''Eriophyes inangulis'' is a

mite Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear evid ...

that forms the alder vein angle gall. It develops in a chemically induced

gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...

; a sub-spherical distortion rising up from the upper surface of the leaves of alder trees ''

Alnus glutinosa ''Alnus glutinosa'', the common alder, black alder, European alder, European black alder, or just alder, is a species of tree in the family Betulaceae, native to most of Europe, southwest Asia and northern Africa. It thrives in wet locations whe ...

'' along the midrib. Synonyms are ''Eriophyes laevis inangulis'', ''Phytoptus laevis'', and ''Cephaloneon pustulatum''.

The physical appearance

The gall's appearance on the upper surface is sub-spherical, smooth and may vary in colour from pale yellow-green to deep red. The adult mite lives on alder tree sap, sucked from the cell tissues. The galls cluster along the midrib in the angle of the veins. The wide opening and interior on the lower epidermis and is lined with large numbers of small hairs. Galls may be so numerous that the leaf expansion is inhibited. Eriophyes inangulis N - lower epidermis

Infestations of alder vein angle galls

The galls induced appear not to affect the health of trees infected with these mite species and no practical way of controlling or preventing them exists.

References

External links

Alder vein angle gall
{{Taxonbar, from=Q5389472 Eriophyidae Animals described in 1919 Arachnids of Europe Galls Taxa named by Alfred Nalepa