Biology, images, analysis, design...
|"It has long been an axiom of mine that the little things are infinitely the most important" |
Brown birch thelaxidIdentification & Distribution Biology & Ecology Other aphids on the same host
Identification & Distribution:Wingless Glyphina pseudoschrankiana viviparae are dark brown to black with variable white markings, usually two spots on each side and traces of a spinal stripe. The base of the fifth antennal segment is 1.0-1.3 times longer than than the second segment of the hind tarsus. The dorsum has numerous short wrinkles, sometimes appearing reticulated. Closed 'warts' are only ever present on the head and thorax and on lateral and ventrolateral regions of the abdomen. Hairs on the third abdominal tergite are longer than 50 μm. The body length of Glyphina pseudoschrankiana apterae is 1.5-1.8 mm.
Alate Glyphina pseudoschrankiana have the third antennal segment with 13-23 hairs (cf. Glyphina betulae in which the third antennal segment has 8-15 hairs). Immature stages of Glyphina pseudoschrankiana are reddish brown (cf. Glyphina betulae in which they are green). The colour of their immatures is much the easiest way to identify the species of Glyphina, but be aware that mixed species colonies are quite common. Glyphina pseudoshrankiana (feeding on downy birch) was only separated from Glyphina schrankiana (feeding on alder) in the 1980s by Blackman (1989) .
The brown birch thelaxid does not host alternate, but lives in colonies on the young shoots of downy birch (Betula pubescens) and related downy birches. It tends to prefer young trees and is usually attended by ants. The life cycle is shortened with sexual forms occurring in July, and eggs laid in August.
Glyphina pseudoschrankiana occurs in north-west Europe and Japan.
Biology & Ecology:
We have only found this species in two sites in southern England, Burton Pond in West Sussex and Darwell Wood in East Sussex. Most colonies have been small as was found by Wieczorek et al. (2014) in Poland, although we did find one large colony (see picture below).
Mixed species colonies of Glyphina betulae and Glyphina pseudoschrankiana have previously been found on Betula pubescens by Wieczorek et al. (2014) , and we have also observed mixed colonies on downy birch (see picture below).
More unusually, although Glyphina pseudoschrankiana is generally restricted to downy birch, we have encountered mixed colonies of Glyphina betulae and Glyphina pseudoschrankiana on what appeared to be silver birch, but was probably a hybrid between silver birch and downy birch (for more information and picture see Glyphina betulae page).
Much like Glyphina betulae, Glyphina pseudoschrankiana is always attended by ants.
For the colonies we have found, Lasius niger seems to be the main species of ant attending.
Other aphids on same host:
Blackman & Eastop list about 72 species of aphids as feeding on birches worldwide, and provides formal identification keys for aphids on Betula. Of the 15 species on Betula pubescens, Baker (2015) lists 14 as occurring in Britain: Betulaphis quadrituberculata, Calaphis betulicola, Calaphis flava, Callipterinella calliptera, Callipterinella minutissima, Callipterinella tuberculata, Clethrobius comes, Euceraphis punctipennis, Glyphina betulae, Glyphina pseudoschrankiana, Hamamelistes betulinus, Monaphis antennata, Stomaphis quercus and Symydobius oblongus.