comparisons is stressed. Where possible gametophytic mitotic observations have been correlated with sporo-phytic meioses from the same gatherings.     

Cladonia azorica in the British Isles

Abstract:Cladonia azorica is widespread in western Great Britain, mainly as the grey colour-form lacking usnic acid. Cladonia azorica is distinguished from the related species C. portentosa and C. mediterranea by the presence of fumarprotocetraric acid, and from C. ciliata by a number of characters including the presence of perlatolic acid. The structure of the pycnidial wall may have some taxonomic significance in Cladonia subgenus Cladina.     

Biatora britannica sp. nov. and the occurrence of Biatora efflorescens in the British Isles

Abstract:Biatora britannica sp. nov. is described from Wales. The species is the sorediate sister taxon of the Madeiran Biatora hertelii. The close relationship is supported by the presence of the hymenial pigment Hertelii-green, which is hitherto known only from these two species. Molecular data from the nuclear ITS-region of 14 Biatora -species renders further support for the close relationship of both species. Sterile, sorediate material from the British Isles earlier referred to B. efflorescens may in fact belong to B. britannica.     

Shingle habitats in the British Isles

RANDALL, R. E., 1989. Shingle habitats in the British Isles . Shingle is the term applied to sediments larger in diameter than sand but smaller than boulders. Around Great Britain there are almost 900 km of pure shingle and vast stretches of rock/shingle, sand/shingle and mud/shingle mixtures. Outside Japan, New Zealand and north-west Europe, shingle is an uncommon coastal sediment. Shingle may form fringing beaches, spits, bars, cuspate forelands and offshore barrier islands, depending upon available supply of sedimentary material and coastal topography.
Species composition on shingle features is partly determined by climate which affects the geographic range of certain species. The other major factors are beach stability and beach composition. Climate results in distinctive patterns in the flora but within the each climate zone beach movement will affect the quantity of annuals, short-lived or long-lived perennials present. The presence or absence and nature of the fine material within the shingle will cause different combinations of species ecologically related to those of sand dunes, salt-marsh or cliff. Coastal shingle vegetation has a distinctive flora which contains several rare or declining species as well as some common coastal and ruderal plants.
At the largest shingle sites a successional sequence can be recorded which initiates with halophytic forbs near the foreshore and moves through neutral to acid grassland species with shrubs and prostrate scrub in the more inland areas.     

The Criconematidae of the British Isles

A total of 2622 soil samples collected throughout the British Isles was examined for nematodes belonging to the family Criconematidae. Twenty-eight species were found representing nine genera, twenty-two of these species being reported for the first time. Only one species previously reported was not found. An analysis of the relationship between eleven of the most common species and biotic and abiotic factors showed vegetation to be of paramount importance.     

Observations on Thorea ramosissimaBory (Batrachospermales,Thoreaceae), a freshwater red alga rarely recorded in the British Isles

The conspicuous macroscopic stage of the freshwater red alga Thorea ramosissima has been re-discovered in the River Thames after a lapse of almost 140 years. In the 1840s it was reported only from Walton-on-Thames, but is now known from 13 localities along a 133 km stretch between Oxford and Teddington. It is transient, often remaining undetected at known localities in subsequent years. All British records are assessed, especially 19th century collections from the Thames. The ecology and the morphology of the macroscopic stage are discussed.