Gracillariidae


Gracillariidae is an important family of insects in the order Lepidoptera and the principal family of leaf miners that includes several economic, horticultural or recently invasive pest species such as the horse-chestnut leaf miner, Cameraria ohridella.

Taxonomy and systematics

There are 98 described genera of Gracillariidae. A complete checklist is available of all currently recognised species. There are many undescribed species in the tropics but there is also an online catalogue of Afrotropical described species ; the South African fauna is quite well known. Although Japanese and Russian authors have recognised additional subfamilies, there are three currently recognised subfamilies, Phyllocnistinae of which is likely to be basal. In this subfamily, the primitive genus Prophyllocnistis from Chile feeds on the plant genus Drimys, and has leaf mines structurally similar in structure to fossils . While there have been some recent DNA sequence-based studies of Palaearctic species, there is need for a satisfactory modern global phylogenetic framework for the subfamilies of Gracillariidae. Some genera are very large, e.g. Acrocercops, Caloptilia, Cameraria, Epicephala and Phyllonorycter.

Distribution

Gracillariidae occur in all terrestrial regions of the World except Antarctica.

Identification

These generally small moths are leaf miners as caterpillars, which can provide a useful means of identification, especially if the hostplant is known. The subfamilies differ by the adult moth resting posture. Most Gracillariinae rest with the front of the body steeply raised; Lithocolletinae and Phyllocnistinae rest with the body parallel to the surface; in Lithocolletinae often with the head lowered.

Life history

The first to fifth-instar larvae are flattened and possess specialised mouthparts adapted for feeding on sap. Older-instar larvae are cylindrical and have normal chewing mouthparts for feeding on plant tissue within the leaf mines, and have a fully functional silk-producing organ, the "spinneret". Some genera have an intermediate stage in this remarkable hypermetamorphosis.

Larval hostplants

Many hostplants are known, generally dicotyledonous trees or shrubs. Patterns of hostplant shifting have been inferred for many United Kingdom species in the genus Phyllonorycter and its sister genus Cameraria. A recent DNA sequencing study mainly of Palaearctic species has shown that the burst of evolutionary adaptive radiation occurred long after that of the larval hostplants, rather than demonstrating a tight coevolutionary process.

Fossils

The family is an old one, with fossil Phyllocnistinae mines known from 97-million-year-old rocks in Kansas and Nebraska. There are other fossil mines known from rocks of Eocene and Miocene age .

Subfamilies and genera

Gracillariidae phylogeny has been revised in 2017 and is now containing eight subfamilies :
Unplaced species